Differences in Diffusion Tensor Imaging White Matter Integrity Related to Verbal Fluency Between Young and Old Adults

Area of Science:

• Neuroscience
• Aging Research
• Cognitive Science

Background:

• The aging brain exhibits structural and functional changes, including alterations in white matter (WM) integrity.
• Previous research explored age-related differences in gray matter and brain function related to language, but the specific role of WM across the lifespan remains less understood.

Purpose of the Study:

• To investigate the structural role of white matter (WM) in adult language production across different age groups.
• To compare white matter diffusion metrics between young and old adults using diffusion tensor imaging (DTI).

Main Methods:

• Diffusion tensor imaging (DTI) was performed on 38 young and 35 old adults.
• The Controlled Oral Word Association Test assessed verbal fluency (VF).
• Tract-Based Spatial Statistics (TBSS) and ANCOVA were used to analyze DTI metrics (FA, MD, AD, RD, LDH) in 12 language-associated WM regions, controlling for sex and education.

Main Results:

• Young adults exhibited significantly higher fractional anisotropy (FA) in the bilateral anterior corona radiata (ACR) and lower mean diffusivity (MD) in the right ACR compared to older adults.
• Older adults showed increased MD in the left uncinate fasciculus (UF), while both groups had decreased radial diffusivity (RD) in the bilateral ACR.
• A significant negative correlation between VF scores and MD in the left UF was observed only in older adults.

Conclusions:

• White matter regions crucial for language production are sensitive to the aging process.
• Age-related changes in WM microstructural integrity, particularly in the ACR and UF, are evident and may influence verbal fluency in older adults.