Early-Onset vs. Late-Onset Alzheimer's Disease: Neuropsychological and Neuroimaging Differences (P05.046)

Abstract

Objective: There are few direct comparisons between early-onset Alzheimer9s disease (EAD) and late-onset Alzheimer9s disease (LAD) patients. This study aims to compare patients with EAD vs. LAD on neuropsychological and neuroimaging measures and identify distinguishing features between the two. Background EAD, with an onset before age 65, has been overshadowed by the more common LAD. Yet, the literature suggest that there are clinical differences between these two forms of the disease. Patients with EAD patients may have more focal neurocognitive deficits and a more aggressive and symmetrical progression than patients with LAD. Design/Methods: Participants included 21 EAD and 24 LAD patients who met criteria for clinically probable AD and had comparable levels of disease progression and severity. The patients underwent neurological examinations, neuropsychological testing, and resting state FDG-PET of the brain. Demographic neuropsychological, neuropsychiatric, and functional variables were compared using Chi Square analyses, independent samples t-tests, and ANCOVA. FDG-PET data was compared using voxel-based analysis with statistical parametric mapping (SPM). Results: There were significant neuropsychological differences between the two groups: the EAD patients were more impaired in response-inhibition and auditory working memory (measures of executive functions), whereas the LAD patients were more impaired on confrontation naming. Caregivers reported greater prevalence of irritability and anxiety in EAD vs. LAD, and EAD patients needed more assistance with initiating grooming, meal preparation, writing, and dressing tasks compared to LAD patients. On SPM PET analyses, the EAD group had greater focal hypometabolism in both frontal and parietal regions compared to LAD. Conclusions: This study shows clear differences between EAD and LAD. Patients with EAD have more focal and frontal dysfunction when compared to LAD patients, and this is reflected in executive function disturbances. Although these findings are partially at variance with prior research, they confirm the presence of clinical differences between these two forms of AD. Supported by: Merit Review, Veterans Affairs. Disclosure: Dr. Kaiser has nothing to disclose. Dr. Liu has nothing to disclose. Dr. Melrose has nothing to disclose. Dr. Jimenez has nothing to disclose. Dr. Monserratt has nothing to disclose. Dr. Sultzer has received personal compensation for activities with Bristol-Myers Squibb Company, Forest Laboratories, Inc., Pfizer Inc, Janssen Pharmaceutica, Abbott Laboratories, Inc., and AstraZeneca. Dr. Sultzer has received research support from Pfizer Inc, and Forest Laboratories. Dr. Mendez has nothing to disclose.