Background:
Smoking is a risk factor for both Alzheimer and vascular dementia. Understanding this risk requires an investigation of relationship between smoking and brain volume loss on MRI, a biomarker for neurodegeneration.
Objective:
To determine the relationship between smoking history and pack years on brain volume loss.
Design/Methods:
In total, 8831 healthy participants from 4 sites were scanned on 1.5T MR with a short whole-body MR imaging protocol. Sequences included whole body coronal T1, STIR from vertex to feet, whole-body axial DWI from vertex to proximal-thighs and axial T2 TSE without fat suppression from skull base to pelvis. Brain sequences were T1 MPRAGE and 2D FLAIR. Deep learning volumetric software, FastSurfer, trained over 134 participants aged 27-66, segmented 96 brain volumes. Smokers versus non-smokers were compared by gray and white matter volumes normalized to total intracranial volume using a two tailed t-test. Partial correlation analysis was done between pack years and brain volumes, controlling of age, sex, and total intracranial volume. The Benjamini Hochberg False Discovery Rate of 5% accounted for multiple comparisons.
Results:
This cohort averaged 52.90 ± 13.06 years, between 23 to 84, with 52.5% men and 47.5% women. Overall, 2860 individuals (32.3%) self-reported a history of smoking. Participants who smoked were older than non-smokers (p = .024). Smokers had lower normalized gray and white matter volumes compared to non-smokers (t = 8.95, p = 4.39e-19). Adjusting for co-variates and multiple comparisons, smoking predicted brain volume loss in: gray and white matter volumes (Partial R =-.08, p = 6.84e-12), hippocampus (Partial R = -.06, p = 3.16e-7), frontal cortex (Partial R = -.08, p = 7.91e-13), temporal lobes (Partial R = -.07, 2.12e-9), left posterior cingulate gyrus (Partial R = -.06, p = 1.99e-8).
Conclusions:
Both smoking history and pack years predict both lower whole brain and regional volumes.
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