How parents treat their adolescent children, including the way they discipline them, as well as the kind of life events and social interactions teenagers experience, can affect an adolescent's risk of depression, regardless of any genetic predisposition towards the mental illness.
These findings from researchers at King's College in London, published in the November/December issue of the journal Child Development, suggest that the environment in which teenagers find themselves has an impact on their risk of depression independent of their genetic background, which is already known to be a strong predictor of depression.
The findings are important because teenage depression is a major contributor to teenage suicide. While previous studies found that individual environmental aspects in a teen's life (which may include favoritism in parenting, bullying of one child but not a sibling, and different friendship circles), are more important than shared environmental factors between siblings (which may include family poverty) in determining the risk of depression, very little research has considered the influence of genetics compared to environmental aspects on the development of depression.
To investigate this question, the researchers asked 328 identical twins aged 12 to 19 and their parents to complete information about depressive symptoms, parenting measures, life events and peer group characteristics.
Questions assessed the use of punitive discipline (i.e., do the parents yell at their children when the child has done something wrong) vs. constructive discipline (i.e., do parents talk to their child when the child has done something wrong), adverse events the child could not control (such as the death of a parent or close friend, or a parent's loss of employment) and adverse events over which the child had some control (such as breaking up with a boy/girlfriend and suspension from school).
They found that the twin with the greatest number of adverse events over which they had some control (twin A) was most likely to have higher levels of depressive symptoms, particularly if their co-twin (twin B) had suffered multiple uncontrollable adverse life events.