EPISODIC SHORT-TERM MEMORY AND SELECTIVE ATTENTION IN PATIENTS WITH ALZHEIMER'S DEMENTIA, MILD COGNITIVE IMPAIRMENT, AND SUBJECTIVE MEMORY IMPAIRMENT

Abstract

Episodic short-term memory (ESTM) and selective attention were assessed in patients with Alzheimer's dementia (AD), patients with amnestic mild cognitive impairment (MCI) and in subjects with subjective memory impairment who had no cognitive impairment in routine dementia tests (SMI). The assessments were performed by means of the MAT (Memory and Attention Test), a newly developed computerized test for the assessment of cognitive impairment. It measures selective attention as well as working and short-term memory for verbal, figural and episodic material. The findings are compared with those of cognitively unimpaired age-, sex- and education-matched reference groups. The MAT has been evaluated in patients with mild-to-moderate Alzheimer's dementia (AD). The MAT was performed in 1) patients with probable mild-to-moderate AD according to NINCDS-ADRDA criteria (n=42; MMS 18-24); 2) patients with amnestic MCI according to the Peterson criteria (n=40; MMS 25-28); 3) persons with SMI (n=40; MMS 29-30). The most obvious differences in the MAT between patients and control groups were found in the domain of episodic short-term memory measured by means of a recognition task (ESTM). Applying a score of less than 1.5 SD below the mean of the age-, sex- and education-matched controls in ESTM as cut-off, 25/42 (60 %) of the AD patients, 15/40 (38 %) of the MCI patients and 8/40 (20 %) of the SMI subjects fulfilled that criterion. In the SMI subjects, the performance in selective attention and episodic working memory tended to be increased (p=0.088), perhaps reflecting efforts to compensate for an impairment in ESTM. Thus, beyond a sensitive and reliable identification of patients with AD, the MAT shows impairments in a significant number of patients with MCI and SMI, particularly an impairment in ESTM. The computerized testing was readily accepted by the subjects. A majority of them (even of the AD patients) preferred the computerized examination to being tested by a person.