Alzheimer's Imaging Consortium.

Area of Science:

• Neuroimaging
• Environmental Health
• Neurodegeneration

Background:

• Environmental noise exposure is a known risk factor for cognitive impairment.
• Few studies have investigated the link between noise exposure and brain structural changes.
• This study introduces the cortical gray to white matter signal intensity ratio (GWR) as a novel biomarker for neurodegeneration in Alzheimer's disease.

Purpose of the Study:

• To investigate the association between environmental noise exposure levels and GWR.
• To explore GWR as a potential neuroimaging biomarker for Alzheimer's disease-related neurodegeneration.
• To determine if noise exposure impacts brain structure as measured by GWR.

Main Methods:

• 106 cognitively normal participants were divided into high- and low-noise exposure groups based on WHO guidelines.
• 3D T1-weighted MRI images were used to calculate whole-brain and regional GWR values.
• T-tests and correlation analyses were performed to compare GWR between groups and with noise levels.

Main Results:

• The high noise exposure group exhibited significantly higher whole-brain GWR compared to the low noise group (p=0.036).
• Specific regions, including the left superior frontal gyrus and precentral gyrus, showed significantly higher GWR in the high noise group (p<0.05).
• Whole-brain GWR correlated positively with nighttime noise levels (r=0.203, p=0.037), and regional GWR correlated with both daytime and nighttime noise.

Conclusions:

• Environmental noise exposure is significantly associated with GWR, a novel neurodegeneration biomarker.
• This study provides evidence linking noise exposure to structural brain changes relevant to Alzheimer's disease.
• GWR shows promise as a biomarker for assessing neurodegeneration associated with environmental noise exposure.