Differences between the behavioral and psychological symptoms of Alzheimer's disease and Parkinson's disease

Aim We compared the behavioral and psychological symptoms of Alzheimer's disease (AD) and Parkinson's disease (PD) in order to determine the characteristic features of each disorder. Methods For this retrospective cohort study, we compared the behavioral and psychological symptoms of 288 AD patients and 189 PD patients (mean age, 74.6 ± 5.9 and 73.0 ± 8.7 years respectively). Symptoms were evaluated using the geriatric depression scale (GDS), apathy scale (AS), and Abe's behavioral and psychological symptoms of dementia score (ABS). Results AD patients had higher AS and ABS scores than PD patients. A gender-dependent comparison showed that ABS scores were worse in female AD patients than in female PD patients (p = 0.001). A subscale analysis of ABS scores revealed that male AD patients were only significantly different from male PD patients in 1 item, whereas female AD patients were significantly different from female PD patients in 4 items. Among patients with mild cognitive decline, no differences in affective scores were observed. Alternatively, among patients with moderate cognitive decline, affective scores on all 3 scales were worse in PD patients than in AD patients. Conclusions The present age- and gender-matched retrospective analysis identified greater behavioral and psychological disease severity in female AD patients relative to female PD patients, and greater affective severity in PD patients versus AD patients with a similar degree of cognitive decline.