Dec. 31, 2012 -- Depression is common among older people who go on to develop Alzheimer’s disease, leading to widespread speculation that it may be one possible cause for age-related dementias.
Now, a new study suggests that rather than being a cause of memory decline, depression in older people may be an early symptom of dementia.
When researchers evaluated 2,000 elderly New Yorkers for depression and then followed them, they found that depression accompanied memory declines but did not necessarily come first.
Depression Predicted Dementia
Having memory problems that are not severe enough to be diagnosed as dementia, but that are more pronounced than the changes associated with normal aging, is known as mild cognitive impairment. Many people with MCI develop dementia, but some do not.
The new research shows that having mild cognitive impairment along with depression doubled the risk of developing full-blown dementia.
But researcher Jose A. Luchsinger, MD, MPH, of Columbia University Medical Center, says depression appears to be a symptom that accompanies age-related memory loss, such as mild cognitive impairment, rather than a separate risk factor for it.
It also means that depression among the elderly should be recognized as a possible early warning sign of age-related memory decline.
The study was published online today in the journal Archives of Neurology.
“When depression and memory complaints occur together in the elderly it is often assumed that the memory problems are caused by the depression,” Luchsinger says. “The thinking is often that by treating the depression the memory problems will go away, but this may not be the case.”
Memory Loss May Lead to Depression
He says older people who are depressed and have memory complaints should be evaluated for mild cognitive impairment or other early signs of dementia.
Neurologist Gayatri Devi, MD, of New York City’s Lenox Hill Hospital, says it makes sense that older people with early memory loss would be more vulnerable to depression.
“Especially in the early stages when people realize that something is not quite right but they don’t really understand what is happening, it is natural to become depressed,” she says.
Devi agrees that depression and memory loss in older patients are too often lumped together instead of being evaluated separately.
“Depression may be related to (memory) decline or it may be totally unrelated,” she says. “From a clinical perspective it is important to understand this. If a patient comes to me in her 70s or 80s with no history of depression and no clear reason for depression, such as the loss of a spouse or a child, I will certainly consider cognitive loss as a possible reason and do the appropriate tests.”