Alzheimer’s Disease: It’s Different Than You Think

Of the many⁤ forms of dementia, Alzheimer’s disease has received the ⁤most research attention. people are ‍often worried they will inevitably contract Alzheimer’s disease⁢ if a parent did.But ⁣increasingly, scientists have found this ⁣is not necessarily the case.

Some People Have a⁣ “Risk⁢ Allele”

Processes in our bodies are regulated by genes,but not everyone has exactly the same version of each gene. These different⁢ versions are called alleles. Different alleles carry different risks ‍for physical conditions in the body, including Alzheimer’s disease and other⁤ dementias.

One of the most strongly replicated findings for genetic⁢ risk of Alzheimer’s disease in late life involves the APOE gene,⁤ and the ε4 allele. You have two alleles for every gene. For the APOE gene, you may have ⁣the ε2, ε3, or ε4 alleles. The ε2 ‍allele appears to⁤ be protective; people who carry it are less likely to develop Alzheimer’s disease. Having one allele with ⁣ε4 increases your risk, however,⁣ and having both alleles⁣ with ε4 raises it even⁣ more.

Distributions of ε4 differ based on ancestry⁢ groups, but in general, it is much less common than ⁤ε3 (the most common). Moreover, the APOE alleles are only risk⁣ and protection factors; they do not determine whether you get the disease.⁣ Even people with the highest risk-double ε4-only develop Alzheimer’s disease about 40% to 60%‍ of the time by age 80. This chart presents a simplified example of the‍ distribution of ⁤the⁢ alleles⁢ and ⁣the likelihood of developing Alzheimer’s disease by age 80. This chart is‍ based on multiple studies; actual rates differ by age, sex, ancestry, and other factors.

Early Onset vs. Late Life Alzheimer’s Disease

It’s critically important to note that early-onset Alzheimer’s disease-which ⁣manifests ⁣before⁢ age 60-has a strong genetic influence. The early form is relatively rare. For example, fewer than 1 in 100,000 adults in their 40s have Alzheimer’s disease.

This genetic influence⁢ is evident in the extended Paisa family ⁢in Colombia, with ⁢6,000 related individuals. they have a very high rate⁢ of early-onset Alzheimer’s disease, starting in their 40s. The disease is tied to a mutation in the PSEN1 gene (E280A); sometimes called the Paisa mutation. individuals with this mutation will almost certainly develop early-onset Alzheimer’s disease. Nevertheless, scientists recently discovered ⁣one of the Paisa family members who had the⁤ mutation but did not have Alzheimer’s disease ‍at age 60, lending additional support for the possibility of protective non-genetic factors.

Is It Really⁤ This⁣ Simple? … ⁢No

You‍ might potentially be thinking, “Wow. That seems so