Many mild cognitive impairment cases appear to resolve over time

Nearly 50% of individuals with incident mild cognitive impairment diagnoses were considered cognitively normal at follow-up, according to results of a community-based cohort study published in Neurology.

“Identifying risk factors of mild cognitive impairment (MCI) — a prodromal phase of dementia — in cognitively normal older adults can aid characterization of a target group for prevention or intervention strategies of dementia,” Milou J Angevaare, MD, of the department of neurology and Taub Institute for Research on Alzheimer’s Disease and the Aging Brain at Columbia University, and colleagues wrote.

“However, not everyone who is diagnosed with MCI subsequently progresses to dementia; longitudinal studies have shown that 5% to 53% of people identified as having MCI at one visit no longer meet MCI criteria at the next visit,” they said. “Thus, identifying risk factors of progression to dementia in individuals diagnosed with incident MCI is equally important to refine the selection of individuals at high risk for dementia.”

The researchers aimed to pinpoint sociodemographic and medical predictors of incident MCI and subsequent MCI course at follow-up, such as sustained MCI diagnosis, cognitively normal classification and progression to dementia. They selected participants from a longitudinal study of aging and dementia among a community that included non-Hispanic white, non-Hispanic Black and Hispanic individuals. They recruited via random sampling 2,903 cognitively normal participants at baseline who were aged 65 years or older and who were eligible for Medicare from three census tracts in New York across three waves in 1992, 1999 and 2009.

Results showed 752 participants developed MCI during an average of 6.3 years, for an incidence rate of 56 per 1,000 person-years. Those with the APOE e4 allele and higher medical burden had increased risk for incident MCI. More years of education, more leisure activities and higher income correlated with lower risk for MCI. After an average follow-up of 2.4 years, 12.9% of incident MCI cases progressed to dementia, 9.6% declined in functioning and failed to meet the algorithmic criteria for MCI and the clinical criteria for dementia, 29.6% continued to meet MCI criteria and 47.9% no longer met MCI criteria. Factors linked to an increased risk for progression to dementia included multidomain MCI, presence of APOE e4, depressive symptoms and antidepressant use.

“Predictors of incident MCI demonstrably differed from those of subsequent MCI course; these findings can refine expectations for cognitive and functional course of those presenting with MCI,” Angevaare and colleagues wrote.