ApoE4 is a variant of the Apolipoprotein E gene, which plays a crucial role in lipid metabolism and the transport of fats in the body. This gene has three common forms: ApoE2, ApoE3, and ApoE4. Individuals who inherit one or two copies of the ApoE4 variant are at a higher risk of developing Alzheimer's disease and other forms of dementia compared to those with the other variants. Research indicates that ApoE4 may influence the accumulation of amyloid plaques in the brain, a hallmark of Alzheimer's disease. While not everyone with the ApoE4 variant will develop cognitive decline, it is considered a significant genetic risk factor, prompting ongoing studies to understand its mechanisms and potential interventions.