RESUMO
BACKGROUND: Alcohol, a known addictive substance, affects the structural properties of the brain. In this study, we explored associations between alcohol use and gray matter properties among firefighters, who are often exposed to significant occupational stress. METHODS: Gray matter volume (GMV) was evaluated using voxel-based morphometry in 287 male firefighters (mean age: 48.8 ± 7.7 years). Firefighters were classified into 32 never-drinkers, 162 non-heavy alcohol users, and 93 heavy alcohol users according to their alcohol consumption. GMV was compared between groups, and the correlations between GMV and alcohol use were investigated. A voxel-wise height threshold of p < 0.001 (uncorrected) was used, with small volume correction applied on cluster level. RESULTS: Heavy alcohol users had lower GMV in the bilateral thalamus than non-heavy alcohol users or never-drinkers. Heavy alcohol users also showed lower GMV in the left insula, compared to other groups. The higher the alcohol consumption among firefighters, the lower the GMV of the right thalamus. CONCLUSIONS: The results of this study show that heavy alcohol use has an association with lower GMV in several core regions, including the thalamus. When considering the impact of these brain regions on cognitive and behavioral control, our findings suggest a need for concern about heavy alcohol use among firefighters.