More recently, medical researchers have found that a strong sense of purpose and well-being correlates with better physical health, especially in older adults. But now there's another reason to rethink that stable but meaningless job versus a more meaningful job, life path, or vocation: it appears that a sense that your life has purpose, and that what you do matters, may actually protect your brain from the clinical effects of Alzheimer's disease.

In a paper coming out this week in the Archives of General Psychiatry, a group of researchers from the Rush University Medical Center in Chicago published the first results of a longitudinal study involving more than 1,400 senior citizens. The goal of the study is to evaluate how a strong sense of purpose in life changes the pathology of Alzheimer's disease, from a neurobiological perspective. A couple of previous studies (including one by Dr. Patricia A. Boyle, the lead researcher on this study) found a link between a sense of purpose in life and a lower risk of cognitive impairment. But in this study, Dr. Boyle's team wanted to find out how, neurobiologically, a strong sense of purpose provided that protective effect.

"What distinguishes this from symptomatic research is, you don't know why something is beneficial until you look at what's going on in someone's brain," Boyle explained. "We can say that physical activity, for example, [is] protective against dementia, because it lowers your risk of developing the clinical side of the disease. But until we know what's actually happening in someone's brain, we don't know how physical activity is working. So the element we added was the measured quantification of the actual changes of Alzheimer's disease. We're the first people to look at how purpose in life changes the effect of the Alzheimer's pathology by measuring in this way."

The study has been underway since 1997, and none of the study participants presented with signs of dementia when they entered the research group. The participants received baseline assessments in physical, social, psychological and cognitive health at the beginning and then received follow-up assessments every year. Along with those health- and lifestyle-oriented assessments, participants were also rated as to how strong their sense of purpose in life was, based on their range of answers to a 10-point questionnaire.

On the questionnaire, participants are asked to rate, on a five-point scale ranging from "totally agree" to "totally disagree," their reaction to statements like: "I feel good when I think of what I've done in the past and what I hope to do in the future." "I used to set goals for myself, but that now seems like a waste of time." "I live life one day at a time and don't really think about the future." Or, "I enjoy making plans for the future and working them to a reality."