PET Tracer Shows Active Brains Have Less Beta-Amyloid

People who keep their brains active with cognitively stimulating activities such as reading, writing and playing games appear to have reduced levels of the beta-amyloid protein that forms a major part of the amyloid plaque in Alzheimer's disease, according to a report published online January 23 in Archives of Neurology.

The finding was made through positron emission tomography (PET) using the radiopharmaceutical carbon 11-labeled Pittsburgh Compound B (C-11 PiB) to image fibrillar forms of the beta-amyloid protein known to be complicit in Alzheimer's development.

In the study led by Susan M. Landau, PhD, of the University of California, Berkeley and the Lawrence Berkeley National Laboratory, C-11 PiB PET and neuropsychological testing were performed in a volunteer sample of 65 healthy older people (average age 76.1 years) plus 10 Alzheimer patients (mean age 74.8 years) and 11 young controls (mean age 24.5 years).

The team characterized beta-amyloid uptake in healthy older people and compared it to young participants and patients with Alzheimer's disease (AD). They also interviewed participants about various lifestyle practices, including how frequently they had participated in cognitively engaging activities at different phases of life. Landau and colleagues found “a direct association between cognitive activity and C-11 PiB uptake, suggesting that lifestyle factors found in individuals with high cognitive engagement may prevent or slow deposition of beta-amyloid, perhaps influencing the onset and progression of AD.”

The results indicate that greater participation in cognitively stimulating activities throughout a person’s life, but especially in the early and middle years, appears to be associated with reduced C-11 PiB uptake. Older people with the highest cognitive activity had C-11 PiB uptake comparable to young people in the control group, whereas those with the lowest cognitive activity had C-11 PiB uptake comparable to patients with AD.

Although greater cognitive activity was associated with greater physical exercise, exercise was not associated with C-11 PiB uptake, the authors note. The researchers suggest that the tendency to engage in cognitively stimulating activities is likely related to a variety of lifestyle practices that have been implicated in other studies showing a reduced risk of AD-related pathology.

The researchers concluded that while AD is a disease with many roots, the study extends previous findings linking cognitive stimulation to the extent of beta-amyloid, a known driver AD risk, the researchers concluded.