The Apolipoprotein E Antagonistic Pleiotropy Hypothesis: Review and Recommendations
Research on apolipoprotein E (APOE) has consistently revealed a relationship between the gene'sε4 allele and risk for development of Alzheimer's disease (AD). However, research with younger populations ofε4 carriers has suggested that the APOEε4 allele may in fact be beneficial in earlier ages and may only confer risk of cognitive decline later in life. Accordingly, we and others have proposed that APOE may represent an example of antagonistic pleiotropy. Antagonistic pleiotropy is an evolutionary biology concept that proposes certain genes or alleles that may differentially impact fitness during different life stages. We critically review this hypothesis in light of new research of the impact of APOE on cognition and neural integrity across the lifespan. We provide recommendations for the revision of the antagonistic pleiotropy hypothesis of APOE and suggest important avenues for future research in this area.