A new study from Sweden found that people who were outgoing, calm and not easily stressed were least likely to develop dementia, but the risk was also lower for calm people who were not socially active. However, the researchers cautioned that although promising, these findings alone are not enough to be sure about clear links between personality, lifestyle and dementia.

The study was the work of Dr Hui-Xin Wang, from the Karolinska Institute in Stockholm, Sweden, and colleagues, and is published in the 20 January print issue of Neurology, the medical journal of the American Academy of Neurology (AAN).

Previous studies have already shown that people with high neuroticism are at higher risk of dementia, and those with an active social lifestyle are at lower risk, but none had explored the separate and combined effects of personality traits, and whether lifestyle also affected the link.

For the study, Wang and colleagues enrolled 506 older people without dementia who were taking part in the Kungsholmen Project, Stockholm, Sweden, and followed them for an average of 6 years, during which time 144 developed dementia. At the start of the study the participants filled in well known questionnaires about their personality traits and lifestyle. Dementia was diagnosed by specialists using criteria from the DSM-III-R checklist.

From the responses to the personality questionnaire the researchers were able to distinguish participants with different degrees of neuroticism, or how easily they became distressed, and also different degrees of extraversion, or openness to talking to others.

People with high neuroticism tend to be emotionally unstable, negative and nervous, whereas people with low neuroticism tend to be calm and satisfied with themselves. People with high extraversion tend to be outgoing, optimistic and socially active, whereas people with low extraversion tend to be reserved and introspective.

From the responses to the lifestyle questionnaire Wang and colleagues were able to see the richness of each participant’s social network and how regularly he or she took part in leisure or organized activities (ie how socially isolated or connected and how active or inactive they were).

Note that the first questionnaire assessed personality traits, that is, using responses the participants selected, the researchers arrived at a measure of their personality (on the dimensions of neuroticism and extraversion). And the second questionnaire (the lifestyle questionnaire) asked the participants what they did in their daily lives. Comparing these two results can lead to some unexpected results, for instance, an easily distressed person who is not outgoing (personality assessment) might have an active life and rich social network (lifestyle assessment).

The results showed that:

  • Neither high neuroticism nor low extraversion alone was related to significantly higher incidence of dementia.
  • But, among participants who were inactive or socially isolated, low neuroticism was linked to a lower risk of dementia.
  • Participants with low neuroticism and high extraversion had a lower risk of dementia, but not those with low neuroticism and low extraversion, nor those with high neuroticism and low extraversion, compared to participants with high neuroticism and high extraversion.
  • Dementia risk was lower for those with a combination of low neuroticism and high extraversion only among participants who were inactive or socially isolated.

The researchers concluded that:

“Low neuroticism in combination with high extraversion is the personality trait associated with the lowest dementia risk; however, among socially isolated individuals even low neuroticism alone seems to decrease dementia risk.”

In other words, it appears that people with a calm, outgoing and optimistic outlook on life are less likely to develop dementia, but perhaps surprisingly, being a calm sort of person also reduces dementia risk among the socially isolated.

Wang said that previous studies had shown that “chronic distress can affect parts of the brain, such as the hippocampus, possibly leading to dementia”, so this might partly explain the biological mechanism behind the link with low neuroticism.

“Personality and lifestyle in relation to dementia incidence.”
H. -X. Wang, A. Karp, A. Herlitz, M. Crowe, I. Kåreholt, B. Winblad, and L. Fratiglioni.
Neurology, Jan 2009; 72: 253 – 259.

Click here for Abstract.

Sources: Journal abstract, American Academy of Neurology.

Written by: Catharine Paddock, PhD