MRI reveals weak links to amygdala in patients with anxiety
The brains of people with generalized anxiety disorder (GAD) have weaker connections between the anterior cingulate cortex, the brain structure that controls emotional response, and the amygdala, according to a study published Sept. 4 in Archives of General Psychiatry. The findings suggest the brain's "panic button" may stay on due to lack of regulation.

Anxiety disorders are the most common class of mental disorders and GAD, which is characterized by excessive, uncontrollable worry, affects nearly 6 percent of the population.

Do P. M. Tromp, MS, of the Waisman Laboratory for Brain Imaging and Behavior at the University of Wisconsin School of Medicine and Public Health in Madison, and colleagues, recruited 49 patients with GAD and 39 healthy volunteer control subjects to undergo diffusion-tension imaging and functional MRI (fMRI) scans.

Compared with the healthy volunteers, the MR images showed the brains of people with GAD had reduced connections between the prefrontal and anterior cingulate cortex and the amygdala via the uncinate fasciculus, a primary white matter tract that connects these brain regions. This reduced connectivity was not found in other white matter tracts elsewhere in their brains.

"We know that in the brain, if you use a circuit you build it up, the way you build muscle by exercise,'' Jack B. Nitschke, PhD, of University of Wisconsin, said in a release.

According to Nitschke and colleagues, the weak connection may result in the intense anticipatory anxiety and worry that is the hallmark of GAD, because the anterior cingulate cortex is unable to tell the amygdala to "chill out." It also suggests that behavioral therapy that teaches patients to consciously exercise this emotional regulation works to reduce anxiety by strengthening the connection.

The researchers identified the need for additional research to determine how worry affects neurobiological characteristics.