06:16am Sunday 22 October 2017

Higher Education May Protect Against Alzheimer's Disease

A recent University of Wisconsin School of Medicine and Public Health study showed that higher education was associated with lower age-related increases of abnormal levels of tau protein in the cerebrospinal fluid of older adults.

“Life experiences that engage the brain, such as higher educational attainment in this case, may protect against biological changes in the brain that underlie Alzheimer’s.”

– Ozimoa Okonkwo

Tau is a biomarker of neurodegeneration caused by Alzheimer’s disease; in the brains of those with Alzheimer’s it creates abnormal tangles in the neurons. While tau levels increased in all the adults in the study as they aged, those with 16 years of education showed smaller increases than their less educated peers.

Scientists have known that people with higher “cognitive reserve” tend to develop dementia less frequently than those with lower reserve. But they didn’t know if cognitive reserve only masked symptoms for longer or whether it was protective against the underlying disease. Cognitive reserve is usually measured by life experiences – such as years of schooling – that help the brain resist dementia.

“Although it has been widely known that persons with high educational attainment are generally less likely to develop Alzheimer’s and other dementias, the underlying reason for this has remained elusive,” says Dr. Ozioma Okonkwo, assistant professor of medicine and the paper’s senior author.

“This work demonstrates for the first time that higher educational attainment provides resilience against the deleterious effect of aging on cerebrospinal fluid biomarkers of Alzheimer’s disease. This suggests a pathway through which educational attainment favorably alters lifetime risk for Alzheimer’s dementia.”

Lead author Rodrigo Almeida and collaborators studied 268 people who had an average age of 62 and had enrolled in either the Wisconsin Registry for Alzheimer’s Prevention (WRAP) study or with the Wisconsin Alzheimer’s Disease Research Center (WADRC). At the time of this research, 211 were cognitively normal while 57 were cognitively impaired.

Participants in Wisconsin Registry for Alzheimer’s Prevention and the Alzheimer’s Disease Research Center come to the UW-Madison campus regularly to have cognitive testing, brain scans, blood work and cerebrospinal fluid drawn. Many of them have parents affected by Alzheimer’s disease, although some are members of a control group with no family history.

The cerebrospinal fluid from the 268 people in the study showed that as people aged, the amount of tau in their cerebrospinal fluid generally increased. But a college education seemed to have a protective effect: As the people grew older, those with higher educational attainment had lower increases in tau levels.

For one type of tau called t-tau, older persons with lower cognitive reserve (i.e., less than a college degree) had levels that were 272 nanograms per liter (ng/L) higher than their younger peers. In contrast, older persons with high cognitive reserve (i.e., at least a college degree) only showed an increase of 70 ng/L compared with their younger college-educated counterparts.

Another type, called p-tau, increased by 29 ng/L in older subjects with less education, but was just 8 ng/L higher in those with 16 or more years of education. 

The protective effect was not seen when education was split at 12 years of schooling, meaning that a high- school diploma level of education was not better than less schooling in slowing this increase in tau as people aged.

Okonkwo cautioned that 16 years of education is being used as a proxy for the larger concept of cognitive reserve. Additionally, a college degree is also associated with other social determinants of good health, including better jobs, higher income levels, less exposure to toxins and other factors that can affect the outcome.

Still, the study does seem to hint at what lifestyle choices may help protect against Alzheimer’s disease.

“Life experiences that engage the brain, such as higher educational attainment in this case, may protect against biological changes in the brain that underlie Alzheimer’s,” says Okonkwo, who has authored earlier studies based on the WRAP study showing that regular exercise may also offer protection.

The paper was published in JAMA Neurology.

University of Wisconsin School of Medicine and Public Health


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