Screening for Cognitive Impairment: A Triage for Outpatient Care

Abstract

The current increase in aged individuals in number and proportionof the general population warrants dependable strategies to improve early detection of cognitive impairment. It was the goal of the present study to develop a triage for bedside testing and outpatient ser vices. In a prospective clinical cohort study at the outpatient Memory Clinic, University of Ulm, Germany, 232 subjects were diagnosed with Alzheimer’s disease [AD; NINCDS-ADRDA criteria; n = 66; age 65.9 ± 7.3 years (mean ± SD); Mini Mental State Examination (MMSE) score 23.4 ± 4.1], mild cognitive impairment (MCI; criteria of Petersen et al.; n = 48; age 66.4 ± 7.1 years; MMSE score 28.3 ± 1.5), and major depressive disorder (DSM-IV criteria; n = 61; age 63.4 ± 8.0 years; MMSE score 28.6 ± 1.6). Diagnosis was secured with extensive neuropsychological, clinical, radiological, and laboratory investigations. Six brief screening tests including the Memory Impairment Screen (MIS), Letter Sorting Test (LST), Verbal Fluency (VF), and Clock Drawing Test (CDT) were assessed independently from the diagnostic procedure. We compared single items and composite scores. LST yielded a diagnostic accuracy of 0.81 and 0.62 for AD and MCI patients versus controls, respectively. With the MIS, diagnostic accuracy was 0.89 and 0.71, respectively. With a combination of LST, MIS, VF, and CDT, a sensitivity for AD and MCI patients of 1.00 and 0.83 was achieved. Thus, single-item screening (e.g. LST, VF) taking little more than 1 min and suitable for bedside testing or brief screening in the general practitioner’s office yields diagnostic accuracy comparable to standard laboratory tests for other diseases. A composite of screening tests suitable for application in general outpatient care in neurological and psychiatric services reliably detects patients with AD and MCI.