Discussion
The present study aimed to investigate whether distinct patterns of ACE co-occurrence exist in a sample of high-risk young adults, and importantly, whether these patterns are associated with differential profiles related to substance misuse. Factor analysis revealed three patterns of adverse experiences in our sample, which we labelled Childhood Maltreatment, Household Dysfunction and Community Adversity. All patterns were significantly and directly associated with an increased likelihood of substance misuse. The hypothesis that these distinct ACE clusters would be associated with distinct profiles was upheld: Child Maltreatment and anxiety were associated with Heavy Drug Use in one model, while Community Adversity and decreased punishment sensitivity were associated with Heavy Drug Use in another – importantly, both models controlled for variables in the other model. There was also evidence of potential partial mediation by anxiety and reduced punishment sensitivity in these respective relationships. Both Household Dysfunction and Community Adversity were related to an increased likelihood of Cannabis Dependence; however, there were no psychological variables that were associated with both Cannabis Dependence and either of the ACE clusters, so they were not examined using logistic regression. We also found no evidence that any pattern of adversity was associated with heightened levels of alcohol consumption. The cultural normalization of dangerous alcohol consumption in the Northern Irish context (Northern Ireland Assembly,
2020) may be one explanation for the non-significant effect of high adversity, anxiety, punishment, and reward sensitivity on this health-harming behavior in our sample.
The adversity clusters found in the present study both converge and diverge from the existing work on ACE clusters. Childhood Maltreatment, Household Dysfunction and Community Adversity – the subtypes which emerged from our sample – are approximately parallel to the ACE clusters reported in other samples (Beale et al.,
2019; Brown et al.,
2019; Mersky et al.,
2017; Rebbe et al.,
2017; Xu et al.,
2021). For example, research by Merians and colleagues (Merians et al.,
2019) found “high ACEs”, “Non-Violent Household Dysfunction”, “Emotional and Physical Abuse” and “Low ACEs” to be the primary ACE subtypes in their sample. Moreover, the clusters of Childhood Maltreatment and Household Dysfunction are partially depictive of the “threat” and “deprivation” clusters that have been put forward by proponents of the DMAP model (Everaerd et al.,
2016; Machlin et al.,
2019). However, in the present results, physical and emotional neglect loaded together with exposures to abuse and violence, which does not marry in with the “threat – deprivation” typology as proposed by Sheridan & McLaughlin (
2014). On the other hand, “Childhood Maltreatment”, as a variable capturing both abuse and neglect, has emerged as an important ACE cluster in other studies that are data-driven (Brown et al.,
2019; Lee et al.,
2020; Shin et al.,
2018). For example, a data-driven study by some of the same researchers who have worked on the DMAP model showed that neglect- and abuse-type adversities tended to cluster together, while parental education status and other indicators of socio-economic status tended to be more reflective of deprivation (Sheridan et al.,
2020). It is possible that the differences between the dimensions proposed by the DMAP model and the patterns found in the present study are reflective of a functional difference between the theory-driven approach of earlier DMAP work and the data-driven approach used here.
Notably, all of the adversities in the ACE-IQ loaded significantly onto one of the three clusters we found, with the exception of child sexual abuse. The contribution of sexual abuse to the factor Childhood Maltreatment fell just below the employed threshold (> 0.40), suggesting it most closely aligns with this factor. This would appear to reflect other data-driven research in which sexual abuse clusters with other interpersonal maltreatment types (Beale et al.,
2019; Lee et al.,
2020). It may be that the exploration of adversity patterns in a larger sample would reveal child sexual abuse to load substantially onto Childhood Maltreatment. It is also possible that child sexual abuse would emerge as its own unique factor, as it may be that environments in which child sexual abuse occurs may be distinct to other environments of adversity.
Another way in which our ACE patterns differed from some of the existing research was the emergence of Community Adversity as a distinct cluster, reflecting experiences of community and collective violence. The inclusion of Community Adversity as a distinct ACE pattern of co-occurrence in this sample is likely reflective of the use of the ACE-IQ, a measurement of adversity that captures community and collective violence. Much of the existing literature excludes these types of adversity, despite evidence that they exert effects that are at least partially unique to other forms of adversity (Cronholm et al.,
2015; Margolin et al.,
2010). Where researchers have included measures of community and collective violence in their studies, they have identified similar Community Adversity-type patterns in their samples (Lee et al.,
2020; Shin et al.,
2018) - though one of these studies did find community adversities to cluster with adversities of household dysfunction (Shin et al.,
2018). Further explaining the emergence of community adversity as a distinct cluster, collective violence and community deprivation are endemic to the NI context (Bunting et al.,
2013; McLafferty et al.,
2016), thus increasing the likelihood that Community Adversity would appear as a significant experience within the sample. Collectively, the results of the factor analysis show that ACEs may be organized into distinct subtypes; further, the emergence of Community Adversity suggests that the composition of these ACE patterns may also be dependent on the measurements used to capture adversity and the demographic attributes of the population from which the data is drawn.
The hypothesis that these distinct ACE patterns would be associated with distinct psychological profiles germane to substance misuse was largely substantiated. This hypothesis was founded on the present research, including research on the DMAP model, which have evidenced at least partially distinct outcomes between individuals who have experienced unique types of adversities (Beale et al.,
2019; Lee et al.,
2020; Miller et al.,
2018; Su et al.,
2019). In the present sample, greater exposure to Childhood Maltreatment and recent anxiety symptoms increased the likelihood of Heavy Drug Use, when controlling for other adversity subtypes and psychological variables. There was also evidence that anxiety may partially mediate the relationship between Childhood Maltreatment and Heavy Drug Use. This is consistent with the literature: children exposed to violent behavior and harm are more likely to develop anxiety (Cougle et al.,
2010; Miller et al.,
2018), which has been shown in turn to heighten the risk of substance misuse (Turner et al.,
2018). Though anxiety was relevant to the association between the Childhood Maltreatment and Heavy Drug Use, the results did not substantiate the relevance of punishment sensitivity to this relationship. Had Childhood Maltreatment aligned more closely with the DMAP conceptualization of “threat”, this association may have manifested in our results. On the other hand, this result may be explicable with further exploration into the concept of punishment sensitivity: punishment sensitivity is thought to represent a stable personality ‘trait’, unlike anxiety which represents a temporary psychological ‘state’ (Lau et al.,
2006). It is possible that the more intense ‘states’ of the construct – i.e., anxiety – may be more pertinent than ‘traits’ to the development of substance misuse in the context of Childhood Maltreatment-type adversities. This non-significant association aside, the results support the existence of a distinct psychological profile linking Childhood Maltreatment to substance misuse.
The present study also found that Community Adversity and reduced punishment sensitivity were associated with Heavy Drug Use, independent of other adversity and psychological variables. This result is difficult to compare to the existing literature, as not many previous studies have explored the distinct outcomes of Community Adversity. For example, Shin and colleagues (Shin et al.,
2018) found community violence and household dysfunction as a pattern of adversity in their sample; as they did not find community violence/adversity as an isolated cluster, it is not possible to compare our results to theirs. In the context of the DMAP model, Community Adversity can be seen as most synonymous with “deprivation”; previous literature (Oshri et al.,
2018; Ursache & Raver,
2015) documents a relationship between experiences of deprivation and reward/punishment sensitivity dysregulation, similar to what is observed here. However, the mechanisms that link Community Adversity to anomalous punishment/reward sensitivity may be different to the mechanisms that link it to experiences of deprivation.
Some previous research has suggested that experiences of Community Adversity are linked to behaviours akin to reduced punishment sensitivity. Impulsivity, the inability to both inhibit potentially risky impulses and heed future consequences (Bakhshani,
2014), has been associated with high levels of exposure to community violence (Lambert et al.,
2010,
2021; Musci et al.,
2019). This construct is similar to blunted punishment sensitivity, as both feature a disregard for risk in decision-making. Other studies have suggested that exposure to community violence is linked to increased reward sensitivity (Gudiño et al.,
2012) and risk-taking (Estrada et al.,
2021) – though this finding was not observed in the present study, the dampened punishment sensitivity we found may imply a similar reduced regard for risk in individuals exposed to Community Adversity. Interestingly, Lambert and colleagues (
2010,
2021) note that it is possible punishment-insensitive traits such as impulsivity can precede and predict exposure to Community Adversity. It is not possible to test whether reduced punishment sensitivity in the current study predicts or emerges from exposure to Community Adversity; however, the idea that reduced punishment sensitivity may increase the likelihood of involvement or exposure to Community Adversity fits in with the bioecological framework of childhood adversity (Bronfenbrenner & Morris,
2006), which emphasises the importance of individual-level factors such as personality in determining the incidence and effects of experiences in childhood.
Implications
The findings produced by this study, once replicated and fortified by further research, may be germane to both theory and practice regarding adversity and substance misuse. Firstly, the meaningful discrimination of ACEs may help to explain the variations in risk that are often observed in the sequelae of ACEs. Future research that accounts for ACE differences may be better equipped to explore the mechanisms that link ACEs to unfavourable outcomes. Moreover, primary care providers may use this information to identify different ACE profiles in their clients and tailor the focus of their treatment accordingly. Secondly, these results endorse more than one mechanism to substance misuse, which challenges the dominance of reward-related theories in the substance misuse literature. In terms of clinical practice, substance misuse interventions may be able to increase their effectiveness and sustainability by specifically targeting the psychological variables that are most relevant to the adversity profile of their service user.
Strengths and Limitations
The results of the study should be interpreted with reference to its strengths and limitations. The data reported here formed distinct profiles that were in keeping with the concept that different subtypes of ACEs confer unique risks (Beale et al.,
2019; Sheridan & McLaughlin
2014; Sheridan et al.,
2020). This finding may contribute to a larger body of research that informs practice in the area of substance misuse prevention and intervention. Moreover, the study was able to investigate these profiles in a clinically significant population. The prevalence and impact of substance misuse in at-risk young adults is high, so information obtained from this sample may shape interventions to disrupt the development of substance misuse most effectively within a key period. Lastly, we adopted the use of the ACE-IQ, which recognises a greater range of adversities than traditional ACE measures – this is in line with the growing thought that greater cross-cultural validity is needed across the ACE measurement research (Mersky et al.,
2017).
On the other hand, the present study was limited by its design. A cross-sectional design meant that causation, and the direction of causation, could not be inferred between the independent and dependent variables. This is important, as it means we do not have a full picture of the distinct profiles that link adversities to substance misuse. Moreover, our substance misuse variables were inconsistent in their period of measurement: alcohol and cannabis use questions were past-year only, while heavy drug use questions looked at lifetime use. This discrepancy means that is not possible to conclude that Heavy Drug Use did not precede instances of adversity or psychopathology (e.g. anxiety) in some cases. However, as the average age of Heavy Drug Use initiation in our sample was 15 years, it is likely that adversity preceded Heavy Drug Use for some of our participants. Finally, the sample used to test the hypothesized profiles was small, warranting further testing of the current findings with larger sample sizes.
Future Directions
While the findings reported here are modest and subject to limitations, they do encourage further research. The profiles investigated would benefit from mediational analysis or longitudinal inquiry, which may capture the temporal sequence between adversity and substance misuse. Future work may also expound upon the findings presented here by exploring the distinct effects of ACE structures on other areas of functioning. Moreover, the use of the ACE-IQ and the finding that Community Adversity is uniquely related to substance misuse, may encourage future research to use expanded ACE measures in their studies of adversity outcomes. Finally, Childhood Maltreatment, Household Dysfunction and Community Adversity predicted different forms of substance misuse, an outcome that was not forecast by theory. It could be conjectured that the distinct developmental changes produced by different types of adversity have an impact on the motivation to use substances; for example, an individual may become more biologically prone to seek either a stimulatory or a depressive effect. This finding may be developed by further research, which may shed further light on the profiles linking adversity to substance misuse.
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