From: olivercranglejr@gmail.com   
      
       
      
       
      
       
      
   What We Know Today About Alzheimer's Disease   
   About Alzheimer's	Inside the Brain	Causes	Treatments   
   Plaques form when beta-amyloid clump together.   
   The Search for Alzheimer's Causes and Risk Factors   
   While scientists know Alzheimer's disease involves progressive brain cell   
   failure, the reason cells fail isn't clear. Like other chronic conditions,   
   experts believe that Alzheimer's develops as a complex result of multiple   
   factors rather than any one    
   overriding cause. Both age and genetics have been identified as risk factors,   
   but many questions still remain. The discovery of additional risk factors will   
   deepen our understanding of why Alzheimer's develops in some people and not   
   others.   
      
   Age and Alzheimer's   
   Family history and Alzheimer's   
   Genetics and Alzheimer's   
   Related information   
   Age and Alzheimer's   
   Although Alzheimer's is not a normal part of growing older, the greatest risk   
   factor for the disease is increasing age. After age 65, the risk of   
   Alzheimer's doubles every five years. After age 85, the risk reaches nearly 50   
   percent.   
      
   Family history and Alzheimer's   
   Another Alzheimer's risk factor is family history. Research has shown that   
   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.   
      
   Genetics and Alzheimer's   
   There are two categories of genes that influence whether a person develops a   
   disease: (1) risk genes and (2) deterministic genes. Researchers have   
   identified Alzheimer's genes in both categories.   
      
   	Genetics in Alzheimer's (approx 14 min.)   
   Risk genes increase the likelihood of developing a disease, but do not   
   guarantee it will happen. Researchers have found several genes that increase   
   the risk of Alzheimer's. APOE-e4 is the first risk gene identified, and   
   remains the gene with strongest    
   impact on risk. APOE-e4 is one of three common forms of the APOE gene; the   
   others are APOE-e2 and APOE-e3.   
      
   Everyone inherits a copy of some form of APOE from each parent. Those who   
   inherit one copy of APOE-e4 have an increased risk of developing Alzheimer's.   
   Those who inherit two copies have an even higher risk, but not a certainty. In   
   addition to raising    
   risk, APOE-e4 may tend to make symptoms appear at a younger age than usual.   
   Scientists estimate that APOE-e4 is implicated in about 20 percent to 25   
   percent of Alzheimer's cases.   
   	Late-Onset Alzheimer's and Genetics (approx 22 min.)   
   Catalyst for progress   
   In 2003, the Alzheimer's Association partnered with the National Institute on   
   Aging to begin recruiting participants for the National Alzheimer's Disease   
   Genetics Study, a federal initiative to collect and bank blood samples from   
   families with several    
   members who developed Alzheimer's disease late in life. The goal is to   
   identify additional Alzheimer's risk genes. The study continues to seek   
   participants.   
   Deterministic genes directly cause a disease, guaranteeing that anyone who   
   inherits one will develop a disorder. Scientists have found rare genes that   
   cause Alzheimer's in only a few hundred extended families worldwide. These   
   genes, which are estimated    
   to account for less than 5 percent of Alzheimer's cases, cause familial   
   early-onset forms in which symptoms usually develop between a person's early   
   40s and mid-50s.   
      
   Although the genes that cause "familial Alzheimer's" are rare, their discovery   
   has provided important clues that help our understanding of Alzheimer's. All   
   of these genes affect processing or production of beta-amyloid, the protein   
   fragment that is the    
   main component of plaques. Beta-amyloid is a prime suspect in decline and   
   death of brain cells. Several drugs now in development target beta-amyloid as   
   a potential strategy to stop Alzheimer's disease or significantly slow its   
   progression.   
      
   Two international investigations are under way to gain further insight into   
   Alzheimer's disease by studying individuals with deterministic Alzheimer's   
   genes: (1) The Dominantly Inherited Alzheimer Network (DIAN), funded by the   
   National Institute on Aging    
   (NIA), includes 10 flagship research centers in the United States, the United   
   Kingdom and Australia. (2) The Alzheimer's Prevention Initiative (API) focuses   
   on an extended family in Antioquia, Colombia, in South America. At 5,000   
   members, this is the    
   world's largest family in which a gene that causes Alzheimer's has been   
   identified. API collaborators include DIAN. Learn more on our Treatment   
   Horizon page.   
   	Early-Onset Alzheimer's and Genetics (approx 26 min.)   
   Genetic tests are available for both APOE-e4 and the rare genes that directly   
   cause Alzheimer's. However, health professionals do not currently recommend   
   routine genetic testing for Alzheimer's disease. Testing for APOE-e4 is   
   sometimes included as a part    
   of research studies.   
      
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   A closer look at genes linked to Alzheimer's   
   The 23 human chromosome pairs contain all of the 30,000 genes that code the   
   biological blueprint for a human being. This interactive illustration   
   highlights the chromosomes containing each of the three genes that cause   
   familial Alzheimer's and the gene    
   with the greatest impact on Alzheimer's risk.   
      
   Roll your mouse over the colored text below to highlight interactive features   
   in the image.   
      
    	   
   23 chromosome pairs   
   Amyloid precursor protein (APP), discovered in 1987, is the first gene with   
   mutations found to cause an inherited form of Alzheimer's.   
      
   Presenilin-1 (PS-1), identified in 1992, is the second gene with mutations   
   found to cause inherited Alzheimer's. Variations in this gene are the most   
   common cause of inherited Alzheimer's.   
      
   Presenilin-2 (PS-2), discovered 1993, is the third gene with mutations found   
   to cause inherited Alzheimer's.   
      
   Apolipoprotein E-e4 (APOE4), discovered in 1993, is the first gene variation   
   found to increase risk of Alzheimer's and remains the risk gene with the   
   greatest known impact. Having this mutation, however, does not mean that a   
   person will develop the    
   disease.   
      
   Catalyst for progress   
      
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