Alzheimer's Patients May Have Symptoms of Depression Years Before Diagnosis
Dec. 9, 1999 (New York) -- Some key symptoms of depression such as lack of
interest, loss of energy, and poor concentration are increased in elderly
people in the years leading up to a diagnosis of Alzheimer's disease (AD),
according to a report in the Dec. 10 issue of the journal Neurology.
Unlike some previous reports suggesting that people who are depressed are more
likely to develop AD or that people with AD become depressed by their mental
deficits, the new study shows that the depressive symptoms are an early sign of
AD and could be important in obtaining the diagnosis.
"Treatment for Alzheimer's disease is becoming increasingly successful,
and the treatment is most likely to succeed if it's given early in the course
of the disease," study author Lars Backman, PhD, states in a press release
issued by the American Academy of Neurology. "Therefore, it is critically
important to diagnose Alzheimer's as early as possible. Looking for these
depression symptoms may be one way to identify who will develop Alzheimer's in
a few years."
Backman and colleagues from the Stockholm Gerontology Research Center in
Sweden examined 222 elderly individuals aged 74 years and older for presence of
depressive symptoms and dementia. After 3 years, 34 individuals had received a
diagnosis of AD.
Compared with nondemented individuals, those with AD were 50% more likely to
have depressive symptoms. Lack of interest, in particular, was three times more
common among people diagnosed with AD. There were no significant differences
between the groups in most mood-related symptoms such as unhappiness or
feelings of guilt, but those with AD tended to have more thoughts of death and
complained more about memory problems. The groups did not differ in rates of
another important depressive symptom, sleep disturbance.
An expert who reviewed the article for WebMD says the findings are
interesting and fit with similar work published earlier this year showing that
motivation-related depressive symptoms occurring prior to Alzheimer's are
likely the result of early changes in the structure of the brain. Doctors and
patients need to realize that there is a big difference between major
depression occurring in an elderly person and the emergence of depressive
symptoms that may be early signs of AD, says Eugene Rubin, MD, professor of
psychiatry at Washington University School of Medicine in St. Louis.
"These subtle changes, which are characteristic of a mild depression,
are just reflections of brain deterioration in Alzheimer's type dementia,"
Rubin tells WebMD. "The major depressions that we see in younger people
that come on fairly quickly are very different from these subtle changes in
some of the same systems that are slowly being nibbled away by Alzheimer's. It
may well be that the same brain regions are being affected, but a very
different cause is damaging those brain regions. This paper supports that whole
notion that Alzheimer's type dementia is an illness that involves multiple,
multiple regions of the brain and presents with symptoms related to mood,
personality -- the whole spectrum of what makes us human. But none of these
people would in any way qualify as having a major depression."
It remains to be determined if patients with pre-AD depression will benefit
from some form of therapy. Rubin says there have been a few articles showing
that patients with depressive symptoms and mild AD can respond to
antidepressants or behavioral therapy. "There's some suggestion that those
symptoms are still partially responsive to treatment. Even though the brain is
being slowly eaten away, there's no reason to assume that treatments will or
won't work," Rubin says. "But when to treat is still an unknown."
One important reason to explore further whether patients with pre-AD depressive
symptoms respond to antidepression treatment is that reducing depressive
symptoms may also reduce the person's risk of subsequent illness and death, he