Parental mental illness a key risk factor for offspring mental illness: new evidence from Australia

What determines who we become? Although there is no easy answer to this question, with a mixture of a wide range of variables having the potential to influence our developmental trajectories, extensive scientific evidence supports the key role of parents (Jami et al., 2021).

Specifically, research consistently shows that parental psychopathology is associated with an increased risk of negative outcomes in their children (e.g., Reupert et al., 2022). Theoretical frameworks have identified two main pathways via which this intergenerational transmission of risk can be passed on: namely, the inheritance of genetic risk factors, and the exposure to environmental stressors (Jami et al., 2021), for example via social learning processes, including particular parenting styles and practices (see our previous blogs by Svenja and Nikki to learn more). Indeed, parental mental health is recognised as a fundamental factor in subsequent child wellbeing (Johnson et al., 2018) and, importantly, a potential target for intervention and prevention strategies.

Mental health disorders often co-occur (Plana-Ripoll et al., 2019), and this comorbidity is frequently associated with a long-lasting and poor illness course (Fusar-Poli et al., 2014). Further, studies highlight that the mental health of children is more strongly impacted when parents experience comorbid mental health disorders, compared to when parents suffer from a single mental health disorder (e.g., Johnson et al., 2018).

This blog post examines a recent study from Watkeys and colleagues (2022), who conducted a comprehensive analysis of parental mental health disorder comorbidities in relation to the psychosocial development of their offspring during early childhood.

Comorbidity among mental health disorders is common and has detrimental impacts on the children of affected parents.

Methods

Watkeys and colleagues (2022) analysed data from 66,154 5-year-old children and both parents from the New South Wales Child Development Study (NSW-CDS), which is a prospective, longitudinal record-linkage cohort study of 91,635 children born in New South Wales (Australia) between 2002 and 2004.

Early childhood developmental vulnerability was assessed via the 2009 Australian Early Development Census (AEDC), which used a reliable and validated teacher-rated questionnaire evaluating five domains of school-aged children. The current study only focused on the emotional maturity domain, which includes anxious and fearful behaviour, aggressive behaviour, and hyperactive and inattentive behaviour.

Previous research conducted by the authors (Green et al., 2018) has allowed for the identification of four classes of developmental vulnerability based on AEDC scores:

• Pervasive risk
• Mild generalised risk
• Misconduct risk
• No-risk

Information on paternal and maternal mental health disorders was obtained from administrative health records. Mental health disorders were grouped according to their International Classification of Diseases 10th Revision (ICD-10) and the number of distinct types of mental health disorders that was diagnosed before 2009 (i.e., before children’s AEDC assessment) determined the number of comorbidities for each parent.

Binomial and multinomial logistic regressions were used to assess the relationship between parental mental health disorder comorbidity and childhood development. The authors estimated both unadjusted and adjusted associations, which accounted for socio-economic disadvantage, Indigenous status, child sex, and number of mental health disorders diagnosed for the other parent.

Results

The authors found that 39.21% of fathers and 30.38% of mothers experienced more than one mental health disorder, with the most common three-disorder comorbidities being mood, neurotic and substance-use disorders.

The unadjusted prevalence ratios of the regression models showed that children of parents with three-to-four disorder comorbidities were:

• 1.54 to 1.86 times as likely to show vulnerabilities on the anxious and fearful behaviour domain
• 1.60 to 2.19 times as likely to be vulnerable on the aggressive behaviour domain
• 1.67 to 2.01 times as likely to be vulnerable on the hyperactivity and inattention domain

All the associations were significant in unadjusted as well as adjusted models. The findings displayed a linear trend, with stronger associations when the number of parental diagnoses increased.

Regarding the link between parental mental health disorders and childhood risk classes, the authors found significant associations for both maternal and paternal diagnoses in both adjusted and unadjusted models. However, in adjusted models, effect sizes were generally lower and the association between four or more paternal mental health disorders and the mild generalised risk class became non-significant.

Belonging to one of the three risk classes, compared to the no-risk class, was linearly associated with an increasing number of maternal diagnoses. For fathers, the results were similar, but the association between paternal mental health disorders and the mild generalised risk class followed a quadratic trend.

The prevalence of developmental vulnerabilities in children increased with the number of parental comorbidities, with overall stronger associations for mothers compared to fathers.

Conclusions

In summary, this study shows how the number of parental mental health disorder diagnoses increases the likelihood of emotional and behavioural developmental vulnerability in their 5-year-old children. As stated by the authors, the risk is especially high for:

Children who have a parent with three or more mental disorders, who were two to three times more likely than children of parents with no mental disorders to display multiple developmental difficulties.

Parental mental health has a strong influence on child development and this study adds to the large body of literature supporting the intergenerational transmission of psychopathological risk,

demonstrating an increased risk of early childhood emotional vulnerabilities and developmental risk classes with increasing parental mental disorder comorbidities.

This study adds to the existing literature on the intergenerational transmission of psychopathology, showing that mental health disorder comorbidities in parents pose their offspring an increased risk of developing negative emotional and behavioural outcomes.

Strengths and limitations

The authors conducted a comprehensive study that pertains to a topic of both clinical and research relevance by analysing a large number of families (including both mothers and fathers) from a longitudinal cohort study, assessing internalising as well as externalising child outcomes. The authors adopted a rigorous analysis strategy, where unadjusted and adjusted associations were estimated and numerous key covariates were accounted for. Moreover, sensitivity analyses were conducted to evaluate the association between specific combinations of parental mental disorders and child developmental outcomes.

However, the results should be considered in light of a number of limitations:

• In primis, child outcomes were assessed at a single timepoint; hence, it was not possible to evaluate the change of the effects of parental comorbidities over time. Arguably, it would be important to examine whether there are specific windows where children are most vulnerable to their parents’ mental health disorders. Further, it would be relevant to understand whether the association between parental comorbidities and offspring negative developmental outcomes remains significant when children grow older.
• Second, there was no information available regarding the onset time and length of parental symptomatology; importantly, these factors may play a role in the intergenerational transmission of developmental vulnerabilities (e.g., Hammen & Brennan, 2003).
• Additionally, it may be argued that the number of parental mental health disorders presented in this research is underestimated, given that the information was obtained solely from government health department records, without capturing mental health issues addressed privately or by GPs.
• Finally, although the authors estimated adjusted associations accounting for socio-economic disadvantage, Indigenous status, sex, and number of mental health disorders diagnosed in the other parent, ethnicity and genetic vulnerabilities might have had a confounding effect as well. Indeed, genes are likely to be at least partially accountable for symptom associations across generations (Ahmadzadeh et al., 2021); however, genetic data was not available for this cohort.

This is a thorough, well-designed study, but further research is needed to investigate the impact of other key factors, such as genes and offspring assessment time, in the association between parental mental health disorder comorbidity and offspring developmental vulnerability.

Implications for practice

This study has important implications for clinical practice, alongside opening up potential avenues for future research.

In line with the literature in the field, this study demonstrates that parental mental health disorders represent a key risk factor for their children’s wellbeing. Consequently, intervention and prevention efforts should be directed towards these parents, especially those experiencing comorbid mental health disorders, to improve the mental health of the parents and promote healthier developmental outcomes in their offspring. On the other hand, children of parents with comorbid mental health disorders should be recognised as a particularly high-risk population, hence early assessment and detection of potential vulnerabilities among these children is warranted and age-appropriate interventions should be prioritised. GPs may be in a particularly privileged position to spot these at-risk families early on and to re-direct them to appropriate services; hence, they should be made aware of the risk that parental mental health disorder comorbidities represent for both parents and their children’s wellbeing.

From a research perspective, it is important to understand whether the association between parental comorbidities and offspring outcomes is primarily influenced by the number of comorbid mental health disorders in parents, or by the severity of these disorders, given that this may direct intervention approaches as well. Moreover, it is crucial to investigate the impact of parental comorbidities on offspring psychosocial development by examining longitudinal and genetically informed studies (e.g., adoption studies), to shed light on the changes of effects over time and to disentangle the role played by genes and by environmental stressors.

Children of parents with experience of mental health disorder comorbidities represent a vulnerable population and should be prioritised in prevention and intervention efforts.

Statement of interests

Nothing to declare.

Links

Primary paper

Watkeys, O. J., O’Hare, K., Dean, K., Laurens, K. R., Harris, F., Carr, V. J., & Green, M. J. (2022). Early childhood developmental vulnerability associated with parental mental disorder comorbidity. Australian & New Zealand Journal of Psychiatry, 00048674221116806.

Other references

Ahmadzadeh, Y. I., Schoeler, T., Han, M., Pingault, J.-B., Creswell, C., & McAdams, T. A. (2021). Systematic review and meta-analysis of genetically informed research: associations between parent anxiety and offspring internalizing problems. Journal of the American Academy of Child & Adolescent Psychiatry, 60(7), 823-840.

Fusar-Poli, P., Nelson, B., Valmaggia, L., Yung, A. R., & McGuire, P. K. (2014). Comorbid depressive and anxiety disorders in 509 individuals with an at-risk mental state: impact on psychopathology and transition to psychosis. Schizophrenia Bulletin, 40(1), 120-131.

Geissler, S. S., Stressed mums and depressed young ones: does parenting play a moderating role? The Mental Elf, 14 March 2023. https://www.nationalelfservice.net/populations-and-settings/parenting/parenting-prenatal-stress-youth-mental-health/

Green MJ, Tzoumakis S, Laurens KR, et al. (2018). Latent profiles of early developmental vulnerabilities in a New South Wales child population at age 5 years. The Australian and New Zealand Journal of Psychiatry, 52, 530–541.

Hammen, C., & Brennan, P. A. (2003). Severity, chronicity, and timing of maternal depression and risk for adolescent offspring diagnoses in a community sample. Archives of General Psychiatry, 60(3), 253-258.

Jami, E. S., Hammerschlag, A. R., Bartels, M., & Middeldorp, C. M. (2021). Parental characteristics and offspring mental health and related outcomes: A systematic review of genetically informative literature. Translational Psychiatry, 11(1), 197.

Johnson, S. E., Lawrence, D., Perales, F., Baxter, J., & Zubrick, S. R. (2018). Prevalence of mental disorders among children and adolescents of parents with self-reported mental health problems. Community Mental Health Journal, 54, 884-897.

Newhouse, N., Systematic review identifies key parenting factors associated with adolescent depression and anxiety. The Mental Elf, 4 February 2014.  https://www.nationalelfservice.net/mental-health/anxiety/systematic-review-identifies-key-parenting-factors-associated-with-adolescent-depression-and-anxiety/

Plana-Ripoll, O., Pedersen, C. B., Holtz, Y., Benros, M. E., Dalsgaard, S., De Jonge, P., … & McGrath, J. J. (2019). Exploring comorbidity within mental disorders among a Danish national population. JAMA Psychiatry, 76(3), 259-270.

Reupert, A., Bee, P., Hosman, C., van Doesum, K., Drost, L. M., Falkov, A., … & Ruud, T. (2022). Editorial Perspective: Prato Research Collaborative for change in parent and child mental health–principles and recommendations for working with children and parents living with parental mental illness. Journal of Child Psychology and Psychiatry, 63(3), 350-353.

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