The desire to better understand and so, too, possibly prevent dementia is common worldwide. The authors of a recent study found that the number of psycho-social stressors measured in middle-aged women was related to distress and incidence of Alzheimer’s disease almost four decades later.
Although they warn of their study’s limitations, the researchers suggest the stress response to life events may trigger physiological changes in the brain that last much longer than commonly thought.
To examine the relation between psychosocial stressors and incidence of dementia, the researchers tracked a group of women from mid-life to late-life over a period of 38 years. They employed the Prospective Population Study of Women in Gothenburg, Sweden, to aid them in their research. This study, which was initiated in 1968 to investigate anemia and health factors related to menopause, examined a total of 1,462 women born in 1908, 1914, 1918, 1922 and 1930. Of the many women participating in the Population Study, the researchers isolated a subsample of 800.
The researchers questioned (at the outset of the study in 1968) whether subsample participants had experienced any of 18 psychosocial stressors: divorce, widowhood, serious problems with children, extramarital childbirth, mental illness in spouse or relative, alcohol abuse in spouse or relative, physical illness or social problems related to spouse, receiving help from Social Security, problem related to husband’s or own work, and limited social network. Additionally, the researchers assessed the level of distress caused by these on a scale from zero to five based on symptoms, such as irritability, fear, and sleep disturbances. They also asked how often participants had experienced these symptoms in the preceding five years. Then, they continued to track their subsample population, recording their responses over time.
In 1968 one in four of the women had experienced at least one stressful event; a similar proportion (23 percent) had experienced at least two, while one in five had experienced at least three. A little over one in ten (16 percent) had experienced four or more. The most commonly reported stressor was mental illness in a close family member.
During the monitoring period, 425 of the women died (at the average age of 79) while nearly one in five (19 percent or 153 women total) developed dementia (and of these 104 women developed Alzheimer's disease specifically). On average, it took 29 years for dementia to develop, with 78 being the average age at which the condition was diagnosed. Analysis showed the number of stressors reported in 1968 was associated with a 21 percent heightened risk of developing Alzheimer's disease and a 15 percent heightened risk of developing any type of dementia. The findings held true even after taking account of factors likely to influence the results, including a family history of mental health problems.
Although warning their study could not be considered conclusive, the authors suggest that stress may cause a number of physiological reactions.
“Psychological stress has been reported to increase the activity of the hypothalamic – pituitary – adrenal axis and the levels of glucocorticoid hormones, cause structural and functional damage to the hippocampus, influence learning and memory processes, increase the production of proinflammatory cytokines in the brain, increase the deposition of β -amyloid peptid and τ -protein in the brain, and increase the frequency of cardiovascular disease and hypertension,” the authors wrote in their conclusions. "All these factors have been linked to dementia.”
Additionally, the researchers stated stress hormones can remain at high levels within the body many years after the experience of a traumatic event.
Source: Johansson L, Guo X, Hallstrom T, et al. Common psychosocial stressors in middle-aged women related to longstanding distress and increased risk of Alzheimer’s disease: a 38-year longitudinal population study. British Medical Journal. 2013.