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Nun Study

The Nun Study of Aging and Alzheimer's Disease is a continuing longitudinal study, begun in 1986, to examine the onset of Alzheimer's disease. David Snowdon, the founding Nun Study investigator, began the research at the University of Minnesota, later transferring the study to the University of Kentucky in 1986. In 2008, with Snowdon's retirement, the study returned to the University of Minnesota. Jim Morteimer and Bill Marksberry, a neurologist specializing in Alzheimer's disease, helped with the Nun Study.
Similar environmental influences and general lifestyles among the participants make the nuns an ideal population to study, and although it is ongoing it has yielded several findings. At the University of Minnesota, Kelvin Lim and Laura Hemmy are developing a new Alzheimer's Disease study working with the School Sisters of Notre Dame.A few of the major findings from the nun study came from archived manuscripts Snowdon came across. Among these archives were several of the sister's autobiographies written just before they took their vows. After coding these archives several themes arose. Positivity was closely related to longevity, as well as idea density. Idea Density is an analysis which measures ideas in speech and writing. This research found the higher idea density scores, the higher chance of having sufficient mental capacity in late-life despite neurological evidence that shows the onset of Alzheimer's disease.In 1992, researchers at Rush University Medical Center Rush Alzheimer's Disease Center (RADC), building on the success of the Nun Study, proposed the Rush Religious Orders Study. The Religious Orders Study was funded by the National Institute on Aging in 1993, and is ongoing. Researchers at the University of Minnesota are collaborating with the Rush Alzheimer's Disease Center on the Religious Orders Study, as well as several other ongoing studies.

Origin and Procedure

The Nun Study, begun in 1986 with funding by the National Institute on Aging, focuses on a group of 678 American Roman Catholic sisters who were members of the School Sisters of Notre Dame. The purpose of the study was to conclude if “linguistic ability in early life is associated with cognitive function and Alzheimer’s disease in late life.” The participants were gathered on a volunteer basis following a presentation on the importance of donating one's brain for research purposes after death. Prior to the study's beginning researchers required the participants to be at least 75 years of age and for them to participate in the study until their deaths. The researchers also required the participants be willing to donate their brains upon their death so that they could be studied for results. All 678 participants willingly signed a form agreeing to the terms of the study. As of 2017, there are three participants who are still living. Studying a relatively homogeneous group (no drug use, little or no alcohol, similar housing and reproductive histories, etc.) minimizes the extraneous variables that may confound other similar research.The study primarily centered on a series of regularly scheduled tests. These were designed to test the subject’s proficiency with object identification, memory, orientation, and language. These categories were tested through a series of mental state examinations with the data being recorded with each passing test. After a period of just over a year most of the original nuns in the study had died of natural causes. As part of the experiment their brains were harvested postmortem and studied for signs of Alzheimer’s Disease through a process called neuropathological evaluation.
During the examination process Snowdon was able to compare the collected cognitive test scores with the data received from examining the brains of the subject. These results assisted in giving new layers of understanding to the nature of Alzheimer’s Disease.

Current findings

Researchers accessed the convent archive to review documents amassed throughout the lives of the nuns in the study. They also collected data via annual cognitive and physical function examinations conducted throughout the remainder of the participant’s lives. After the death of a participant, the researchers would evaluate the brains of the deceased to study any diseases of the central nervous system.One of the major findings from the nun study was how the participants lifestyle and education can be a potential preventative measure for Alzheimer’s. Participants who had an education level of a bachelor’s degree or higher were less likely to develop Alzheimer’s later in life. Furthermore, the participants word choice and vocabulary were also correlated to the development of Alzheimer’s. Among the documents reviewed were autobiographical essays that have been written by the nuns upon joining the sisterhood. Upon review, it was found that an essay's lack of linguistic density (e.g., complexity, vivacity, fluency) functioned as a significant predictor of its author's risk for developing Alzheimer's disease in old age. However, the study also found that the nuns who wrote positively in their personal journals were more likely to live longer than their counterparts. Snowdon and associates found three indicators of longer life when coding the sister's autobiographies; the amount of positive sentences, positive words, and the variety of positive emotions used. The less positivity in writing the greater the mortality rate. There were many variables this study was unable to glean from the autobiographies of the sisters such as long term hopefulness or bleakness in one's personality, optimism, pessimism, ambition, and others. The approximate mean age of the nuns at the time of writing was merely 22 years. Some participants who used more advanced words in their autobiography had less symptoms of Alzheimer’s in older adulthood. Roughly 80% of nuns whose writing was measured as lacking in linguistic density went on to develop Alzheimer's disease in old age; meanwhile, of those whose writing was not lacking, only 10% later developed the disease. This was found when researchers examined the sisters neuropathology after they died and it confirmed that most of those who had a low idea density had Alzheimer’s disease and most of those with high idea densities did not.
In 1992 a genetic component was found to be linked to the development of Alzheimer’s disease. A gene called Apolipoprotein E, responsible for carrying fat and cholesterol through the bloodstream had been correlated to the development of Alzheimer’s. Through his study Snowdon discovered that the gene present in an individual does not predict the presence or future presence of Alzheimer’s. Snowdon found that exercise was also correlated to the development of Alzheimer’s disease. Participants who engaged in some sort of daily exercise were more likely to retain their mental durability in their later years. Participants who started exercising later in life were still more likely to retain mental stability, even if they hadn’t exercised before. Comparisons between subject’s brains have also led to the theory that low weight or extreme weight loss could have a stronger negative effect on cognitive ability in Alzheimer’s patients.
One of the major findings by Snowdon was the existence of plaques and tangles in the brain. Plaques are abnormal clusters of dead brain cells that build up between nerves in the brain while Tangles are twisted strands of dead and dying protein. The original experiment helped to draw some connection between the location of the of neurofibrillary tangles and the type of impairment caused by the disease, though this connection is described by Snowdon himself as being somewhat inconsistent. Results did indicate that neurofibrillary tangles located in regions of the brain outside the neocortex and hippocampus have less of an effect than ones located within those areas. Another potential factor is brain weight, as subjects with brains weighing under 1000 grams were seen as higher risk than those in a higher weight class.
Overall, findings of the Nun Study have suggested multiple factors concerning expression of Alzheimer's traits. The data primarily states that age and disease do not always guarantee impaired cognitive ability and "that traits in early, mid, and late life have strong relationships with the risk of Alzheimer's disease, as well as the mental and cognitive disabilities of old age."The findings from this study have influenced many other scientific studies and discoveries. One of these studies includes the finding that if a person has a stroke, there is a smaller requirement of Alzheimer’s brain lesions necessary to diagnose a person with dementia. Another is that postmortem MRI scans of the hippocampus can help distinguish that some nondemented individuals fit the criteria or Alzheimer’s disease. Researchers have also used the autopsy data from this study to determine that there is a relationship between the number of teeth an individual has at death with how likely they were to have had dementia. Those with less teeth were more likely to have dementia while living. In another study researchers were able to confirm that neuronal hypertrophy is one of the first steps towards getting Alzheimer’s disease on the cellular level. This same study reaffirmed the findings of The Nun Study that state that higher idea density is connected with better cognition with age, even if the individual had brain lesions tied to Alzheimer’s disease.

Posted on Jun 22, 2021.

Psychology term of the day

June 22nd 2021

cognitive neuroscience

a hybrid discipline aimed at identifying the biologicalbases of cognitive processes by combining techniques forthe study of cognitive processes with measures of physiological processes.