24 Aug New theory: Alzheimer’s affects women more because of stress
Alzheimer’s disease is the most common type of dementia. Affecting millions of people in the
The United States, this progressive condition has no proven cause, treatment, or cure.
What researchers do know, however, is that women bear the brunt of the condition.
Almost two-thirds of U.S. individuals with Alzheimer’s are women, according to the Alzheimer’s
However, only theories exist to explain this difference; there is no concrete evidence.
One understudied area — say researchers at the Johns Hopkins University School of Medicine in
Baltimore, MD — is the role of stress on cognitive function.
Previous research has shown that age can have a significant impact on women’s stress response,
and that stressful life experience can cause memory and cognitive issues. However, these
problems tend to be short term.
Researchers have now decided to look at the relationship between stress and the long term
cognitive decline associated with Alzheimer’s.
A normal stress response causes a temporary increase in stress hormones like cortisol and, when
it’s over, levels return to baseline and you recover, says Cynthia Munro, Ph.D., associate
professor of psychiatry and behavioral sciences.
But with repeated stress, or with enhanced sensitivity to stress, your body mounts an increased
and sustained hormone response that takes longer to recover [from]. We know if stress hormone
levels increase and remain high, this isn’t good for the brain’s hippocampus — the seat of
Data from more than 900 Baltimore residents have revealed a link that could be key in proving
why women aged 65 and above have a 1 in 6 chance of developing Alzheimer’s. The team’s
findings now appear in the International Journal of Geriatric Psychiatry.
The residents had participated in the National Institute of Mental Health’s Epidemiologic
Catchment Area study. Participants first joined the study in the early 1980s.
Following enrollment, they took part in interviews and checkups on three separate occasions:
once in 1982, once during 1993–1996, and once during 2003–2004. The average age of the
participants during the 1990s was 47, and 63% were women.
During their third interview of four, the researchers asked each participant if they had
experienced a traumatic event in the past year. Such events included rape, physical attacks,
threats, natural disasters, or watching another person sustain an injury or lose their life.
A second question asked if they had had stressful life experience at the same time period, such
as divorce, the death of a friend or family member, severe illness, marriage, or retirement.
The number of men and women reporting a traumatic experience was similar (22% of men and
23% of women). The same went for stressful life events, with 47% of men and 50% of women
saying that they had experienced at least once during the previous year.
At their third and fourth appointments, the participants all took a standardized memory test. One
the notable activity involved having to remember 20 words that testers spoke aloud and repeating
them straight away, as well as again 20 minutes later.
After analyzing their answers, the researchers determined a women-only relationship between
stressful life events during midlife and a greater deterioration in remembering and recognizing
Women who’d had at least one stressful life experience remembered one fewer word at the fourth
a visit than the third, while women in the same category recognized 1.7 fewer words at their fourth
On average, women who reported no life stressors remembered 0.5 fewer words and recognized
1.2 fewer words.
Traumatic life events did not result in the same decline. According to Munro, this is because
chronic stress may have a greater impact on brain functioning than a short term traumatic
Notably, there was no link between midlife stressful or traumatic experiences and memory
decline in men. Stressful experiences that occurred earlier in life also had no impact on men or
Stopping stress is an almost impossible task, but it may be possible to change the way the body
reacts to it. Munro explains that medications that could change how the brain copes with stressful
events are in the development stage.
Combining these with well-known stress-relieving techniques may help as people, particularly
These findings are similar to those of a 2013 Swedish study in the journal BMJ Open.
That team found a link between an increased number of midlife psychosocial stressors — such as
divorce, problems with children, and mental illness in a close relative — and an increased risk of
Further studies will need to examine if there are a cause and effect relationship between stress and
cognitive decline. If this is the case, altering the body’s stress response may be even more