Women who are anxious, jealous, or moody and distressed in middle age may be at a higher risk of developing Alzheimer’s disease later in life, according to a nearly 40-year-long study published in the October 21 issue of Neurology.
“Most Alzheimer’s research has been devoted to factors such as education, heart and blood risk factors, head trauma, family history, and genetics,” said lead author Lena Johansson, PhD, of the University of Gothenburg in Sweden. “Personality may influence the individual’s risk for dementia through its effect on behavior, lifestyle, or reactions to stress.”
For the study, 800 women with an average age of 46 were followed for 38 years and given memory tests and personality tests that examined their levels of neuroticism and extraversion or introversion. Of these participants, 19% developed dementia.
Neuroticism involves a predisposition to distress and personality traits such as worrying, jealousy, or moodiness, according to the researchers. People who are neurotic are more likely to express anger, guilt, envy, anxiety, or depression. Introversion was defined as shyness and reserve, and extraversion was associated with affability.
The investigators also asked the women whether they had experienced any period of stress that lasted one month or longer in their work, health, or family situation. Stress referred to feelings of irritability, tension, nervousness, fear, anxiety, or sleep disturbances. Responses were categorized from 0 to 5, with 0 representing never experiencing any period of stress, and 5 representing an experience of constant stress during the past five years. Women who chose responses from 3 to 5 were considered to have distress.
Women who scored highest on the tests for neuroticism had double the risk of developing dementia, compared with those who scored lowest on the tests. The link depended on long-standing stress, however.
Being either withdrawn or outgoing did not appear to raise dementia risk alone, but women who were easily distressed and withdrawn had the highest risk of Alzheimer’s disease in the study. Sixteen of the 63 women, or 25%, who were easily distressed and withdrawn developed Alzheimer’s disease, compared with eight of the 64 people, or 13%, of those who were not easily distressed and were outgoing. Extraversion was associated with a lower degree of long-standing distress, but had no impact on Alzheimer’s disease dementia.