What proportion of Alzheimer's Disease cases is classified as early onset?

The classification of early onset Alzheimer's Disease, which typically refers to cases that occur before the age of 65, represents a smaller subset of the overall prevalence of the disease. Current statistics indicate that approximately 5% of all Alzheimer's cases are classified as early onset. This percentage is derived from the understanding that while Alzheimer's is predominantly an age-related condition, exceptions exist where genetic factors or other influences may lead to earlier manifestations.

The other options suggest significantly higher proportions of early onset cases, which does not align with the available epidemiological data. Thus, identifying early onset Alzheimer's as comprising around 5% of total cases is consistent with the current understanding of the disease's demographics and pathology. This statistic is particularly important for genetic counselors and medical professionals in understanding risk factors and the need for targeted genetic testing in families affected by early onset forms of the disease.