Heavy Smoking Linked to Alzheimer’s Brain Atrophy
# Smoking’s Toll on the Brain: Unraveling the Link Between Pack years, Brain Atrophy, and the Potential Role of BMI
New research published in *NPJ Dementia* sheds light on the detrimental effects of smoking on brain health, revealing important brain atrophy in individuals with a history of smoking, particularly those with higher pack-year histories. The study, which analyzed a large cohort of 10,134 healthy individuals, also explored the potential mediating role of Body mass Index (BMI) in this relationship, suggesting that obesity might influence the extent of smoking-induced brain volume loss.
## Smoking and Brain Volume: A Comprehensive analysis
The study aimed to investigate the relationship between pack-years of smoking and brain regions using two distinct statistical models. Model 1 adjusted for age, sex, and study site, while Model 2 further incorporated BMI into the analysis.
### Study Findings: unpacking the Data
participants in the smoking group,compared to non-smokers,were more likely to be women,Caucasian,have a higher BMI,be older,and exhibit higher rates of type 2 diabetes mellitus and hypertension. The average smoking history among participants was 11.93 pack-years.Groupwise regional comparisons demonstrated that smokers generally had lower brain volumes than non-smokers. A Pearson bivariate correlation revealed a modest positive association between higher BMI and increased smoking pack-years.
Crucially, when BMI was introduced into the models (comparing Model 1 and Model 2), the study observed a weakening of statistical significance and effect sizes across 11 brain regions. This finding suggests a potential, though not definitively proven, mediating effect of BMI in the association between increased smoking pack-years and reduced brain volumes.Despite the influence of BMI, smokers still exhibited significant brain atrophy in multiple regions. Notably, these included areas critical for Alzheimer’s disease pathology, such as the hippocampus, posterior cingulate, and precuneus, even after accounting for BMI.
## Conclusions: Smoking, BMI, and Dementia Prevention
The current research underscores that individuals with a history of smoking and higher pack-years experience brain atrophy. The preliminary findings also point towards BMI playing a potential, exploratory role in the relationship between cigarette smoking and brain volume loss. This suggests that obesity and smoking, as two significant risk factors, could be targeted in future strategies for preventing dementia, including Alzheimer’s disease.
### Future Directions and Limitations
Further research is warranted to thoroughly examine the potential mediating effects of white matter hyperintensity volume and brain atrophy concerning smoking history and pack-years.
The study’s key strength lies in it’s analysis of a large cohort with detailed smoking history data and quantitative structural brain imaging. This enabled the measurement of regional brain volumes known to be at risk for Alzheimer’s disease pathology, such as the hippocampus, posterior cingulate, and precuneus.
Though, the cross-sectional design of the study limits the ability to establish causation. The lack of temporal resolution also hinders reliable mediation or moderation testing. Furthermore, the absence of cognitive testing or Alzheimer’s biomarkers, such as amyloid or tau, restricts the direct linkage of observed brain atrophy to dementia. Consequently, the role of BMI in the relationship between smoking and brain atrophy requires validation through more longitudinal analyses.
Journal reference:
- Meysami, S. et al. (2025). Smoking predicts brain atrophy in 10,134 healthy individuals and is potentially influenced by body mass index. NPJ dementia. 1(1),1-7. https://doi.org/10.1038/s44400-025-00024-0. https://www.nature.com/articles/s44400-025-00024-0