Effects of smoking on brain aging, 1

The chronic effects of smoking on regional cerebral blood flow (CBF), and on serum lipids and lipoprotein levels in neurologically normal subjects from 25 to 85 years old were studied. CBF was studied by the 133-Xenon inhalation method and gray matter flow was calculated following the method of Obrist et al. A hundred and twentyfive subjects who had no abnormalities in neurological examinations nor in CT scan, were divided into two groups smokers (48) and non-smokers (77). Those who had a smoking index (Number of cigarettes/day) x (years of smoking history)>200 were designated as smokers. The mean smoking index of smokers was 697. sixty-five of the 77 subjects in the non-smoking group had never smoked, and the mean smoking index of non-smokers was 16. Increased reduction of CBF with advancing age was clearly observed. In the male, CBF was significantly lower in smokers than in non-smokers (mean CBF 15% lower in smokers, p<0.001). Compared to non-smokers, CBF in smokers was found to be significantly lower than the expected age matched value. Serum high density lipoprotein cholesterol values in smokers were significantly lower, and total cholesterol levels significantly higher than in non-smokers. We concluded that smoking chronically reduced CBF. Age dependent decrease of CBF was deteriorated by chronic smoking. Then, chronic smoking was suggested to be a risk factor for brain aging. Decrease of CBF in smokers was probably due to advanced atherosclerosis which produces vascular narrowing and raised resistance in cerebral blood vessels. (author)