Early onset of Alzheimer's disease (AD) is a diagnosis that occurs prior to the age of 65. While it can develop among people in their 30s and 40s, it is more common among those in their 50s. Early-onset Alzheimer's bears unique characteristics from traditional Alzheimer's, causing distinct brain changes, physical symptoms and social effects.
Genetic Component
According to the Alzheimer's Society, early-onset Alzheimer's runs in families and has been linked to three genes that are distinct from those related to traditional Alzheimer's. A genetic abnormality on chromosome 21 of the amyloid precursor protein (APP) gene affects the production of the protein amyloid, causing a buildup of the protein in the brain and the development of Alzheimer's. Genetic faults on two presenilin genes--PSEN1, or chromosome 14, and PSEN2, or chromosome 1--also lead to early onset of the disease. These genes are rare and account for less than 1 of every 1,000 incidences of Alzheimer's cases. Those who do carry the genes tend to develop the condition in their 30s or 40s.
Brain Changes
Early-onset Alzheimer's is associated with changes in the brain that distinguish it from traditional Alzheimer's. According to the Cleveland Clinic, those with early onset disease tend to have more twisted nerve cell fibers (neurofibrillary tangles) and sticky proteins called beta amyloids that form plaques in the brain. Plaques and twisted nerve fibers cause damage to surrounding cells and lead to erosion and shrinking of the brain. It may be that more of these microscopic brain changes are seen in those with early-onset Alzheimer's simply because it takes more to damage a younger person's brain; thus, researchers are not clear as to whether these symptoms are truly distinct from traditional Alzheimer's or are more a byproduct of age.
Physical Symptoms and Decline
In terms of physical symptoms, early-onset Alzheimer's is more commonly associated with a condition that causes muscle spasms and twitching (myoclonus) than late-onset Alzheimer's. While there is some information that suggest early-onset AD progresses faster than traditional Alzheimer's, the Mayo Clinic advises that there is currently no definitive evidence to support this notion. Because the disease starts progressing at an earlier age, individuals may need supportive care earlier, leading to the view that physical and mental deterioration happened more quickly; but this may just be perception.
Personal, Social and Psychological Effects
Although Alzheimer's disease presents difficult challenges at any age, early-onset Alzheimer's disease tends to cause a specific set of emotional, social and practical problems because it affects individuals who are typically still active in their jobs and busy managing family and financial responsibilities. According to the Alzheimer's Association, people with early-onset Alzheimer's are likely to feel denial, fear of losing friends, family, career and financial resources, anger, frustration, depression and a feeling of isolation. According to the Mayo Clinic, loss of intimacy is a common feeling that arises as patients and their spouses face the prospect of spending their later years without an active partner.
