Smoking is associated with reduced cortical regional gray matter density in brain regions associated with incipient Alzheimer disease

Objectives: The results of observational studies suggest that smoking increases the risk of Alzheimer disease (AD). The authors designed this study to determine if older people who smoke have decreased gray matter density in brain regions associated with incipient AD. Methods: The authors recruited 39 pairs (N = 78) of smokers/never-smokers 70 to 83 years of age who were matched for age, sex, education, and handedness. Participants were free of clinically significant cognitive impairment, depression, stroke, or other serious medical conditions. Gray matter density was determined by voxel-based morphometry using statistical parametric mapping of T1-weighted magnetic resonance images. Results: Smokers bad decreased gray matter density in the posterior cingulum and precuneus (bilateral), right thalamus, and frontal cortex (bilateral) compared with never-smokers. Conclusions: Smoking is associated with decreased gray matter density in brain regions previously associated with incipient AD. Longitudinal investigations fire required to clarify whether these changes are progressive in nature.