Uneasy Inheritance

Scientists from the University of Maryland and partner institutions have discovered a brain circuit that appears to play an important role in the transmission of extreme anxiety from parents to their offspring.

Building on recent advances in genetics and brain imaging, the new study marks the first demonstration that neural connections in the central extended amygdala—a brain structure associated with fear—play a role in the genetic transmission of extreme anxiety.

"This work provides invaluable new clues about the brain circuits to focus on in human patients, especially youth, and promises to accelerate the development of new treatments for early life anxiety," said Alex Shackman, a professor in the Department of Psychology and Neuroscience and Cognitive Science program at UMD and a co-author of the study published in the Journal of Neuroscience.

Although anxiety disorders are consistently ranked among the top 10 causes of global disability and sickness by the World Health Organization, existing treatments frequently are ineffective and sometimes have significant side effects.

Like other mental illnesses, anxiety disorders are heritable: Parents who are anxious are more likely to have children who suffer from extreme shyness, inhibition and anxiety. Yet the brain circuits underlying the intergenerational transmission of extreme anxiety have long remained mysterious.

Researchers in the new study, conducted with colleagues at the University of Wisconsin-Madison and the California National Primate Research Center, used the same brain imaging techniques used in human studies to study young rhesus monkeys, who express anxiety in similar ways to human children.

The sample size—an extended family of nearly 2,000 individual monkeys—“increases our confidence in the replicability and robustness of these effects,” says Shackman, who leads several other ongoing brain imaging studies at the University of Maryland aimed at understanding the role of this circuitry in mood and anxiety disorders in adolescents and young adults.