Does this patient have dementia?

Abstract

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. To review the literature concerning the practicality and accuracy of brief cognitive screening instruments in primary care. 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. Studies of patients aged 60 years and older and use of an acceptable criterion standard to diagnose dementia were considered. Studies were assessed by 2 independent reviewers for eligibility and quality. A third independent reviewer adjudicated disagreements. Data for likelihood ratios (LRs) were extracted. 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. 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. 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.