Thursday, October 8, 2009

Is there a Link Between Level of Education and Alzheimer's Disease?

An interesting association between low education level and Alzheimer’s disease has been noticed by the professional, however the exact reason for this phenomenon is not clear. Some scientists believe it has to do with synaptic concentration (the amount of alternative routes a neuron can use to communicate with other neurons). The suggestion is that the higher your education level, the more synaptic connections your neurons have had to make in order to process all the information stored in your brain, and this is considered as cognitive or neurological reserve.

This threshold model proposes that a more educated person might have more synapses to lose before behavioral problems how up or that they exhibit dementia only if their cognitive reserve capacity falls below a specific threshold.

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A 2008 research confirmed the theory that education can delay the onset of the dementia and cognitive decline that are characteristic of the disorder. Scientists at the Alzheimer's Disease Research Center at Washington University School of Medicine in St. Louis found that some study participants who appeared to have the brain plaques long associated with Alzheimer's disease still received high scores on tests of their cognitive ability. Participants who did well on the tests were likely to have spent more years in school.

"The good news is that greater education may allow people to harbor amyloid plaques and other brain pathology linked to Alzheimer's disease without experiencing decline of their cognitive abilities," says first author Catherine Roe, Ph.D., research instructor in neurology.

Roe and her colleagues at the Alzheimer's Disease Research Center used the study participants' education levels to approximate a theoretical quality called cognitive reserve: improved abilities in thinking, learning and memory that result from regularly challenging and making use of the brain. Neurologists have long speculated that this quality, roughly equivalent to the benefits that accrue in the body via regular physical exercise, can help the brain cope with the damage caused by Alzheimer's disease.

Doctors still cannot conclusively diagnose Alzheimer's disease in any manner other than post-mortem brain examination. But Washington University scientists have shown that an imaging agent for positron emission tomography scans, Pittsburgh Compound B (PIB), can reveal the presence of amyloid plaques, a key brain change that many neurologists suspect either causes Alzheimer's or is closely linked to its onset.

In addition to scanning the participants' brains with PIB, the participants took several tests that assessed their cognitive abilities and status. They also ranked their educational experience: high-school degree or less, college experience up to an undergraduate degree, and graduate schooling.

As expected, those whose brains showed little evidence of plaque buildup scored high on all the tests. But while most participants with high levels of brain plaque scored poorly on the tests, those who had done postgraduate work still scored well. Despite signs that Alzheimer's might already be ravaging the brains of this subgroup, their cognitive abilities had not declined and they had not become demented.

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The obtained results were reproduced by the recent 2009 study at the Department of Psychiatry, Klinikum rechts der Isar, Technische Universität München, investigated the effects of formal education on the symptoms of Alzheimer's disease. They researchers were able to show that education diminishes the impact of Alzheimer's disease on cognition even if a manifest brain volume loss has already occurred. Dr. Robert Perneczky explains: "We know that there is not always a close association between brain damage due to Alzheimer's disease and the resulting symptoms of dementia. In fact, there are individuals with severe brain pathology with almost no signs of dementia, whereas others with only minor brain lesions exhibit a considerable degree of clinical symptoms."

These phenomena are often ascribed to the theoretical concept of cognitive reserve. A high level of cognitive reserve results in a strong individual resilience against symptoms of brain damage; cognitive reserve can therefore be seen as protective against brain damage.

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However, while education level and brain activity has proven to allow certain delay (protection) for the Alzheimer’s disease development, but it is not able to slow memory loss once it starts, says another study. Reporting in the Feb. 3, 2009 issue of Neurology, scientists say they found that education does not appear to protect against how fast people lose memory once forgetfulness begins.

"This is an interesting and important finding because scientists have long debated whether aging and memory loss tend to have a lesser effect on highly educated people," says study author Robert S. Wilson, PhD, with the Alzheimer's Disease Center at Rush University Medical Center in Chicago. "While education is associated with the memory's ability to function at a higher level, we found no link between higher education and how fast the memory loses that ability."

He and colleagues tested the thinking skills of 6,500 people from the Chicago area with an average age of 72 and varying levels of education. The level of education of people in the study ranged from eight or fewer years of school to 16 or more years. Interviews and tests about memory and thinking functions were given every three years, up to 14 years.

When the study started, people with more education were found to have better memory and thinking skills than those with lesser education. The results remained the same regardless of other factors related to education, such as job status, race, and the effects of practice with the tests.

Further analysis, however, showed that the "rate of cognitive decline at average or high levels of education was slightly increased" during early years of follow-up study, but then decreased slightly later, compared to people with low levels of education. "The results suggest that education is robustly associated with level of cognitive function, but not with rate of cognitive decline," they conclude.

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