Supervisor: prof Jaanus Harro
Opponent: dr Nela Pivac (Ruđer Bošković Institute, Zagreb, Croatia)
Although development of the application of molecular genetic strategies to psychiatric genetics started in 1980s, we are still searching for a new genes associated with behavioural phenotypes or psychiatric disorders. We are still in our way towards understanding of gene-environment interplay. In this dissertation I could contribute to this field with new knowledge on gene-environment interplay within a population representative sample of adolescents and young adults. Thus, it is possible to generalize the results to healthy people and general population. I studied gene x environment interactions on behaviour within three different genes and found family relations to be an important contributor to gene-behaviour association in all three genes. Adolescents with certain genotype were more vulnerable to adverse family relations than adolescents with another genotype of the same gene. Vulnerability revelad in higher impulsivity or depressivity, that are traits associated with many psychiatric disorders. But genetically driven deficits would not have been maintained throughout evolution if they only exerted negative effects without conveying any gain of function. Our results support the notion that "vulnerability genes" might, at times, be more appropriately conceptualized as "plasticity genes", because they seem to make individuals more susceptible to environmental influences-for better and for worse. For example I found that in the presence of life adversity, males with a certain genotype have to pay the price in featuring higher maladaptive impulsivity and accordingly increased risk for related psychopathology. Under positive conditions, males with the same genotype display increased adaptive impulsivity and extraversion. Thus, good family relations might prevent developing traits associated with psychiatric disorders and help to reveal best traits in subjects with malleable genotype, although single gene x environment effect on behavior is very small.