October 22, 2007
Do you tend to be self-disciplined, scrupulous and goal oriented? Would you describe yourself as someone who always gets the job done? Someone who is productive and able to control stray impulses? In other words, a "conscientious" person? You may be less likely to develop Alzheimer's disease. Those are the intriguing findings from a study that appeared in the Archives of General Psychiatry, a publication of the American Medical Association.
Conscientiousness, according to the study authors, refers to a person's tendency to control impulses and pursue a purpose. A conscientious person might be described as a good or dependable worker, for instance, or someone who tends to be organized, thorough and having a plan. The personality trait has been shown to be correlated with avoiding a wide range of mental and physical disorders and may be important for maintaining overall health. These findings could suggest that conscientiousness may help keep the brain vital and the memory strong.
The findings come from Robert S. Wilson and colleagues at Rush University Medical Center in Chicago and are part of the Religious Orders Study, a large and ongoing study of Catholic clergy members from 40 locales across the United States. They studied 997 older Catholic nuns, priests and brothers, none of whom had Alzheimer's disease when the study began, in 1994. Participants underwent yearly medical evaluations over the next 12 years that included testing of memory and thinking skills.
Participants were also asked to rate themselves, on a scale of one to five, on various personality traits. Conscientiousness was measured with such questions as, "I am a productive person who always gets the job done,""I see myself as someone who always does a thorough job" or "I makes plans and follow through with others."
Other personality traits were also ranked through a series of questions. These included neurotic behavior and moodiness ("I often feel inferior to others"); extraversion, optimism and sociability ("I laugh easily"); openness, curiosity and independence of judgment ("I often try new and foreign foods"); and agreeableness and altruism ("I would rather cooperate with others than compete with them.")
Conscientiousness was most closely associated with a lower risk for developing Alzheimer's disease. The participants had an average conscientiousness score of 34 out of 48. Through a maximum of 12 years of follow-up, 176 individuals developed Alzheimer's disease. Those who had conscientiousness scores in the 90th percentile (40 points) or higher had an 89 percent lower risk of developing Alzheimer's disease than those whose scores ranked in the 10th percentile (28 points) or lower.
The authors also took into account known Alzheimer's disease risk factors, such as exercise, smoking, heart disease and participation in mentally stimulating activities. Such factors did not substantially change the results. Conscientiousness also was associated with a slower rate of cognitive decline and a lower risk of mild cognitive impairment, a condition that may precede Alzheimer's disease.
The researchers also analyzed results from brain autopsies of 324 participants who died during the study. In these patients, a high level of conscientiousness was not linked to lower levels of the hallmark signs of Alzheimer's disease, including brain plaques and tangles. However, people who were highly conscientiousness did appear to have stronger cognitive abilities despite the presence of tangles or blood vessel blockages in their brains.
There are several ways by which conscientiousness might protect against Alzheimer's disease, the authors explain. First, conscientious individuals may be more likely to experience educational or occupational success, both of which have been associated with a reduced risk of Alzheimer's disease. In addition, conscientiousness has been linked to resilience and to coping actively with difficulties.
"These factors might lessen the adverse consequences of negative life events and chronic psychological distress, which have been associated with risk of dementia in old age," the authors note.
"In conclusion, level of conscientiousness is associated with incidence of mild cognitive impairment and Alzheimer's disease but not with the pathologic hallmarks of these conditions," they continue. "Understanding the mechanisms linking conscientiousness to maintenance of cognition in old age may suggest novel strategies for delaying the symptoms of Alzheimer's disease."
Robert S. Wilson, Ph.D., Julie A. Schneider, M.D., Steven E. Arnold, M.D., et al: "Conscientiousness and the Incidence of Alzheimer Disease and Mild Cognitive Impairment." Archives of General Psychiatry, Volume 64(Number 10), October, 2007, pages 1202-1212. American Medical Association.