The influence of cerebrovascular risk factors on incident dementia in patients with Parkinson's disease

OBJECTIVE: To examine if risk factors for cerebrovascular disease would increase the risk for dementia in patients with Parkinson's disease (PD). METHODS: Non-demented patients were recruited from an epidemiological study of PD in the county of Rogaland, Norway. PD and dementia were diagnosed according to strict diagnostic criteria. Established cerebrovascular risk factors were recorded at baseline, and their influence on incident dementia was assessed 4 years later using logistic regression analysis. RESULTS: A total of 171 non-demented PD patients constituted the at-risk population. Seventy-two (55%) had at least one cerebrovascular risk factor. A total of 130 subjects (96% of survivors) completed the follow-up examination. Forty-three (33%) new cases of dementia were found. Twenty-five of the 72 (35%) patients with and 18 of the 58 (31%) subjects without any risk factor developed dementia (ns). A significant association with dementia was found for a diagnosis of heart failure in the univariate analyses. However, in the logistic regression analysis none of the cerebrovascular risk factors were significantly associated with incident dementia. CONCLUSIONS: In this large and representative cohort of patients with PD cerebrovascular risk factors were not associated with incident dementia, indicating that the disease-related degenerative brain changes are the main causes of dementia in PD.