Early exposure to a hostile environment causes long-standing behavioural problems in mice.
Neuroscientists have found that social stress early in life can cause long-term problems with anxiety and aggression.
The conclusion comes from experiments on mice which were exposed to chronic levels of stress at a young age (Kovalenko et al., 2014).
The mouse equivalents of adolescents were placed in a cage with an aggressive mouse for two weeks.
Although the mice were separated from each other, the adolescent was exposed to repeated short attacks from the aggressive adult mouse.
After their experience, the mice’s behaviour was tested.
The stressed mice showed high degrees of social defeatism, a lack of enthusiasm for social interaction and a lower ability to communicate with others.
Their brains also showed less growth in an area of the hippocampus that is affected in depression.
Abnormal aggression
Another group of mice were given a rest period after the exposure to the aggressive adult mice.
During the rest period, these mice recovered in terms of their brain cells and their behaviour.
However, they were still abnormally anxious and aggressive.
One of the study’s authors, Dr Dr. Enikolopov, explained:
“The exposure to a hostile environment during their adolescence had profound consequences in terms of emotional state and the ability to interact with peers.”
Image credit: PixCat
