Key findings
We found that a higher proportion of men and women with depression report physical IPV perpetration in the past year compared to men and women without depression, after controlling for confounders. Across all studies for which data were available, reported prevalence of past-year physical IPV perpetration was higher for women (0.9–28.4%) than it was for men (0.5–8.0%). The same pattern was observed for past-year severe physical IPV perpetration for women (0.5%-10.7%) and men (0.2–3.2%). However, an insufficient number of studies reported data on other types of IPV for men and women, and for physical IPV perpetration, only four studies could contribute to this meta-mediation analysis, highlighting the lack of data available to test our hypotheses. In this meta-mediation analysis, we found no evidence, for either men or women, that alcohol misuse mediated the relationship between depression and physical IPV perpetration in the past year. Past-year IPV victimisation was found to mediate 45% of the total effect of depression and past-year perpetration of physical IPV among women. Also, among women, IPV victimisation was estimated to mediate between 50 and 60% the total effect of depression on past-year perpetration of severe physical IPV.
Depression has previously been shown to be associated with an increased risk of having ever perpetrated physical IPV [
3,
5,
39]. This study extends these findings, demonstrating, first, that depression is also associated with having perpetrated physical IPV in the past year, and second, that the association persists after controlling for age, education, income, and number of children. Our finding of higher reported IPV perpetration among women than men has also been reported elsewhere [
40‐
42]. Our analyses were unable to take account of the frequency, pattern, or context of physically violent acts, and may reflect misclassification bias; elsewhere, analyses have shown that the majority of injurious and high-frequency IPV is experienced by women [
31]. Findings may reflect differential under-reporting among men versus women [
43], whereby men who perpetrate IPV may seek to underplay their violent behaviour [
44], although the mechanisms behind this are poorly understood.
Previous studies have shown that alcohol misuse is causally associated with both IPV perpetration [
45] and depression [
46,
47]. Whether alcohol misuse mediates the relationship between depression and past-year IPV perpetration has received limited previous attention, but analysis of longitudinal data from the National Epidemiologic Survey on Alcohol and Related Conditions (NESARC) has shown that substance abuse comorbidity increased the risk of violence perpetration generally in people with mental disorder in a general population sample [
48]. These findings contrast with the results of this analysis, which found no evidence that alcohol misuse mediated the relationship between depression and IPV perpetration. This apparent discrepancy may be due to misclassification bias (i.e., under-reporting of alcohol misuse and/or IPV perpetration); insufficient power to detect an association due to small numbers of those reporting all three of IPV perpetration, depression, and alcohol misuse; or high heterogeneity as a result of insufficient variable harmonisation. As there was significant variation in how alcohol misuse was measured across datasets, it is most likely that this result is due to insufficient data harmonisation. It may also be the case that alcohol misuse may confound rather than mediate the association between depression and past-year physical IPV perpetration.
IPV victimisation was found to explain a significant portion of the total effect of depression on IPV perpetration among women. This is in keeping with the findings of a systematic review of longitudinal data, which established that depression is associated with incident IPV victimisation among women [
8], and findings that a high proportion of women who report the use of physical violence against intimate partners also report IPV victimisation [
10,
49]. Research suggests that many couples experience bidirectional violence [
13,
50], and that poor mental health, including depression, is more common where violence is bidirectional versus unidirectional [
13,
15,
32,
51]. Self-defence and retaliation are commonly described motivators for women’s use of violence in intimate relationships [
52], although this is contentious [
42]. Straus (2010), for example, highlights research which has concluded that only a small portion of women’s IPV is explained by self-defence, and notes that most research does not collect the same data for men, and therefore, it cannot be assumed that women’s use of violence differs from men. In this study, we were not able to determine the context of either IPV perpetration or IPV victimisation. We were also not able to investigate whether the association between depression and past-year IPV perpetration was mediated by IPV victimisation for men. Previous analyses of cross-sectional data from Wave 1 of the National Survey of Families and Households (included in this IPD meta-mediation analysis) have shown, however, a stronger link between bidirectional IPV and depression among women than for men [
13].
Strengths and limitations
The review used a comprehensive search strategy, and took a systematic approach to data management and harmonisation. Analyses were conducted separately by sex, considered alcohol misuse and IPV victimisation as potential mediators of these relationships, and accounted for a number of key covariates. Eligibility was limited to studies that used samples that were representative of the general population and used validated diagnostic or screening measures of mental disorder, reducing the risk of selection and measurement bias. Datasets were included from several countries, broadening generalisability in a high-income country context.
However, several limitations should be noted. First, due to the use of cross-sectional data, the direction of the observed associations cannot be inferred. Although some longitudinal data were available, we could not conduct analysis of temporal associations between depression and IPV perpetration either, because studies did not measure past-year IPV perpetration and/or mental health at multiple time points, or they did not collect data on the same population in each wave, or because there was significant attrition between time points. Although our aim by analysing associations between mental disorder and IPV perpetration in the past 12 months was to establish that these occurred, if not concurrently, over a short period, findings should be considered preliminary, and tested in future models using longitudinal data. Second, due to limited availability of data, analyses of the association between mental disorder and IPV perpetration could be conducted only for depression, and some mediation analyses could not be carried out for data on men due to small numbers and perfect prediction. Previous research indicates that there is an increased risk of lifetime IPV perpetration across a range of mental disorders [
5,
53]; it is not yet clear whether this is also the case for past-year IPV perpetration. When analysing associations between depression and IPV, we were only able to consider associations with physical IPV perpetration and could not investigate the perpetration of psychological and sexual IPV, or of coercive and controlling behaviours. We were also unable to analyse, due to a lack of data, whether IPV victimisation mediated the relationship between depression and past-year physical IPV perpetration among men. Third, heterogeneity in the measurement of potential mediators (e.g., alcohol misuse) meant that data harmonisation was challenging; heterogeneity for each analysis may be attributable to inadequate harmonisation. Several potential mediators of interest were excluded from the analysis, because they could not be adequately harmonised or because they were not consistently available across datasets. Fourth, due to insufficient data across datasets, we could not control for a number of key confounders, such as exposure to IPV during childhood or childhood experiences of abuse, which we know are associated with both mental disorders and IPV perpetration [
14,
26,
28]. This may have resulted in an over-estimate of the true effect of depression on past-year IPV perpetration. Finally, data were drawn from high-income countries only to minimise heterogeneity, and thus, findings cannot be generalised to low- and middle-income country settings. Future research should consider replicating the methodology of this study using datasets from low- and middle-income countries.
Implications
Mental health services, criminal justice services, and domestic violence perpetrator programmes should be aware that, although most people with mental disorders are not violent, depression is associated with an increased risk of IPV perpetration. Longitudinal research is clearly needed to explore directions of causality, and underlying mechanisms, for men and women, which may differ by sex. To our knowledge, there has also been no research examining whether treatment of depression (e.g., by antidepressants) impacts on the risk of IPV perpetration.
Evidence is lacking on the effectiveness of perpetrator programmes for perpetrators with mental disorders [
2,
54] and future research should address this gap as a matter of priority. If effective, these programmes may not only reduce IPV perpetration, but also depression among those who perpetrate IPV and their victims. In clinical settings, professionals working with perpetrators should consider whether there are potentially modifiable risk factors for IPV perpetration that could be addressed. Relevant responses may include psychological therapies for emotional regulation and/or treatment with antidepressants or mood stabilisers; the latter is known to be associated with reduced risk of violent crime [
55], but to our knowledge, this has not been investigated in relation to IPV perpetration. Although alcohol misuse was not found to mediate the relationship between depression and IPV perpetration, it is a known risk factor for IPV perpetration that should also be considered an intervention target [
56].
Mental health and other professionals working with women with mental disorders who report or are known to be perpetrators of IPV should be aware of the high prevalence of IPV victimisation among this group. Barriers to disclosure of IPV victimisation, and other forms of trauma, should be considered [
57] and where elicited, safety of both partners prioritised. Therefore, there may be multiple risks that need to be assessed and considered when managing care. Findings also raise the possibility that interventions aimed at reducing risk of IPV victimisation in women might be helpful in preventing IPV perpetration. Evidence suggests that advocacy (empowerment, safety information, and referrals) interventions, such as those typically provided by specialist violence against women and girls services, can help men and women in terms of both safety and recovery [
58,
59].
Our review identified very few studies with the data we needed to investigate associations between mental disorder and IPV perpetration. This study has also highlighted the need to strengthen collection of these data within population-based surveys, and for greater consistency of data collection across these surveys. At a minimum, the collection of data on violence should include physical, sexual, and psychological violence, and, for each type of violence, the number of repetitions in the past year, the sex of the perpetrator and of the victim, and the relationship between the perpetrator and the victim [
60]. Studies should additionally collect data on a range of mental disorders, particularly anxiety disorders, personality disorders, and substance abuse disorders, which have been shown elsewhere to be associated with increased risk of IPV perpetration [
3,
5], and key covariates, particularly substance misuse, childhood trauma (including physical abuse, sexual abuse, witnessing IPV, and neglect), and IPV victimisation in adulthood.