Types of Alzheimer's Disease

1. Early Onset Alzheimer's
2. Late Onset Alzheimer's

Early Onset Alzheimer's

Early onset Alzheimer's is a rare form of the disease diagnosed in people under the age of 65. It is a form of dementia believed to be linked to a genetic defect on chromosome 14. People with Down syndrome are at higher risk for this type of Alzheimer's and may experience symptoms as early as their mid-40s to early 50s. Early onset Alzheimer's results in a higher incidence of brain abnormalities and people experience more muscular symptoms such as muscle spasms and twitches, than those with late onset of the disease.

Familial Alzheimer's is a rare form of Alzheimer's with genetic causes. It is diagnosed when Alzheimer's is seen in patients in at least two of the previous generations. It is generally early-onset with symptoms sometimes visible in the early 40s.

Late Onset Alzheimer's

Late onset Alzheimer's accounts for 90 % of the cases of the disease, and does not usually appear until after age 65. This form of dementia appears to be age-related, with the incidence doubling for every five years one is over the age of 65 and is most often seen in people over the age of 85. There does not appear to be any genetic abnormality of chromosome 14 in this type of Alzheimer's disease.