Confusional symptomatology distinguishes early- and late-onset Alzheimer's disease.

Symptoms of confusion were examined in 75 patients with Alzheimer's disease (AD). Mild confusion was found in 20, and mode-rate/severe confusion in 8 patients. Confusion was more frequent in the late-onset (26/44-59%) than in the early-onset AD group (2/31-6%) (p less than 0.0001), and patients with confusion were older (p less than 0.0001) than those without confusion. The frequency of confusion was higher in patients with ischemic heart disease (13/28-46%) than in patients without this vascular factor (10/47-21%) (p less than 0.05). An inverse relation was found between confusional symptomatology and parietal-lobe symptoms. The findings in this study suggest that a subgroup of AD patients, fulfilling the NINCDS-ADRDA criteria for probable AD, is characterized by a clinical picture of mild confusional symptomatology together with no or mild parietal-lobe symptomatology, higher age and higher frequency of ischemic heart disease. This group contrasts with the other subgroup of pure AD, which is characterized by a clinical picture of marked parietal-lobe symptomatology, almost no confusional symptomatology, lower age and lower frequency of ischemic heart disease.