In 1993, geneticists identified a link between the incidence of late-onset AD and APOE 4, one of three common alleles that can fill the APOE gene. Therefore, scientists continue looking for other causes. Some are investigating environmental factors, such as exposure to aluminum, which is present in unusually high levels in AD patient brain tissue. People with higher education are statistically less likely to get it. Having a family member with AD increases the risk.
Some evidence suggests that women are more likely then men to get the disease.
An examination of the brain tissue remains the only definitive diagnosis. By integrating information from the patient's medical history, mental ability tests, and physical, psychological and neurological exams, doctors can exclude other causes of dementia and, by a careful and informed process of elimination, zero in on Alzheimer's Disease. An early diagnosis of AD is a good idea, particularly for the benefits it provides in planning for the future. So while simple memory lapses are natural in older people, whenever there is evidence of unusual difficulty communicating, thinking or reasoning, a medical diagnosis should be sought as soon as possible. Experts caution against premature genetic testing, however.