Neuropsychological functioning in cortical-basal ganglionic degeneration: Differentiation from Alzheimer's disease

Patients with cortical-basal ganglionic degeneration (CBGD) display prominent rigidity and apraxia, exhibit an asymmetric onset of symptoms, and may show other symptoms including abnormal saccadic eye movements, the ''alien limb'' sign, limb dystonia, and myoclonus. We compared the neuropsychological test performances of 21 CBGD patients with 21 Alzheimer's disease (AD) patients displaying no extrapyramidal symptoms and with 12 AD patients who did show such symptoms. Groups were matched for age, educational level, and overall severity of dementia. Since the cognitive deficit was mild in most CBGD patients, most AD patients included in this study were also only mildly demented. The CBGD patients performed significantly better than the AD patients on tests of immediate and delayed recall of verbal material; whereas the AD patients (with or without extrapyramidal symptoms) performed better on tests of praxis, finger tapping speed, and motor programming. The CBGD and AD groups all displayed prominent deficits on tests of sustained attention/mental control and verbal fluency, and exhibited mild deficits on confrontation naming. The CBGD patients endorsed significantly more depressive symptoms on the Geriatric Depression Scale.