White matter changes in empirically derived incident MCI subtypes in the Mayo Clinic Study of Aging

Area of Science:

• Neuroimaging
• Neurology
• Cognitive Science

Background:

• White matter hyperintensities (WMH) and fractional anisotropy (FA) are key indicators of brain health.
• Mild cognitive impairment (MCI) is a heterogeneous condition with distinct subtypes.

Purpose of the Study:

• To investigate white matter hyperintensities (WMH) and fractional anisotropy (FA) in empirically derived incident mild cognitive impairment (MCI) subtypes.
• To understand the relationship between specific MCI subtypes and white matter integrity.

Main Methods:

• Evaluated 188 participants with incident MCI from the Mayo Clinic Study of Aging (MCSA).
• Classified MCI participants into four subtypes: subtle cognitive impairment, amnestic, dysnomic, and dysexecutive.
• Utilized linear regression for WMH volume analysis and diffusion tensor imaging for FA examination in a subset of 63 participants.

Main Results:

• Amnestic and dysexecutive MCI subtypes exhibited distinct patterns of increased WMH compared to cognitively unimpaired individuals.
• The dysexecutive subtype showed higher WMH volumes than the subtle cognitive impairment subtype.
• Widespread white matter degeneration was observed in association and commissural fibers across amnestic, dysnomic, and dysexecutive subtypes, with corpus callosum FA significantly correlating with global cognition.

Conclusions:

• White matter integrity, assessed by WMH and FA, plays a crucial role in the cognitive manifestations of incident MCI.
• Specific patterns of white matter changes are associated with different MCI subtypes, suggesting distinct underlying pathologies.