Reversion from mild cognitive impairment to normal or near-normal cognition: risk factors and prognosis.

OBJECTIVES: We sought to identify characteristics of individuals with mild cognitive impairment (MCI) that are associated with a relatively high probability of reverting back to normal cognition, and to estimate the risk of future cognitive decline among those who revert.
METHODS: We first studied 3,020 individuals diagnosed with MCI on at least 1 visit to an Alzheimer's Disease Center in the United States. All underwent standardized Uniform Data Set evaluations at their first visit with an MCI diagnosis and on a subsequent visit, about 1 year later, at which cognitive status was reassessed. Multiple logistic regression was used to identify predictors of reverting from MCI back to normal cognition. We then estimated the risk of developing MCI or dementia over the next 3 years among those who had reverted, compared with individuals who had not had a study visit with MCI.
RESULTS: About 16% of subjects diagnosed with MCI reverted back to normal or near-normal cognition approximately 1 year later. Five characteristics assessed at the first MCI visit contributed significantly to a model predicting a return to normal cognition: Mini-Mental State Examination (MMSE) score, Clinical Dementia Rating (CDR) score, MCI type, Functional Activities Questionnaire (FAQ) score, and APOE ε4 status. Survival analysis showed that the risk of retransitioning to MCI or dementia over the next 3 years was sharply elevated among those who had MCI and then improved, compared with individuals with no history of MCI.
CONCLUSIONS: Even in a cohort of patients seen at dementia research centers, reversion from MCI was fairly common. Nonetheless, those who reverted remained at increased risk for future cognitive decline.