Subjective complaints and self-evaluation of memory test performance in Questionable dementia.

Background: The clinical significance of subjective memory complaints in elderly subjects has been an area of active research. In this study, we evaluated subjective complaints and self-evaluation of memory test performance in subjects with Questionable dementia (QD) and mild Alzheimer's disease (AD).

Methods: Ninety-two subjects (35 cognitively intact normal controls NC, 33 QD, and 24 mild AD) were assessed. Subjective memory complaints were evaluated using a memory inventory for the Chinese (MIC); objective assessment of awareness was assessed by the self-evaluation of own memory test performance. Cognitive function was assessed with the Alzheimer's Disease Assessment Scale-Cognitive subscale (ADAS-Cog), Category Verbal Fluency Test (CVFT) and Executive Interview (EXIT-25). Depressive symptoms were evaluated with the Cornell Scale for Depression in Dementia (CSDD).

Results: The total number of subjective memory complaints (MI-tol) were significantly different between different subject groups (Kruskal Wallis test, chi2 = 13.19, p = 0.001). Significant correlations between scores of the MI-tol and CSDD (r = 0.33, p < 0.001), CMMSE (r = -0.33, p < 0.001), CDR (r = 0.36, p < 0.001) were found. In self-evaluation of memory test performance, the NC group tended to under-estimate while the AD subjects tended to over-estimate their performance. Group differences in the discrepancies of self-evaluation of memory performance were significant for both the immediate (Kruskal Wallis test, chi2 = 9.86, p = 0.007) and delayed recall (Kruskal Wallis test, chi2 = 10.55, p < 0.001) trials.

Conclusions: Subjects with QD and mild AD showed higher frequency of subjective memory complaints, reflecting that the subjects still retain some ability to appreciate own memory function. However, the trend for over-estimation of performance in AD subjects suggests that the precision of estimation may be suboptimal. Moreover, depressive symptoms may affect the presentation of memory complaints and this factor should be carefully considered in future prospective studies.