An Alzheimer’s disease test can be performed to evaluate the APP, PS1 and PS2 genes to predict if the individual has an inherited type of Alzheimer’s, states the Alzheimer’s Society. The numbers of people who inherit this disease are small.
Around 99 percent of older family members with this condition do not pass it on to younger generations, states the Alzheimer’s Society. While genetics play a large role in disease, lifestyle and environment heavily influence disease and may even adjust the effects of genetic inheritance.
Determining if dementia is inherited primarily depends on the cause, says the Alzheimer's Association Huntington’s disease is an autosomal dominant illness, meaning only one defective copy of the gene is needed for a family member to inherit this form. This gene defect causes brain protein irregularities that have several symptoms, including decline in thinking, depression, involuntary movement and irritability.
Early-onset Alzheimer’s disease is another form of dementia that is inherited, says the Alzheimer's Society. It often collects within families and can spread for several generations. The symptoms are severe. Those who suffer with early-onset Alzheimer’s can be affected in their 30s onward. Having relatives with late-onset Alzheimer’s increases a person’s risk of getting the condition.