What Causes Anxiety? We May Inherit Mental Illness From Our Parents, Study in Monkey Suggests

Scientists believe the connectivity between the central nucleus of the amygdala and the bed nucleus of the stria terminalis could be passed on in families. Getty Images

The connections in the regions of the brain that contribute to whether we develop anxiety disorders may be something we inherit, according to a study.

Scientists believe the connectivity between two regions, the central nucleus of the amygdala and the bed nucleus of the stria terminalis, could be passed on in families, according to research in monkeys.

A team at the University of Wisconsin School of Medicine and Public Health studied 378 preadolescent rhesus macaques. Young ones were chosen, as extreme anxiety in childhood carries a risk factor for anxiety and depression in humans.

The researchers hope their findings, published in The Journal of Neuroscience, form a basis for further studies to identify risk factors for anxiety in children.

Dr. Ned Kalin, professor in the department of psychiatry at the University of Wisconsin School of Medicine and Public Health, told Newsweek, "We are continuing to discover the brain circuits that underlie human anxiety, especially the alterations in circuit function that underlie the early childhood risk to develop anxiety and depressive disorders.

"In data from a species closely related to humans, these findings strongly point to alterations in human brain function that contribute to the level of an individual's anxiety. Most importantly, these findings are highly relevant to children with pathological anxiety, and hold the promise to guide the development of new treatment approaches."

Kalin leads an ongoing brain-imaging study of risk in anxious preteen girls, and is about to launch a second study of both boys and girls with clinically significant anxiety disorders.

But while the study is illuminating, Jonathan Oler, co-author of the study and an associate scientist at the University of Wisconsin-Madison School of Medicine and Public Health, told Newsweek it was limited by the fact that the connectivity only accounts for around 4 percent of the variance in the anxious temperament measure.

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"This is not at all surprising, as most genetic studies of psychiatric disorders often identify effects that only account for very small proportions of the variance," Oler said, indicating that this connectivity related to anxiety was "not the whole story."

"We need to keep studying this model to get the full picture of the complex neural and genetic mechanisms that underlie anxiety and anxiety disorders," he said.

Anxiety disorders include generalized anxiety disorder, where a person worries excessively; panic disorder, where sufferers are hit with panic attacks; and social anxiety disorder, characterized by a fear of social or performance situations.

Current treatments focus on dealing with the symptoms of anxiety disorders but do not stop them from developing. Psychotherapies such as cognitive behavioral therapy are commonly used to treat anxiety, as is medication that can ease physical and mental symptoms.

Such research is vital, considering around 40 million adults between 18 and 54 years old are affected by anxiety, according to the National Institute of Mental Health.

No one thing causes an anxiety disorder, scientific research suggests, though experiencing stressful life events, being female, socioeconomic status, and having a parent experiencing mental illness can be factors.