Alzheimer's Disease Genetic Risk Factor APOE-ε4 Also Affects Normal Brain Function

Area of Science:

• Neuroscience
• Genetics
• Alzheimer's Disease Research

Background:

• APOE-ε4 is the primary genetic risk factor for Alzheimer's disease (AD).
• AD pathology begins decades before clinical symptoms manifest.
• The precise onset and early-life impact of APOE-ε4 on brain function remain unclear.

Purpose of the Study:

• To investigate the effects of APOE-ε4 on normal brain function in early life.
• To determine if APOE-ε4 influences brain structure and signaling in the absence of gross AD pathology.
• To explore the lifelong consequences of APOE-ε4 inheritance on brain activity and AD risk.

Main Methods:

• Studies in mice expressing APOE4 assessed spatial learning, NMDAR signaling, and neuronal structure.
• Functional magnetic resonance imaging (fMRI) examined brain activity in young humans with and without APOE-ε4.
• Behavioral tasks were administered to young human carriers of APOE-ε4.

Main Results:

• Mice with APOE4 exhibited spatial learning deficits and reduced NMDAR signaling.
• APOE4 expression in mice led to structural changes in hippocampal neurons.
• Young APOE-ε4 carriers showed distinct medial temporal brain activity patterns and varied performance on behavioral tasks.

Conclusions:

• APOE-ε4 influences normal brain function from early life, independent of overt AD pathology.
• Inheritance of APOE-ε4 induces lifelong alterations in brain neurochemistry, structure, and function.
• These early-life changes may underlie the increased risk for Alzheimer's disease associated with APOE-ε4.