Victim-to-Victim Intergenerational Cycles of Child Maltreatment: A Systematic Scoping Review of Theoretical Frameworks

Objectives: Child maltreatment is a serious problem worldwide associated with numerous developmental and psychological problems that can impede children’s short and long-term functioning. The negative effects of maltreatment may put children on a trajectory where they are likely to experience later abuse and even abuse their own children. While studies have focused primarily on the intergenerational transmission of maltreatment (victim-to-perpetrator cycles), there are studies, albeit fewer, documenting cycles of intergenerational continuity of maltreatment (victim-to-victim cycles; e.g., child sexual abuse). Clear theoretical frameworks are lacking from studies on intergenerational maltreatment. This review aimed to systematically identify theories, theoretical or conceptual frameworks that have been used to explain the victim-to-victim cycles of maltreatment. Methods: Searches were executed in PsychINFO, Medline, and Scopus. Fifteen papers were included in this review. Results: The most common theories used to explain the intergenerational continuity of maltreatment victimization were attachment theory and traumatic stress models. Other identified theories include those from social, developmental, and biological domains. Notably, there were only five papers on the intergenerational continuity of child sexual abuse, highlighting a lack of focus on the theoretical explanations of this issue. Based on the findings, a unified model of victim-to-victim cycles of maltreatment is proposed to guide future studies. Implications: Future research in this area could include testing and comparing theoretical explanations and advancing the current state of the literature by using qualitative and mixed methods.


Introduction
Intergenerational continuity of maltreatment describes situations wherein a person experiences some form of childhood abuse or neglect and later has a child who also experiences abuse or neglect, regardless of the perpetrator's identity (e.g., Berlin et al. 2011). The prevalence of cycles of maltreatment over generations ranges from 7 to 88% (Langevin et al., 2019); the wide range reflects differences between maltreatment subtypes and methodological factors. The effects of child maltreatment have frequently been explained using a conceptualization of complex trauma. Complex trauma involves exposure to stressors that are repetitive and prolonged; the harm is typically caused by caregivers, occurs at developmentally vulnerable times, and sets off a cascade of negative consequences, including dissociation, emotion dysregulation, and somatic stress (Courtois & Ford, 2009). These negative sequelae may derail a child's developmental trajectory and impact their adult life in ways that contribute to maltreatment victimization continuity. However, just as children who have experienced abuse can demonstrate resilience in various areas of functioning (e.g., Yoon et al., 2020), it is important to identify factors contributing to resilience with regard to ending cycles of maltreatment victimization.
There is well-developed theoretical knowledge on cycles of violence focused on physical abuse. As noted by Kim et al. (2007), investigation of the intergenerational transmission of physical abuse is largely focused on how a victim becomes a perpetrator (i.e., victim-to-perpetrator cycles). In contrast, the intergenerational continuity of other types of abuse (e.g., sexual abuse or exposure to intimate partner violence) can represent victim-to-victim cycles wherein the maltreated parent is not the perpetrator. To illustrate this view, child sexual abuse (CSA) victimization is a prevalent problem that can lead to victim-to-victim cycles, such as when a non-offending parent experienced CSA and later their child experiences this same kind of abuse perpetrated against them (Cyr et al., 2013). On the other hand, a victim-toperpetrator cycle of abuse would be when an individual experiences abuse and then abuses their child, whether it be physically, emotionally, or sexually. The importance of ending victim-to-victim cycles of abuse is evidenced by the negative impacts of child maltreatment victimization on individuals' lives. For example, CSA is associated with devasting consequences for children's development, as documented by an increased risk of psychopathology and physical health problems (e.g., Fergusson et al., 2013;Hailes et al., 2019;Hébert et al., 2017). The negative ramifications of CSA can persist into adulthood in the form of experiencing intimate partner violence (IPV) and adult sexual assault revictimization (Papalia et al., 2020), as well as mental health problems, such as anxiety (Gardner et al., 2019) and posttraumatic stress (Adams et al., 2018).
Prevalence rates of victim-to-victim cycles of maltreatment are not well documented. As an example, of the few studies providing prevalence rates, estimates of CSA continuity vary from 26.6 to 51.0% (Grunsfeld, 2018;Leifer et al., 2004;McCloskey & Bailey, 2000;Testa et al., 2011). Regarding the intergenerational continuity of child maltreatment in general, a recent systematic review showed that rates could range from 7 to 88% depending on sample characteristics, maltreatment types examined, definitions of maltreatment, age range of participants, and measures (Langevin et al., 2019). Concerning victim-to-perpetrator cycles, researchers have estimated that around 30% of maltreated parents are likely to abuse their children (Kaufman & Zigler, 1987), while other studies have documented prevalence rates ranging from 1% to 38% (Ertem et al., 2000). To distinguish victim-to-victim cycles from victim-toperpetrator cycles, researchers must collect information about perpetrator identity and clarify the types of intergenerational cycles they are investigating.
Although exact prevalence estimates of victim-to-victim cycles are not known, understanding the mechanisms involved in these cycles is crucial. Several mechanisms have been proposed to explain how any type of abuse may continue within families, including compromised parent-child attachment and parenting behaviours (see Langevin et al., 2019 for review), impairments in mental and physical health (Maniglio, 2009), and adverse educational and occupational outcomes that may confer risk to the next generation (Currie & Widom, 2010). Since the literature pertaining to victim-to-victim cycles of maltreatment is limited and scattered, a systematic review of the theories related to this topic will guide future research methodology and, ultimately, encourage more comprehensive investigations that strive to explain this problem. An enhanced theoretical base could also contribute to improved intervention and prevention efforts by highlighting specific factors that practitioners could target to enhance families' resilience to end cycles of child maltreatment.
The present systematic review will summarize the theoretical literature on the intergenerational continuity of child maltreatment, focusing on victim-to-victim cycles, and integrate the findings into a unified and parsimonioushence clinically relevant -model. Selecting a few key targets that have been incorporated in theoretical models, as well as empirically supported, would contribute to clinicians' work with individuals and families to reduce the risk of maltreatment continuity, as well as to work with families to enhance coping skills and resilience when victim-to-victim cycles have been reported. A simplified model would also be practical for clinicians to integrate in their practice, compared to more complex and comprehensive models that may be harder to implement.

Method
A systematic scoping review was determined to be appropriate to address the objective of identifying and summarizing theories, as this research objective is broad and qualitative. Scoping reviews are useful when the aim is to provide an overview of research without answering a specific research question (Arksey & O'Malley, 2005).

Article Search and Selection
The initial search was built in PsycINFO (Ovid, 1806 to Present) in collaboration with a subject expert librarian and was subsequently adapted to Medline (Ovid MEDLINE(R) ALL, 1946-) and Scopus. Retrieved articles were organized into Endnote and Rayyan (Ouzzani et al., 2016); the latter was used to apply inclusion and exclusion criteria. The search combined terms related to abuse, intergenerational relations, and theory (Table 1). Family and marital conflict were included as search terms to obtain papers that might have included an examination of exposure to intimate partner violence. Hand searching was also conducted to identify articles outside the main database search.

Inclusion and Exclusion Criteria
Articles were included if authors presented a clear summary of a theory, theoretical framework, or conceptual framework used to explain victim-to-victim cycles of maltreatment within the introduction, results, or discussion sections. The maltreatment types examined include neglect, physical, emotional, and sexual abuse, as well as exposure to domestic violence. As described by Creswell and Creswell (2017), "a theory in quantitative research is an interrelated set of constructs (or variables) formed into propositions, or hypotheses, that specify the relationship among variables (typically in terms of magnitude or direction)" (p. 52). The definition of a theoretical framework guiding this review is that a framework is the application of a theory or set of concepts drawn from a theory to explain a phenomenon (Imenda, 2014). No restrictions were placed in terms of publication date. However, articles needed to be useful and relevant to the current state of evidence to contribute to future research and were therefore excluded if too outdated. One article (Ney, 1988) was excluded because all three authors concluded that the model was not in line with the current conceptualization of victim-to-victim cycles and reflected antiquated ideologies that could be interpreted as victim-blaming, thereby limiting its use to orient future research and intervention on intergenerational cycles of maltreatment. Only published research articles and book chapters (English and French) were included to maximize the quality of included theories. Quantitative, qualitative, and review papers were included. To address the gap in the literature that is more specific to victim-to-victim cycles of child maltreatment and to account for the potentially different mechanisms involved, articles were excluded if the theories presented focused solely on explaining victim-toperpetrator cycles. Victim-to-perpetrator cycles have largely been explained so far using social learning theories (e.g., Tomsich, 2015). After the first author conducted title and abstract screening, both the first and third authors reviewed the 45 full-text articles for possible inclusion. Discrepancies were discussed among all authors to agree upon the final sample.

Data Extraction and Analysis
Data were systematically extracted from full-text articles. Tables 2 and 3 were used as organizing grids to present information from each article: the type of paper (e.g., review, empirical), the name of theory or framework, the applicability of the theory in explaining the continuity of maltreatment (i.e., how did the authors use the theory to explain this problem), and the type of maltreatment that was examined.  Alexander (2015) Book chapter -narrative review Attachment and family systems theories CSA Baril & Tourigny (2015) Review and presentation of explanatory model Trauma theory CSA Maker & Buttenheim (2000) Narrative review and presentation of a clinical case Trauma theory CSA Greenspun (1994) Description of integrated theoretical model and case studies Transmission is explained using projective identification Psychoanalytic and family system theories Fatherdaughter incest Bennett (1992) Narrative review and presentation of clinical case study  Morton & Browne (1998) Narrative review Attachment theory CMG Sperlich et al. (2017) Review and presentation of conceptual framework Attachment and trauma theory CMG Courtois & Ford (2009) Guide for treating complex stress disorders Trauma theory CMG Tuohy (1987) Review of the role of defense mechanisms of parents who experienced abuse   Alexander (2015) Risk for revictimization and cycles of CSA is best captured using an attachment and family dynamics framework. Pathways to cycles of violence are associated with a break down in family structure and attachment relationships. Trajectories of risk include early onset of puberty, risky behaviour, partner relationships, parenting, and sexual revictimization.
-CSA is associated with the timing of puberty. Family-related factors also affect the timing of puberty: parental conflict, poor mother-daughter relationship, lower socioeconomic status (e.g., Alvergne et al., 2008;Downing & Bellis, 2009).
-CSA survivors are more likely to be aggressive and display less warmth toward their children (e.g., Banyard, 1997;Barrett, 2010). Baril & Tourigny (2015) Explanatory model of intergenerational CSA suggests that the long-term effects of CSA, including psychological difficulties, parenting problems, and intimate partner violence, increase the risk of a child's sexual victimization. Intergenerational CSA is defined as both parent and child experienced CSA, and the parent is not the abuser.
Research supporting parenting problems in CSA survivors (Banyard, 1997;Barrett, 2010;DiLillo & Damashek, 2003). (2000) Trauma theory is used to illustrate the repetition of a mother's abuse with her child -the focus is on how sexual abuse affects parenting, ultimately increasing the risk of sexual abuse in the next generation. Trauma theory: abuse triggers fear and shame; trauma may be re-experienced, and the individual is flooded with affect that was present in the original traumatic situation.

Maker & Buttenheim
-Clinical case illustrates a mother who experienced CSA and difficulties parenting her son. Her concern was that her son would sexually abuse her daughter, just as she experienced growing up.
-Sexually abused patients fear becoming bad parents and have unrealistically high expectations of parenting (Herman, 1981). (trauma-related shame and guilt) Bennett (1992) The family is viewed as a multigenerational system of emotional interaction. Differentiation of self: an individual's emotional independence and maturity. Multigenerational transmission: people tend to marry others with similar levels of self-differentiation.
-Low differentiation in a family is associated with elevated levels of anxiety and depression (Bowen, 1978).
-Myths within families maintain low self-differentiation and can impact the motherchild relationship (Seltzer & Seltzer, 1983); undifferentiation may be transmitted to the next generation (Kerr, 1988).

Alink et al. (2019)
Attachment theory: attachment relationships depend on the parenting a child receives. Attachment styles of maltreated children affect adult relationships and problematic parenting behaviours of their own children. Neurophysiological models: stress regulation is affected by early maltreatment. Increased stress response in adulthood can affect parenting behaviours. Developmental psychopathology models: maltreated children experience difficulty with developmental tasks, resulting in cognitive, social, emotional, and neurophysiological deficits; this can ultimately lead to psychopathology. Psychopathology can influence parenting behaviours as well as a parents' risk of maltreatment. Heritability models: heritable factors may explain the transmission of maltreatment and parenting.
-Maltreatment is related to deficits in social information processing (Keil & Price, 2009).
-Attachment styles of maltreated children are often insecure (Cyr et al., 2010). Insecure attachment is related to parenting problems and maltreatment (Reijman et al., 2017). (attachment theory) -Altered stress regulation found in maltreating parents (Reijman et al., 2015;. (neurophysiological models) -Maternal depression mediates childhood experiences of physical abuse and subsequent insensitive parenting (Madigan et al., 2015). (developmental psychopathology models) -Behavioural genetic studies have shown partial heritability of abuse and neglect (Fisher et al., 2015). Cicchetti & Rizley (1981) Examines etiology and transmission of child maltreatment with a focus on risk factors. Two categories of risk: 1) potentiating factors and 2) compensatory factors. Maltreatment is transmitted across generations through the transmission of risk factors for maltreatment.
Factors that reduce vulnerability or stress, or that increase buffers or protective factors, should decrease the probability of maltreatment occurring, as well as its transmission across generations.
De Bellis (2001) Maltreatment is transmitted across generations primarily through its effect on parental psychopathology -PTSD symptoms affect mental health in infancy, childhood, and adolescence.
-PTSD can influence behavioural and emotional regulation development and later mental health problems (Pynoos et al., 1995).

Summary of Evidence (reported by original authors)
-Increased rates of depression, PTSD, substance abuse, and antisocial behaviours in parents of maltreated children have been reported (Famularo et al., 1992). Geiger et al. (2015) Reviews theories and how they pertain to the intergenerational transmission of child maltreatment. Bowlby's attachment theory is described -attachment relationship serves as the basis of a child's development and foundation for future relationships. Insecure attachment styles can contribute to difficulties in parentchild relationships. Ecological framework: there are multiple mechanisms involved in explaining continuity of child abuse at multiple and interacting levels; risk and protective factors interact with each other (e.g., personality, family factors, societal factors). Risk and resilience: literature on resilience and protective factors to prevent child abuse are reviewed (e.g., financial stability and social support, education, marriage, partner violence, history of abuse, maternal warmth).
-Insecure attachment styles may be passed on to the next generation (Crittenden & Ainsworth, 1989). (attachment theory) -Dixon et al. (2009) -financial stability and social support reduce the risk of maltreatment. (ecological framework) -Example of a protective factor in breaking the cycle of maltreatment: safe, stable, and nurturing relationships (Conger et al., 2013). (resilience framework) Levendosky et al. (2012) Proposes a model using attachment theory to explain how intimate partner violence (IPV) may affect children and the intergenerational transmission of IPV. The betrayal involved in experiencing IPV damages an individual's internal working models of relationships, which influences parenting behaviours, consequently affecting the child's development of internal working models, and behavioural and emotional regulation.
Children of parents who have experienced IPV are at an increased risk of both later victimization and perpetration (Levendosky et al., 2006). Increased vulnerability is explained by IPV's effects on parents' and children's internal working models, which disrupts attachment representations and parenting behaviours (Levendosky et al., 2006). Morton & Browne (1998) Maltreatment can be seen as insensitive parenting -infants form internal representations of caregivers as being unresponsive and unreliable. Maltreated children may be unable to form secure attachments with their children -this is hypothesized as the process by which maltreatment continues in the next generation.
Early exposure to stress and trauma can have long-lasting impacts on an individual's stress response (Glaser, 2000). Documented links between impaired bonding, postpartum depression, problems in the dyadic relationship, and greater risk of maltreatment (van Ijzendoorn et al., 1999). Courtois & Ford (2009) Complex PTSD results from a series of events or prolonged exposure to trauma. Somatization, dissociation, and affect dysregulation are proposed as being the three main symptoms of complex PTSD.
This model conceptualizes PTSD as beyond a list of symptoms to more comprehensively understand the consequences of repeated trauma exposure, such as often the case with maltreatment. Tuohy (1987) Child abuse is conceptualized as resulting from impaired separation and individuation of the child from the parent. If parents use repression and isolation of painful affect, situations where abuse could occur may be more likely, while having access to childhood pain may deter them from repeating behaviours. Fraiberg (1975) describes problems with parent-child attachment as resulting partly from maladaptive defense mechanisms. Defense mechanisms are highlighted as contributing to perpetuating intergenerational cycles of abuse.
Chu & DePrince (2006) Authors use betrayal trauma theory (Freyd, 1996) and the Discrete Behavioral States model (Putnam, 1997) to guide their study. Betrayal trauma proposes that when violence is experienced from someone close to the victim, memory disruption, dissociation, and cognitive dysfunction are resulting consequences that maintain attachment between the victim and perpetrator. Dissociation is hypothesized as a mechanism by which trauma-related information is blocked.
Child maltreatment may lead to dissociation, leading to impairments in processing safety cues and social rules, potentially resulting in decreased parental monitoring of the child's environment.

Results
A total of 617 articles were identified through database searching. After duplicates were removed, 448 articles remained, and the titles and abstracts were screened. Two articles (one published in French) that were identified through hand searching were included. After this screening process, 403 articles were excluded, leaving 45 articles eligible for full-text assessment. Thirty full-text articles were excluded. A total of 15 articles were eligible for inclusion in this review (Figure 1). Five included articles presented theories relevant to the study of CSA specifically. Nine articles presented theories to explain child maltreatment more broadly (without focusing on specific types), and one article was explicitly focused on the intergenerational transmission of betrayal trauma and dissociation. The following section summarizes the main theories presented in these articles (see Tables 2 and 3).

Attachment Theory
Attachment theory was the most commonly reported framework, as seven articles summarized this theory and its relation to explaining victim-to-victim cycles of maltreatment (Alexander, 2015;Alink et al., 2019;Geiger et al., 2015;Levendosky et al., 2012;Morton & Browne, 1998;Sperlich et al., 2017). While Tuohy (1987) explicitly uses psychoanalytic perspectives (psychoanalysis, ego psychology, object relations theory, and self-psychology) to describe the assessment and treatment of children, the intergenerational cycle of abuse is described primarily based on attachment issues between parent and child.
Attachment theory, originally put forth by Bowlby (1969Bowlby ( /1982, provides valuable insight into how things may go awry in parent-child relationships, thereby contributing to lifelong struggles and an increased risk of later victimization. More specifically, attachment styles represent patterns of interactions and behaviours between caregivers and their children, are established early in life, and set the stage for how individuals perceive and interact in future relationships. Attachment theory postulates that the quality of the attachment relationship between a child and their caregiver depends on the caregiver's level of sensitivity and responsiveness towards the child (Bowlby, 1969(Bowlby, /1982. Ainsworth et al. (1978) described attachment classifications as secure and insecure (i.e., anxious-avoidant and anxious-resistant). Main and Solomon (1990) later added the disorganized-disoriented insecure attachment style. A secure attachment style is a protective factor for children's development, while insecure attachment styles are associated with various difficulties, including internalizing and externalizing problems (Colonnesi et al., 2011;Fearon et al., 2010). The security of the attachment relationship is compromised in situations of abuse or neglect because the primary caregiver, who is responsible for providing safety and protection, may fail to protect the child against a threat or pose a threat to the child through their actions (Cloitre et al., 2011). Consequently, children who have experienced maltreatment commonly develop an insecure attachment with their caregivers (Cyr et al., 2010), and may go on to have insecure attachments with their children when they become parents themselves (van IJzendoorn et al., 2019). For example, Trickett and colleagues (2011) argue that attachment relationships following CSA are important for a child's adjustment, as sexual abuse activates a child's attachment system leading them to seek comfort and security from nonabusive caregivers. Parental support plays a critical role when children disclose their sexual abuse, as perceived positive support is associated with adaptive psychological and relational outcomes (adult attachment, psychological symptoms, and dyadic adjustment related to relationship quality and satisfaction) (Godbout et al., 2014). Thus, in victimto-victim cycles, where parents are not the perpetrators of the abuse, a child may rely on their parent for support. However, in cases of intergenerational continuity, where parents also have a history of CSA, the ability to bond with their child and engage in responsive parenting behaviours may be negatively affected by their distress (Courtenay et al., 2015), rendering it such that the child may not receive optimal support. Therefore, the child might learn that they cannot rely on their parent for physical or emotional comfort, leaving them to seek proximity to others to meet their attachment needs, putting them in vulnerable situations and increasing the risk of victimization.
Another attachment mechanism through which victim-to-victim cycles may perpetuate themselves is through internal working models. Internal working models are cognitive representations of individuals' views of themselves, others, and expectations in relationships (Bowlby 1969(Bowlby /1982. According to Levendosky et al. (2012), the effects of IPV on parents' and children's internal working models may lead to an increased vulnerability for later victimization. In contexts in which abuse occurs, children may grow up more helpless and less competent, and develop interpersonal schemas (thoughts, feelings, and behaviours concerning relationships) that contribute to victimization (e.g., by selecting partners who re-enact abusive behaviours or relationship dynamics experienced in childhood) (Cloitre et al., 2011). Thus, the attachment styles and internal working models of maltreated children ultimately affect adult relationships and can lead to problematic parenting behaviours, high levels of conflict, and even IPV in the household (Alink et al., 2019;Levendosky et al., 2006;Reijman et al., 2017), thereby continuing a cycle of victim-to-victim maltreatment wherein children in the next generation are exposed to IPV.

Traumatic Stress Models
Theories conceptualizing trauma and its sequelae were integrated into five papers (Baril & Tourigny, 2015;Courtois & Ford, 2009;De Bellis, 2001;Maker & Buttenheim, 2000;Sperlich et al., 2017). Traumatic stress models can be used to explain victim-to-victim cycles of maltreatment as resulting from the negative and long-lasting impacts that trauma has on psychological functioning. Maker and Buttenheim (2000) presented a clinical case to illustrate the repetition of a parent's abuse with their child. The authors focused on how CSA impacts parenting, which ultimately increases the risk of CSA in the next generation. For example, abuse can trigger feelings of fear and shame in the child that may be re-experienced in the parental role, particularly when individuals are confronted with their child's developmental challenges pertaining to sexuality and aggression (Maker & Buttenheim, 2000). In these situations, parents may be flooded with emotions that were present in the original traumatic situation, and these symptoms can persist in the form of intrusive flashbacks, nightmares, and dissociative symptoms that interfere with parenting. Shame and fear related to trauma have also been associated with beliefs about parenting such that individuals who experienced CSA might fear becoming bad parents, perceive themselves as less competent in the parental role, or have unrealistically high expectations concerning their child's level of autonomy (Bailey et al., 2012;Cohen, 1995;Herman, 1981). Thus, these parenting difficulties, such as inaccurate risk assessment, may lead some children to end up in risky situations where abuse could be perpetrated by someone else. It is important to note that these difficulties with the parenting role and problems with parent-child attachment are the result of the original perpetrators' actions.
De Bellis (2001) proposed a developmental traumatology model based on a post-traumatic stress disorder (PTSD) model, highlighting that PTSD is commonly seen in maltreated children. Intergenerational maltreatment is described as being transmitted primarily through parental mental illness resulting from the experience of traumatic stress during childhood, which impacts biopsychosocial development. The central argument is that the negative effects of trauma on mental health can lead to maladaptive parenting. In support of this notion, PTSD resulting from child maltreatment has been associated with caregiver-infant bonding impairments (Muzik et al., 2016) and lower levels of parental sensitivity (Muzik et al., 2013). Similarly, CSA has been associated with depressive symptoms that can interfere with parental engagement, sensitivity, and responsiveness (Lovejoy et al., 2000;Zvara et al., 2017) as well as parenting difficulties such as lower levels of parental warmth, higher levels of psychological aggression, and corporal punishment (Barrett, 2009). The mental health problems that emerge as a consequence of child maltreatment may contribute to an increased risk of abusing or neglecting one's own children (victim-to-perpetrator cycle) or to victimto-victim cycles that may arise from parental disengagement as a consequence of the trauma they have personally experienced. A similar argument was outlined by Chu and DePrince (2006), who discussed the role of betrayal trauma history in the development of dissociative symptoms. The authors proposed that child maltreatment can lead to dissociation, which in turn can contribute to alterations in processing social rules and safety cues, thereby impairing the parent's ability to monitor the safety of their child's environment. Sperlich et al. (2017) used theories on attachment and trauma to propose a cycles-breaking framework to guide perinatal research and interventions (Figure 2). This was the only identified model that placed emphasis on the perinatal period. Evidence supporting such a framework comes from findings that early exposure to stress and trauma can have long-lasting impacts on an individual's stress response and vulnerability to psychiatric disorders (Glaser, 2000). This model highlights the links between impaired mother-infant bonding, depression, problems in the dyadic relationship, and a greater risk of maltreatment (van Ijzendoorn et al., 1999). At all stages of this cycle, it is acknowledged that there could be the presence of an abusive partner or family member. The utility of this model is the focus on breaking cycles of maltreatment and mental health problems, which is illustrated at various points in the cycle to emphasize optimal times for intervention.
The Complex Post-Traumatic Stress model (CPTSD; Courtois & Ford, 2009), which was identified through handsearching, is also applicable. The CPTSD model highlights the numerous and lasting impacts that chronic exposure to interpersonal violence, especially early exposure, can have on an individual's functioning and mental health. This model is particularly relevant to explaining victim-to-victim cycles since child maltreatment is associated with negative psychological consequences that can impact interpersonal functioning, including parenting and bonding with one's own children (e.g., Zvara et al., 2015).

Figure 2. Reproduction of Sperlich et al. (2017)'s cycles-breaking framework
Lastly, Baril and Tourigny (2015) published a comprehensive model explaining the intergenerational continuity of CSA (Figure 3). Though this model is based on traumatic stress models, elements of attachment theory are also incorporated. The model suggests that the long-term effects of CSA, including psychological difficulties, parenting problems, and IPV, primarily explain the increased risk of a child's sexual victimization. Other factors are also included, such as genetic factors, coping strategies, prenatal care, and children's characteristics. However, the emphasized continuity mechanism concentrates more on mental health and relational issues that can impair parenting.

Family Systems Theory
Three papers (Alexander, 2015;Bennett, 1992;Greenspun, 1994) explained victim-to-victim cycles of maltreatment using family systems theory, initially proposed by Bowen (1978). Family systems theory conceptualizes the family as a multigenerational system of emotional interaction. Alexander (2015) highlighted evidence of the family role in continuing cycles of maltreatment, such as through parental conflict, poor mother-daughter relationships, and lower socioeconomic status (SES). In the paper by Bennett (1992), two aspects of family systems theory are particularly relevant to explaining a clinical case of incest: differentiation of self, which is an individual's emotional independence and maturity, and multigenerational transmission, which is the notion that people tend to marry others with similar levels of differentiation of self. Essentially, it is hypothesized that individuals who grew up in families with a lack of interpersonal boundaries may enter relationships with rejecting and abusive partners, contributing to the continuity of abuse in the next generation. Further, when incest is present, family members may accept the notion that it is appropriate for adults to abuse children. Acceptance of these notions can impact the parent-child relationship (Seltzer & Seltzer, 1983) and may be passed onto the next generation through continued parent-child boundary issues (Kerr, 1988). In support of this notion, evidence suggests that survivors of CSA may have more difficulty establishing hierarchical boundaries with their children or be more likely to engage in role reversals whereby they rely on their children for emotional support (DiLillo & Damashek, 2003). As such, children placed in this parentified role may be given levels of autonomy that are not developmentally appropriate, making them more vulnerable as targets to potential perpetrators. Baril and Tourigny's (2015) model of the intergenerational continuity of CSA

The Ecological Framework
Building from the ecological model for human development, originally put forth by Bronfenbrenner (1979) and later by Belsky (1980), Cicchetti and Rizley (1981) describe the use of an ecological framework to explain the intergenerational continuity of child maltreatment. The framework proposed in this paper is broad in describing maltreatment and focuses on factors that confer risk or, conversely, can have a buffering effect against intergenerational continuity. More specifically, potentiating factors that increase the probability of child maltreatment include vulnerability factors, which are enduring features that increase risk, as well as challengers, which are transient but significant stresses. For instance, vulnerability factors may include personality attributes, such as poor frustration tolerance, or situational variables, such as poverty. In contrast, challengers may include significant stressors like the loss of a loved one, physical illness or injury, marital problems, problems with disciplining children, or legal difficulties. In contrast, compensatory factors that decrease the risk of maltreatment include protective factors, which are enduring conditions or attributes that decrease risk, and buffers, which are defined as transient conditions that defend against transient increases in stress. Protective factors may include traits such as an easy temperament, intelligence, physical health, and interpersonal skills, while buffers may include financial savings and social support. The proposition made by the authors is that child maltreatment is transmitted across generations primarily through the transmission of risk factors. They assert that maltreatment can only occur when potentiating factors override compensatory ones.

Developmental Theories
Developmental psychopathology models have also been used to explain intergenerational cycles of maltreatment. As summarized by Alink et al. (2019), these models propose that maltreated children might have trouble negotiating developmental tasks, which could result in cognitive, social, emotional, and neurophysiological deficits that ultimately lead to psychopathology. In turn, psychopathology can increase parenting stress (see Hugill et al., 2017 for review), contributing to negative parenting behaviours or increasing parents' risk of maltreating their children. Negative parenting behaviours may also unintentionally put children in risky situations where abuse could occur, such as limited or absent parental supervision.

Neurophysiological Models.
These models highlight that early maltreatment affects stress regulation and argue that dysregulated stress response in adulthood can affect parenting behaviours (Alink et al., 2019). This has been supported by research that shows altered stress regulation in maltreating parents (Reijman et al., 2016), which has been related to disengaged parenting (Reijman et al., 2015). These findings suggest that altered stress regulation and its effects on parenting could serve as a mechanism by which child maltreatment could continue within families. In support of this notion, other research has shown the importance of gene-environment interactions in predicting stress reactivity, such that youth who have experienced adverse life events and who also have certain genetic variants exhibit enhanced heart rate reactivity to psychosocial stressors compared to those with fewer genetic susceptibility variants (Allegrini et al., 2019). Therefore, those who have underlying genetic vulnerabilities that are compounded by experiences of child maltreatment may demonstrate greater stress reactivity in adulthood, which could interfere with the parental role.

Heritability Models.
Patterns of intergenerational child maltreatment and problematic parenting can also be explained by heritable factors, though these models were only referenced in one paper. Alink et al. (2019) summarized some of the behavioural genetic findings supporting the use of these models. Most research on heritability models has come from animal studies, though some research shows partial heritability of abuse and neglect in humans (Fisher et al., 2015). Based on a longitudinal study of twins followed until the age of 18, Fisher et al. (2015) reported significant but modest heritability for crime victimization, peer or sibling victimization, and internet or mobile phone victimization. Sexual victimization in adolescence did not seem to be under genetic influence; rather, environmental risk factors better accounted for this abuse (Fisher et al., 2015). The authors highlight that their genetic findings support the notion that victimization experiences appear to be more strongly related to being exposed to risky environments instead of heritable characteristics. Part of a risky environment could indeed be difficulties with the parenting role. A meta-analysis conducted by Kendler and Baker (2007) supports the role of genetics in partially explaining parenting behaviour, as they report on heritability estimates for certain parenting traits, such as parental warmth (34-37%), protectiveness (20-26%) and control (12-17%). With respect to victim-to-victim cycles, parents may have a combination of genetic and environmental risk factors, along with the symptoms and consequences resulting from their own trauma, that can interfere with adaptative parenting.

Discussion
Nearly four decades ago, Cicchetti and Rizley (1981) emphasized the importance of documenting differential risk patterns to understand the continuity of different types of child maltreatment across generations. This scoping review aimed to identify and summarize theoretical explanations pertaining to the victim-to-victim cycles of maltreatment, and integrate these findings into a model that could illustrate the theoretical and empirical explanations related to victim-to-victim cycles. An overview of theories related to these cycles is necessary to contribute to the literature, as there is evidence for their existence (e.g., Grunsfeld, 2018). Yet the mechanisms explaining them are not well documented or understood, particularly in comparison to the literature documenting how individuals who experienced maltreatment may become perpetrators. It is evident from this review that the literature on victim-tovictim cycles needs more theoretical and empirical development. Out of the 15 papers included in this review, five articles discussed CSA specifically, while the remaining articles explained the intergenerational continuity of maltreatment more broadly.

Critique of Theories
Attachment theory was one of the most documented theoretical frameworks used to explain victim-to-victim cycles identified through this review. Both attachment and traumatic stress models were used to create a cyclesbreaking framework proposed by Sperlich et al. (2017). This model offers strengths in guiding perinatal research and the depiction of a diagram regarding points in the cycle where interventions could be implemented to break the cycle of abuse. Though the focus of Sperlich's paper is on the perinatal period, the study of pre-and postnatal influences in victim-to-victim cycles could be further investigated. The role of mental health in victim-to-victim cycles is a recurring theme in the literature. Therefore, implementing early interventions with pregnant mothers demonstrating specific risk factors (e.g., mental health problems, history of child maltreatment, experiences of IPV) could potentially break these cycles.
De Bellis's (2001) developmental traumatology model relies primarily on the notion that early-onset PTSD and subsequent difficulties with mental health and parenting may explain the intergenerational continuity of child maltreatment. However, more empirical investigations are needed to determine how the model could be applied to enhance our understanding of victim-to-victim cycles more specifically. While PTSD is a documented outcome of child maltreatment (e.g., Messman-Moore & Bhuptani, 2017), there are many other factors involved in explaining continuity and discontinuity that this model does not thoroughly capture (e.g., SES and relational factors).
Regarding biological explanations of victim-to-victim cycles of maltreatment, Pittner et al. (2020) reported heritability estimates for experiencing maltreatment ranging from 30% for neglect to 62% for severe physical abuse. Genetic factors related to the risk of experiencing maltreatment and negative parenting behaviours need further investigation in samples of children who have experienced various types of maltreatment. These factors could be integrated into theoretical frameworks to explain victim-to-victim maltreatment. This would encourage researchers to consider biological factors in the study of this issue and the role of gene-environment interactions in the mental health and resilience of survivors of abuse (e.g., Normann & Buttenschøn, 2020).
While the ecological framework identified in this review is useful in studying child maltreatment more broadly, risk and protective factors may differ or have greater importance depending on the type of maltreatment being studied. Although parenting, attachment, and other family-related factors are implicated in maltreatment cases and play a role in maltreatment continuity (e.g., Egeland et al., 1988), there are several risk and protective factors that likely interact with each other to explain why abuse may continue across generations.
Although Belsky's (1980) ecological model of child maltreatment was not identified through the article search, it is worth highlighting that this conceptual framework has been widely used to identify risk and protective factors at multiple, interactional levels of functioning. Belsky (1980) describes the role of factors at various levels, including the ontogenetic (individual; e.g., maltreatment history, child-rearing); microsystem (child, family, and peers; e.g., parenting behaviours, family interactions); exosystem (neighbourhood characteristics; e.g., community resources); and the macrosystem (social and cultural influences; e.g., societally acceptable parenting practices, observation of violence through media). In investigations of victim-to-victim cycles of maltreatment, it is important to consider risk and protective factors at these multiple levels.
Through this review, it was evident that the theoretical models pertaining to victim-to-victim cycles of abuse do not typically highlight the role of the perpetrator, though this is an essential feature to consider. Individuals can face innumerable negative consequences at multiple levels of functioning after experiencing child abuse. These consequences can make it more likely that a victim-to-victim cycle continues. However, these cascading effects result from the perpetrator's actions who inflicted the abuse in the first place. Individuals are then left to face the aftermath as children and as adults, possibly across generations. It is also worth noting that much of the published research on this topic has focused on mothers (Langevin et al., 2019), which may lead to an overemphasis on the role of women in intergenerational cycles of maltreatment, and victim-blaming. Future studies need to engage more with the role of the perpetrators themselves and of other parents and caregivers.

Unifying Model of Victim-to-Victim Cycles of Maltreatment
A unified and more parsimonious model highlighting the key factors that are recurrently appearing in the literature as being involved in victim-to-victim cycles of maltreatment was needed. Such a model should highlight entry points for interventions that aim to foster resilience by breaking victim-to-victim cycles of maltreatment and should also benefit researchers. While the model proposed by Baril and Tourigny (2015) is comprehensive, it is specific to CSA, and it may not be the most readily applicable model in terms of research and clinical practice because of its complexity. In comparison to more complex theoretical models, a unified parsimonious model allows researchers to flexibly choose different methodologies and measures to examine the most salient variables involved in victimization cycles to address this issue from multiple perspectives and further our understanding of the mechanisms involved. Thus, conceptual models can help guide future research, especially an understudied topic such as victim-to-victim cycles of maltreatment. The model presented in Figure 4 was developed through trimming, summarizing, and integrating the theoretical knowledge identified through this review. The model is a starting point and could be amended to incorporate new findings since the number of investigations into this research problem increases. Within our proposed model, the outcome is second-generation child maltreatment. Child maltreatment is depicted as having negative impacts on relationships and mental health (mediators), both of which can affect the other. In turn, relationships and mental health can influence parenting, leading to an increased risk of maltreatment victimization. Parenting difficulties are represented as an outcome of child maltreatment, mental health issues, and relational issues and can predict second-generation maltreatment. On a broader level, there are also contextual risk and protective factors (e.g., macrosystem-level, such as cultural beliefs and values, and exosystem-level, for instance, neighbourhood and community-level factors), and neurobiological components (moderators) that can impact each of these variables and their relationships. Researchers may wish to use this model to guide their investigations of the mechanisms contributing to the continuity of maltreatment within families, by including relationships (e.g., intimate partner, parent-child), parental mental health, and parenting-related factors as mediators that can lead to second generation maltreatment, and how neurobiological and contextual factors may moderate the relationships within this model (e.g., socioeconomic factors moderating the association between parental histories of child maltreatment and adult mental health). The moderating role of positive relationships could also be further investigated in studies of resilience since the role of safe, stable, and nurturing relationships has been documented as a protective factor against intergenerational cycles of abuse (Jaffee et al., 2013). Additionally, the model could be enriched through clinicians' modifications based on their experiences with families who have experienced intergenerational maltreatment. In this way, the model could be informed and strengthened by empirical and practice-based evidence.
While there is not an extensive amount of research on victim-to-victim cycles of maltreatment, the model aligns nicely with empirical findings synthesized in a recently published systematic scoping review on psychosocial risk and protective factors involved in intergenerational cycles of child maltreatment (Langevin et al., 2019). For instance, in this review, the authors documented the role of individual, relational, and contextual factors that have been investigated as mediators or moderators of intergenerational cycles of maltreatment. Specifically, parental mental health was a well-documented risk factor in perpetuating maltreatment, in addition to relational factors, including couples adjustment, attachment and social support, and contextual factors such as socioeconomic status and community violence (Langevin et al., 2019).

Moderators Strengths and Limitations
A strength of this review is the comprehensive summary of theoretical explanations pertaining to the intergenerational continuity of maltreatment, with a specific focus on identifying theories relevant to the understudied issue of victim-to-victim cycles. While a systematic scoping review was appropriate for describing and synthesizing research, there are several limitations associated with this approach. For example, scoping reviews do not typically evaluate the quality of evidence; they may be based on broad and less defined search strategies requiring hand searching; and they do not provide a concrete answer to a specific research question (Sucharew & Macaluso, 2019). Despite our systematic approach and strategies to minimize bias (e.g., having two people screen articles), there is always a risk of bias involved in scoping reviews.
Most of the included studies provided a general narrative overview of theories and their application to victimization cycles. Only two papers presented a concrete theoretical framework depicted with a diagram and provided the narrative overview (Baril & Tourigny, 2015;Sperlich et al., 2017). Only two papers provided concrete clinical case examples to complement theoretical explanations (Bennett, 1992;Maker & Buttenheim, 2000). Most of the time, the discussion of theories or theoretical frameworks in the papers included in this review lacked specificity in terms of accounting for victim-to-victim cycles of maltreatment.

Future Directions
One avenue for future investigation and consideration when formulating theoretical frameworks include examining fathers' role, which would provide further support for the use of attachment and family systems theories. The proposed unified model has the advantage of being applicable to fathers who have histories of child maltreatment as well. Additionally, many of the theories reviewed in this paper have not provided an extensive discussion of the role of SES or other contextual factors (e.g., neighbourhood characteristics, social and cultural influences), apart from the ecological framework.
Future qualitative research may be particularly beneficial in terms of generating a theory or complementing existing theoretical explanations, such as with the grounded theory methodology. While many qualitative studies are exploring various issues related to child abuse (e.g., Fong et al., 2020), qualitative and mixed-method studies exploring themes related specifically to continuity and discontinuity of victim-to-victim maltreatment cycles are lacking. These methodologies have the advantage of answering research questions that quantitative studies alone cannot to identify gaps in research and practice.
Ultimately, it is imperative that future studies explicitly identify theoretical frameworks used to explain victimto-victim cycles of maltreatment, as this is not always the case (Schelbe & Geiger, 2017).

Implications
Child maltreatment and victim-to-victim cycles has consequences for the family as a unit. In the spirit of taking a family-based approach to victim-to-victim cycles of maltreatment, it could be helpful for clinicians to search for resilience -what the family has done well in the past and how they have successfully solved problems (Nichols & Davis, 2017). Families who have experienced adverse events, as in the case of a parent dealing with a disclosure of their child's sexual abuse when they themselves experienced this abuse as a child, may be overcome with frustration, discouragement, as well as blame or guilt. Even the most discouraged families have been successful at times (Nichols & Davis, 2017), which makes it even more important for clinicians to identify and enhance the positive things this parent has done for their child, in addition to working on the factors that have been summarized in our unified model, such as attachment, parenting, mental health, and access to resources (i.e., the contextual-level). As illustrated in the model, interventions could be planned to target parent-child attachment relationships to develop more secure bonds (e.g., "Child-Parent Psychotherapy", Cicchetti et al., 2006; "Minding the Baby", Sadler et al., 2013). Parental mental health problems could be addressed through counselling or medication, emphasizing on early prevention and intervention, such as during the prenatal period. As parenting has been documented as a problematic area among survivors of abuse (Lange et al., 2020;Wark & Vis, 2018), psychoeducation and therapy could also be beneficial in terms of cultivating more positive parenting practices (e.g., by targeting appropriate parent-child roles, parenting styles, communication strategies, discipline, and supervision) to reduce the likelihood of maltreatment victimization continuity and foster resilience.

Conclusion
Promotion of individual-and family-level factors have indeed been documented as components that can contribute to resilience in children who have experienced maltreatment (Meng et al., 2018). Prominent themes in the literature surrounded the role of parenting, attachment, and mental health in the pathway to maltreatment continuity. Based on these findings, a unified model of these results is proposed, which has the advantage of research and clinical practicality. However, future studies employing diverse samples are needed to test this model in research and clinical populations across cultures.

Funding
This research was supported by the Joseph-Armand Bombardier Canada Graduate Scholarship -Doctoral Award provided by The Social Sciences and Humanities Research Council of Canada (SSHRC). Kerr, M. (1988). Family evaluation: An approach based on Bowen theory. W W Norton & Co.