Early onset dementia may be related to different illnesses. The life expectancy for people with a form of early onset dementia varies from person to person and depends upon the type of dementia that they have.
Early onset dementia refers to any type of dementia that occurs in people younger than 65 years of age. The most common form of dementia is Alzheimer's disease.
Dementia is characterised by a decline in cognitive abilities. Those with some form of early onset dementia may experience memory loss, changes in personality, behavioural disturbances and communication problems.
According to a study conducted by researchers from the Mayo Clinic in Rochester, Minnesota, in 2008, dementia in people ages 45 and younger is more likely to be caused by multiple sclerosis (MS), Huntington's disease or HIV than by Alzheimer's disease. People with MS can expect to live a normal lifespan minus seven years, those with Huntington's can live 15 years after onset of the disease and people with HIV live nearly 25 years.
According to Cleveland Clinic, early onset Alzheimer's disease may progress more quickly than late onset Alzheimer's disease. However, according to MayoClinic.com, early onset Alzheimer's may not progress any more quickly.
The prognosis for irreversible forms of dementia is a continued decline in cognitive ability until the patient dies. Life expectancy varies from person to person, though the average amount of time that people live with Alzheimer's disease is approximately seven years, according to the Encyclopedia of Mental Disorders.