The Effect of Smoking on Brain Metabolism and Cognitive Reserve

Introduction. Cognitive reserve defines the brain’s ability to withstand aging and pathology through adaptation and is subserved by tissue metabolic integrity. Smoking can trigger brain abnormalities that are likely to alter cognitive reserve and accelerate brain aging. Here, we test the impact of smoking on brain metabolism and cognitive reserve. Methods. Healthy right-handed volunteers (17 smokers/16 non-smokers, age:31.2±5.3;14F/19M) underwent calibrated task-fMRI to quantify metrics of brain metabolism [Cerebral Blood Flow (CBF), Oxygen Extraction Fraction (OEF)] within task-relevant regions. After adjusting for sleep quality and task accuracy, these metrics were compared to the Cognitive Reserve Index (CRI), assessed via a questionnaire (CRI-q). Results. There was no between-group difference in CRI and metabolic metrics (p>0.05). The relationship between CRI and metabolic metrics differed between the groups (p<0.02): in non-smokers, CRI showed higher values for lower CBF (r=- 0.84, p<0.001) and higher OEF (r=0.65, p=0.011); in smokers, no significant correlations were found. Discussion. Despite similar baseline levels, the relationship between brain metabolism and cognitive reserve differs between smokers and non-smokers. Specifically, increasing levels of cognitive reserve reflect higher efficiency in energy supply and utilization in non-smokers, indicating that maintaining brain metabolic health is important to preserve brain adaptation.