Alzheimer's Disease

Sister Ada, a nun suffers from Alzheimer's disease and like 4 million other Americans, she'll gradually lose her memory, her personality and finally all cognitive function. Along with hundreds of other nuns in their order, the School Sisters of Notre Dame have joined a long-term study of Alzheimer's disease which could lead to significant advancements in understanding the disease.

Little is known about the deadly disease, which threatens to strike 14 million Americans by 2050. Its cause is still very mysterious, and effective treatments are still years away. However, epidemiologists are beginning to research what kinds of people are most seriously consumed by Alzheimer's and which people tend to escape it. Most of this knowledge comes from a single and ongoing research, named Nun Study. Since 1986, University of Kentucky scientist David Snowdon has been studying 678 School Sisters by researching their personal and medical histories, testing them for cognitive function and even dissecting their brains after death. Scientists do know that genes can predispose people to Alzheimer's disease. However, as described in dozens of scientific papers, Snowdon's study has shown that a history of stroke and head trauma increase chances of Alzheimer's symptoms later in life. A surprising result of the research was that after analyzing short autobiographies of almost 200 nuns, Snowdon found that the sisters who had expressed the most positive emotions in their writing ended up living longest, and those on the road to Alzheimer's expressed fewer positive emotions as their mental functions declined.

The records found by Snowdon were relatively standardized and so he could extend his study of aging far beyond the few years in late life. With these documents, Snowdon could measure the sisters' cognitive abilities while they were still young. The first results confirmed earlier studies which suggested that people with the most education were most independent and competent later in life. The drawback to studying the sisters for Alzheimer's is that there is only one way to diagnose it, which was by examining the patient's brain after he or she dies. Thus, more than 90% of the sisters living in the Mankato convent agreed to donate their brains and after visiting six other convents, Snowdon ended up with a 68% consent rate overall, one of the highest in any tissue-donation study.

The study the nuns' youthful autobiographies and their relationship led to an interesting discovery during autopsies, scientists had shown that the physical destruction by Alzheimer's didn't inevitably lead to mental deterioration. The reason, according to a leading theory, was that some individuals might have an extra reserve of mental capacity that kept them functioning despite the loss of brain tissue. Thus, Snowdon and others analyzed the autobiographies for evidence of such extra capacity. They found that the elderly sisters who showed signs of Alzheimer's had consistently authored essays low in both idea density and grammatical complexity a half-century or more earlier. Snowdon found by reading nuns' early writings,