While only one in four Americans now light up, cigarette use hovers near 90 percent among schizophrenics. But for folks with this personality disorder, smoking may be a form of self-medication. Nicotine, it seems, counteracts some of the impairments caused by schizophrenia and the drug most often used to treat it.

In experiments at Duke University Medical Center, nicotine patches boosted schizophrenics’ performance on tests of short-term memory and of mental processing speed abilities with which Haloperidol, the leading antipsychotic drug, interferes. Nicotine also improved participants’ attention spans as they tackled a boring computer task for 14 mind-numbing minutes, reports Duke professor of psychiatry Edward D. Levin, Ph.D., in the journal Neuropsycho-pharmacology.

However, given tobacco’s well-documented health hazards, Levin and his colleagues don’t recommend that schizophrenics cultivate a cigarette habit. But he says the study supports the idea that for schizophrenics, smoking is probably an unconscious attempt to restore some of their blunted mental abilities.