Nun Study as unique source for the long-term Alzheimer’s research
In 1991, David A. Snowdon, Ph.D., Professor at Sanders-Brown Center on Aging College of Medicine, University of Kentucky, Lexington, began what has come to be known as the Nun Study. Participants in this study are 678 American members of the School Sisters of Notre Dame religious congregation. The nuns in the study are age 75 to 106.
The Nun Study is an ongoing, one-of-a-kind resource for the study of brain diseases in the elderly. It is expected that data, tissue, and genetic material collected in this study will be used by scientists for decades into the future.
Each of the 678 participants in the Nun Study agreed to participate in annual assessments of their cognitive and physical function, medical exams, blood drawing for genetic and nutritional studies, and brain donation at death for neuropathologic studies. The Nun Study represents the largest brain donor population in the world. In addition, the sisters have given investigators full access to their convent and medical records. The convent archives are particularly useful in our study of Alzheimer's disease because they contain accurate risk factor data spanning the entire lifespan of the participants. Accurate information on early and mid-life risk factors is difficult or impossible to obtain in most other studies on Alzheimer's disease because individuals with this memory disorder cannot accurately recall their history. The convent archives contain a wealth of information including baptismal records, birth certificates, socioeconomic characteristics of the family, education documentation, autobiographies written in early, mid, and late life, as well as residential, social, and occupational data describing their mid and late lives.
Many factors that confound (or confuse) the findings of other studies are either eliminated or minimized because of the relatively homogeneous adult lifestyles and environments of these women. Participants in this study are non-smokers, drink little if any alcohol, have the same marital status and reproductive history, have lived in similar housing, held similar jobs, and had similar access to preventive and medical care.
Findings from Nun Study
Some of the findings received from the Nun Study confirm the results, received from other researches, but there are some absolutely new insights obtained for the additional risk factors and causal relationship between personal characteristics and traits to the chance of the Alzheimer’s development at some moment in life.
Among the findings were:
1. Those, who had revealed better linguistic abilities in early life, were less likely to have dementia later.
2. Those, who demonstrated set of positive emotions in early life, had greater longevity.
3. Low linguistic ability in early life was associated both with dementia in later life and less longevity.
4. Those with low serum folate levels were more likely to have Alzheimer's disease of other dementia.
5. There was no significant relationship found between dental amalgams (silver fillings) and dementia.
6. Those with brain infarcts had poorer cognitive function and a higher prevalence of dementia.
7. Dementia was unrecognized by nursing staff in a number of cases.
8. Higher education in early life was associated with less cognitive decline in later life.
The study has confirmed, for example, that a history of stroke and head trauma can boost your chances of coming down with debilitating symptoms of Alzheimer's later in life; and that a college education and an active intellectual life, on the other hand, may actually protect you from the effects of the disease.
One of the most surprising results of the Nun Study, however, is the discovery that the way we express ourselves in language, even at an early age, can foretell how long we'll live and how vulnerable we'll be to Alzheimer's decades down the line. After analyzing short autobiographies of almost 200 nuns, written when they first took holy orders, he found that the sisters who had expressed the most positive emotions in their writing and who expressed the better linguistic abilities as girls ended up living longest, and that those on the road to Alzheimer's expressed fewer and fewer positive emotions as their mental functions declined.
So, the study found that low idea density shown in the writings of the young women was strongly linked with low cognitive test scores and the presence of Alzheimer's disease in late life. For example, the nuns with low idea density scores were 30 times more likely to do poorly on a standard measure of cognitive function, the Mini-Mental State Exam, than those with more complex writings. An even more dramatic difference was observed when cognitive ability and characteristics of brain tissue were compared in the nuns who died. Neurofibrillary tangles of Alzheimer's disease appeared in about 90 percent of those nuns who had low linguistic ability in early life.
Among other findings there are some, which still do not have the valid scientific explanation, as why there is not always the direct correlation between the medical evidence for the Alzheimer’s disease appearance in the brain and the actual behavioral symptoms doctors can see on these patients.
"Most of the brains neatly fit our expectations, with little or no evidence of disease in a tack-sharp sister and abundant damage seen in a sister who had dementia," Dr. Snowdon wrote. "But sometimes (Dr. Bill) Markesbery (the neurologist who did the autopsies) finds little evidence of Alzheimer's in a sister who had the classic symptoms of the disease. And sometimes brains from other sisters who appeared mentally intact when alive show extensive evidence of the disease."
This surprising information wasn't a set-up by the researchers. In fact, Dr. Snowdon noted that Dr. Markesbery was not informed prior to conducting the autopsy about the mental status of that particular sister. After the autopsy, Dr. Markesbery met with Dr. Snowdon and the study's neuropsychologist, Dr. Kathryn Riley, to compare notes.
In one case - that of Sister Maria - Dr. Markesbery found that the nun had some plaques and tangles, but the number was not large. The nun's brain itself weighed within the normal range (most Alzheimer's brains have lower weights). Furthermore, the sister's brain rated Stage II on the Braak scale. (The Braak scale defines six distinct stages of the disease based on an autopsy. Stage 0 indicates the general absence of tangles. Stages 1-VI described the increasing range of the number and spread of the tangles throughout the brain.)
Following Dr. Markesbery's report, Dr. Riley shared Sister Maria's scores on three evaluations conducted prior to her death. These evaluations showed that Sister Maria had suffered progressive loss of her mental, physical and social functions in a way that was consistent with Alzheimer's disease.
Yet the reverse can happen as well. For instance, Dr. Markesbery's autopsy of Sister Bernadette's brain yielded the findings that she had Braak Stage VI, which indicates the most severe presence of Alzheimer's. However, Dr. Riley's report on the cognitive evaluations conducted in the years prior to Sister Bernadette's death showed that the nun was mentally sharp.
"The Nun Study's real eye-opening findings...are the ones that add to the evidence that Alzheimer's is not a yes/no disease," Dr. Snowdon wrote. "Rather it is a process - one that evolves over decades and interacts with many other factors." Using the data from the Nun's Study, Dr. Snowdon pointed out, "Of sisters in stages I or II, only 22 percent had evidence of dementia. For stages III and IV, that jumped to 43 percent. And by stages V and VI, 70 percent of the sisters had dementia."
While there is no magical cure for Alzheimer’s so far, the findings from Nun Study may give a hope that even you may not be able to eliminate the negative neurochemical changes in your brain, you still can fight the symptoms actual appearance by filling your life with regular physical and mental exercises, healthy diet, lowering stress, attempting to happy and present, etc. This way, you can be proactive in altering how this disease may affect you at some point, if you have predisposition, and follow in Sister Bernadette's footsteps, living a long and vital life.
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