Childhood Stress Can Impair Adult Brain's Reward System

Early childhood stress appears to affect the adult brain’s reward system, according to a new study led by Duke University. The findings suggest a potential pathway by which childhood stress may increase one’s risk of depression and other mental health problems in adulthood.

Previous research has well established that childhood stress is linked to later mental health issues in adults, but exactly why this occurs is less understood. In an effort to investigate this matter further, the researchers used functional magnetic resonance imaging (fMRI) to examine the connection between childhood stress and reward-related brain activity in adults.

The participants were all part of the Fast Track Project, which in 1991 began tracking how children developed across their lives. Beginning in kindergarten, the 72 participants were closely monitored until they underwent brain scans as adults.

Researchers focused on the levels of stress that the participants had been exposed to early in development. At age 26, the subjects took part in an experimental game to assess how their brains processed rewards and positive feedback. The scientists focused on reward-related activity in an area of the brain known as the ventral striatum, measured using fMRI.

“We found that greater levels of cumulative stress during childhood and adolescence predicted lower reward-related ventral striatum activity in adulthood,” said study lead author Dr. Jamie Hanson, a postdoctoral researcher at Duke’s Center for Child and Family Policy and the Duke Department of Psychology and Neuroscience.

The findings showed that early stress, specifically between kindergarten and grade three, was most strongly associated with muted responses to rewards in adulthood. Previous studies have identified this type of brain activity as a marker for increased risk of depression and anxiety.

“In participants with the greatest levels of early stress, we saw the lowest levels of activity in the ventral striatum in response to a reward,” Hanson said.

“We think reward-related ventral striatum activity is an important marker of mental health,” Hanson explained. “Past studies have focused on the processing of threat and negative emotion after early stress. Generating positive emotions may potentially buffer some of the effects of stress.”

The researchers say that a variety of early life stresses may influence whether children will grow up to be at risk for mental health problems. They add that further work in this area may lead to the development of new treatments that will help prevent negative mental health outcomes after childhood stress.

The findings are published in the journal Social Cognitive and Affective Neuroscience.

Source: Duke University

 
Boy with stress photo by shutterstock.