Fostering the development of mental health : risk and promotive factors

The Developmental Origins of Health and Disease (DOHaD) framework posits that foundations of mental health can be traced to the earliest stages of life, namely to the prenatal and early childhood periods. Evidence exists that early life stress (ELS) in childhood, including e.g., physical and emotional maltreatment, and in the prenatal period, including e.g., maternal psychological distress during pregnancy, is associated with adverse mental health and psychological development in the offspring. According to extensive evidence, the adverse effects of ELS extend to mental health in early adulthood, but less is known about whether ELS is associated with the risk of psychopathology still in late adulthood. Moreover, much less is known about whether there may be promotive and protective factors for offspring mental health during pregnancy, such as positive maternal mental health. This thesis investigates the associations of positive maternal mental health during pregnancy, including maternal positive emotions and social support, with mental health and cognitive development in the offspring, utilizing two prospective longitudinal pregnancy cohorts. Furthermore, the thesis investigates the associations of childhood ELS with late adulthood anxiety, utilizing a third birth cohort. The thesis consists of four studies. Studies I−II investigated the associations of positive maternal mental health during pregnancy with child mental and behavioral disorders among 3378 mother-child-dyads (Study I) and with psychiatric problems in children in early and late childhood among 2636 mother-child-dyads (Study II) of the Finnish Prediction and Prevention of Preeclampsia and Intrauterine Growth Restriction (PREDO) study. Study III investigated the associations and timing effects of maternal social support during and after pregnancy on child cognitive development, more specifically general cognitive ability in late childhood, among 5784 mother-child-dyads of the UK-based Avon Longitudinal Study of Parents and Children (ALSPAC) and among 420 mother-child-dyads of the PREDO studies. Finally, Study IV examined the association of ELS, defined here as physical and emotional maltreatment, parental divorce, death of a family member, low socioeconomic status (SES) and separation from parents in childhood, with anxiety symptoms at age 65−77 years among 1872 participants of the Finnish Helsinki Birth Cohort Study (HBCS). The results of this thesis indicated that positive maternal mental health during pregnancy was associated with a lower risk of mental and behavioral disorders from birth to 8.4−12.8 years of age and with lower dimensionally assessed psychiatric problems at 1.9−5.9 and at 7.1−12.1 years of age among children. Furthermore, higher perceived maternal social support during and after pregnancy was associated with higher general cognitive ability among children at 8 years of age; pregnancy emerged as a potential sensitive period for the beneficial effects of maternal social support on cognitive ability in children. The associations in all three studies were independent of maternal depressive and/or anxiety symptoms during pregnancy and of lifetime mental and behavioral disorders. The associations were also independent of later positive maternal mental health. Finally, experiencing physical and emotional maltreatment and lower SES in childhood were associated with higher anxiety symptoms in late adulthood, and these early life adversities and parental divorce in childhood were further associated with a risk of clinically relevant anxiety symptoms. The accumulation of ELS experiences was associated with higher risks of both dimensionally assessed and clinically relevant anxiety symptoms. The findings of this thesis support the DOHaD framework by suggesting that both the prenatal and postnatal environment contribute to the programming of child development, and that this programming extends from early adversities to promotive features such as positive maternal mental health during pregnancy. Positive maternal mental health provided protection also to children exposed to co-occurring maternal psychological distress during pregnancy. The effects of positive maternal mental health during pregnancy may persist throughout childhood. Similarly supporting the DOHaD framework, the findings on the association between ELS and anxiety in late adulthood suggest that the adverse effects of ELS experienced in childhood may extend throughout the life course until late adulthood. Together these findings suggest that preventive efforts to diminish the risk of ELS and to promote positive environments should be directed to early life, already to the prenatal period.