Does This Patient Have Dementia?

Abstract

CONTEXT: While as many as 5 million individuals in the United States have dementia, many others have memory complaints. Brief tests to screen for cognitive impairment could help guide dementia diagnosis. OBJECTIVE: To review the literature concerning the practicality and accuracy of brief cognitive screening instruments in primary care. DATA SOURCES: A search of MEDLINE (including data from AIDSLINE, BioethicsLine, and HealthSTAR) and psycINFO was conducted from January 2000 through April 2006 to update previous reviews. STUDY SELECTION: Studies of patients aged 60 years and older and use of an acceptable criterion standard to diagnose dementia were considered. DATA EXTRACTION: Studies were assessed by 2 independent reviewers for eligibility and quality. A third independent reviewer adjudicated disagreements. Data for likelihood ratios (LRs) were extracted. DATA SYNTHESIS: Twenty-nine studies using 25 different screening instruments met inclusion criteria; some studies evaluated several different instruments, thus, information could be examined for 38 unique instrument/study combinations. RESULTS: For the commonly used Mini-Mental State Examination, the median LR for a positive result was 6.3 (95% confidence interval [CI], 3.4-47.0) and the median LR for a negative result was 0.19 (95%CI, 0.06-0.37). Briefer approaches are available but have not been studied as frequently. Reports from an informant that the patient has memory loss yields an LR of 6.5 (95% CI, 4.4-9.6) for dementia. The Memory Impairment Screen takes 4 minutes to ask 4 items and has an LR for a positive result of 33 (95% CI, 15.0-72.0) and an LR for a negative result is 0.08 (95% CI, 0.02-0.3). Clock drawings are helpful in 1- to 3-minute forms, but must be scored appropriately and sensitivity to mild forms of impairment can be low. CONCLUSIONS: Clinicians should select 1 primary tool based on (1) the population receiving care; (2) an awareness of the effects of educational level, race, and age on scoring; and (3) consideration of adding 1 or 2 other tools for special situations as needed.