People who have a cynical distrust of others, and think their motives are selfish, could have a higher risk of developing dementia, a study has said.
Researchers compared levels of cynical distrust in 622 people with the incidence of dementia.
They said people with high levels of distrust were twice as likely to develop dementia.
Experts said any findings that helped understand the disease were important, but called for larger studies.
Personality and disease
Dementia is a syndrome categorised by a decline in memory, thinking speed, mental agility, language, understanding and judgement.
One in three people aged over 65 in Britain will develop dementia, according to the Alzheimer's Society in the UK.
In 1998, volunteers, with an average age of 71, were asked to rate their agreement with statements such as "I think people would lie to get ahead", or "it is safer to trust nobody", said the researchers.
Scientists at the University of Eastern Finland said 46 people had developed dementia in the following decade.
Fourteen of the 164 people who showed high levels of cynical distrust in 1998 had developed dementia in this time, compared with nine out of the 212 people with low levels.
Dr Anna-Maija Tolppanen at the University of Eastern Finland led the study.
She said: "These results add to the evidence that people's view on life and personality may have an impact on their health."
Explaining the results, Dr Tolppanen said: "People with different personality traits may be more or less likely to engage in activities that are beneficial for cognition, such as healthy diet, cognitive or social activities, or exercise.
"Or personality may act via morphological changes or structural differences in brains. Also, inflammation has been suggested as one link between cynicism and worse health outcomes."
She said the study was controlled for socioeconomic factors, age, sex, health status, and lifestyle, such as smoking and alcohol use.
Role of depression
But Dr Tolppanen said she had not accounted for people becoming depressed after the first stage of the assessment, or that the volunteers' depression might not have showed up adequately in questionnaires.
She added it was "really important" to replicate the findings on a much larger scale, to prove the link.
Dr Simon Ridley, head of research at Alzheimer's Research UK, said: "With the rising numbers of people affected with dementia, any addition our understanding of what might affect disease development is important."
He said that as only a small number of people in the study developed dementia, he would want to see a larger study conducted to be "more confident" in the proposed link.
Dr Ridley said the volunteers with a high level of cynical distrust could have been already beginning to develop dementia, and that depression, which may be both a risk factor and a symptom for dementia, could account for the cynicism.
"The biggest risk factor for dementia is age, by far," he said.