Clinical and neuropsychological correlates of impaired awareness of deficits in Alzheimer disease and Parkinson disease: A comparative study

Objective: To compare patients with Alzheimer disease (AD) and Parkinson disease (PD) with regard to their awareness of cognitive, emotional/social interaction, self-care, and motor-related neurologic deficits. Background: Unawareness of deficits, a clinically important symptom, is found in AD. It has been hypothesized to be associated with disruption of frontal-subcortical circuits but has been little studied in other neurodegenerative disorders. Because PD has a different anatomic-pathologic substrate, a comparison of impairment of awareness in AD and PD may shed light on the neural basis of this phenomenon. Method: Impairment of awareness was measured as the difference between patient self-report and caregiver ratings of patient abilities on questionnaires tapping cognitive, emotional/social interaction, self-care, and motor function. These "discrepancy scores" were then compared between the two diagnostic groups and examined in relation to selected neuropsychological test data. Results: In general, both AD and PD patients rate themselves as being less impaired than do their caregivers. The two diagnostic groups, AD and PD, differ significantly, however, on awareness discrepancy measures in the cognitive domain. In their ratings of patient cognitive skills, AD caregivers rate patients as significantly more impaired than patients rate themselves, whereas PD caregivers and patients do not differ significantly on these ratings. Impaired awareness in PD but not in AD is associated with poorer overall cognitive function and performance on tests measuring memory, attention, and constructional ability. Conclusions: Both AD and PD patients display impaired awareness of deficits in multiple domains, including motor-related neurologic function. Parkinson disease patients with comparatively intact cognitive function display relatively preserved awareness of motor and other deficits.