MONDAY, June 27, 2005 (HealthDay News) -- Chronic insomnia may provoke and perpetuate depression among the elderly, two new studies claim.
One study found that elderly patients with a history of depression were more likely to continue being depressed over the course of a year if they also suffered from persistent insomnia.
The second study suggested that even without a history of depression, elderly patients -- particularly women -- who struggle with chronic sleeplessness are at a higher risk for becoming severely depressed than patients who report no trouble sleeping.
Both studies are the result of work being conducted at the University of Rochester Sleep and Neurophysiology Research Laboratory. They were presented recently at the Associated Professional Sleep Societies annual meeting in Denver.
"The biggest question for us now is can we get to those cases where elderly people have chronic insomnia and treat that -- and prevent or at least delay chronic depression," said Dr. Michael Perlis, the sleep lab's director.
Taken together, the findings support the notion that insomnia may be more than a symptom of depression; it may also be a cause.
Perlis' team notes that 2 million older Americans suffer from some form of severe depression, characterized by a loss of hope and profound sadness. Another 5 million cope with milder forms of the illness.
And prior research suggests that more than 40 percent of the elderly face trouble getting a good night's sleep, the researchers added.
In the Rochester lab's first study, researchers tracked the mental health of more than 1,800 men and women over the age of 65 diagnosed with severe and/or mild depression.
After determining whether or not participants had persistent insomnia, the patients were assessed twice, first at the six-month mark and then after one year, for signs of depressive illness.
Individuals who suffered from insomnia were almost 11 times more likely to continue being depressed after six months and 17 times more likely to be depressed after a year compared to non-insomniacs.
In the second study --scheduled for publication in the Journal of Behavioral Sleep Medicine -- Perlis and his team focused on 147 men and women over the age of 60 with no history of mental illness at the start of the study. Thirty-four of the patients suffered from persistent insomnia, 47 had less persistent "indeterminate insomnia," while 66 had no sleep troubles.
After conducting two tests spread over a one-year period, the researchers found that 12 patients experienced new-onset depression during the course of the year. Half of these newly depressed patients suffered from persistent insomnia, the investigators note, while four had indeterminate insomnia. Two had no trouble sleeping.
Persistent insomniacs most at risk for developing depression were the so-called "middle insomniacs" -- those whose sleep patterns were typically disturbed by waking up in the middle of the night.
Overall, elderly patients with persistent insomnia are six times more likely to experience serious new-onset depression than individuals who sleep easily, the authors concluded.
However, they also noted that 10 of the 12 depressed patients were women, and all the patients who became depressed while suffering from a persistent form of insomnia were female.
Perlis said its unclear why elderly women might be at especially high risk for the insomnia-depression connection.
"What we do know is that insomnia is a risk factor for depression, it precedes depression, and it seems to make depression resistant to treatment," he said. "Insomnia is a clear and present danger for depression."
Dr. Gregg Jacobs, of the Sleep Disorders Center at Beth Israel Deaconess Medical Center in Boston, was slightly more cautious.
"It's an interesting finding, and it's provocative, but the number of patients studied is way too small to be meaningful," he remarked. "And although there is evidence from prior studies that insomnia seems to predict new cases of depression, the actual risk is very low."
Perlis and Jacobs agreed, however, that more research is needed to explore whether insomnia itself is directly related to depression or whether it is instead a red flag for other factors that might make a patient more likely to develop both insomnia and depression.
Treatments for both conditions were also a topic of discussion at the sleep conference, where Sepracor, the makers of the new sleep medication Lunesta, presented four studies focused on the effectiveness of that drug.
Researchers from the University of Pittsburgh School of Medicine, as well as Wake Forest University Medical Center and Duke University Medical Center announced the findings.
Lunesta was approved as a prescription sleep aid by the FDA in April. To date, it is the only sleep medication deemed safe for long-term use of up to six months.
In the first Pittsburgh study, involving 545 men and women suffering from both insomnia and depression, researchers explored how well the prescription drug works when taken in combination with Prozac, an antidepressant.
When compared to patients who took only Prozac, the researchers found those taking both medications over an eight-week period were able to fall asleep faster, sleep longer, and stay asleep with less disruption.
The drug combo also improved sleep quality and depth, while boosting alertness and the ability to concentrate throughout the day. And in a second Pittsburgh study, patients who took Lunesta for a full year experienced improved sleep habits across the board. Patients who took Lunesta for just six months -- after taking a placebo for the prior six months -- experienced a quick and notable improvement in their sleep habits shortly after beginning the Lunesta regimen.
In the Wake Forest study, researchers reported that patients taking this same Lunesta-Prozac combination were more likely to experience reduction or elimination of depression -- and less likely to require an increase in their Prozac dosage -- than patients taking Prozac alone.
Finally, scientists at Duke found that when patients taking both Lunesta and Prozac for eight weeks ceased taking Lunesta for a two-week period, their sleep habits continued to improve significantly.
For more on insomnia, check out the National Institutes of Health.