Nicotine Offers Clue To Biology Of Schizophrenia
Scientists have found an intriguing association between a gene linked to nicotine and a trait common among schizophrenics, an inability to filter information.
The finding could lead to novel drug treatments and might explain a puzzling phenomenon: Many schizophrenics are heavy smokers.
“This finding gives us an anchor,” said Dr. Robert Freedman, a professor of psychiatry at the University of Colorado and the Denver Veterans Affairs Medical Center. “We’ve long known that 80 percent of schizophrenics smoke. Now, it looks like nicotine may be a clue to the biology of the disease.”
Freedman said his research shows that the information-filtering problem can occur not only in schizophrenics but also in their non-schizophrenic family members, suggesting that other genes, viruses or environmental events probably are necessary to trigger the devastating brain illness.
The findings are to be published today in the Proceedings of the National Academy of Sciences.
The Colorado researchers tested 104 people in nine families, each with at least two schizophrenics. Freedman recorded brain-wave activity while subjects listened to sounds and found that many schizophrenics and their family members had problems processing the sounds.
Freedman traced the physiological defect through the nine families and found an exact area on chromosome 15 was critical to the inheritance of this processing problem, he said.
Animal studies by the team found that the brain chemical acetylcholine normally works at the so-called nicotinic receptor to alert the rest of the brain about the importance of a particular stimuli and screen out trivial information. Nicotine also can stimulate these receptors, perhaps giving schizophrenics a brief period of calm and explaining why they often are chain-smokers.
“It (the study) gives us a handle on one neurobiological event associated with schizophrenia,” said Dr. Elliot S. Gershon at the National Institute of Mental Health.