Antidepressant medications taken by roughly 7 percent of American adults effect profound personality changes in many patients with depression, far beyond simply lifting the veil of sadness, a study has found – raising the possibility that a basic shift in personality is what drives the cure.
The study, published last week, found strong downward shifts in levels of neuroticism and extraversion in patients taking antidepressants, two of five traits thought to define personality and shape a person’s daily thoughts and behavior. The findings are striking, researchers said, because psychologists have long thought that such fundamental traits are moorings of an adult’s personality that shift very little over a lifetime.
The medications would seem to relieve depression by chemically altering brain processes that spawn the negative thoughts to begin with rather than just alleviating symptoms associated with a depressed state, said Northwestern University psychologist Tony Z. Tang, the lead author of the study.
The findings, published in the journal Archives of General Psychiatry and funded by the National Institute of Mental Health, could have significant implications for depression treatment, researchers not connected with the study said.
It is unclear how long-lasting the changes in personality are, the authors said. But the study found that patients whose personalities shifted the most were less likely to fall back into depression once treatment had ended.
In the study, 240 adults with moderate to severe depression participated in a trial designed to compare the benefits of medication and cognitive therapy.
Of these, 120 were given the selective serotonin reuptake inhibitor paroxetine (Paxil) for 16 weeks. Another 60 received cognitive therapy but no medication for 16 weeks, and 60 others were given a placebo alone for eight weeks.
All subjects who reported improvements in their depression in response to psychotherapy or medication were followed for a year.
Patients who received paroxetine were more likely to have their symptoms ease, and they also showed more dramatic changes in personality.
Those given placebo pills did report early improvements in depressive symptoms almost as great as those reported by those on medication – at the eight-week mark of the study.
But their underlying personalities “didn’t budge,” said Northwestern’s Tang. And their relief from depressive symptoms was more muted and less lasting than the improvement of those on medication or cognitive therapy. They were given the antidepressant if their condition failed to improve after eight weeks.
The findings figure to rekindle debate on the effectiveness of selective serotonin reuptake inhibitors, or SSRIs, on which Americans spent $9.6 billion last year. SSRIs increase the levels of a key brain chemical, serotonin, low levels of which are linked to depression.