PREVALENCE AND SEVERITY OF COGNITIVE IMPAIRMENT WITH AND WITHOUT DEMENTIA IN AN ELDERLY POPULATION

Background Not all cognitively impaired people have dementia, but thos e who do not meet current criteria for dementia have received little s tudy. We report a comprehensive estimate of the prevalence of ''cognit ive impairment, no dementia'' (CIND) in an elderly population. Methods The Canadian Study of Health and Aging gathered population representa tion information about elderly Canadians aged 65 and over from 36 citi es and surrounding areas in five regions. In each region, the sample s ize was 1800 people in the community and 250 people in institutions. P atients in the community were screened for cognitive impairment by mea ns of the modified mini-mental state examination. Those who scored bel ow the cut-off point (n=1106) and a randomly selected sample of those who scored above the cut-off point (n=494) were referred for clinical examination. 59 individuals unable to take the screening test were als o assessed clinically. We selected 17 long-term care institutions in e ach region, and then randomly selected consenting residents of these i nstitutions for clinical assessment (n=1255). Results The prevalence o f CIND was 16.8%, which was more than all types of dementia combined ( 8.0%). The prevalence of all types of cognitive impairment, including dementias, increased with age. Patients with CIND were three times mor e likely to be living in institutions than were cognitively unimpaired patients (odds ratio 3.1 [95% CI 2.4-3.9]). Circumscribed memory loss has a prevalence of 5.3% in the elderly Canadian population, and was the most common category. CIND was related to some degree of functiona l impairment in elderly patients. Interpretation CIND is commonly asso ciated with functional disability and a need for institutional care. T his diagnostic category includes a costly group of disorders that meri t further study.