Microstructural alteration of the anterior cingulum is associated with apathy in Alzheimer disease.

OBJECTIVES

To identify regional alterations of white matter integrity associated with apathy in Alzheimer disease (AD).

DESIGN

Cross-sectional study.

SETTING

University Dementia Clinic.

PARTICIPANTS

Fifty-one very mild or mild probable AD subjects.

INTERVENTION: Volumetric magnetic resonance imaging with diffusion tensor imaging.

MEASUREMENTS: Volume of interest analyses were performed to compare regional fractional anisotropy (FA) between apathy and apathy-free group, and to test linear relationship between regional FA and apathy severity. Apathy was assessed by the Neuropsychiatric Inventory.

RESULTS

Apathy group showed significantly lower FA values than apathy-free group in the left anterior cingulum (A-C), regardless of concomitant depression and psychotropic medications. Left A-C FA values also had significant linear relationship with apathy-composite scores as a measure of apathy severity, even after controlling gray matter density of the ipsilateral anterior cingulate cortex.

CONCLUSIONS

Our findings support that communication failure between the anterior cingulate cortex and other brain structures via the A-C contributes to the development and aggravation of apathy in AD, additionally supporting the general notion of disconnection syndrome for clinical manifestation of AD.