APOE ɛ4/ɛ4 Is Associated with Aberrant Motor Behavior Through Both Lewy Body and Cerebral Amyloid Angiopathy Pathology in High Alzheimer's Disease Pathological Load.

BACKGROUND

Aberrant motor behavior (AMB) is a neuropsychiatric symptom (NPS) prevalent in Alzheimer's disease (AD), known to cause great distress to both patients and caregivers. Apolipoprotein E4 (APOE4) is the most important genetic predictor of AD, and it has been associated with high NPS prevalence.

OBJECTIVE

To investigate the neuropathological substrates and risk factors associated with AMB in AD patients.

METHODS

Cases with Braak stage I-II and CERAD 0-1 were classified as Low AD (LAD), while Braak stage III-IV and CERAD 2 were grouped as Intermediate AD (IAD). Cases with Braak stage V-VI and CERAD 3 were classified as High AD (HAD) in accordance with NIA-Reagan criteria. All cases were stratified by APOE genotype, yielding No ɛ4 & ɛ4 and ɛ4/ɛ4 groups depending on ɛ4 copy number within APOE. Presence of AMB was assessed using NPI-Q.

RESULTS AND CONCLUSION

AMB increased in parallel with CERAD and Braak & Braak scores. Hypercholesterolemia, but no other cardiovascular risk factors, was associated with AMB in HAD. AMB prevalence in HAD was significantly increased in the presence of two APOEɛ4 alleles as compared to No ɛ4 & ɛ4. The relationship between homozygous APOE4 and AMB was strongly associated with the presence of both Lewy bodies and cerebral amyloid angiopathy pathologies in both sexes.