Running From Depression?

Aug. 22, 2008— -- Watching the best athletes in the world in the Olympics, with their fit and trim physiques, has me thinking about exercise. We all know it is great for cardiovascular health, but what about for mental health? Does swimming five miles a day put Michael Phelps in a good mood?

An article in this month's "Archives of General Psychiatry" suggests that, as we might expect, regular exercise is associated with reduced symptoms of depression and anxiety.

But there is a bit of a surprise: The researchers also found that exercise did not appear to cause decreased depression and anxiety. Instead, common genetic factors seemed to underlie both a predisposition to exercise more and a predisposition to experience less depression and anxiety.

The study took advantage of a Dutch sample of almost 6,000 twins. For any given individual, exercising more when measured at a given time point correlated with fewer mood symptoms at the same time point.

But for identical twins, who are genetically the same, more exercise in one twin predicted fewer mood symptoms in the other. This did not hold for fraternal twins, who are only halfway similar genetically.

It was also noted that for any individual, more exercise at one time point did not predict fewer mood symptoms at a later time point.

The message: happy people are exercise-friendly people.

But what about the "runner's high"? Many people have heard about how exercise increases beta-endorphin, a natural opiate in the brain that is associated with feeling good. A study published earlier this year that scanned the brains of runners did show increased release of this natural buzz chemical and a correlation of its release with perceived euphoria.

There is also evidence that exercise can increase levels of the brain chemicals serotonin and norepinephrine, neurotransmitters which have long been known to play a role in mood regulation. The antidepressants all boost levels of these same chemicals.

A group at Yale University led by Ronald Duman examined the "runner's high" in running mice. In a paper published last year in Nature Medicine, they observed that a week of exercise in mice led to changes in the expression of genes in their brain, including an increase in one called VGF, which promotes growth of brain cells.