‘One in every ten mothers experience repeated episodes of major depression over their life course—on average, experiencing depression one in every six days of their lives.'
This story is part of our 10 of the Best, 2016 edition. 10 of the Best is an annual NHMRC publication, showcasing 10 NHMRC-funded health and medical research projects.
Professor Jackob Najman and his team have been following the lives of mothers and their children for almost 40 years to identify the genetic and environmental contributions to mental illness. With over 250 publications to date, this study uses a large amount of previously and recently collected data to understand the genetic markers of vulnerability to mental disorders and how they interact with environmental factors, such as childhood trauma.
Still ongoing today, this study received its first NHMRC grant in 1981—following a sample of 4000-5000 mothers and their children from birth to 30 years of age.
'This is a population based study that has gathered a large amount of data on a large cohort. It is one of the few studies of its type internationally to track both mothers and their children for such a long time period.'
‘With over 5000 variables for each person in the study, the logistics of gathering and storing this large body of linked data has been challenging,’ Professor Najman said.
This study specifically examined the effects of environmental exposures—such as marital breakdown, poverty and childhood traumas like neglect and abuse—on the mental health of both the child and the mother over 30 years.
One of the key questions was why some children who experience high levels of trauma show little evidence of negative outcomes, while others who experience more minor adverse events experience negative mental and physical health outcomes.
‘The most common mental disorders include anxiety, depression and substance use, which together constitute a major disease burden and cost on the health system. The challenge is to track these conditions across generations and identify the contribution of genetic and environmental factors to their generational continuity,’ he explains.
‘Little is known about their causes and patterns of occurrence over the life span.’
‘This study has contributed to knowledge in such diverse areas as the impact of maternal mental health and family poverty on child health outcomes, the link between mental health and such physical health outcomes as obesity, and the development of cardiovascular disease and diabetes,’ Professor Najman concluded.
Next steps
Continuing to follow their lives, the researchers are now turning to the next generation—the ‘children of the children’—looking at the generational transmission of mental illness. A major challenge is to distinguish the impact of grandparents from parents as they predict child health and mental health outcomes.
Professor Najman’s group is also interested in the broader health inequalities that can continue from one generation to the next and how lifestyle and environmental factors through poverty can contribute to these inequalities.
1 J. M. Najman, M. Plotnikova, G. M. Williams, R. Alati, A. A. Mamun, J. Scott, N. Wray and A. M. Clavarino, 2017, Trajectories of maternal depression: a 27-year population-based prospective study. Epidemiol Psychiatr Sci. 2017 Feb;26(1):79-88. doi: 10.1017/S2045796015001109. Epub 2016 Jan 19
