Older adults who struggle with depression may be at much greater risk of remaining depressed if they experience persistent or worsening sleep problems, according to a new study published in the journal Sleep.
“We can’t say that the sleep disturbances we’re seeing are necessarily causing the poor depression outcomes,” said senior author Adam Spira, Ph.D., professor in the department of mental health at Johns Hopkins Bloomberg School of Public Health.
“But the results suggest that older adults who are being treated for depression and whose sleep problems are persistent or worsening need further clinical attention. They also suggest that treating sleep problems should be explored further as a potential means to improve depression outcomes in older people — as well as the poor cognitive and general health outcomes that have been tied to disturbed sleep in this population.”
For the study, a team from the Bloomberg School of Public Health analyzed data from nearly 600 people over age 60 who had visited primary care centers in the Northeast U.S. All patients met clinical criteria for major or minor depression at the beginning of the study.
The findings show that patients with a pattern of worsening insomnia symptoms throughout the following year were almost 30 times more likely to have major depression at the end of that year, compared to patients whose sleep had improved.
Participants with worsening insomnia were also much more likely to have a diagnosis of minor depression and were more likely to report suicidal thoughts at the end of the year.
Compared to patients whose sleep had improved, those with insomnia symptoms that persisted but did not worsen were more likely to have persistent major or minor depression, but their risk was not as high as patients with worsening sleep.
“These results suggest that, among older adults with depression, insomnia symptoms offer an important clue to their risks for persistent depression and suicidal ideation,” Spira said.
A lack of sleep has long been considered a potential risk factor for mood disorders, and has more recently been studied in relation to suicidal thinking. In a previous study of older adults living in low- and middle-income countries, the team found that older adults reporting insomnia symptoms and poor sleep quality were more likely to report having suicidal thoughts, and that participants with insomnia symptoms were more likely to report a prior suicide attempt.
The new analysis looked at data from a sleep and mental health study conducted from May 1999 to August 2001, covering older adults at 20 primary care centers in New York City, Philadelphia and Pittsburgh.
“There otherwise hasn’t been much research on insomnia and depression in older adults in primary care settings — even though primary care is where most people with depression are treated,” Spira says.
The analysis involved 599 patients, 429 (71.6 percent) of whom were women. At the start of the study, the patients’ average age was 70.3 years, and two-thirds met criteria for major depression, while the rest met criteria for minor depression.
The researchers evaluated the patients’ reports of insomnia symptoms — primarily difficulty falling asleep or waking without a full night’s sleep — over 12 months, and sorted them into three groups based on their reports: 346 patients who started with fewer sleep problems and slept much better by the end of the study; 158 who started with more sleep problems and stayed the same or improved only slightly over the year; and 95 patients who at baseline had more sleep problems and worsened over the year.
The findings show that, compared to the patients whose sleep had improved, subjects with worsening sleep disturbances had 28.6 times the odds of having a diagnosis of major depression at the end of the year, as opposed to no longer having a depression diagnosis.
The patients whose sleep worsened also had 11.9 times the odds of having a diagnosis of minor depression at the end of the year and were 10 percent more likely to report having suicidal thoughts at the end of the year.
The study’s lead author was Joseph Gallo, M.D., M.P.H., professor in the Bloomberg School’s Department of Mental Health.