Specific brain areas, mechanisms associated with depression, anxiety

More than 350 million people worldwide suffer from clinical depression and between 5 and 25 percent of adults suffer from generalized anxiety, according to the World Health Organization. The resulting emotional and financial costs to people, families, and society are significant. Further, antidepressants are not always effective and often cause severe side effects.

Today's new findings show that:

• A molecule in the immune system may contribute to depression, suggesting a potential biomarker for the disease
• Decreasing a chemical signal in the amygdala, a brain area associated with emotional processing, produces antidepressant-like effects in mice
• MicroRNAs, tiny molecules that alter gene expression, correlate with how mice respond to socially stressful situations that cause depressive-like behavior. The findings may help determine why some people are more likely to suffer from depression than others

Other recent findings discussed show that:

• A pathway between two brain regions, the amygdala and the hippocampus, plays a significant role in anxiety. Shutting down this connection can decrease anxiety-like behavior in mice
• Aversive experiences can change how humans, particularly those with anxiety disorders, perceive stimuli. After a severe negative incident, patients with anxiety disorders over-generalize the experience and have increased emotional responses to subsequent similar situations

"Today's findings represent our rapidly growing understanding of the individual molecules and brain circuits that may contribute to depression and anxiety," said press conference moderator Lisa Monteggia, PhD, of the University of Texas Southwestern Medical Center, an expert on mechanisms of antidepressant action. "These exciting discoveries represent the potential for significant changes in how we diagnose and treat these illnesses that touch millions."