Photo: Thinkstock

In the commencement speech for my high school, our class valedictorian (who also happened to be one of my best friends), told us to seek out and pursue our passion, whether it be the presidency of a company or a country or a weasel on the beach. (Okay, so the actual script of her speech included the word "easel," but we privately agreed that it'd be infinitely more interesting if one of our classmates discovered a thing for seafaring weasels).

My friend could never have known it at the time, but her advice to follow a purpose-focused life--a message that will be echoed by countless speakers at graduations across the country this month--would turn out to be a scientifically-backed way to protect our brains against the almost-inevitable deterioration and damage of age. In one of the most inspiring things I've read this year, a paper in the Archives of General Psychiatry discusses how a sense of meaning can mitigate the symptoms of Alzheimer's disease.

As an article in the Atlantic explains, a group of researchers from the Rush University Medical Center in Chicago have been following more than 1,400 senior citizens since 1997. Study participants were asked to complete a questionnaire about their purpose in life, and then, after they died (from whatever cause, at whatever time), their brains were analyzed as part of an autopsy. Those who rated high on the "purpose" scale didn't necessarily have healthier brains--many had the same amounts of harmful plaques and "tangles" associated with Alzheimer's and dementia as others at different points on the scale. However, while alive, the living-for-a-reason people showed a 30 percent lower rate of cognitive decline. In other words, they didn't show as many outward signs of the disease. One of the researchers told the Atlantic that she and her team "were surprised at just how 'robustly protective' a strong sense of purpose in life really was." [Read more about the study, and the power of purpose, at Atlantic.com]

As I get older and start to think more about putting one foot in front of the other instead of where I want those footsteps to take me, this research was a reminder of my friend's youthful advice—and it gave me a reason to resume the search for that elusive weasel frolicking in the surf.