DEPRESSION AS A RISK FACTOR FOR DEMENTIA
A new study by
neuropsychiatric researchers at Rush University Medical Center gives insight
into the relationship between depression and dementia. The study is published
in the July 30, 2014, online issue of Neurology. the medical journal of the
American Academy of Neurology.
"Studies have
shown that people with symptoms of depression are more likely to develop
dementia, but we haven't known how the relationship works," said study
author Robert S. Wilson, PhD, neuropsychiatrist at the Rush Alzheimer's Disease
Center and lead study investigator. "Is the depression a consequence of
the dementia? Do both problems develop from the same underlying problems in the
brain? Or does the relationship of depression with dementia have nothing to do
with dementia-related pathology?"
The current study
indicates that the association of depression with dementia is independent of
dementia-related brain changes. "These findings are exciting because they
suggest depression truly is a risk factor for dementia, and if we can target
and prevent or treat depression and causes of stress we may have the potential
to help people maintain their thinking and memory abilities into old age,"
Wilson said.
The study involved
1,764 people from the Religious Orders Study and the Rush Memory and Aging
Project with an average age of 77 who had no thinking or memory problems at the
start of the study. Participants were screened every year for symptoms of
depression, such as loneliness and lack of appetite, and took tests on their
thinking and memory skills for an average of eight years. A total of 680 people
died during the study, and autopsies were performed on 582 of them to look for
the plaques and tangles in the brain that are the signs of dementia and other
signs of damage in the brain.
During the study, 922
people, or 52 percent of the participants, developed mild cognitive impairment (MCI),
or mild problems with memory and thinking abilities that is often a precursor
to Alzheimer's disease. A total of 315 people, or 18 percent, developed
dementia.
The researchers found
no relationship between how much damage was found in the brain and the level of
depression symptoms people had or in the change in depression symptoms over
time.
People who developed
mild cognitive impairment were more likely to have a higher level of symptoms
of depression before they were diagnosed, but they were no more likely to have
any change in symptoms of depression after the diagnosis than people without
MCI. People with dementia were also more likely to have a higher level of
depression symptoms before the dementia started, but they had a more rapid
decrease in depression symptoms after dementia developed.
Having a higher level
of depression symptoms was associated with more rapid decline in thinking and
memory skills, accounting for 4.4 percent of the difference in decline that
could not be attributed to the level of damage in the brain.
The study was
supported by the National Institute on Aging and the Illinois Department of
Public Health.
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