Cognitive activity linked to brain protein related to Alzheimer disease, study suggests

The recent development of the radiopharmaceutical carbon 11-labeled Pittsburgh Compound B ([¹¹C]PiB) has made it possible to image fibrillar (fiber) forms of the β-amyloid (Αβ) protein.

In the study by Susan M. Landau, Ph.D., University of California, Berkeley and the Lawrence Berkeley National Laboratory, and colleagues, [¹¹C]PiB PET (positron emission tomography) and neuropsychological testing were performed in a sample of cognitively normal older participants. Αβ was characterized as mean cortical [¹¹C]PiB PET uptake and was examined in healthy older people and compared to young participants and patients with Alzheimer disease (AD). Participants completed an interview about various lifestyle practices, including how frequently they participated in cognitively engaging activities at different phases throughout life (from age 6 to their current age.)

"We report a direct association between cognitive activity and [¹¹C]PiB uptake, suggesting that lifestyle factors found in individuals with high cognitive engagement may prevent or slow deposition of β-amyloid, perhaps influencing the onset and progression of AD," the researchers write.

The study included a volunteer sample of 65 healthy older people with a mean (average) age of 76.1 years plus 10 patients with AD (mean age 74.8 years) and 11 young controls (mean age 24.5 years).

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 [¹¹C]PiB uptake. Older people with the highest cognitive activity had [¹¹C]PiB uptake comparable to young people in the control group, whereas those with the lowest cognitive activity had [¹¹C]PiB uptake comparable to patients with AD.

Although greater cognitive activity was associated with greater physical exercise, exercise was not associated with [¹¹C]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.

"It is unlikely that our results reflect a single unitary cause of AD, which is a complex disease with many potential pathogenetic processes. Furthermore, cognitive activity is just one component of a complex set of lifestyle practices linked to AD risk that may be examined in future work," the researchers conclude. "However, the present findings extend previous findings that link cognitive stimulation and AD risk (an indirect downstream effect of ?β) by providing evidence that is consistent with a model in which cognitive stimulation is linked directly to the AD-related pathology itself."