If you are moody or emotionally unstable, you are more likely to experience cognitive decline late in life than people who are organised, and with high levels of self-discipline, find a study.

The research, published in the Journal of Personality and Social Psychology, focused on the role three of the so-called "Big Five" personality traits - conscientiousness, neuroticism, and extraversion - play in cognitive functioning later in life.

"Personality traits reflect relatively enduring patterns of thinking and behaving, which may cumulatively affect engagement in healthy and unhealthy behaviours and thought patterns across the lifespan," said lead author Tomiko Yoneda, from the University of Victoria.

"The accumulation of lifelong experiences may then contribute to the susceptibility of particular diseases or disorders, such as mild cognitive impairment, or contribute to individual differences in the ability to withstand age-related neurological changes," Yoneda added.

Individuals who score high in conscientiousness tend to be responsible, organised, hard-working, and goal-directed. Those who score high on neuroticism have low emotional stability and have a tendency toward mood swings, anxiety, depression, self-doubt and other negative feelings.

Extraverts draw energy from being around others and directing their energies toward people and the outside world. They tend to be enthusiastic, gregarious, talkative and assertive, according to Yoneda. For the research, the team analysed data from 1,954 participants, without a formal diagnosis of dementia, from 1997 and continuing to the present.

Participants who scored either high on conscientiousness or low in neuroticism were significantly less likely to progress from normal cognition to mild cognitive impairment over the course of the study. "Scoring approximately six more points on a conscientiousness scale ranging 0 to 48 was associated with a 22 per cent decreased risk of transitioning from normal cognitive functioning to mild cognitive impairment," said Yoneda.

"Additionally, scoring approximately seven more points on a neuroticism scale of 0 to 48 was associated with a 12 per cent increased risk of transition." In addition, individuals who are lower in neuroticism and higher in extraversion were more likely to recover to normal cognitive function after receiving a previous diagnosis of mild cognitive impairment, suggesting that these traits may be protective even after an individual starts to progress to dementia.

In the case of extraversion, this finding may be indicative of the benefits of social interaction for improving cognitive outcomes, according to Yoneda. However, the team found no association between any of the personality traits and total life expectancy.