Heavy Smoking Linked to Brain Atrophy in Alzheimer's Disease Risk

A recent study published in *npj Dementia* has highlighted a concerning link between heavy smoking and atrophy in critical brain regions associated with Alzheimer’s disease (AD). Led by Dr. Sara Meysami of the University of California, the research analyzed MRI scans from 10,134 individuals, revealing that smokers exhibited significantly reduced gray and white matter brain volumes compared to non-smokers, with the risk potentially exacerbated by higher body mass index (BMI).

The study's findings are particularly alarming given the rising global prevalence of dementia, with the World Health Organization estimating that approximately 47 million people currently live with dementia, a number projected to increase by 10 million annually. Smoking has been implicated in up to 14% of dementia cases worldwide, primarily through neuroinflammation mechanisms that could significantly contribute to neurodegenerative disorders like AD.

Dr. Meysami stated, "Our study provides critical insights into the direct impact of smoking on brain structure, particularly in regions vulnerable to Alzheimer’s pathology, including the hippocampus and posterior cingulate. This is the first large-scale study to correlate smoking history with MRI-measured brain atrophy."

Participants in the study were aged between 18 and 97 and had undergone non-contrast whole-body MRI scans. Data collection included detailed questionnaires addressing demographics, medical history, and smoking habits. The analysis utilized the FastSurfer network, a deep-learning model that quantifies brain volumes from 3D T1 scans. Results showed that smokers had a mean pack-year value of 11.93, indicating prolonged exposure to tobacco.

Moreover, the relationship between smoking pack-years and brain volume loss diminished when BMI was factored into the analysis, suggesting that while BMI may play a mediating role, smoking still independently correlates with significant brain atrophy in key areas.

Dr. Emily Carter, a neuropsychologist at the Mayo Clinic, noted, "This study underscores the importance of considering lifestyle factors such as smoking and obesity in dementia prevention strategies. The evidence suggests that smoking cessation could be a vital step in reducing the risk of cognitive decline."

Despite the robust cohort size and the innovative use of MRI technology, the study's cross-sectional design limits the ability to establish causation definitively. Future longitudinal studies are deemed necessary to explore the mediating effects of BMI and other factors on brain health.

In conclusion, the research advocates for public health initiatives aimed at smoking cessation as a potential avenue to mitigate the risk of Alzheimer’s disease and other forms of dementia. As the population ages and the burden of neurodegenerative diseases escalates, these findings may inform future strategies to combat this growing health crisis.

**References:** 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.