Age-dependent cognitive and affective differences in Alzheimer's and Parkinson's diseases in relation to MRI findings

Objective To compare age-dependent changes in cognitive and affective functions related to white matter changes between patients with Alzheimer's disease (AD) and Parkinson's disease (PD). Methods We retrospectively compared age-dependent cognitive and affective functions in 216 AD patients, 153 PD patients, and 103 healthy controls with cerebral white matter lesions (WMLs), periventricular hyperintensity (PVH), deep white matter hyperintensity (DWMH), micro-bleeds (MBs), and lacunar infarcts (LIs). Results The average mini-mental state examination (MMSE) scores were 19.6 ± 6.1 and 26.8 ± 3.6 in AD and PD patients, respectively. Significant decreases were found in the MMSE score, Hasegawa's dementia scale-revised (HDS-R) score, frontal assessment battery score, and Abe's BPSD score (ABS) among the age-dependent AD subgroups and in the MMSE, HDS-R, Montreal cognitive assessment, geriatric depression scale, and ABS scores among the age-dependent PD subgroups; they were worse in AD patients. White matter changes were observed in > 88% and > 72% of patients with AD and PD, respectively. An age-dependent direct comparison of AD and PD showed significant differences in the PVH and DWMH grades, and numbers of MBs and LIs. Conclusion WML-related cognitive and affective functions worsen with age in AD and PD patients; however, the abnormalities were more frequent and stronger in AD patients.