People who don’t typically get distressed by routine events that might unnerve others seem to have a reduced likelihood of developing dementia in old age, concludes a study of elderly Swedish people published in the Jan. 20 Neurology.
Physician Laura Fratiglioni of the Karolinska Institute in Stockholm and her colleagues studied 506 people in their 80s who didn’t have dementia upon enrolling in a long-term medical study. All participants agreed to take personality tests, filling out a questionnaire that assessed what scientists call neuroticism, a state of being easily distressed. The questions also revealed how extroverted a person is.
Interviews of the participants determined whether a person was likely to be socially active or to live a more isolated life.
Over the six-year study, 144 of the participants developed dementia. An analysis of the personality and lifestyle data suggested that people with low levels of neuroticism and high scores on extrovert traits were the least likely to develop dementia. When addressed in the context of an individual’s lifestyle — ranging from social butterfly to shut-in — the findings suggested that having a socially integrated lifestyle may provide a buffer against the pro-dementia risk of being easily distressed. But in people leading more isolated lives, having low neuroticism scores still seemed to offer some protection against dementia.
The researchers accounted for differences among the participants in age, gender, education, depression symptoms, vascular problems, genetic factors linked to Alzheimer’s risk and cognitive function at the start of the study.
The findings confirm past reports suggesting that personality and lifestyle factors can contribute to dementia risk in some way other than well- established risk factors, says neuropsychologist Robert Wilson of Rush University Medical Center in Chicago. Those factors include amyloid-beta plaques, Lewy body deposits, tau tangles in cells and brain-tissue damage from strokes.
Wilson’s group has conducted autopsy studies of people and found no relationship between neuroticism and plaques or the other familiar hallmarks of dementia. “There must be some sort of novel mechanism involved that somehow renders you more likely to express dementia,” he says. “No one is sure what it is.”
There are theories. For example, people with high neuroticism scores also have high circulating levels of stress hormones. “Generally, that’s bad for you over time,” Wilson says. Studies in animals suggest that these extra hormones damage parts of the brain implicated in memory and thinking, he says.
The new study and other research linking personality and lifestyle to dementia risks will help to focus researchers’ attention on this remaining riddle, he says. “If we could understand why personality traits like neuroticism contribute to risk … it might offer insights into novel ways to reduce that risk.” These might include exercise, antidepressants or dietary changes, Wilson says.
The study suggests that an active lifestyle may buffer against the negative effects of high neuroticism, even in extroverts, says study coauthor Hui-Xin Wang, a research scientist also at the Karolinska Institute. “But it is difficult to say to what extent lifestyle intervention can offset a person’s basic personality characteristics,” she cautions.