Effects of smoking on regional cerebral blood flow in neurologically normal subjects.

Abstract

SUMMARYThe chronic effects of smoking on regional cerebral blood flow (CBF), and on serum lipids and lipoprotein levels in neurologically normal subjects, were studied. CBF was studied by the 133-Xenon inhalation method and gray matter flow was calculated following the method of Obrist et al. One hundred and eleven subjects, who had no abnormalities in neurological examinations nor in CT scans, were divided into two groups: smokers (37) and non-smokers (74). 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 760. Sixty-two of the 74 subjects in the non-smoking group had never smoked, and the mean smoking index of non-smokers was 17. In the male, CBF was significantly lower in smokers than in non-smokers (mean CBF, 12.5% lower in smokers, p < 0.001). Increased reduction of CBF with advancing age was also observed. 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 reduces CBF. Decrease of CBF in smokers was probably due to advanced atherosclerosis which produces vascular narrowing and raised resistance in cerebral blood vessels. Stroke 56In all of these earlier studies however, CBF was measured before and just after smoking and these results described only the acute effects of smoking. Since these reports conflicted with the fact that ciga rettes are a risk factor for CVD, we suspected that the acute pharmacological effects and chronic or long term effects of smoking on CBF were quite different. In the present study, therefore, we attempted to observe the chronic effects of smoking on CBF and on lipoprotein levels in neurologically normal subjects. MethodsRegional cerebral blood flow was measured by the 133-Xenon inhalation method using the Aloka RRG-526 CBF measurement system (Aloka Co., Ltd., To kyo). The study was carried out with patients lying on a bed with closed eyes covered with gauze in a quiet semidarkened room. Smoking was prohibited for them from three hours before examination. Radioactive Xe non gas inhalation procedures according to Obrist et al. 7 were followed, where 1 minute of inhalation was followed by 10 minutes of clearance. Cerebral activity was monitored by 7 pairs of Nal(Tl) scintillation de tectors, each 1 inch long and 1 inch in diameter held in parallel position on both sides of the subject's head. Endo-tidal air radioactivity was recorded by an addi tional detector and was used to correct the recirculation of Xenon gas. An arterial blood sample was drawn immediately after the test to determine pC02 and p0 2 . Each detector was incorporated into an on-line com puterized system. The CBF was computed according to Obrist et al. , 7 using a two compartmental model in which the faster clearing compartment was considered to represe...

Functional brain imaging of tobacco use and dependence

“…Similarly, smokers who smoke ad lib prior to SPECT scanning (including the morning of the scan) have decreased global brain activity compared to former smokers and non-smokers (Rourke et al, 1997). These findings are generally supported by studies using transcranial Doppler ultrasound or the Xe 133 inhalation method to measure responses to smoking, with some (Cruickshank et al, 1989;Kubota et al, 1983Kubota et al, , 1987Rogers et al, 1983), but not all (Kodaira et al, 1993;Terborg et al, 2002), studies showing diminished cerebral blood flow.…”

Alcohol consumption and cerebral blood flow among older adults

“…Candidate covariates were selected based on literature review of variables impacting CBF as well as exploratory analyses. Specifically, previous studies have identified relationships between CBF and age (Kubota et al, 1983;Naritomi et al, 1979), gender (Gur et al, 1982), and intima-media thickness (Claus et al, 1996;Nobili et al, 1993). Systolic and diastolic blood pressure, body mass index (BMI), and smoking status were also examined as potential covariates.…”

Neural Correlates of Response Inhibition and Cigarette Smoking in Late Adolescence

“…Chronic smoking decreases basal cerebral blood flow (Kubota et al, 1983) and increases hematocrit (Isaka et al, 1993), which increases the blood oxygenation level-dependent (BOLD) contrast (Levin et al, 2001). As the fMRI signal in this study is based on BOLD contrasts, group differences in the coupling between neural function and associated increases in cerebral blood could introduce a potential confound for interpretation of BOLD signal change (Jacobsen et al, 2002).…”