Stress and Adolescence: The Perfect Storm?

Teen Hormone Turmoil

By Jacqueline Ruttimann, Ph.D.,
Cover Story, January 2012 Edition, Endocrine News
The Endocrine Society

Teen Hormone TurmoilAsk meteorologists to describe teenagers and they might say: “partly sunny with a chance of showers, possibly turning into strong gusts and storm conditions.” The turbulent teenage years are often rough for adolescents and parents alike, but this mercurial phase is necessary for youngsters to develop into healthy, independent adults. Yet too much stress can take a toll on a teen and lead to future psychiatric diseases as well as metabolic problems like obesity and anorexia.

“Stress and adolescence have the makings of a perfect storm. There’s a convergence of a lot of bodily and hormonal changes and the brain is still developing. This is also the time of life when many bad things start to happen, such as depression, schizophrenia, anxiety, risk-taking behavior, and drug abuse,” noted Russell Romeo, Ph.D., an assistant psychology professor at Barnard College of Columbia University and moderator of the “Stress and the Adolescent Brain and Behavior” mini symposium at the Society for Neuroscience’s annual meeting in November in Washington, D.C.

Previously, researchers have devoted their energies to adult diseases that emerge after adolescence (see CDC sidebar), but evidence that these diseases crop up earlier is mounting, especially in rodent studies.

Of Mice and Teens

Rodents also experience age-related moodiness. Between 30 and 60 days of age, they undergo somatic, physiological, behavioral, and neurobiological changes akin to puberty in humans and non-human primates.Dr. Romeo detailed a series of experiments conducted by his research group with Sprague-Dawley rats.

The investigators first tested whether prepubescent and adult rats’
stress responses differ, subjecting prepubescent rats (day 30) and adult rats (day 70) to 30 minutes of restraint stress by placing the animals in a wire mesh strainer to inhibit their movement. The team measured adrenocorticotropic hormone and corticosterone levels—two key stress hormones (see HPA axis sidebar)—before and immediately, 30, 60, and 120 minutes after the stressor. The groups had similar hormone concentrations both at baseline and after restraint, but their recovery times differed. Whereas hormones in the adults returned to baseline after 30 minutes, those in prepubescent rats took 2 hours.

Dr. Romeo’s group next looked at what happens among the two age groups during chronic stress. Typically, animals subjected over time to the same kind of stress become habituated so the response is dampened. However, after repeated exposure to stress of some kind, a different stress produces an exaggerated response.

To produce this, the team placed prepubescent and adult rats in
one of three conditions with the mesh strainer: acute stress (30 minutes once), homotypic stress (30 minutes/day for 8 days), or heterotypic stress (30 minutes of cold exposure for 7 days followed on the 8th day by 30 minutes of restraint). The teenage rats reacted differently than the adults. Teens exposed to acute stress had the same results as in the previous experiment, but those exposed to homotypic stress did not become habituated. In the heterotypic stress experiment, they eventually habituated, but it took them longer than the adults.

The same concept is applicable in social bullying, according to Dr. Buwalda; due to personality and social
buffering, not everybody becomes victimized.

To prove this point, Dr. Buwalda’s group used two different rat strains: a male Wistar rat, which is highly domesticated, non-aggressive, and vulnerable to social stress, and a wild-type Groningen rat (from fields near the university) that has highly variable physiology and behavior. Each rat was exposed as an adolescent to a highly aggressive adult male wild-type Groningen rat. Three to six weeks later only the Wistar rats avoided contact with unfamiliar wild-type male as well as female rats. The Groningen rats never changed their behavior. Rats that were socially stressed as adolescents also had a reduced behavioral and physiological response to an adult social stress exposure.

“Rats that experience social stress during adolescence cope better with a social stress in adulthood because they show subordinate behavior,” said Dr. Buwalda, extrapolating that in humans, teen parents could ponder whether they’d want their child to be more subordinate later in life.

Adolescents who weather the worst storms may end up better off in adulthood, he concluded.

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