New research has discovered a link between a particular gene variant in children and wider mood swings.
Children with this variant tend to react with more aggression in negative situations but also react more positively during the good times, according to the researchers from the Norwegian University of Science and Technology (NTNU).
In any random group of people (children and adults), some will react more strongly to stress, while others will maintain their composure in nearly any situation. Genes can at least partly explain this phenomenon, and in this particular case, the gene being studied is involved in dopamine breakdown in the brain.
For the study, the researchers, led by Beate W. Hygen of NTNU’s Department of Psychology and NTNU Social Research, found a correlation between aggression and a particular gene variant present in children whether or not they had experienced serious life events.
This finding was a confirmation of previous studies, but the Norwegian researchers also found that children who were more aggressive when they were exposed to stress were the least aggressive when they were not exposed to stress. This indicated that they had a tendency to greater variation in behavior in both directions than their less aggressive counterparts.
The findings help support “differential susceptibility,” a theory which suggests that some individuals are more susceptible to environmental conditions, for better or for worse, partly because of their genotype.
Previously, scientists thought that some children are more vulnerable than others when experiencing trauma or stress, and that these vulnerable children function on an equal footing with others in positive environmental conditions.
Differential susceptibility theory, however, suggests that those individuals most affected by adverse conditions may also benefit most from positive conditions. In other words, these individuals function better under positive environmental influences than those who are not as susceptible to environmental conditions.
The researchers suggest that having more emotionally intense or aggressive individuals among us may not be such a bad thing. In fact, it may be a helpful adaptation to society.
For example, in a stable situation with adequate resources, people with a stable temperament will have an advantage, while those with more aggressive temperaments are more likely to overreact to slighter problems.
However, as soon as conditions change, such as an increase in the struggle for resources, those who react more strongly to external influences may have the advantage. Therefore, the best scenario, according to some experts, would be for a population to have a broad mix of people with varying tendencies to react aggressively.
The results of the Norwegian study were recently published in Developmental Psychology.