What is Alzheimer’s disease?
Alzheimer’s disease is a progressive brain disorder that gradually destroys memory and other important mental functions. It is the most common form of dementia, accounting for 60 – 70% of approximately 48 million dementia cases per year. More than 90% of Alzheimer’s cases are the late-onset form, with symptoms not appearing until after 65 years of age.
What causes Alzheimer’s disease?
The cause of late-onset Alzheimer’s disease is currently unknown, but is likely due to a combination of environmental, lifestyle and genetic factors. Variation in the APOE gene is the strongest genetic factor influencing the risk of late-onset Alzheimer’s disease. There are three common variants (alleles) of APOE, known as e2, e3 and e4. Each of us inherit two copies of the APOE gene, and our APOE genotype indicates our risk of late-onset Alzheimer’s disease:
- e2/e2 – reduced risk
- e2/e3 – reduced risk
- e2/e4 – 3X increased risk
- e3/e3 – does not affect your risk
- e3/e4 – 3X increased risk
- e4/e4 – 10X to 15X increased risk