depression symptoms that steadily increase in older adults are more strongly linked to dementia than any other types of depression, according to new research.
The
new study, published in The Lancet Psychiatry journal, notes
that the steadily increasing depression symptoms may actually indicate the
early stages of dementia.
Symptoms
of depression are common in people with dementia, but previous studies have
often looked at single episodes of depression, failing to take into account how
depression develops over time, researchers said.
The
course of depression varies greatly between individuals, they said. Researchers
note that some people might experience depressive symptoms only transiently,
followed by full remission, while others might have remitting and relapsing
depression, while still others might be chronically depressed.
Different
courses of depression may reflect different underlying causes, and might be
linked to different risks of dementia, according to the researchers.
The
new study included 3,325 adults aged 55 and over, who all had symptoms of
depression, but no symptoms of dementia at the start of the study.
Data
was gathered from the Rotterdam Study, a population-based study of various
diseases in the Netherlands that allowed the researchers to track depressive
symptoms over 11 years and the risk of dementia for a subsequent 10 years.
Using
the Center for Epidemiology Depression Scale (CES-D) and the Hospital Anxiety
and Depression Scale-Depression (HADS-D), the researchers identified five
different trajectories of depressive symptoms:
- Low depression symptoms (2,441 participants);
- Initially high symptoms that decreased (369);
- Low starting scores that increased, then remitted (170);
- Initially low symptoms that increased (255); and,
- Constantly high symptoms (90).
Of
the 3,325 participants, 434 developed dementia, including 348 cases of
Alzheimer’s disease.
Among
the group with low symptoms of depression, 10 percent (or 226) developed
dementia.
The
researchers said they used this as the benchmark against which to compare other
trajectories of depression as the study did not compare the risk of dementia
following depression with the risk of dementia for adults without depression.
Only
the group whose symptoms of depression increased over time was at an increased
risk of dementia — 22 percent, or 55 people, developed dementia, according to
the study’s findings.
This
risk was particularly pronounced after the first three years, the researchers
reported.
Individuals
with remitting symptoms of depression were not at an increased risk of dementia
compared to individuals with low depressive symptoms, according to the study’s
findings.
The
researchers say this suggests that having severe symptoms of depression at one
point in time does not necessarily have any lasting influence on the risk of
dementia.
The
researchers add their findings support the hypothesis that increasing symptoms
of depression in older age could potentially represent an early stage of
dementia.
They
also say that the findings support previous suggestions that dementia and some
forms of depression may be symptoms of a common cause. They explain that at the
molecular levels, the biological mechanisms of depression, and
neurodegenerative diseases overlap considerably, including the loss of ability
to create new neurons, increased cell death and immune system dysregulation.
“Depressive
symptoms that gradually increase over time appear to better predict dementia
later in life than other trajectories of depressive symptoms, such as high and
remitting, in this study,” said Dr. M. Arfan Ikram, of the Department of
Epidemiology at Erasmus University Medical Center in Rotterdam.
“There
are a number of potential explanations, including that depression and dementia
may both be symptoms of a common underlying cause, or that increasing
depressive symptoms are on the starting end of a dementia continuum in older
adults,” he said. “More research is needed to examine this association, and to
investigate the potential to use ongoing assessments of depressive symptoms to
identify older adults at increased risk of dementia.”
No comments:
Post a Comment