MAO-B a target for developing depression treatments

A new CAMH study shows for the first time that people experiencing clinical depression have higher levels of a brain protein called MAO-B. The finding – published online today in JAMA Psychiatry – opens the door to a new area of exploration for developing depression treatments. Depression affects an estimated 15 per cent of people over their lifetime, and is the leading cause of disability worldwide.

“Half of the people with depression had higher MAO-B levels than those without the illness,” says Dr. Jeffrey Meyer, Canada Research Chair and Scientist in CAMH’s Campbell Family Mental Health Research Institute. “The most commonly prescribed antidepressants aren’t designed to act on this brain protein, making this a new focus for developing treatments different from the usual medications.” Most antidepressants work on the brain chemical serotonin.

MAO-B plays roles in keeping the brain healthy, including getting rid of an excess of the brain chemicals dopamine and norepinephrine, and creating signals promoting the turnover and death of old cells. “The brain needs these functions,” says Dr. Meyer, senior author of the study. “But when MAO-B levels are elevated, we see this as an imbalance that may lead to depression.” For example, higher levels of MAO-B may deplete dopamine and norepinephrine, which are involved in brain pathways that are essential for maintaining a healthy mood and experiencing enjoyment. At the same time, higher levels of MAO-B, through a process called oxidative stress, may affect memory and concentration.

In the past, MAO-B was thought to be unimportant in depression, so the only antidepressant medications that target it have extremely difficult side-effects or tend to be very expensive. For example, in the case of a medication called EMSAM, available in the U.S. only, costs may be up to a couple thousand dollars monthly. For these reasons, less than 1% of people with depression take an antidepressant medication that affects MAO-B.

Source: CAMH study reveals a new target for developing treatments for depression