Doing puzzles and reading books have been linked with a decreased risk of Alzheimer's disease, and a new study may explain why — it reduces the accumulation of harmful proteins in the brain.
In the study, older adults who said they engaged in mentally stimulating activities throughout their lives had fewer deposits ofbeta-amyloid, the hallmark protein of Alzheimer's. The findings were true regardless of the participants' gender or years of education.
The findings suggest that cognitive therapies that stimulate the brain may slow the progression of the disease, if applied before symptoms appear, said study researcher William Jagust, a professor at the University of California, Berkeley's Helen Wills Neuroscience Institute.
The researchers note Alzheimer's is a complex disease that likely has more than one cause. In addition, other lifestyle factors not accounted for in the study may influence the link.
The study is published online today (Jan. 23) in the journal Archives of Neurology.
Plaques in the brains
An estimated 5.4 million Americans live with Alzheimer's disease, and between 2000 and 2008, deaths from the disease increased by 66 percent.
In the study, the researchers asked 65 healthy, cognitively normal adults ages 60 and over (the participants' average age was 76) to rate how frequently they participated in such mentally engaging activities as going to the library, reading books or newspapers, and writing letters or email. The questions focused on various points in life from age 6 to the present.
The participants also completed tests to assess memory and other cognitive functions, and received positron emission tomography (PET) scans using a new compound that was developed to visualize the amyloid protein.
The brain scans of the older adults were compared with those of 10 patients diagnosed with Alzheimer's disease and 11 healthy people in their 20s.
The researchers found a significant association between higher levels of cognitive activity over a lifetime and lower levels of in the PET scans. Older adults with the highest reported amounts of cognitive activity over a lifetime also possessed levels of amyloid comparable to young people. In contrasts, older adults with the lowest reported amounts of cognitive activity possessed amyloid levels comparable to patients with Alzheimer's disease.
Lifetime activity matters
The researchers did not find a strong connection between amyloid deposits and levels of current cognitive activity alone.
"What our data suggests is that a whole lifetime of engaging in these activities has a bigger effect than being cognitively active just in older age," said study researcher Susan Landau, also of UC Berkeley. ]
However, the researchers said there was no downside to stimulating the brain later in life.
The researchers note that the buildup of amyloid can also be influenced by genes and aging — one-third of people age 60 and over have some amyloid deposits in their brain — but how much reading and writing one does is under each individual's control.
Pass it on: Cognitive stimulation such as reading a book may reduce the brain's accumulation of beta-amyloid, the hallmark protein of Alzheimer's disease.
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