White and grey matter changes in the language network during healthy aging

Area of Science:

• Neuroscience
• Aging Research
• Cognitive Neuroscience

Background:

• Neural structures undergo age-related changes, but the specific mechanisms remain unclear.
• Understanding these changes is crucial for comprehending cognitive decline and maintaining brain health in older adults.

Purpose of the Study:

• To investigate age-related changes in white and grey matter within the human language network.
• To test the hypothesis that neural structures mature and age according to a "last in, first out" principle.

Main Methods:

• Utilized fractional anisotropy (FA) of white matter and cortical thickness of grey matter to assess neural integrity.
• Measured these parameters in two independent groups of participants aged 50-79 years.
• Focused analysis on specific pathways within the language network, including dorsal and ventral connections.

Main Results:

• The dorsal pathway connecting the superior temporal cortex (STC) and inferior frontal cortex (IFC) showed greater age-related changes in both white matter FA and grey matter thickness.
• This most affected pathway matures later in development compared to other pathways within the language network.
• Results were validated in a separate cohort, confirming the robustness of the findings.

Conclusions:

• The findings support the "last in, first out" theory of aging, suggesting that neural structures maturing later are more susceptible to age-related decline.
• This provides a novel framework for understanding neural aging within the language network.
• Highlights the differential impact of aging on distinct neural pathways based on their developmental timing.