For starters, antidepressants don’t work for more than half the people who take them. New findings from an investigation at Northwestern University’s Feinberg School of Medicine suggest that antidepressants fall short because they’re aimed at the wrong biochemical targets in the brain.

Research led by Northwestern psychiatry professor Eva Redei, Ph.D., using rats (their brains are remarkably similar to ours in areas related to depression), suggests that antidepressants are more suited to treating stress than depression and undermines the belief that stress itself can be a major cause of depression.

Redei’s research further suggests why antidepressants that aim to boost levels of the neurotransmitters serotonin, norepinephrine and dopamine are also often ineffective. Her team did not find the dramatic differences in the levels of genes controlling the function of these neurotransmitters that would be expected if depression were related to their activity.

In a Neuroscience 2009 conference presentation, Redei concluded that today’s antidepressants have been focusing primarily on the effects of depression, not its cause. Renowned integrative physician Andrew Weil comments that in his view, meditation and regular aerobic exercise are more effective depression busters.