Another strong risk factor is family history. Those who have a parent, brother, sister or child with Alzheimer’s are more likely to develop the disease. The risk increases if more than one family member has the illness. When diseases tend to run in families, either heredity (genetics) or environmental factors, or both, may play a role.
www.alz.org/alzheimers_disease_causes_risk_factors.aspThere is no single test that proves a person has Alzheimer's. A diagnosis is made through a complete assessment that considers all possible causes.
www.alz.org/alzheimers_disease_steps_to_diagnosis.asp