Characterizing individuals who revert from mild cognitive impairment to normal or near-normal cognition

Abstract

Mild cognitive impairment (MCI), particularly the amnestic subtype, is often regarded as an intermediate state on a path from normal cognition to dementia. Yet several epidemiologic studies have found that transitioning from MCI back to normal cognition is fairly common. Identifying such individuals may be important to avoid exposing them prematurely to anti-dementia treatments that may do them more harm than good. We studied 2,676 individuals diagnosed with MCI on at least one visit to an Alzheimer's Disease Center (ADC) in the U.S. since 2005. All underwent a structured evaluation using the Uniform Data Set on their MCI visit and on a subsequent visit about a year later at which cognitive status was re-assessed. Logistic regression was used to identify predictors of transitioning from MCI to normal or near-normal cognition (no longer meeting criteria for MCI). Candidate predictors included demographic factors, clinical manifestations and severity of MCI, MCI subtype and presumed etiology, comorbidity, and ApoE e4. In this cohort, patients diagnosed with MCI had about a 16% chance of reverting to normal or near-normal cognition a year later. In the subgroup with complete covariate data, five characteristics assessed at the MCI visit all contributed significantly to a logistic model predicting such improvement: age (OR=0.972 per year of age), impaired memory (OR=0.41), impaired judgment (OR=0.50), Mini-Mental Status Examination score (OR=1.34 per scale point), and ApoE e4 (OR=0.44). Even in a cohort of patients seen at dementia research centers, recovery from MCI was fairly common. Younger patients, those with milder MCI, and those without the ApoE allele associated with Alzheimer's disease were more likely to revert to normal or near-normal cognition, while those with impaired memory or judgment were less likely to improve. Clinicians may be able to use such information to help decide who is, and who is not, a candidate for early anti-dementia therapy.