Environmental noise pollution is increasingly recognized as a contributor to neurodegenerative processes, yet its relationship with early Alzheimer's disease biomarkers remains unclear.
Objective
This pilot study aimed to assess the feasibility of using gray-to-white matter signal intensity contrast (GWC) as a potential biomarker to explore associations between environmental noise exposure and early neurodegenerative changes.
Methods
A total of 106 participants (mean age 35.97 ± 9.21 years, range 20–55), without cognitive impairment or neurological disorders, were included. Environmental noise levels were estimated using spatial interpolation from the National Noise Information System. Based on WHO guidelines (>60 dB daytime or >55 dB nighttime), participants were categorized into high- and low-noise groups. Whole-brain and regional GWC values were derived from 3D T1-weighted MRI using FreeSurfer. Correlations between noise exposure and GWC were analyzed with Pearson's correlation.
Results
The high-noise group exhibited elevated whole-brain GWC values (20.11 ± 0.93) compared with the low-noise group (19.68 ± 0.96; p = 0.036). Regional analyses revealed higher GWC in the superior frontal gyrus, precentral gyrus, and paracentral lobules (all p < 0.05, FDR corrected). Nighttime noise exposure correlated more strongly with increased GWC (r = 0.203, p = 0.037) than daytime exposure.
Conclusions
This pilot study provides preliminary evidence of an association between environmental noise—particularly nighttime exposure—and subtle structural brain changes, as indicated by elevated GWC values. These findings suggest a potential neurobiological pathway linking noise exposure to early markers of neurodegeneration, warranting validation in larger, longitudinal studies.
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