The Nun Study
What 678 nuns taught us about aging brains
Starting in 1986, researcher David Snowdon began studying 678 Catholic nuns, and what he found reshaped our understanding of aging. The nuns donated their brains for autopsy, and many had also written autobiographical essays in their early 20s. Snowdon discovered something remarkable: the linguistic complexity of those young-adult essays predicted who would develop Alzheimer's decades later.
Even more striking, some nuns whose brains showed extensive Alzheimer's pathology at autopsy had shown no symptoms in life. Their brains had built enough cognitive reserve through education, mental engagement, and social connection to mask the underlying damage. The Nun Study became one of the foundations for the cognitive reserve hypothesis: the same disease can affect different brains very differently, depending on what's been built up over a lifetime.
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The Nun Study