Too Depressed to Remember
Why are many elderly people forgetful? It may be the blues.
For many people, depression appears to cause similar damage; their cortisol levels remain slightly elevated as long as they are depressed. This moderate but constant drip-drip of the cortisol faucet appears to wear down the hippocampus.
In a review of several long-term studies published in the October 1999 issue of Reviews in the Neurosciences, Lupien concluded that this process is particularly damaging in the elderly.
But there's no strong evidence that the hippocampus shrinks as a part of normal aging. In one recent study, Yvette Sheline, MD, a professor of psychiatry at Washington University in St. Louis, used magnetic resonance imaging to measure the hippocampus of 48 women aged 23 to 86, half of whom had a history of clinical depression, half of whom did not.
The women with depression had smaller hippocampuses and scored lower on memory tests than the non-depressed group, regardless of age.
"We expected to see an effect from aging. Instead we saw significant volume loss only in patients with a history of depression," says Sheline, whose study was published in the June 14, 1999 issue of the Journal of Neuroscience.
"Research shows that when depression is treated, cognitive function, including memory, improves. The earlier we can recognize the symptoms, the more likely we are to arrest or slow down the degeneration of the brain," McEwen says.
Still, more studies are needed to fully understand the connection between emotions and memory, cautions Mony de Leon, a psychiatrist and professor at New York University's medical school. The cortisol-hippocampus research is an exciting start, he says, but much remains a mystery.
For example, researchers haven't yet determined what, if any, role cortisol plays in Alzheimer's disease. Studies show all people with Alzheimer's have hippocampal damage, but their cortisol production varies. "All of these things remain somewhat foggy," says de Leon. "It requires much more extensive investigation."
As for Cusenza, no one has any plans to measure her hippocampus. Such tests are rarely done, and they would tell doctors little because it wasn't measured before the onset of her symptoms. Still, her family is hopeful that treating her depression will put a halt to her slide into forgetfulness -- and dependence.
Kate Rauch has written about medicine for The Washington Post, Newsday, and many other publications. She lives in Albany, Calif.