It wasn't that the depressed patients suddenly became happy-go-lucky, carefree social butterflies, Tang said. On scales of extraversion and neuroticism, their levels were still barely in the normal range -- but they were better than they were before.
Relapsing after stopping treatment, or even while still receiving treatment, is a problem for people with depression. About two-thirds of patients relapse within a year of halting medications, while about 45 percent to 50 percent relapse even if they're still on medication, Tang said.
"Our findings seem to suggest one of the very good predictors for how well you'll do over the long term is how much your personality changes in response to the medication," he said. "For example, how much your neuroticism improved predicted how likely you were to relapse in a year after the treatment."
Bernard Carroll, scientific director of the Pacific Behavioral Research Foundation in Carmel, Calif., said any excitement over the results should be tempered by the fact that the improvements in depression from taking paroxetine weren't much better than from a placebo or cognitive therapy.
"The study confirms that paroxetine is not an especially effective antidepressant drug," said Carroll, past chairman of the U.S. Food and Drug Administration's (FDA) advisory committee for psychiatric drugs. "In this sample, it barely beat the placebo."
Instead, paroxetine is more commonly prescribed for anxiety disorders, which is why researchers may have noted the personality changes. "Paroxetine wouldn't be anybody's number one choice for depression," Carroll said. "But it just might make sense that improving certain personality dimensions helps the patient's resilience against future relapse."
Deciding whether to take an SSRI or not has to be weighed against possible side effects, Carroll said, citing a recent study
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