Scientists find link between nicotine, schizophrenia

WASHINGTON (AP) — Scientists have located a gene that may increase the risk of inheriting schizophrenia — a finding that, in an unusual twist, could also explain why many schizophrenics chain smoke.
Essentially, nicotine appears to briefly override a brain defect characteristic of the devastating mental illness, providing frenzied patients a few minutes of calm, researchers reported in today’s edition of Proceedings of the National Academy of Sciences.
“Schizophrenics are the most heavy smokers of any psychotic patients,” said Dr. Robert Freedman of the Denver Veterans Affairs Medical Center. “They had discovered this (effect) before we had, and it had been overlooked as a clue to the biology of schizophrenia.”
At issue is the inability of many schizophrenics to filter out unnecessary sights, sounds and other stimuli — that tapping tree branch or the refrigerator hum that healthy people can ignore — so they essentially suffer information overload.
Freedman and colleagues at the University of Colorado discovered that this trait is inherited. And they linked a gene that appears responsible for that to a brain receptor that helps filter information, a receptor that can be stimulated by nicotine.
That means schizophrenics who smoke get enough nicotine to switch on this receptor for brief relief, Freedman explained. “All the patients report they feel great after a cigarette,” he said.
The study is “an excellent piece of work,” said Dr. Elliott Gershon, neurogenetics chief at the National Institutes of Health.
But Gershon cautioned that while Freedman has strong evidence linking this schizophrenia trait to the nicotine receptor gene, he doesn’t yet have proof — especially because Freedman has not found the gene mutation that would cause it.
Still, “it’s an important step forward” that points to a potential new target for drug therapy, Gershon said.
Indeed, while Freedman is searching for the mutation, he has begun working with drug companies to find treatments that target this receptor.
“We certainly don’t recommend people take up smoking to try to combat their schizophrenia because the effect literally lasts just a few minutes” and smoking causes killer diseases like lung cancer, he stressed. But the findings are “reassuring to family members who wonder why their (schizophrenic) children can’t stop smoking.”
Some 4 million Americans suffer schizophrenia, a mental illness characterized by hallucinations, delusions, bizarre behavior and the inability to feel pleasure.