Alzheimer's disease is a type of dementia characterized by the accumulation of toxic, misfolded beta-amyloid proteins that form plaques in the brain. A new study in Neurology suggests that beta-amyloid may begin accumulating decades earlier than believed, starting as early as our 20s .
The researchers analyzed beta-amyloid accumulation in 76 healthy people ranging in age from 20 to 60 using a PET scan. Beta-amyloid PET scans allow doctors to look at the brains of living people and measure plaques. In 20 year olds, the PET scans found beta-amyloid in a region of the brain called the temporal cortex. The researchers also saw that it gradually accumulated throughout life, corroborating previous research that found beta-amyloid plaques in the brain decades before the onset of Alzheimer's symptoms .
It's important to note that the amount of beta-amyloid found in this study did not meet the diagnostic criteria for Alzheimer's. (Alzheimer's diagnosis requires that beta-amyloid plaques accumulate to a specific level that is likely to cause symptoms including dementia.) While younger people did have beta-amyloid in their brains, none had an amount consistent with Alzheimer's disease and symptoms of dementia. Also, the beta-amyloid plaques were not found in the regions of the brain normally consistent with an Alzheimer’s diagnosis.
The study does suggest that people should begin thinking about Alzheimer's prevention earlier rather than later. Other research has found that people with more educational attainment and those who learn new things throughout life have a lower risk of developing Alzheimer's. We also know that some people with enough beta-amyloid plaques to meet the criteria for Alzheimer's never develop symptoms of dementia. One study found that 44% of cognitively healthy 90-year-olds had this "asymptomatic Alzheimer's" .
Interestingly, asymptomatic Alzheimer's is more common in highly educated people. It's possible that these people have more cognitive reserve. Even after they accumulate enough beta-amyloid to develop Alzheimer's, their brains can compensate and delay the onset of symptoms. In fact, a recent review of modifiable risk factors for Alzheimer’s reported that not attending secondary school may increase your risk by 60% .
To protect your brain now, prioritize learning and take the other six steps we recommend for a healthy brain. The damage that leads to Alzheimer's may begin in our youth, but the protective effect of education and other healthy choices can begin then, too.
Nick McKeehan is Assistant Director, Aging and Alzheimer's Prevention at the Alzheimer’s Drug Discovery Foundation. He served as Chief Intern at Mid Atlantic Bio Angels (MABA) and was a research technician at Albert Einstein College of Medicine investigating repair capabilities of the brain. He received a bachelor of science degree in biology from Purdue University, where he was awarded a Howard Hughes Scholarship. Mr. McKeehan also writes about the biotechnology industry for 1st Pitch Life Science.
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