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No, Nicotine Probably Doesn't
Ward Off Alzheimer's
Mon Feb 7, 5:31 PM ET
NEW YORK (Reuters Health) - The final excuse for smoking -- that it might reduce the risk of developing Alzheimer's disease -- has just been stubbed out, findings from an animal study suggest.[/size]
Past animal and human studies have indicated that nicotine exposure inhibits the formation of amyloid plaque, a key feature of Alzheimer's disease. However, the new study shows that chronic nicotine use appears to worsen the effects of a brain protein called tau, which is responsible for the fibrous tangles that are the other hallmark of the disease.
So, at best, the effects of nicotine are probably canceled out, according to the researchers.
Dr. Frank M. LaFerla, from the University of California at Irvine, and colleagues administered nicotine to a genetically engineered strain of mice that develops Alzheimer's disease.
Nicotine treatment produced an increase in nicotine receptors in the animals' brains that correlated with a dramatic rise in the aggregation and activity of the tau protein. This indicates that the disease-causing effects of tau were worsened, the team reports in the Proceedings of the National Academy of Sciences.
Moreover, in these experiments, chronic nicotine administration had no effect on levels of soluble amyloid, the researchers point out.
The results emphasize the importance of assessing nicotine's affects on all aspects of the disease, they write. "Our findings suggest that the use of nicotine as a potential therapy for Alzheimer's disease should be reevaluated."
SOURCE: Proceedings of the National Academy of Sciences, early edition February 7, 2005.
Copyright © 2005 Reuters Limited. All rights reserved.
Heavy smoking 'may affect memory'BBC News UK EditionThursday, May 19, 2005
Prolonged heavy nicotine use has a negative effect on day-to-day memory, according to research. Researchers from five universities asked smokers and non-smokers to rate their long-term memory, for example remembering to send birthday cards.
They found that smoking significantly impaired memory, with heavy smokers reporting the most errors.
The survey was carried out by teams from Newcastle, Wales, Northumbria, Westminster and Teesside universities.
The survey involved more than 700 people.
Researcher Dr Tom Heffernan, of the human cognitive neuroscience unit at Northumbria University, also tested everyday memory including remembering where people had put things.
The teams also took into consideration how much people smoked - a heavy smoker was classed as having more than 15 cigarettes a week and a light smoker between one and four cigarettes a week.
Dr Heffernan said: "The result of the study revealed that smokers reported more errors in their long-term memory than non-smokers with an additional difference between non-smokers and heavy smokers.
"There was also a significant detrimental effect of cigarette use on everyday memory function.
"For example a typical heavy smoker reported 22% more memory-related problems than a non smoker and around 12% more problems than those who smoked only relatively a small number of cigarettes.
"It is concluded that chronic, heavy smoking is associated with impairments in everyday memory, although the precise nature of the deficits are as yet unknown."
The research was carried out via an internet questionnaire and published in scientific journal Drug and Alcohol Dependence.
Online source link: http://news.bbc.co.uk/1/hi/england/4561437.stmCopyright BBC News 2005
Smoking impacts on prefrontal attentional network function in young adult brains. Psychopharmacology (Berl), August 2006 [Epub ahead of print]
Musso F, Bettermann F, Vucurevic G, Stoeter P, Konrad A, Winterer G.
Department of Psychiatry, Heinrich-Heine University, Bergische Landstr. 2, 40629, Duesseldorf, Germany.
RATIONALE: There is abundant evidence from clinical and preclinical studies that acute administration of nicotine has beneficial effects on attentional network function in the brain. In contrast, little is known about potentially neurotoxic effects on the attentional network during neurodevelopmentally critical periods, such as during adolescence and early adulthood.
METHODS: Using event-related functional MRI (fMRI), we investigated prefrontal attentional network function in young adults (n=15 regular smokers and n=12 never-smokers; age: 22.61.5 years). Duration of smoking was 6.92.3 years (range of 2-10). Smokers were allowed to smoke ad libitum before the fMRI scanning was conducted.
RESULTS: As expected from literature, prefrontal attentional network activity was significantly reduced in smokers compared to nonsmokers (Z=2.1; P=0.036). In smokers, we found that the history of smoking duration (years) is directly related to the extent of diminished attentional network activity (R=-0.67; P=0.012).
CONCLUSIONS: To our best knowledge, the relationship between the duration of smoking history and prefrontal attentional network function has not yet been reported. This finding might suggest that several years of chronic nicotine abuse may be sufficient to exert long-lasting effects on the brain function of adolescents and young adults.
PMID: 16937098 [PubMed - as supplied by publisher]