The effect of age of onset of PD on risk of dementia

• Published in: Journal of neurology Vol. 254; no. 1; pp. 38 - 45
• Main Authors: AARSLAND, D, KVALØY, J. T, ANDERSEN, K, LARSEN, J. P, TANG, M. X, LOLK, A, KRAGH-SØRENSEN, P, MARDER, K
• Format: Journal Article
• Language: English
• Published: Berlin Springer 2007; Springer Nature B.V
• Subjects: Age; Age of Onset; Aged; Aged, 80 and over; Alzheimer's disease; Ambulatory care; Biological and medical sciences; Cohort Studies; Degenerative and inherited degenerative diseases of the nervous system. Leukodystrophies. Prion diseases; Dementia; Dementia - epidemiology; Dementia - etiology; Disease; Disorders of higher nervous function. Focal brain diseases. Central vestibular syndrome and deafness. Brain stem syndromes; Female; Hospitals; Humans; Male; Medical sciences; Medicin och hälsovetenskap; Nervous system (semeiology, syndromes); Neurology; Neuropsychological Tests; Neuropsychology; Older people; Parkinson Disease - complications; Parkinson Disease - epidemiology; Parkinson's disease; Patients; Proportional Hazards Models; Risk; Survival Analysis; Time Factors; Denmark; New York; United States > US; Norway; Nervous system diseases; Age of onset; Central nervous system disease; Risk factor; Parkinson disease; Degenerative disease; Parkinson's disease · dementia · age at onset · age; Cerebral disorder; Extrapyramidal syndrome; Dementia
• ISSN: 0340-5354; 1432-1459
• DOI: 10.1007/s00415-006-0234-8

Dementia occurs in the majority of patients with Parkinson's disease (PD). Late onset of PD has been reported to be associated with a higher risk for dementia. However, age at onset (AAO) and age at baseline assessment are often correlated. The aim of this study was to explore whether AAO of PD symptoms is a risk factor for dementia independent of the general effect of age. Two community-based studies of PD in New York (n=281) and Rogaland county, Norway (n=227) and two population-based groups of healthy elderly from New York (n=180) and Odense, Denmark (n=2414) were followed prospectively for 3-4 years and assessed for dementia according to DSM-IIIR. All PD and control cases underwent neurological examination and were followed with neurological and neuropsychological assessments. We used Cox proportional hazards regression based on three different time scales to explore the effect of AAO of PD on risk of dementia, adjusting for age at baseline and other demographic and clinical variables. In both PD groups and in the pooled analyses, there was a significant effect of age at baseline assessment on the time to develop dementia, but there was no effect of AAO independent of age itself. Consistent with these results, there was no increased relative effect of age on the time to develop dementia in PD cases compared with controls. This study shows that it is the general effect of age, rather than AAO that is associated with incident dementia in subjects with PD.