Today is World Alzheimer’s Day! It’s unusual to utter such a statement with enthusiasm, but the spirit of World Alzheimer’s Day is an admirable one: to raise awareness about a devastating disease that affects more and more people every day.
It wasn’t until the 1980s that clinicians began distinguishing Alzheimer’s as its own disease. Previously, it simply fell under the big umbrella of “dementia,” but since its distinction as a unique illness, the diagnoses have been increasing at an alarming rate. Today, 5.4 million Americans are living with Alzheimer’s disease. There’s no getting around it, that is a big number—5.4 million is greater than the population of Colorado and roughly the number of people born in the European Union member states in 2009. Even scarier than that figure is 16 million, which is the number of Americans predicted to be living with Alzheimer’s by 2050. That means 1 in 5 senior citizens (65 and older) will have the disease.
Alzheimer’s isn’t just about memory loss, either. It’s the sixth leading cause of death in America, and the only one in the top 10 with no way to prevent, cure, or slow its progression. There are a number of promising drugs in clinical trials now, but other researchers have recognized the economic and timely value in identifying lifestyle factors that might contribute to cognitive decline later in life. One such researcher is David Snowdon, the founding investigator of a renowned project known as The Nun Study.
This year marks the 25th anniversary of The Nun Study’s inception. It began in 1986 as a pilot study at the University of Minnesota. Researchers studied the older School Sisters of Notre Dame in Mankato, Minnesota, and four years later, expanded their clinical population to include Notre Dame sisters in Midwestern, Eastern, and Southern regions of America.
But why study nuns, you ask? After all, they represent an extremely specific lifestyle. However, the relatively uniform lives of these women eliminate any potentially confounding variables in the researchers’ findings: participants do not smoke, drink little or no alcohol, have the same reproductive history and marital statuses, live in similar housing, and have similar access to healthcare.
Perhaps more important than the homogeneity of their daily lives are the convent archives, which provide information about potential risk factors for Alzheimer’s in the nuns’ early and middle stages of life. Additionally, all participants agree to brain donation after death, giving scientists the opportunity to examine brain pathology and structure and its relation to late-life cognitive function. Furthermore, because the study includes the entire population of Notre Dame sisters, participants vary greatly in cognitive and physical ability; for example, there are women in their mid-seventies who are so disabled that they are bedridden.
Conversely, there are woman over 100 with sharp mental acuity who are in excellent physical condition. One such woman, Sister Matthia, died a week before her 105th birthday. Despite her advanced age, she remained happy, productive, and dementia-free even in her final days. Her brain, however, showed that at her time of death, she exhibited Alzheimer’s disease pathology with a score of four, or moderate spread. Even more puzzling is Sister Bernadette, who died at the age of 85 from a massive heart attack. Postmortem examination of her brain revealed that she had Alzheimer’s disease pathology with a score of six, the highest score on the scale, indicating the greatest spread of Alzheimer’s pathology. Her annual cognitive evaluations prior to death, however, showed no signs of her mental deterioration. This is perhaps because, though she was in the 90th percentile for neurofibrillary tangles (one of the criterion for Alzheimer’s pathology analysis), she was also in the 90th percentile for grey matter—as if her brain was resistant to the Alzheimer’s-related neurodegeneration.
The differences between the women who developed Alzheimer’s symptoms and those who did not, despite having similar Alzheimer’s pathology in their brains, creates as many questions as it does answers. The ultimate question is, of course, can Alzheimer’s symptoms be prevented? Incidentally, it is The Nun Study that has given us most of the information about what aspects of lifestyle may influence cognitive function later in life. The Nun Study investigators believe that resistance to developing dementia may be formed during fetal, childhood, and adolescent development by things like genetic expression, education, and nutrition. However, this resistance must be maintained throughout life through exercise, a healthy diet, social support, and access to preventative medical care.
Though it began 25 years ago, The Nun Study is an ongoing effort to unveil exactly how some individuals live into their 100’s without mental deterioration. In the meantime, keeping your physical health in check might ensure your mental health down the road. While the search for effective Alzheimer’s drugs continues, so will the investigations of The Nun Study. In the words of one Notre Dame sister, “The Nun Study allows me to keep teaching, even after I die.”
Alzheimer’s Association (www.alz.org)
Snowdon, D.A. (2003). Healthy aging and dementia: findings from The Nun Study. Annals of Internal Medicine, 139: 450-454.