Individuals with a first-degree relative (parent, sibling, or child) diagnosed with Alzheimer’s dementia are more likely to develop the condition. The risk is further increased if more than one family member has the condition. Despite this fact, many individuals with a family history of dementia do not develop the disorder, and many individuals without a family history of dementia go on to develop the disorder.
Genetic testing is available for Alzheimer’s dementia. The gene with the strongest correlation to the development of dementia is apolipoprotein E4, or ApoE4. Individuals who inherit one copy of the ApoE4 gene are at a twofold to fourfold increased risk for developing Alzheimer’s dementia. Individuals who inherit two copies of the gene have a tenfold higher risk, but are not certain to develop dementia. Inheritance of this gene may also be implicated in the onset of dementia at a relatively young age. Routine genetic testing for dementia is not recommended and is usually done as part of research studies.