Research shows chronic stress in early life may cause anxiety and aggression in adulthood


2014-03-28 11:08
Mice

Stress early in life not only causes uncomfortable feelings for kids, it may also lead to problems later in life. Kids often share their negative feelings about being stressed too much by acting up. It is always a relief to see a kid smiling and playing when that stress is lifted. New research shows by keeping life as stress free as possible for kids you are probably also helping them achieve better mental health later in life.

People who are exposed to social stress in childhood may be predisposed to developing psychoemotional disorders in adulthood, reports PLOS One. Researchers used an animal model in order to determine the influence of a hostile social environment in adolescence on behavior which occurs during adult life. An adult aggressive male mouse was placed in a common cage with one-month-old adolescent male mice for 2 weeks.

The mice were separated by a transparent perforated partition. However, the adolescent male mouse was exposed to short attacks everyday from the adult male. After they were exposed to social stress, some of the adolescent mice were placed in comfortable conditions for 3 weeks. After a period of rest a range of behavioral tests were used in order to study the stressed young males and adult males with an interest in evaluating levels of anxiety, depressiveness, and communicativeness experienced with an unfamiliar partner. Adult mice who were exposed to social stress in adolescence were found to be engaged in agonistic interactions.

The researchers observed that 2 weeks of social stress resulted in a lowering of communicativeness in the home cage and diminished social interactions when on novel territory. Stressed adolescents demonstrated a high level of anxiety and helplessness. Most behavioral characteristics in different tests did not differ from those of the respective control mice after 3 weeks of rest. However, it was observed that the level of anxiety remained high in adult males who were exposed to chronic social stress in childhood. Also, it was observed that these males were more aggressive in the agonistic interactions. It was therefore concluded that a hostile social environment in adolescence disturbs psychoemotional state and social behaviors of animals during their adult life.

Neurobiologists have found that chronic stress in early life causes anxiety and aggression in adulthood, reports Cold Spring Harbour Laboratory in a review of this research on March 27, 2014. A research team led by Associate Professor Grigori Enikolopov of Cold Spring Harbor Laboratory (CSHL) reported that their research indicates a “hostile environment in adolescence disturbs psychoemotional state and social behaviors of animals in adult life.”

In the research the young males were exposed daily to short attacks by the adult males. This type of chronic activity produces what neurobiologists refer to as social-defeat stress in the young mice. A range of behavioral tests were than used to study these mice. Enikolopov said, “The tests assessed levels of anxiety, depression, and capacity to socialize and communicate with an unfamiliar partner.”

It was revealed by the tests that in young mice, chronic social defeat was associated with high levels of anxiety and helplessness. There was also less social interaction observed in these mice, including a decreased ability to communicate well with other young animals. Furthermore, the portion of the hippocampus which is known to be affected in depression, the subgranular zone of the dentate gyrus, showed less nerve-cell growth in the stressed mice.

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