Women who deal with a lot
of day-to-day stressors
in middle-age may have a somewhat higher risk of developing Alzheimer's
later in life, a new study suggests.
The findings, published
online in BMJ Open, do not prove that your job or your family
are raising your dementia risk. But experts said they add to evidence that
chronic stress may contribute to the development of Alzheimer's disease in some
No one is sure why, but
there are theories, according to Robert Wilson, a professor of neurological
sciences and psychology at Rush University Medical Centre, in Chicago.
It's possible that chronic
stress, via effects on certain hormones, may reduce the efficiency of people's
"brain circuitry", explained Wilson, who was not involved in the new
study. And that could leave some people more vulnerable to the impact of
Alzheimer's-related brain changes later in life.
But past studies have
generally focused on the possible effects of stress from more-severe traumas.
The new study looked at "common" stressors, said lead researcher Lena
Johansson, of the Sahlgrenska Academy at Gothenburg University, in Sweden.
Her team studied data from
800 Swedish women who were followed for nearly four decades, starting when they
were in their late 30s to early 50s. The women underwent periodic psychiatric
exams and answered questions about everyday stressors – such as divorce, job
strain and family members' health issues.
In tandem with stressors
Over 37 years, 19% of the
women developed dementia – most often Alzheimer's disease. And the risk
climbed in tandem with the number of life stressors that the women had reported
four decades earlier. For each stressor, the risk of Alzheimer's crept up by 17%.
That doesn't prove that a
stressful life is to blame, said Dr Marc Gordon, chief of neurology at Zucker
Hillside Hospital in Glen Oaks, New York.
But, he noted, the
researchers did account for a number of other explanations for the link –
including whether the women had high blood pressure or diabetes, were
overweight or had low incomes.
Other studies have tied
heart disease risk factors, such as high blood pressure, to Alzheimer's, and
lower income and education levels have also been linked to the disease.
Still, Johansson's team
found, stressors themselves were connected to an increased risk of Alzheimer's.
Gordon, who was not
involved in the study, agreed that it's "biologically plausible" that
chronic stress could contribute to dementia. But a big unanswered question is
whether any efforts to reduce stress in your life can also trim the risk of
Alzheimer's later on.
"This type of study
can't tell us if there's an intervention that can affect people's
outcomes," Gordon said. "We can't make any recommendations based on
An interesting finding,
Rush University's Wilson said, was that the number of stressors in a woman's
life seemed to matter, regardless of whether she felt "stressed out"
Women in the study were
asked about their typical "distress" levels – including tension,
fear or sleep problems related to work, family or their health. Women with
"longstanding" distress were at increased risk of Alzheimer's. But so
were women with a greater number of life stressors.
That suggests that
stressors can take a toll, even if you do not feel overwhelmed, according to
study author Johansson.
"These are the kinds
of stressors that grate on people day to day," Wilson noted. And this
study, he said, suggests that these issues should not "just be brushed
off". He agreed, though, that the question remains: Could stress reduction
make a difference in people's Alzheimer's risk?
Zucker Hillside's Gordon
said more studies are also needed to confirm these results in other groups of
people, since this focused on white women. And even if common types of stress
are linked to Alzheimer's risk, any effect on an individual could be small.
No one is sure what causes
Alzheimer's, but Gordon said it's thought to be a mix of genetic factors,
family history and environmental influences.
"This would be only
one of many potential factors," Gordon noted.
The Alzheimer's Association
has more on Alzheimer's disease risk factors.