Browsing by Author "Mikkonen, Janne"

Studies on the intergenerational transmission of depressive symptoms form a long research tradition. Numerous studies have indicated that children of depressed mothers face an up to 3-fold risk of exhibiting depressive symptoms later in life compared with those children whose mother has not had depressive symptoms. Later studies have observed that paternal depressive symptoms pose an almost equal risk factor particularly for boys. After having established the association between parental and offspring depressive symptoms, research has focused on exploring the mechanisms underlying the transmission of risk. These are also the principal point of interest in the present thesis that gives particular weight to the role of gender, socioeconomic circumstances (parental education and household income) and timing of exposure, belonging to often-hypothesized but seldom-examined shapers of the transmission of risk. Besides these, the study sheds light on the significance of gender of which previous research has produced mixed results. The interpretation of the results leans on the conceptual framework of life course epidemiology, which understands the development of a disease or a disorder as the outcome of biological, psychosocial, and environmental processes that entangle with each other throughout the life course. The study utilized the register-based EKSY014 data set that contains a 20% random sample of all Finnish households with at least one child aged 0-14 years at the end of 2000. Information on the purchases of prescription medicines and visits to inpatient and outpatient care were used as proxy for the incidence of depressive symptoms. Cox proportional hazards regression model, which belongs to the field of survival analysis, was used to compare the event rates between the groups of interest. Exposure to depression of biological parents was measured when persons were 9-14 years old, and the follow-up of an individual’s own depressive symptoms started on the first day of the year the person turned 15 and ended on the last day of the year the person turned 20. Altogether, the principal study population included more than 130,000 persons born between 1986 and 1996. A smaller sub-sample was used to study the effects of an early-life exposure at age 0-5 years and recurrent parental depressive symptoms. According to the analysis, exposure to maternal depressive symptoms at age 9-14 years poses an equally large 2-fold risk for boys and girls. Paternal depressive symptoms put boys at an equal risk as maternal depressive symptoms, but for girls, they pose a smaller 1.5-fold risk. Among those persons who are living with their biological parents, controlling for the effects of socioeconomic factors weakens the association only little and no differences are seen in the risk of intergenerational transmission across the groups of socioeconomic status. Exposure to both maternal depressive symptoms and paternal depressive symptoms poses a bigger risk than a single exposure among both girls and boys. The analysis conducted with the smaller sub-sample implies that an exposure at age 9-14 years poses a bigger risk than an exposure at age 0-5 years. Recurrent exposure to maternal depressive symptoms appears to be a particularly severe risk factor. The results of the study support the life course epidemiological processes of accumulation of risk and chains of risk: Exposure to depressive symptoms in both parents and the long-term chaining of parental depressive symptoms put the person at the greatest risk. Parental depressive symptoms and socioeconomic status appear as largely independent risk factors of adolescent depressive symptoms; thus, those adolescents having a low socioeconomic status and a history of parental depressive symptoms face a particularly elevated risk of exhibiting depressive symptoms. The preliminary analysis did not give support to the assumed sensitive period in the first years of life, but the question should be examined further with a larger sample. Overall, the results advocate a more holistic approach to the prevention of adolescent depressive symptoms, beginning from the identification of familial risk and leading to actions that target all members of the family.