Myths vs facts: APOE and fatigue

The claim that APOE gene variants directly cause fatigue is largely a myth. APOE (apolipoprotein E) is primarily linked to lipid metabolism and Alzheimer's disease risk. Some studies suggest an association between APOE4 and increased fatigue after traumatic brain injury or in Alzheimer's patients, but evidence in healthy individuals is weak and inconsistent. Fatigue is multifactorial (sleep, stress, nutrition, exercise). DNA tests marketing APOE as a 'fatigue gene' overstate its predictive value. The effect size is small, and lifestyle factors dominate. APOE testing may be useful for assessing cardiovascular or Alzheimer's risk, but not for explaining fatigue. Evidence grade: human-moderate (for specific subgroups), otherwise marketing. Safety note: APOE4 increases Alzheimer's risk; results should be discussed with a physician.