An American study has found that stress in adolescent rats better prepares them for adulthood.

A rat exposed to stress during adolescence is better equipped for handling challenges of adult life, according to researchers from Penn State University.

A number of studies have focused on this subject and the consequences of stress related to poor environmental conditions or intimidation or abuse in children and teens. Results have shown that this kind of environment could be associated with behavioral changes as well as changes in the cognitive and physiological abilities of teenagers, however very few longitudinal studies exist on the subject.

To better study this phenomenon on animal subjects, the researchers chose rats as they have a short lifespan, making it easier to identify long-term effects of stress.

The study consisted of exposing rats to different levels of frequent and erratic physical and social stress over a period of time equivalent to that of adolescence. The rats were placed in cages of reduced size, tilted or overcrowded. They were also socially isolated from each other and subject to predatory sounds and smells. After five weeks, the researchers subjected the animals to a series of tests in both standard and high-stress conditions to identify the durable effects of stress and evaluate their capacity to resolve tasks.

When the rats were subjected to stressful conditions, the adult rats that had experienced similar conditions during their adolescence showed a tendency to forage for food sooner than other rats and visited 20 per cent more food patches. This group of subjects obtained 43% more food than rats that had not been previously exposed to stress. Exposed to standard, stress-free conditions, the same rats took their time to forage for food while their counterparts began searching for food sooner.

The results, published in the October edition of the journal Animal Behavior indicate that these animals solved problems and tackled obstacles more efficiently in stressful situations. They also presented no cognitive decline.

The research team outlined that unpredictability was at the core of the experiment. "Unpredictable stress can have dramatic and lasting consequences, both for humans and free-living animals. Unpredictability is part of what can make stress so toxic. You don't have control over your environment, you don't have control over what's going to happen next, you're not able to predict it," outlined Lauren Chaby. Although exposing the rats to stress during adolescence better prepared the rats for the unpredictable aspect of stress, there may still be a cost in the longer term, both for animals and humans, noted the researchers, who hope the results can help provide insights for approaches to studying adolescent stress in humans.