Treatment effects of therapeutic cholinesterase inhibitors on visuospatial processing in Alzheimer's disease: a longitudinal functional MRI study

Abstract

Background/aims: Visuospatial impairments are known to occur in Alzheimer's disease (AD). We hypothesised that functional magnetic resonance imaging (fMRI) response in task-related brain regions would be impaired in patients with AD during the task and that treatment with acetyl cholinesterase inhibitors would enhance activations in brain regions concerned with this visual perceptual processing.

Method: Ten AD subjects were neuropsychologically assessed and underwent fMRI imaging whilst performing a series of visuospatial perception tasks, before and after treatment with acetyl cholinesterase inhibitors. Eleven healthy elderly comparison subjects were also scanned twice.

Results: Regions of increased brain activation in AD included the left precuneus, left cuneus, left supramarginal gyrus, right parieto-temporal cortex and right inferior parietal lobule. Further, increased activation in the left precuneus was found to correlate significantly with improved functioning of activities of daily living.

Conclusions: We believe this to be the first fMRI study that, after controlling for the confound of repeat scanning, demonstrates altered patterns of brain activation associated with visuospatial processing following treatment in patients with AD. The treatment-related improvement of visual perception in AD may rely on enhanced attentional mechanisms, thereby possibly supporting independent living through improvement on activities of daily living.