OBJECTIVETo investigate the clinical features of Alzheimer's disease (AD) and vascular dementia (VaD), and to find effective methods for differential diagnosis between the two entities.

METHODSTotally 112 AD patients and 92 VaD patients were enrolled in this study, consisted of patients from the memory clinics and patients from the community population visited during the epidemiological survey from 1996 to 2000. Diagnosis of dementia, probable AD and probable VaD were made according to international criteria. Results of specific neuroimaging examination were referred to verify the diagnosis and the final diagnosis of each patient was determined from the discussion between clinical experts and radiological professionals. Analysis on clinical and neuroimaging data was performed, aiming at finding differential points between the two dementia-subtypes. A logistic binary multiple regression analysis was performed to pick out those statistically significant clinical features for differential diagnosis at last.

RESULTSAD and VaD patients have different clinical features in various demented stages, therefore the indexes that differentiate the two dementia subtypes change accordingly. The predominant features of mild AD appear to be deficits of prolonged memory and learning ability, while the major impairment of mild VaD patients is decline of calculating ability. With the progress of dementia, learning ability and attention turn to be the effective indexes for differential diagnosis. In the mild and moderate demented stage, AD patients are inferior to VaD patients in handling finacial affairs and making phone calls, while VaD patients often degenerate in daily activities concerning with both physical ability and intellectual level. Severe VaD patients appears more global degeneration of living ability compared to AD patients. The difference of ADL scores between the two subtypes is significant in moderate to severe demented patients (P < 0.05). Psychological behavior symptoms, such as repeatedly collecting useless things, are the characteristic manifestation to differentiate AD from VaD in all clinical stages.

CONCLUSIONSThe results of our study indicate that substantial differences exist between AD and VaD patients. Such differences can be attributed to the differences of lesion nature and distribution, as well as the underlying pathophysiological procedures of each disease.