Effects of white matter hyperintensities on isolated executive function assessed by the Trail Making Test

Area of Science:

• Neurology
• Neuroimaging
• Cognitive Science

Background:

• White matter hyperintensities (WMHs) on MRI are linked to cognitive decline, including executive dysfunction.
• The distinct contributions of periventricular (PVH) and deep/subcortical (DSWMH) WMHs to isolated executive function, independent of aging, require further investigation.

Purpose of the Study:

• To examine the association between WMH burden (PVH and DSWMH) and performance on the Trail Making Test (TMT).
• To assess the TMT's ability to evaluate isolated set-shifting and working memory in relation to WMH severity.

Main Methods:

• 74 participants with normal cognition or mild cognitive impairment underwent TMT subtests (TMT-A, TMT-B) and MMSE.
• WMH severity (PVH and DSWMH) was graded using the Fazekas scale (0-3).
• Correlation analyses adjusted for age assessed the relationship between WMH grades and TMT performance times.

Main Results:

• No significant differences in Mini-Mental State Examination (MMSE) scores were observed across PVH or DSWMH grades.
• Increased time for TMT-A, TMT-B, and TMT-B minus TMT-A correlated with higher PVH and DSWMH grades.
• After age adjustment, only DSWMH grade showed a significant association with the TMT-B minus TMT-A time difference.

Conclusions:

• Both PVH and DSWMH differentially impact executive functions assessed by TMT subtests.
• DSWMH severity is significantly associated with deficits in set-shifting and working memory, independent of age and general cognitive status.