People with anxiety disorders may have low levels of a brain chemical known as neuropeptide Y (NPY), according to researchers at the National Institute on Alcohol Abuse and Alcoholism (NIAAA). Released during times of stress, NPY works to reduce anxiety. Variations in NPY may explain why some people handle stress better than others, the researchers say.

Found in the brain as well as in other tissues in the body, NPY has been shown to regulate emotion, appetite and weight. The NIAAA researchers looked at gene variations that affect levels of NPY in different people.

In the study, participants were shown images of threatening facial expressions while being monitored with functional brain imaging. Participants with the gene variant associated with the lowest levels of NPY reacted with the most heightened emotions.

In a second study, the participants with the low levels of NPY were shown to have a lower tolerance to muscle pain. Additionally, they reacted more emotionally to pain than other participants.

In a small group of people with anxiety disorders, researchers found that the low level NPY gene variant was more common than other variants. The researchers say that NPY plays an important role as an anxiety-reducing peptide, and the variations in the gene may explain why some people are more resilient under stress than others.