Sleep apnea, APOE4 and Alzheimer's disease 20 years and counting?

Alzheimer's disease (AD) is acknowledged to be at least partially genetic, and one of the key genotypic markers for this condition is the APOE4 allele. Links between sleep apnea and AD have long been suspected because of mental impairment seen in some sleep apnea patients and possible evidence suggesting higher rates of sleep apnea in some dementia patients. The recent demonstration of an association between the APOE4 genotype and sleep apnea has rekindled further interest in this topic, particularly because sleep apnea is characterized by multiple genetic vulnerabilities. We review here evidence related to associations between sleep apnea and dementia, the role of APOE4 as a likely marker for cerebrovascular disease, and discuss treatment considerations relevant to sleep apnea as a potentially reversible cause of dementia.