FRIDAY, Oct. 14, 2005 (HealthDay News) -- Smoking can cloud the brain, according to a new study that found long-term tobacco use was linked to dulled thinking and lower IQ.
The finding contradicts what many smokers claim -- that smoking a cigarette helps them concentrate and feel more alert.
"The exact mechanism for smoking's impact on the brain's higher functions is still unclear, but may involve both neurochemical effects and damage to the blood vessels that supply the brain," lead researcher Jennifer Glass, of the University of Michigan, said in a prepared statement. "This is consistent with other findings that people with cardiovascular disease and lung disease tend to have reduced neurocognitive function."
Reporting this week in the online issue of Drug and Alcohol Dependence, Glass' team had originally focused their study on the long-term effects of alcoholism on the brain and thinking skills. The study included 172 alcoholic and nonalcoholic men.
Their research did confirm previous findings linking long-term alcohol use with lowered IQ and thinking problems. However, this effect was most evident among men who'd also smoked for years, the Michigan team noted.
Among the alcoholic men, smoking was associated with increased thinking problems and lowered IQ, even after the researchers factored in alcohol and drug use.
According to the investigators, this is the first study to suggest a direct association between tobacco use and neurocognitive function among male alcoholics. The results also suggest that smoking affects thinking ability in nonalcoholic men.
The results need to be duplicated in other studies before any definitive conclusions can be made about the effect that smoking has on the brain, the researchers added, or before these findings can be considered relevant for women.
The U.S. National Center for Chronic Disease Prevention and Health Promotion has more about the health effects of smoking.