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BEDREHELSE-Bedre helse og livskvalitet

A gene-environment model for the study of the development of mental problems in youths

Awarded: NOK 6.0 mill.

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Project Period:

2012 - 2016


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Mental health includes both mental illnesses/symptoms and mental strengths/resources. Knowledge about the causes behind youth mental health problems and resources is important both for understanding and intervention. Results based on data from our twin study shows that the variation in both difficulties (experienced loneliness) and resources (resilience) is highly rooted in genetic differences. Causes in the environment are associated with conditions that work differently for members of the same family, while common shared environment do not come out with any effect on these characteristics. Symptoms of anxiety are prevalent in adolescence, and therefore a target for both treatment and prevention interventions. Based on a selection of over 1,000 twin pairs between 12 - 18 years, we found a high heritability in anxiety as measured through a combination of reports from mothers, fathers and the youths themselves. The heritability coefficient of anxiety was 65% for boys and 74% for girls, while the remaining variation was explained by elements in the adolescents' environment unique to each twin. The results also showed that each informant contributed with unique perspectives not represented in any of the other informants. Certain psychological problems in adolescence are often associated with other mental health problems, and this can complicate the possibility of improvement and symptom-oriented intervention. One example of symptoms that often correlate among adolescents are anxiety, depression and somatic complaints. In our twin material we found that it was possible to represent these three symptom groups with a common latent factor that was considerably genetic (44%). The three symptom groups also had common environmental sources. 25% of the variation in the latent factor was associated with environmental conditions that differed between twins, while 31% of the variation was explained by factors that were unique to each twin in the pair. The latent factor loaded highest on depressive symptoms and least on somatic complaints, and each symptom group had sufficiently unique cause sources to support that they belong to different disorders.

Investigation of gene-environment interaction and gene-environment correlations is at the front line of modern behaviour genetics. The present application concerns the funding of a diagnostic interview at age 18 yrs. of the remaining two of all together s even national cohorts of adolescent twins. Method: 2800 twins between the ages of 12 to 18 years and their parents have answered a survey every second year in three waves (3.wave completed by the end of 2011). The survey includes a number of scales assess ing anxiety, depression, somatoform, eating, substance abuse, conduct disorders, school behavior, socioeconomic status, life events, integration in society, parenting style and religious orientation. Resilience, self-efficacy, loneliness and subjective we ll-being are also included as potential mediators and moderators. At age 18, DSM-IV axis I (clinical conditions) and Axis II (personality disorders) will be assessed by means of the structural interview (MINI, life time form and SIDP-R). Childhood trauma and adversity will also be assessed. R&D challenges: Testing a top-down model for GxE interaction and rGE in the relationship between life stressors and mental disorders in adolescence. Application potentials: Longitudinal twin studies on the gene/environ ment interplay in mental disorders play an important role in guiding and validating studies from molecular genetics and animal designs.

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Funding scheme:

BEDREHELSE-Bedre helse og livskvalitet