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Epidemiological survey of dementia in parkinsonism and control population
Abstract:
In a 13-year (1967-1979) survey of Rochester, Minnesota residents, 138 new cases of parkinsonism were recognized. For each case, 2 age- and sex-matched residents from the community were identified who attended the same medical facility as the patient did. Original medical records for 40 years preceding the diagnosis and control selection were reviewed on all patients and controls. Diagnosis of dementia was made three times more frequently in patients than in the controls, but the age at diagnosis was similar in the two groups. Those cases where neither of the three matched individuals had dementia at the time of initial recognition of parkinsonism were further followed. Dementia emerged significantly more frequently in patients than in controls. The subgroup of patients treated with levodopa had higher frequency of dementia than the controls. It is concluded that dementia is significantly more common in parkinsonian patients than in a comparable population. Dementia is believed to be either an integral part of the disease process or these patients are prone to some other illness that produces dementia. Our data conclusively show that dementia is not a reflection of old age. Higher incidence of dementia in levodopa-treated cases may be due to case-selection artifact or an as yet unrecognized effect of levodopa.
Insights
Dementia is significantly more common in patients with parkinsonism than in the general population. This suggests dementia may be an integral part of Parkinson's disease or linked to other conditions.
Area of Science:
- Neurology
- Epidemiology
Background:
- Parkinsonism is a neurological disorder with various causes.
- The relationship between Parkinson's disease and dementia requires further investigation.
Purpose of the Study:
- To determine the incidence of dementia in patients diagnosed with parkinsonism.
- To compare dementia rates in parkinsonism patients versus a matched control group.
Main Methods:
- A 13-year population-based survey (1967-1979) identified 138 new parkinsonism cases in Rochester, MN.
- Each case was matched with two community controls based on age, sex, and medical facility.
- Medical records spanning 40 years pre-diagnosis/control selection were reviewed for dementia diagnosis.
Main Results:
- Dementia was diagnosed three times more frequently in parkinsonism patients than controls.
- Dementia emerged significantly more often in patients during follow-up.
- Levodopa-treated patients showed a higher frequency of dementia compared to controls.
Conclusions:
- Dementia is significantly more prevalent in parkinsonian patients than in the general population.
- Dementia may be an intrinsic aspect of the parkinsonism disease process.
- The higher incidence in levodopa-treated patients could be due to selection bias or an unrecognized levodopa effect.