“I donated my brain, so when the time comes, they can make a study of it. The fact that I have not had any of this Alzheimer’s disease, or even an inclination so far is something they would naturally want to study.”— Sister M. Celine Koktan, 97 years old in March 2009

“We’ve received over 500 brains.”— Dr. Karen Santa Cruz, neuropathologist.

Can you imagine being asked to be part of a study where the researcher asks if you not only would be willing to take part, but would mind terribly donating your brain to be dissected after you’re gone?

That is exactly what was asked of the nuns participating. Of the 678 sisters in the original study about four dozen are still living. But researchers already have begun analyzing the more than 500 brains saved to dissect and study.

The nun study is one of the most dynamic and powerful studies on the impact of positive emotions and thoughts in the history of positive psychology. Researchers Danner, Snowdon, and Friesen (2001) from the University of Kentucky sampled the nuns, perfect subjects for a study because of the profound similarities around their physical health. They have similar, regularized diets, live together in similar surroundings, do not have children, and do not smoke or drink to excess. In other words, their physical backgrounds and conditions are about as controlled for as any group of human beings might be.

Four features formed the study’s foundation.

Initially, it was predicated by other findings which demonstrated that negative emotions suppress the immune system and increase the risk of infections and disease. It was also known that positive emotions would have the opposite effect.

Because temperament seems to have great consistency over the lifespan, the nun study looked at the degree to which a positive or negative approach to life would affect lifelong physical health. Since the nuns’ living conditions, histories and environmental factors were “controlled” by their life choice, the impact of their emotional disposition would help determine their longevity.

Temperament also determines people’s capacity for coping with stress and life challenges. Those with positive outlooks manage better. Positive attitudes not only provide a type of inoculation to immune system insults, but continuing defenses against the effects of life stressors.

Finally, research prior to the nun study had shown that people who write about their emotions articulate and demonstrate their emotional outlook.

The researchers hypothesized that analyzing autobiographies the nuns had written as young women would reveal their emotional temperament and the basic aspects of their outlook. A second hypothesis involved whether a positive versus a negative expression could predict the nuns’ health and longevity.

These autobiographies were written in the 1930s and 1940s, at the time the nuns were seeking entry into the convent; average age was 22. Researchers coded them in terms of positive, negative and neutral words. Ultimately the research focused on three features of these statements: positive emotion words, sentences, and variety of positive emotional expressions.

In addition to the brains of the sisters who have died, the archive has medical, dental and academic records. But to understand what these researchers were looking for in those original autobiographies, look at these samples taken from the original study.

Sister 1 (low positive emotion): I was born on September 26, 1909, the eldest of seven children, five girls and two boys . . . . My candidate year was spent in the Motherhouse, teaching Chemistry and Second Year Latin at Notre Dame Institute. With God’s grace, I intend to do my best for our Order, for the spread of religion and for my personal sanctification.

Sister 2 (high positive emotion): God started my life off well by bestowing upon me a grace of inestimable value… . The past year which I have spent as a candidate studying at Notre Dame College has been a very happy one. Now I look forward with eager joy to receiving the Holy Habit of Our Lady and to a life of union with Love Divine.

The analysis was done roughly 60 years later, when the study was undertaken and the nuns were between 75 and 94 years old. By that time 42 percent of them had died.

What researchers found in their data was astonishing. Simply put, the nuns who expressed more positive emotions lived, on average, a decade longer than their less cheerful peers. By the average age of 80, 60 percent of the least happy nuns had died. This isn’t a misprint: A full 60 percent of the least happy nuns had died. The probability of survival was consistently in favor of the more positive nuns. There seems to be a direct relationship between being positive and longevity.

What is most intriguing about this landmark study is that it wasn’t just about happiness. It was actually about Alzheimer’s disease. Researchers considered the effect these positive approaches toward life might have on the devastating effects of dementia.

A decade after the original study was conducted, ongoing research about these nuns is more than curious. Not only did the sisters who seemed to have a more positive outlook on life have less disease and lower mortality rates, they also seemed to have a natural immunization against the ravages of Alzheimer’s disease.

Researchers have begun to study the nuns’ donated brains. What has been found? About half of the brains are free of Alzheimer’s. And yes, there is a strong, seemingly causal, correlation: The nuns with positive perspectives on life were free of the disease, and those with negative outlooks had symptoms of dementia.

There is an interesting twist in the study. To date, there are about 15 brains so far that appear diseased, but the nuns showed no signs of dementia when they were alive. In other words, in spite of the disease actually being present they did not have the symptoms associated with it. Consider how powerful this data is. Not only can a positive way of being in the world perhaps keep you from getting disease, but even if you do contract it — even if the physical features of the disorder are present — you may somehow have the capacity to transcend its clutches.

In an unprecedented move, to advance the study of this phenomenon the University of Minnesota has agreed to digitally scan the images of these brains so that researchers around the world can have access to the data.

To recap: A positive outlook on life may not only help you live longer and prevent you from having a disease, but if you do have the disease you may not be as affected by it as your less optimistic and less cheerful counterparts.

Heaven is, indeed, helping.

Author’s note: While “nuns” and “sisters” frequently are used interchangeably in everyday conversation, technically, nuns are cloistered and live lives of contemplation. Sisters often live in community, but may hold outside jobs and live in private homes.

For more information on the study, please review the official site.