Since its inception in 1986, the “Nun Study” has become a pivotal research project offering profound insights into Alzheimer’s disease and cognitive health. This decades-long study, led by neurologist David Snowdon, involved nearly 700 Catholic religious sisters who provided invaluable data on the progression of dementia. The study continues to yield critical findings that have advanced our understanding of cognitive health across the lifespan, particularly emphasizing the importance of lifelong education and cognitive stimulation.
A Unique Opportunity for Research
Dr. Snowdon’s decision to focus on Catholic sisters for this monumental study stemmed from the distinct advantages of studying a population with such similar life experiences. “Normally, it’s hard to pinpoint what causes some people to develop dementia while others remain healthy because people can have very different lifestyles, environments, and biology,” explained Kyra Clarke, a doctorate student at UT Health San Antonio and one of the authors of the historical review published in Alzheimer’s & Dementia journal. “But Catholic sisters from the same order share the same environment for most of their adult lives: similar marital histories, housing, nutrition, health care, income, and social networks.” This consistency allowed researchers to isolate factors that truly influence the risk of dementia.
The Study’s Foundation and Methodology
The Nun Study began with a pilot program in cooperation with the School Sisters of Notre Dame (SSND). The first cohort included 678 sisters, drawn from a pool of 1,000 candidates across seven major convents in cities like Chicago, Baltimore, and Dallas. The sisters’ ages ranged from 75 to 102 at the time of enrollment, and almost all of them were at least college graduates, with nearly 90% having taught at some point in their lives.
Researchers employed a variety of methods to track the cognitive function of the sisters over time, using autobiographies they had written before taking their vows, medical records, academic transcripts, and annual neuropsychological assessments. “A 66% participation rate is a truly impressive amount for a longitudinal study requiring participants to undertake extensive cognitive testing every year for the rest of their lives and agree to brain donation as well,” Clarke noted. This high level of dedication from the sisters demonstrated their unwavering commitment to the study and its potential benefits for future generations.
Key Findings and Their Impact
The findings from the Nun Study have had a lasting impact on dementia research. One of the most significant discoveries is that “higher early-life cognitive ability seems to be protective against dementia,” according to Clarke. Sisters who had higher educational attainment and better academic performance—measured through school transcripts stored in convent archives—tended to have higher scores on cognitive tests later in life and a lower risk of developing dementia. Additionally, those with better written language skills in their earlier years showed a reduced risk of cognitive decline in their later years.
“The Nun Study really emphasized that maintaining cognitive health is a lifelong task and emphasized the importance of education and cognitive stimulation in reducing the risk of dementia,” Clarke stated. These findings highlight the essential role that lifelong learning and mental engagement play in maintaining cognitive health.
Continuing the Legacy
Although all of the sisters involved in the study have since passed away, their contributions continue to inspire ongoing research. “The scientists are deeply appreciative of their dedication to education and helping the lives of others,” Clarke said. Researchers maintain close contact with representatives of the SSND, providing updates on the study’s progress and sharing the latest findings with the communities that supported the research.
The Nun Study stands as a testament to the extraordinary dedication and generosity of the sisters who participated. Their commitment to the study has had a profound and lasting impact on dementia research, and their legacy continues to guide scientists in the ongoing quest to understand and treat this debilitating disease.
In the words of Clarke, “Their kindness and generosity made the Nun Study an iconic and groundbreaking contribution to dementia research and continuously inspires us to keep pushing towards understanding and treating this debilitating disease.”
A Call to Action for Lifelong Learning
The findings of the Nun Study serve as a reminder to all of us that maintaining cognitive health is not only the result of genetics but also a product of the choices we make throughout our lives. As Catholics, we are called to embrace the value of lifelong learning, keeping our minds sharp through study, prayer, and engagement in our communities. The wisdom gained from the Nun Study encourages us to prioritize education and mental stimulation as part of our holistic approach to health, and to recognize the profound ways that such efforts can benefit both ourselves and those we serve.
Source: Clarke, Kyra, et al. “The Nun Study: A Historical Review.” Alzheimer’s & Dementia, February 2025.
