Smoking normalizes cerebral blood flow and oxygen consumption after 12-hour abstention

Abstract

Acute nicotine administration stimulates [14 C]deoxyglucose trapping in thalamus and other regions of rat brain, but acute effects of nicotine and smoking on energy metabolism have rarely been investigated in human brain by positron emission tomography (PET). We obtained quantitative PET measurements of cerebral blood flow (CBF) and metabolic rate of oxygen (CMRO 2) in 12 smokers who had refrained from smoking overnight, and in a historical group of nonsmokers, testing the prediction that overnight abstinence results in widespread, coupled reductions of CBF and CMRO 2. At the end of the abstention period, global grey-matter CBF and CMRO 2 were both reduced by 17% relative to nonsmokers. At 15 minutes after renewed smoking, global CBF had increased insignificantly, while global CMRO 2 had increased by 11%. Regional analysis showed that CMRO 2 had increased in the left putamen and thalamus, and in right posterior cortical regions at this time. At 60 and 105 minutes after smoking resumption, CBF had increased by 8% and CMRO 2 had increased by 11-12%. Thus, we find substantial and global impairment of CBF/CMRO 2 in abstaining smokers, and acute restoration by resumption of smoking. The reduced CBF and CMRO 2 during acute abstention may mediate the cognitive changes described in chronic smokers.