Cognitively stimulating activity, particularly in early and midlife, is associated with lower brain deposition of the major protein constituent of amyloid plaques in Alzheimer's disease later in life, based on findings from a cross-sectional clinical study.
The study's direct association between cognitive activity and beta-amyloid (A-beta) protein suggests that the lifestyles of those with greater cognitive engagement might play a role in the onset and progression of Alzheimer's disease (AD), particularly because participation in cognitively stimulating activities has been linked with other lifestyle practices associated with reduced Alzheimer's risk, Susan M. Landau, Ph.D., of the University of California, Berkeley, and her colleagues reported.
PET imaging of the binding of the radiopharmaceutical carbon 11 labeled Pittsburgh Compound B ([.sup.11]CPiB) to A-beta protein showed comparable A-beta deposition in older adults in the highest cognitive activity tertile and young controls.
On the other hand, older adults in the lowest cognitive activity tertile had mean cortical [.sup.11]CPiB uptake comparable with the Alzheimer's patients, the investigators reported (Arch. Neurol. 2012 Jan. 23 [doi:10.1001/archneurol.2011.2748]).
The researchers defined cognitively demanding activities in terms of activities that depended minimally on socioeconomic status, such as reading books or newspapers, writing letters or e-mails, and playing games.
The greatest association was seen between higher past cognitive activity scores (based on levels from ages 6 to 40 years, compared with those from ages 40 and older) and lower [.sup.11]CPiB uptake.
However, the association between cognitive activity and lower [.sup.11]CPiB uptake existed across the life span after age, sex, and years of education were taken into account, the investigators noted.
Although previous epidemiologic studies also have demonstrated a link between cognitive stimulation throughout life and a reduced risk of cognitive decline and Alzheimer's disease, these findings "suggest a novel mechanism in which increased cognitive activity may play a direct role in reducing A-beta before disease onset," the investigators wrote.
The notion that cognitive activity influences the development of Alzheimer's disease pathology is supported by recent findings of reduced hippocampal atrophy--another biomarker of Alzheimer's pathology--in cognitively normal older adults with greater life-long complex mental activity levels, they said.
"Our cognitive activity measurement is likely just one of a variety of interrelated lifestyle factors that are difficult to quantify. …