White matter microstructure associations with episodic memory in adults with Down syndrome: a tract-based spatial...

Area of Science:

• Neuroscience
• Medical Imaging
• Genetics

Background:

• Down syndrome (DS) is associated with a high risk of Alzheimer's disease (AD) pathology starting in the 40s.
• Early AD biomarkers are needed in DS to inform clinical trials.
• White matter degeneration occurs in preclinical AD and is understudied in DS.

Purpose of the Study:

• To investigate the association between white matter microstructure and episodic memory in adults with Down syndrome.
• To identify potential early biomarkers for cognitive changes in DS.

Main Methods:

• Diffusion tensor imaging (DTI) measures, fractional anisotropy (FA) and mean diffusivity (MD), were used to assess white matter microstructure in 52 adults with DS.
• Episodic memory was assessed using a combined measure from the Free and Cued Recall test and the Rivermead Behavioural Memory Test.
• Tract-based spatial statistics (TBSS) analysis was performed to correlate DTI measures with episodic memory performance.

Main Results:

• A significant positive correlation was found between episodic memory and FA in major white matter tracts.
• A significant negative correlation was observed between episodic memory and MD in major white matter tracts.
• These correlations remained significant after adjusting for age, imaging site, and cognitive ability.

Conclusions:

• White matter degeneration may contribute to early episodic memory decline in adults with Down syndrome, preceding dementia onset.
• Episodic memory performance is coupled with white matter microstructure, independent of chronological age.
• These findings suggest white matter DTI measures could serve as early biomarkers for cognitive changes in DS.