To our knowledge this is the first population cohort study to demonstrate a clear association between depression in fathers in the postnatal period and later psychiatric disorders in their children. This association is independent of maternal postnatal depression, psychosocial risk, and depression in fathers after the postnatal period, at 21 months.
The findings highlight three important factors regarding depression in men in the postnatal period. First, depression in men is relatively common. Overall, the rates of depression found in this study are comparable with prevalence estimates from other studies using 30-day rates (e.g. 2.4% in men in the Australian National Survey 29
), although lower than in studies that have used longer time frames (such as the 12 month prevalence rates of 6% seen in the National Comorbidity Study 30
). There is a suggestion from these findings that depressive symptoms are even more common in the prenatal period than postnatally, although the proportion of fathers with very high scores changes little across this period. There has been limited previous work investigating the course of depression during the perinatal period, although some research suggests that men experience higher levels of stress prenatally, and that there is not a significant increase in symptoms thereafter 5
. Similar patterns of depression have also been seen in women31
Second, depression in fathers in the postnatal period was strongly predictive of increased rates of psychiatric disorders, particularly oppositional defiant or conduct disorders, in their children 7 years later, as well as increased rates of social difficulties. These findings complement and contrast with the large number of studies examining the effect of postnatal depression in mothers on children's social, emotional and cognitive development 13, 15
. Although our understanding of the father's role in child development has increased significantly in recent years 32, 33
, there has been very little longitudinal research examining the association between paternal depression early in children's lives and their subsequent development 11, 12
. This study is the first to demonstrate an association with psychiatric disorder, particularly oppositional defiant or conduct disorders. It is also notable that these are findings from a large, prospective study using a community sampling frame, and that maternal depression effects were controlled for in the analyses.
Previous work has pointed to an increased risk of behavioral problems in children of fathers with depression 11
, but the current findings point to a persisting, and clinically significant level of disturbance, with more significant implications for the future functioning of the children, and for society. Conduct problems at this age are strongly predictive of later serious conduct problems, increased criminality, and significantly increased societal costs34
. Depression in fathers seems specifically related to behavioral and peer relationship difficulties, whereas maternal depression appears to be associated with a broader spectrum of child disturbance 3
. This relative specificity of the link between paternal depression and more antisocial behavior in the child may reflect the father's role in socializing children, or an association between depression in fathers and more disruptive parenting. Depression, with core symptoms of low mood, lack of energy and loss of interest, is likely to severely disrupt the ability of any parent to undertake the tasks of parenting, particularly affecting the day-to-day interactions of parent and child 3, 9
. It is unclear whether the very early days of a child's life are a particularly sensitive period during which the infant is more vulnerable to the effects of stressors such as parental depression 13, 35
. The finding from this study, that paternal depression early in the child's life is associated with these persisting problems, even controlling for later paternal depression, raises the intriguing possibility that such a sensitive period might be operative, particularly in relation to the effects of parental depression. However, we were not able to control for concurrent depression at age 7 years, and so further research is required to test this question in more detail.
Third, factors including a past history of depression (as measured by father self-reported history), and symptoms of depression and anxiety in the prenatal period, are strongly predictive of depression in the postnatal period in men. Prenatal depression in the female partners of these men was also related to an increased risk of postnatal depression in the men. The co-occurrence of depression in partners 11, 36
and the consequences of depression in one partner for the other are important factors for family functioning and the developing child 37
. It may be that effects previously attributed solely to maternal depression are, in fact, partly accounted for by paternal effects or factors related to both parents38
. The difficulties often experienced in researching men's health, such as relatively high attrition rates, lead to an under-involvement of men in research and so a poorer understanding of many men's health issues. This is perhaps particularly the case for psychiatric research (which has tended to ignore men's – and fathers' - health) and the study of family life and child development, undermining our understanding of these important issues.
This study has a number of key strengths. It is based on a large population cohort study and so is free of the selection biases inherent in studying clinical populations. The data were collected prospectively. The psychiatric diagnoses in the children were based on a structured clinician assessment incorporating questionnaire data from parents and teachers. There are limitations to consider. First, the assessment of depression in the fathers was based on a questionnaire report (the Edinburgh Postnatal Depression Scale (EPDS)). However, the EPDS is the most widely used and validated questionnaire for depressive symptoms in the postnatal period, and has been validated in men as well as women. Misclassification is unlikely to be related to the outcome in such a way that a systematic bias would be introduced. Second, although the associations seen were robust when controlling for some important potential confounding variables, it remains possible that the findings are in part due to some other (unmeasured) confounding factors, such as early marital difficulties. Similarly, we were unable to control for depression in the father at ages 6 and 7 years, and so it is possible that some of the effect seen was due to concurrent effects of depression rather than depression early in the child's life. We were able to overcome this to some extent by controlling for depression at a later time point (21 months), and also by having mothers report on the children's functioning. While a later report of depression would have been ideal, the minimal attenuation seen when depression at 21 months was controlled for, does suggest that this may not have altered the findings. Third, there was significant attrition from the study over the time period studied. This is common across most longitudinal studies, but may have had an effect on the results seen. Fathers from lower socio-economic groups were less likely to participate in the study and so this may limit somewhat the generalizability of the findings. In addition those fathers with higher levels of depressive symptoms were more likely to provide incomplete data. However, this should have had the effect of making it more difficult to identify associations with paternal depression. We have attempted to overcome this problem by imputing missing data on confounding variables, including later depression. Such a strategy provides more robust estimates, and it is reassuring that similar findings were obtained when the same analyses were undertaken with and without the use of imputation. However, the attrition seen in this study does highlight an important point about researching men's health. It is generally more difficult to involve fathers (and men in general) in medical research, perhaps particularly that which involves the study of psychological factors. This has been one of the factors that have led to men being left out of many studies of child development, with a consequent under-estimation of their role and importance in family life.
Overall this study highlights the importance of depression in men in the postnatal period. The findings suggest that depression may have an impact not only on the men themselves but also on the development of their children. Perinatal services, where they exist, currently focus on mothers. While we recognize the primacy of the maternal role, it is important to consider broadening the focus of such services. A wider family focus would encompass the common co-occurrence of depression in mothers and fathers. Although fathers do not have as much contact with perinatal services, such as obstetric and primary healthcare, it would be possible to involve them more actively – something that may have positive spillover effects for the mother. Screening questionnaires, such as the Edinburgh Postnatal Depression Scale, used here, are reasonable screening tools in men, as well as women. If the findings of the present study are confirmed in other populations, then the identification of depression in fathers could represent an important opportunity for prevention: to improve fathers' health, family functioning, and children's future psychiatric and social functioning39, 40
. Given the strong association of postnatal depression in men with previous depression and depressive symptoms during their partner's pregnancy, fathers at risk could be identified.