Happiness in Early Adulthood May Protect Against Dementia
rael-science
Happiness in Early Adulthood May Protect Against Dementia
Summary: Depression
experienced during early adulthood increases the risk of developing
cognitive impairment and dementia later in life, a new study reports.
Source: UCSF
While
research has shown that poor cardiovascular health can damage blood
flow to the brain increasing the risk for dementia, a new study led by
UC San Francisco indicates that poor mental health may also take its
toll on cognition.
The
research adds to a body of evidence that links depression with
dementia, but while most studies have pointed to its association in
later life, the UCSF study shows that depression in early adulthood may
lead to lower cognition 10 years later and to cognitive decline in old
age.
The study publishes in the Journal of Alzheimer’s Disease on Sept. 28, 2021.
The
researchers used innovative statistical methods to predict average
trajectories of depressive symptoms for approximately 15,000
participants ages 20 to 89, divided into three life stages: older,
midlife and young adulthood.
They
then applied these predicted trajectories and found that in a group of
approximately 6,000 older participants, the odds of cognitive impairment
were 73 percent higher for those estimated to have elevated depressive
symptoms in early adulthood, and 43 percent higher for those estimated
to have elevated depressive symptoms in later life.
These
results were adjusted for depressive symptoms in other life stages and
for differences in age, sex, race, educational attainment, body mass
index, history of diabetes and smoking status. For depressive symptoms
in midlife, the researchers found an association with cognitive
impairment, but this was discounted when they adjusted for depression in
other life stages.
Excess Stress Hormones May Damage Ability to Make New Memories
“Several
mechanisms explain how depression might increase dementia risk,” said
first author Willa Brenowitz, PhD, MPH, of the UCSF Department of
Psychiatry and Behavioral Sciences and the Weill Institute for
Neurosciences.
“Among
them is that hyperactivity of the central stress response system
increases production of the stress hormones glucocorticoids, leading to
damage of the hippocampus, the part of the brain essential for forming,
organizing and storing new memories.”
Other
studies have linked depression with atrophy of the hippocampus, and one
study has shown faster rates of volume loss in women, she said.
In
estimating the depressive symptoms across each life stage, researchers
pooled data from younger participants with data from the approximately
6,000 older participants and predicted average trajectories. These
participants, whose average age was 72 at the start of the study and
lived at home, had been enrolled by the Health Aging and Body
Composition Study and the Cardiovascular Health Study. They were
followed annually or semi-annually for up to 11 years.
U-Shaped Curve Adds Credence to Predicted Trajectories
While
assumed values were used, the authors stated, no longitudinal studies
have been completed across the life course. “Imputed depressive symptom
trajectories fit a U-shaped curve, similar to age-related trends in
other research,” they noted.
Participants
were screened for depression using a tool called the CESD-10, a 10-item
questionnaire assessing symptoms in the past week. Moderate or high
depressive symptoms were found in 13 percent of young adults, 26 percent
of midlife adults and 34 percent of older participants.
Some
1,277 participants were diagnosed with cognitive impairment following
neuropsychological testing, evidence of global decline, documented use
of a dementia medication or hospitalization with dementia as a primary
or secondary diagnosis.
“Generally,
we found that the greater the depressive symptoms, the lower the
cognition and the faster the rates of decline,” said Brenowitz, who is
also affiliated with the UCSF Department of Epidemiology and
Biostatistics. “Older adults estimated to have moderate or high
depressive symptoms in early adulthood were found to experience a drop
in cognition over 10 years.”
With
up to 20 percent of the population suffering from depression during
their lifetime, it’s important to recognize its role in cognitive aging,
said senior author Kristine Yaffe, MD, of the UCSF departments of
Psychiatry and Behavioral Sciences, and Epidemiology and Biostatistics.
“Future work will be needed to confirm these findings, but in the
meantime, we should screen and treat depression for many reasons.”
Co-Authors:
Eric Vittinghoff, PhD, from UCSF; Adina Zeki Al Hazzouri, PhD, from
Columbia University; Sherita H. Golden, MD, from Johns Hopkins
University School of Medicine; and Annette L. Fitzpatrick, PhD, from
University of Washington.
Funding: National Institutes of Health and National Institute on Aging (1RF1AG054443).