NEW YORK, (Reuters Health) -- In the elderly, symptoms of
depression such as low energy and concentration problems may be early signs of
Alzheimer's disease, according to Swedish researchers.
The results of their study suggest that these symptoms are not due to
patients realizing that their memories are failing, but rather that depressive
symptoms are part of the early stages of Alzheimer's.
In a 3-year study that followed 222 people aged 74 and older, researchers
found that those who developed Alzheimer's were 50% more likely than other
participants to have suffered depressive symptoms at the study's start.
"The people who developed Alzheimer's weren't even close to a clinical
diagnosis of depression, but they did have more symptoms of depression, such as
a lack of interest, loss of energy and difficulty concentrating," lead
researcher Dr. Lars Backman said in a statement. Backman and his colleagues at
the Stockholm Gerontology Research Center report their findings in the December
10th issue of the journal Neurology.
Although other investigators have noted a link between depression and
Alzheimer's, the nature of this relationship has been unclear. Some studies have
suggested depression may be a risk factor for Alzheimer's; other researchers
have concluded that Alzheimer's patients suffer depression as an emotional
response to the loss of memory and thinking abilities that mark the disease.
This study, according to Backman's team, suggests that depression is
neither a response to Alzheimer's nor a risk factor, but rather an early sign of
the disease.
Backman and colleagues looked at two types of depression among the study
participants -- "mood-related" symptoms such as unhappiness, guilt and thoughts
of death; and "motivation-related" symptoms including lack of energy and
interest, and concentration problems. They found that at the start of the study,
participants who would later develop Alzheimer's commonly had motivation-related
symptoms.
"That provides further evidence that the symptoms are not related to
people's feelings about their cognitive difficulties, and actually reflect
changes in the brain regions involved in attention and energy," Backman
explained in the statement.
Alzheimer's currently affects about 4 million Americans; as the elderly
population grows, that number is expected to jump to 14 million over the next 50
years, according to the Chicago-based Alzheimer's Association. There is no one
test that diagnoses the brain disease. Rather, physicians rely on a combination
of physical, psychological and neurological tests to diagnose "probable"
Alzheimer's.
According to Backman, because the depressive symptoms that emerged in his
study are fairly common among the elderly, they may be "easily overlooked" as
early signs of Alzheimer's disease.
