Researchers say women who are neurotic during middle-age - defined as being anxious, jealous or moody - may be at higher risk of Alzheimer's.
Alzheimer's disease is more common in women than men, with 3.2 million of the 5 million Alzheimer's cases in the US affecting women.
According to the Alzheimer's Association, a woman aged 65 or over has a 1 in 6 chance of developing the disease in her lifetime, compared with a 1 in 11 chance for men.
The researchers of this latest study - including Lena Johannsson, PhD, of the University of Gothenburg in Sweden - say the majority of Alzheimer's research has looked at how genetics, head trauma, heart and blood problems and education influences disease risk.
For example, a study reported by Medical News Today earlier this year revealed a gene variant that may increase Alzheimer's risk in women.
However, Johannsson and colleagues note there is very little research on how certain personality traits may influence the risk of Alzheimer's. As such, the team looked to determine the association between personality and Alzheimer's through a study involving 800 women of an average age of 46.
Alzheimer's risk higher for neurotic women
During the 38 years of follow-up, the women were required to complete personality tests that assessed their levels of neuroticism (characterized by anxiety, moodiness and jealousy) and extraversion (characterized by assertiveness, energetic behavior and a preference for social interaction) or introversion (characterized by shyness and preference for one's own company).
The women were also asked to disclose whether they had experienced periods of stress - which the team defined as feelings of fear, nervousness, anxiety, sleep problems, tension or irritability - associated with family, work or health that lasted for 1 month or more.
Periods of stress were measured on a scale of 0-5; women who scored 0 had never experienced a stressful period, while women who scored 5 had experienced constant stress over the past 5 years. Women were considered to be distressed if they scored 3-5.
During the study period, 19% of women developed dementia. Results of the study revealed that women who had the highest scores on neuroticism tests were twice as likely to develop Alzheimer's than those who had lower neuroticism scores, but this association appeared to be stronger among participants who had experienced long periods of stress.
Furthermore, the team found that women who scored high on both neuroticism and introversion were at highest risk of Alzheimer's.
Commenting on what the team's findings suggest, Johannsson says:
"Personality may influence the individual's risk for dementia through its effect on behavior, lifestyle or reactions to stress."
Earlier this year, MNT reported on another study published in Neurology, which claims to shed light on how depression is associated with dementia.