Alzheimer's disease and idiopathic Parkinson's disease coexistence.

Abstract

Idiopathic Parkinson's disease (IPD) and Alzheimer's disease (AD) are common neurologic diseases of old age. Parkinson syndrome is easy to recognize even at an early stage, but identifying early AD is often difficult. Accurate clinical diagnosis is important for assigning the prognosis and for studies aimed at assessing the efforts to slow down progression of these diseases. During 22 years, we identified six patients who had clinical features of parkinsonism and dementia and who at autopsy had both IDP and AD and 20 parkinsonian patients without dementia who at autopsy had only IPD. The clinical profile in these two groups was compared. The onset of Parkinson syndrome in the patients with dual pathology had a bimodal distribution--before or after age 65 years. In the three cases with onset before age 65 years, there was sequential evolution of IPD and AD. In contrast, those older than 65 years at onset manifested the clinical features of both IPD and AD simultaneously. The mode of onset and the dominant parkinsonian features in the three patients with sequential clinical evolution were similar to those seen in the nondemented IPD cases; however, lack of self-confidence and inability to make decisions resulted in considerably greater functional disability than could be accounted for by parkinsonism alone. These characteristics may be helpful in early recognition of dual IPD and AD pathology. Psychiatric side effects of levodopa therapy were more common in those with dual pathology than in those with IPD alone.