Alzheimer's is not just an "old person's" disease. There are 400,000 Americans under the age of 65 who have this mind-crippling disease, according to the Alzheimer's Association 2. The association makes no distinction between life expectancy for those with this younger onset form of the disease versus those who were diagnosed as seniors, but research suggests the symptoms of this disease may progress more rapidly in those who have early onset than their older onset counterparts 2.

Characteristics

Generally most early onset diagnoses occur when people are in their 50s, but AD has been known to occur in people as young as 30. The familial connection with this type of AD is strong; three genes have been linked to this form, according to the Mayo Clinic.

Longevity

The Alzheimer's Association reports the average life expectancy for those with AD is four to six years after the date of diagnosis 2. In a study conducted by the University of Aberdeen and University of Edinburgh, the five-year survival rate was 32 percent for men and 43 percent for women, of the 451 patients with early onset that were studied. Studies published in the Journal of Geriatric Psychiatry and the American Academy of Neurology reported similar rates -- 36 percent and 23 percent, respectively. Both rates exceeded the American Academy of Neurology's expected mortality rate of 9.5 percent.

Causes of Death

According to the Cleveland Clinic, those with early onset AD experience some physical symptoms that are absent in older onset, including muscle twitches and spasms. But the actual cause of death closely parallels that of their counterparts. In the study in the Journal of Geriatric Psychiatry, 73 percent of those who died succumbed to pneumonia. Other leading causes of death included malignancy, or the general worsening of the illness, and heart disease.

Research

The Cleveland Clinic suggests those with early onset decline at a faster rate because they are typically active at the young age of their diagnosis and don't handle it well -- succumbing to frustration and depression. In addition, those with early onset often depend on a husband or wife who may also be caring for an elderly parent and young child. The stress may be too much for the caregiver to bear, leading him or her to place the loved one in a long term care facility, hastening the progression of symptoms. The American Academy of Neurology reported that in a five-year study, 63 percent of AD survivors were in nursing homes.

Coping

The Alzheimer's Association supports the use of non-medical therapies in conjunction with medical treatment 2. They have suggested these therapies can delay the progression of symptoms and also help the families who are living with this traumatic disease. Non-drug approaches include establishing an environment that's calm and simple -- cut down on noise, glare and distractions from electronics and TV. You need to avoid sounding harsh or judgmental when, for example, a loved one starts to talk about a long-dead parent. Instead, the association suggests saying something like, "Your mother is wonderful. I'd like to see her, too."