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Object alternation and orbitofrontal system dysfunction in Alzheimer's and Parkinson's disease
1Department of Medicine (Division of Neurology), University of Toronto.
Brain and Cognition
|November 1, 1990
Summary
Alzheimer's disease patients show significant object alternation deficits, unlike Parkinson's dementia patients, indicating distinct frontal lobe dysfunction. Alzheimer's patients exhibit perseverative errors, suggesting orbitofrontal damage.
Area of Science:
- Neuroscience
- Neurology
- Cognitive Psychology
Background:
- Frontal system dysfunction is implicated in neurodegenerative diseases.
- Orbitofrontal system damage is suggested in Alzheimer's disease but not Parkinson's dementia.
Purpose of the Study:
- To differentiate Alzheimer's disease (AD) from Parkinson's dementia (PD) using the object alternation (OA) task.
- To investigate the specific frontal lobe systems affected in AD and PD.
Main Methods:
- Administered the object alternation (OA) task to patients with AD, PD, and normal controls.
- Equated dementia severity across AD and PD groups.
- Performed error analysis on OA task performance.
Main Results:
- Object alternation (OA) was significantly more impaired in Alzheimer's disease compared to Parkinson's dementia.
- Alzheimer's patients exhibited abnormal response perseveration, unlike Parkinson's patients.
- Parkinson's patients showed milder, qualitatively different deficits on the OA task.
Conclusions:
- The object alternation task effectively distinguishes between Alzheimer's disease and Parkinson's dementia.
- Marked perseverative deficits in Alzheimer's disease suggest orbitofrontal system dysfunction.
- Milder deficits in Parkinson's disease may indicate dorsolateral frontal system involvement.