Insomnia and depression are closely linked. The majority of people with depression experience insomnia, and people with insomnia are more likely to develop depression than people without insomnia. For example, insomnia is associated with twice the risk of developing depression in people over 60 years of age.
Insomnia is very common among older people. It is associated with the development of depression in individuals with no history of depression and with recurrence of depression in individuals who have previously had depressive episodes.
Although many older people with depression respond partially to medication and/or psychotherapy, only about a third experience complete remission of symptoms. Preventing depression would probably be a more effective approach to alleviating distress and disability than treating symptoms as soon as they appear. In a recent article published in JAMA Psychiatry, Michael Irwin and colleagues report the results of a study examining the effect of treating insomnia on the later development of major depression in people aged 60 and older.
Cognitive behavioral therapy for insomnia (CBT-I) is an effective treatment for insomnia. It is recommended as a first-line treatment for sleep disorders and is more effective than other widely used non-pharmacological approaches, including sleep therapy (SET). SET “targets everyday behavioral and environmental factors that contribute to poor sleep” and includes providing information on “sleep hygiene, sleep biology, characteristics of healthy sleep, stress biology and effects on sleep”.
Irwin and colleagues enrolled a community sample of 291 people ages 60 and older who had a confirmed insomnia disorder. Individuals with a major depressive episode in the previous 12 months were excluded from the study. Participants were randomly assigned to receive either CBT-I or SET in weekly two-hour group sessions for two months. CBT-I was administered by a trained psychologist; SET was carried out by a trained health educator. Participants were monitored for the occurrence of a major depressive episode over the subsequent 36 months using the DSM-5 Structured Clinical Interview (SCID-5).
The researchers found that the group treated with CBT-I was 50% less likely to develop depression than the group treated with SET. About 26% of those receiving SET developed depression versus about 12% in the CBT-I group. More people in the CBT-I group experienced remission of their insomnia disorder: 51% versus about 38% in the SET group.
The research team also looked at the occurrence of depression in patients who experienced sustained remission of insomnia compared to those who did not achieve sustained remission. They found that only 5% of those who experienced remission of insomnia in the CBT-I group developed a subsequent episode of major depression, versus 19% of those who experienced remission in the SET group. Of those who did not achieve insomnia remission, 15% in the CBT-I group developed a depressive episode versus 28% in the SET group. Therefore, treatment with CBT-I was associated with preventing subsequent depression, even in those whose insomnia did not fully resolve.
As discussed in an accompanying commentary by Pim Cuijpers and Charles Reynolds, these results demonstrate the ability to prevent the development of depression in a high-risk group, ie older individuals with insomnia. Would such a strategy work for younger individuals with insomnia? Would effective pharmacological treatments for insomnia have similar effects? Could parallel strategies be developed to treat other conditions that increase the risk of depression?
It is important to determine whether the results from the Irwin et al. Replicate study in larger clinical trials. Forms of CBT-I that can be administered electronically (digital CBT-I) are available, and if they are also effective in preventing depressive episodes, they could provide broader access to this potentially important intervention. We also note that insomnia is a common residual symptom of depression, which increases the risk of relapse. It would be important to determine whether CBT-I is an effective relapse prevention strategy.
Depression is one of the most disabling diseases worldwide. It is strongly associated with completed suicides. In addition, mortality from other diseases is increased when depression is also present.
Successful treatment of depression is important. Preventing depression could change the lives of many people for the better.
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Eugene Rubin MD, PhD, and Charles Zorumski, MD wrote this article.