Topographical recognition memory sensitive to amnestic mild cognitive impairment but not to depression

Amnestic mild cognitive impairment (aMCI) involves episodic memory. The person who presents aMCI has a high risk of developing Alzheimer's disease (AD). However, prediction of deterioration to dementia in cases of aMCI can be confounded with depression due to lack of specificity on selective memory tests. Finding a test sensitive to aMCI but not to depression would be potentially most useful to subsequent longitudinal studies researching the neuropsychological markers of preclinical AD. We hypothesized that the performance on a topographical memory task would be sensitive to the aMCI condition, while depression would not influence such a performance.

A group of 137 community-dwelling French-speaking subjects between 55 and 70 years old was administered a topographical recognition memory task. Based on aMCI and depression criteria, 45 subjects were selected and divided into four groups: 11 patients with aMCI without depression, nine depressive patients with aMCI, ten depressive patients without cognitive impairment and 15 control subjects. The remaining non-selected participants did not belong to any of the previous interest groups.

The 'aMCI' factor had a significant effect on the topographical recognition memory task scores, while the 'depression' factor did not. The aMCI patients performed worse than the non-aMCI.

Although these results were found with relatively small groups, deficits in topographical recognition memory were observed in aMCI patients and did not seem to be sensitive to depression. Further longitudinal studies are needed to examine whether deficits in topographical recognition memory are a neuropsychological marker of preclinical AD.