Evaluation of visual recognition memory for the early diagnosis of Alzheimer's disease in patients over 75 years

Abstract

IntroductionCurrent diagnostic criteria of Alzheimer Disease (AD) are mainly based on clinical definition. In France, the Delayed Matching Sample (DMS48) test, a recently introduced test that explores visual object recognition, is recommended for the early diagnosis of AD. However, little is known on the DMS48 performances of older subjects over 75 years. Therefore, our aim was to assess its specific clinical value for early detection of AD in older patients. MethodWe studied 93 consecutive patients over 75 years from an expert memory clinic in a geriatric hospital. This population included 31 patients with single domain amnestic Mild Cognitive Impairment (aMCI), 31 AD patients and 31 controls subjects. Results and discussionThe aMCI and AD performances on the DMS48 were significantly lower than those of the control subjects (set 1 and set 2, P<10−7). The DMS48 performances in the healthy group appeared closely related to the previously published normative data. However, the DMS48 performances appeared unexpectedly high in these older patients, especially in the AD subgroup (set 1, 82.2±12.1 and set 2, 75.2±16.2). Moreover, there was an unexpected frequent discordance between the results on the DMS48 and the Free and Cued Selective Reminding tests (FCSR). The DMS test appears useful for highlighting the heterogeneity of the syndromes of aMCI and AD in old-old people aged 75+: our results also underline the need for further characterization of cognitive impairment in this fastest growing subgroup of patients.