In a study of nuns residing in a convent, David Snowdon and his colleagues from the University of Lexington in Kentucky examined the autobiographical essays that all the candidate nuns were required to write when they joined the convent. The young nuns who had low "idea density" (number of ideas per every ten words) were significantly more likely to be diagnosed with Alzheimer's disease (diag nosed by brain autopsy) in their old age, compared to nuns who had written essays with high idea density when they joined the convent.
Does this mean that the template for developing Alzheimer's disease in old age is already set when we are young? We know that there is a strong genetic component to this disease, but for some reason it does not show up clinically until we are much older. Could it be that the educational process, and the additional mental challenges that galvanize us in many of our occupations, can stave off the illness for years, maybe even an extra decade? If that were true, it would represent one of the most intriguing interactions between genetics and environment.
But if you step back and think about this issue a little, you will recognize a few flaws in this tale. First, "idea density" is a poorly studied concept that does not directly follow from education or intelligence. Second, based on the results of the nuns study, the number of people with Alzheimer's disease should be far greater in underdeveloped countries with low levels of education and high levels of illiteracy, but cross-national studies show that this is definitely not the case. Stay tuned as further research helps to clarify this puzzle.
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