WHAT IS ALZHEIMER DISEASE AND HOW

SUMMARY: Alzheimer disease prevails as a major cause of disability in the elderly population and ranks as the most common form of dementia that affects 1 of 8 individuals older than 65 years of age. Most AD cases are late in onset and are probably influenced by both genetic and environmental factors. Apart from age, the risk factors include family history; brain injury, both traumatic and vascular; and metabolic diseases, such as diabetes, hypercholesterolemia, and obesity. Based on twin studies, inheritance plays a role in approximately 80 % of cases (familial and sporadic). ABBREVIATIONS: AD Alzheimer disease; APP amyloid protein precursor; PENS1 presenilin 1; PENS2 presenilin 2; A amyloid-; APOE apolipoprotein E While current therapies remain largely limited, advanceshave been made in clarifying genetic factors related to the development of Alzheimer disease. Autosomal dominant inheritance of 3 genes, PSEN1, PSEN2, and APP, is associated with an early-onset form. Late-onset disease is the most com-mon form and has a risk association with the APOE 4 allele. Genetic testing is available for these mutations, and research continues to improve prognostication and may inspire novel treatments