Patients Diagnosed With Incident MCI Classified as Cognitively Normal at Follow-Up
The study had a relatively high proportion of Black and Hispanic participants, with higher MCI among these patients.
Jennifer J. Manly, PhD
A recent community-based study found that nearly half of patients diagnosed with incident mild cognitive impairment (MCI) were cognitively normal at follow-up. Investigators noted that findings may inform expectations for the cognitive and functional course of those presenting with MCI, as predictors of incident MCI differ from those of the ensuing MCI course.
A total of 2903 participants from the Washington Heights-Inwood Columbia Aging Project (WHICAP) who were cognitively normal at baseline were included in the community-based cohort. The present study had a diverse population and a high proportion of Black and Hispanic participants, as WHICAP was a longitudinal study of aging in patients who were non-Hispanic White, non-Hispanic Black, and Hispanic.
Over an average of 6.3 years (standard deviation [SD], 4.5), 752 participants developed MCI (incidence rate: 56/1000 person-years). An increased risk of incident MCI and higher medical burden was found in patients who also had a presence of the APOE4 allele. Comparably, those who had more years of education, record of more leisure activities, and a higher income had a decreased risk.
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After an average follow-up period of 2.4 years, 480 of the 752 patients with incident MCI had at least 1 follow-up visit. Of this subgroup, 12.9% (n = 62) progressed to dementia; 9.6% (n = 46) declined in functioning, not meeting the algorithmic criteria for MCI or the clinical criteria for dementia; 29.6% (n = 142) continued to meet MCI criteria; and 47.9% (n = 230) did not meet MCI criteria anymore. These nondemented patients who did not meet MCI criteria only had subjective complaints, only had objective cognitive impairment, only had no functional impairment, or a combination of 2, but not all 3 criteria. Increased risk of progression to dementia was indicated by multidomain MCI, presence of APOE4 allele, depressive symptoms, and antidepressant use.
Patients totaled 11,208 visits, averaging 3.7 visits (SD, 1.8) over the 6.3 years of follow-up. Patients that did not have a follow-up visit after MCI diagnosis were slightly younger (79.9 vs 81.4 year), more likely to be part of the first 2 recruitment waves, had lower medical burden (2.31 vs 2.63), reported more leisure activities (6.83 vs 6.19), and had lower levels of occupation and income, when compared with those who did have a follow-up visit.
Investigators noted the high proportion of Black and Hispanic participants as a strength of the study, in addition to its extensive follow-up. “Based on studies that show the incidence of dementia is higher among non-Hispanic Black and Hispanic older adults compared to Whites, we also expected higher MCI incidence in these groups,” corresponding author Jennifer J. Manly, PhD, professor of neuropsychology in neurology, Gertrude H. Sergievsky Center and the Taub Institute for Research in Aging and Alzheimer’s Disease, Columbia University, et al wrote.
“We observed that in separate models, Hispanics were at higher risk of incident MCI, but this association did not survive the fully adjusted model. This change is likely due to collinearity of this group membership with other predictors, as for example, the Hispanic population sampled in the WHICAP cohort, representative of the Northern Manhattan community, is on average lower educated Future research is warranted to fully deconstruct differences across race and ethnicity with regard to risk and associated predictors of incident MCI, diagnostic status after incident MCI, and the longitudinal course between incident MCI and a diagnosis of dementia,” Manly et al added.
The study was limited due to a small proportion with follow-up after incident MCI and short follow-up time after incident MCI, investigators wrote. Another limitation was a lack of plasma AD biomarker information on participants. According to investigators, future research should evaluate the course of MCI in multiple follow-up visits over a longer period of time.
