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Study offers insights into the biology of anxiety

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Anxiety disorders are among the most common type of mental disorder in the United States, affecting about 29 percent of adults at some point, according to National Institute of Mental Health statistics. These disorders often appear early on, and among children can cause trouble sleeping, difficulty concentrating, or avoidance of social events.

A recent study sheds new light on the biology of anxiety, identifying a circuit in the brain that is associated with anxious temperament and that’s passed down from parents to children. The findings, which appeared in Proceedings of the National Academy of Sciences, may ultimately lead to better-targeted treatments for anxiety and depression, which has similar biological roots to those of anxiety.

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The study, led by researchers at the University of Wisconsin-Madison, centered on nearly 600 young rhesus monkeys from a large, multigenerational family. Rhesus monkeys are valuable for understanding human anxiety because of similarities in brain function and behavioral responses. Young rhesus monkeys, for instance, behave similarly to young children when faced with anxiety-provoking situations.

The researchers scanned the brains of the young monkeys, some anxious and some not, while exposing them to a mildly threatening situation — a stranger entering a room and not making eye contact. This allowed the researchers to identify brain regions that were overactive in monkeys with an anxious temperament. By comparing this pattern of functioning relevant to anxious temperament with those of related monkeys, the researchers were able to identify a brain circuit that seems to be responsible for parent-to-child transmission of anxiety.

Though researchers have known that anxious temperaments are inherited, they have not understood how they are passed down. Understanding how this occurs and which brain areas are involved can be helpful for developing effective early-life interventions. Around half of kids with extremely anxious temperaments develop an anxiety or depressive disorder later on.

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The circuit the researchers identified as hereditable involved three regions related to survival: the brain stem, the brain’s most primitive area, which is responsible for a reflexive alarm response; the amygdala, an area linked to fear responses; and the prefrontal cortex, which is highly evolved and plays a role in regulating behavior and emotions, including anxiety. All three regions are involved in normal responses to stress or threats, but may become overactive in those with anxious temperaments.

Future research will aim to better understand the chemistry and molecules involved in the overactivity of this brain circuit, said senior author Ned Kalin, chair of psychiatry at the University of Wisconsin School of Medicine and Public Health. This could help not only in the development of new medications, but also in finding other ways to help kids at risk of anxiety or depressive disorders. These may include cognitive training or helping parents interact with kids in certain ways.

“Parents who are anxious themselves, while focused on helping their children, may unintentionally reinforce the tendencies their kids have because of the way they behave,” he said.

Previous research has shown links between biological changes and non-drug-based treatment. Neuroimaging studies of cognitive behavioral therapy in people with anxiety disorders, for instance, have shown changes in brain activation patterns over the course of treatment, which are associated with how well patients respond to the therapy. As scientists understand more about the brain, they hope the research will not only lead to better treatment, but that patients will be matched to the best treatment for them.

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Ami Albernaz can be reached at ami.albernaz@gmail.com.