Dementia Among U.S. Primary Care Patients Ages 55 Years and Older without Previously Diagnosed Cognitive Impairment

BACKGROUND Estimates of the prevalence of unrecognized dementia are needed to gauge the potential impact of routine dementia screening. METHODS Adults ages ≥ 55 years without dementia or mild cognitive impairment diagnoses were recruited from primary care practices in New York City, NY and Chicago, IL (n = 853). Dementia was defined as significant cognitive impairment, as indicated by score > 1.5 standard deviations below age and education adjusted norms on the Montreal Cognitive Assessment, with impairment in one or more of 7 instrumental activities of daily living (IADL). RESULTS Mean age was 67.3 years. Moderate-severe cognitive impairment was observed in 10.3% and impairment in ≥ 1 IADL in 44.8%. Estimated undiagnosed dementia prevalence was 6.2% (95% CI 4.5% to 7.7%) overall and 5.9% (95% CI 3.9% to 9.0%) among participants ages ≥ 65. CONCLUSIONS Routine screening in primary care would identify substantial numbers of individuals with previously undiagnosed dementia.