Someone who is interested in dementia, might have read the name APOE4 online. APOE refers to Apolipoprotein E gene, a particular gene responsible for creating a protein that carries cholesterol and other fats in our bloodstream.
This gene is considered to be one of the main causes of early-onset dementia and dementia with a genetic cause. In certain cases, this gene undergoes a mutation and people may therefore carry a polymorphic allele. Individuals carrying the E4 allele have a sensibly higher risk of developing dementia.
The APOE4 gene is, however, considered to be a serious risk factor, not only for dementia, but also for vascular diseases and for increased cognitive decline in normal aging, even when not talking about dementia.
Not everybody who presents the mutated gene will go on to develop dementia necessarily, but the increased risk is considerable, estimated to be between 3-12 times higher than for an APOE4 non-carrier.
Because of the apparently relevant role the APOE4 gene plays in the development of dementia, scientists think that new treatments targeting this specific gene may be developed in the future. Until now, unfortunately, no drug as yet been developed, and therapeutic approaches are still at the preclinical level or Phase 1 testing.
What is available, is genetic testing to find out if someone is an APOE4 carrier, though many are sceptical regarding it real utility. The test can only tell if a person is a carrier, but cannot say anything regarding the actual risk of an individual to develop dementia later on. Not all of APOE4 carriers go on to develop dementia, and not all people living with dementia are APOE4 carriers. In fact, most researchers believe genetic testing to be useful for studying large populations and the related risk of developing Alzheimer’s disease, or when used in clinical trials. Another case when genetic testing is warranted is in cases of younger-onset dementia, where it can be helpful for an accurate diagnosis. In other cases, it is otherwise not recommended.
Liu, C. et al. (2013), Apolipoprotein E and Alzheimer disease: risk, mechanisms, and therapy, Nature Reviews Neurology, 9(2), pp. 106-118.