%0 Journal Article
%A Mayeux, R.
%A Chen, J.
%A Mirabello, E.
%A Marder, K.
%A Bell, K.
%A Dooneief, G.
%A Cote, L.
%A Stern, Y.
%T An estimate of the incidence of dementia in idiopathic Parkinson's disease
%D 1990
%R 10.1212/WNL.40.10.1513
%J Neurology
%P 1513-1513
%V 40
%N 10
%X The proportion of patients with idiopathic Parkinson's disease (PD) who are considered demented ranges from 10% to 15%. Because dementia may affect survival in PD, the incidence rate of dementia, rather than proportion, would be a more accurate measure of disease frequency. We previously estimated the proportion of patients with PD and dementia to be 10.9% from the records of a cohort with the idiopathic form of PD in a major medical center. We reviewed the clinical records of this cohort after 4 years and 9 months to estimate the incidence rate of dementia. We identified 65 new cases of dementia from the 249 patient-records available. Using the number of person-years of follow-up for each case as the denominator, we estimated the overall incidence rate to be 69 per 1,000 person-years of observation. The mean age of this cohort was 71.4 years. The cumulative incidence of dementia increased with age. By 85 years of age, over 65% of the surviving members of the cohort were demented. The age-specific incidence rates for dementia in this cohort of PD were significantly greater than for a similarly aged cohort of healthy elderly people. The age-specific standard morbidity ratios indicated that, compared with people of similar ages, patients with PD have the highest increase in risk for dementia between ages 65 and 75.
%U https://n.neurology.org/content/neurology/40/10/1513.full.pdf