Undetected Dementia in Community-dwelling Older People: the Canadian Study of Health and Aging

Objective: To estimate the frequency and correlates of undetected dementia in community-dwelling older people.

Design: Secondary analysis of data from the Canadian Study of Health and Aging (CSHA) prevalence survey of dementia.

Setting: All 10 provinces of Canada excluding Indian reserves and military units.

Participants: A total of 252 community-dwelling older adults diagnosed with dementia in the CSHA survey.

Main Outcome Measure: Undetected dementia, defined as occurring in persons who meet standard diagnostic criteria for dementia but who report never having seen a doctor for memory problems.

Results: Of the 252 subjects, 64% had undetected dementia. Subjects with mild functional impairment were significantly more likely to have undetected dementia (odds ratio = 2.4, 95% confidence interval 1.2, 5.0). Older subjects and those with mild cognitive impairment showed a trend toward undetected dementia, although the results did not achieve statistical significance. Educational level, number of comorbid conditions, and degree of social support were not significantly associated with undetected dementia.

Conclusions: A large number of older persons are living in the community with undetected dementia. These older people may be at significant risk for delirium, motor vehicle accidents, medication errors, and financial difficulties. As preventive strategies are developed and new cognitive enhancing therapies emerge, we need to reexamine our current guidelines about screening for cognitive impairment in older adults.