Nicotine might help to treat people with Parkinson's disease or Alzheimer's disease, according to preliminary findings presented recently at the annual meeting of the American Association for the Advancement of Science.
Dr Paul Newhouse (University of Vermont college of medicine, US) explained that previous studies had shown a marked reduction in cortical nicotinic receptor binding that paralleled the degree of dementia in Parkinson's disease and increasing age. There was a similarity between the binding site loss in Parkinson's disease and that in Alzheimer's disease. Nicotine had been found to induce the release of dopamine from the striatum and thus might protect nigrostriatal neurones from degeneration.
Dr Newhouse said that the study involved 15 patients with mild-to-moderate Parkinson's disease and took place in two phases. In the first phase, immediate, short-term effects of nicotine on tests for attention and arousal were looked for. Patients were given intravenous doses of nicotine or a placebo, over a period of 30 minutes. Nicotine was found to improve attention and arousal. In the second phase, patients wore a nicotine patch for 16 hours a day for 14 days, with the dose doubled during the second week if the patch was well tolerated. Improvement in three motor performance tests (stand-walk-sit test, finger dexterity test, and tests of hand movements) was seen, which persisted after nicotine withdrawal and started to decline two weeks later.
Overall, the researchers found that treatment with nicotine had positive effects on certain cognitive and motor aspects in early Parkinson's disease, particularly in the area of attention and motor speed. Dr Newhouse commented that the persistence of effects for several weeks suggested sustained increases in the release of dopamine. The development of nicotine and/or novel nicotine agonists for therapeutic augmentation in Parkinson's disease should be continued, he said.