A new study from the United States reveals how stress early in life leads to a disruption in the functioning of the brain’s reward circuitry, which could be at the root of several important mental disorders.
- Stress and adversity early in life produce a disruption in the development of the brain’s reward circuitry in mice, reducing pleasure as well as motivation for pleasure, food, and sexual cues.
- This discovery offers a new therapeutic target for the treatment of certain mental illnesses.
- Impaired function of the reward circuitry could underlie several major disorders, such as depression, substance abuse, and excessive risk taking.
University of California researchers have discovered a new brain connection that explains how early life stress and adversity lead to disrupted functioning of the brain’s reward circuitry. This discovery offers a new therapeutic target for the treatment of certain mental illnesses, since the altered function of this circuit could be the basis of several major disorders, such as depression, drug addiction and excessive risk-taking, according to several scientific works. .
In an article published online February 25, 2023 in the journal NatureCommunicationsresearchers Tallie Z. Baram and Matt Birnie describe cellular changes in brain circuitry caused by exposure to adversity and stress during childhood.
Brain: Childhood stress disrupts reward behaviors
“We know early life stress impacts the brain, but until now we didn’t know how.said Tallie Z. Baram in a communicated. We discovered a new pathway in the reward circuitry, the basolateral cerebral amygdala-nucleus accumbens pathway, which expresses a molecule called corticotropin-releasing hormone that controls our responses to stress. We found that negative experiences make this brain pathway overactive.”
“These pathway changes disrupt reward behaviors, reducing pleasure as well as motivation for pleasure, food, and sexual cues in mice”, she adds. Before continuing: “In humans, such behavioral changes, called ‘anhedonia’, are associated with emotional disturbances. Importantly, we have found that when we silence this pathway using modern technology, we let’s restore the brain’s normal reward behaviors.”
The differential effect of early stress by gender remains to be studied.
The researchers studied two groups of male and female mice. One was exposed to stress and adversity early in life living for a week in cages with little bedding and nesting material, and the other was raised in normal cages. In adulthood, male mice in the first group (but not females) had little interest in sweet foods or sexual cues compared to mice in the second group. In contrast, females in the adversity group were more attracted to rich, sugary foods. Inhibition of the above brain pathway restored normal reward behaviors in males, but had no effect in females. “Future studies are needed to increase our understanding of the differential and gender-specific effects of early adversity on behavior” notes Dr. Baram.
“Our findings provide groundbreaking insights into the impact of early life adversity on brain development and the control of reward behaviors that underlie many emotional disorders, and identify an important new therapeutic target”concludes the researcher.
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