Wednesday, July 15, 2015
Alzheimer's disease may affect the brain differently in African-Americans than white Americans of European descent, scientists have said
Researchers who conducted the study in the United States said that their findings have important clinical implications as they may suggest a need for different types of Alzheimer's prevention and treatment in African-Americans. Alzheimer's disease is the most common cause of dementia and sees proteins build up in the brain to form structures called plaques and tangles. Scientists looked for these plaques and tangles in the brains of people who had died as well as other brain changes that can cause dementia, such as infarcts (tissue death), which are associated with stroke, and Lewy bodies (tiny deposits of protein in nerve cells), which is also seen in Parkinson's disease. They found that only about half of the European-Americans had pure Alzheimer's disease pathology, while the rest also had either infarcts or Lewy bodies in their brains. In contrast, fewer than 25% of the African Americans had pure Alzheimer's disease pathology and three-quarters (71%) of the African-Americans had Alzheimer's disease pathology mixed with another type of pathology. Study author Lisa Barnes, associate professor and cognitive neuropsychologist at Rush University Medical Center in Chicago, said: "Because some studies suggest that Alzheimer's disease is more common among older African-Americans than European-Americans, we wanted to see whether the brain changes caused by Alzheimer's are different in these two racial groups. Our study has important clinical implications because it may suggest a need for different types of Alzheimer's prevention and treatments in African-Americans. Indeed, current Alzheimer's drugs primarily target specific Alzheimer pathologies in the brain. Given the mixed pattern of disease that we see in African-American brains, it will be important to develop new treatments that target these other common pathologies, particularly for African-Americans." Dr Doug Brown, director of research at Alzheimer's Society, said that most of the 850,000 people with dementia in Britain have Alzheimer's disease. "This new study shows that most people with Alzheimer's disease also have signs of other forms of dementia, and this is more common in black people than white," he added. "Through research we are learning more about the complexities of what happens in the brain and this finding reinforces that we cannot view Alzheimer's disease in isolation – all forms of dementia desperately need new treatments. This study also demonstrates the need to get as many people from all ethnic backgrounds involved in research. To make this possible, Alzheimer's Society has helped to launch Join Dementia Research, an online service to make taking part in research easier, which has already signed up over 8,000 volunteers around the country."