Psychiatric Comorbidity: The Case for Treating Insomnia

A review of studies of the treatment of insomnia occurring in association with other psychiatric disorders suggests that the secondary insomnia model fails to explain adequately the relationship between insomnia and the associated conditions and also fails to lead to optimal clinical management. This literature demonstrates that both initial adjunctive insomnia treatment and treatment of residual insomnia has positive effects on the response to antidepressant treatment. Published literature provides strong support for a model in which insomnia occurring with major depression is of high clinical relevance and an important target for therapy. Whether treatment of insomnia occurring with generalized anxiety disorder and alcoholism affects outcome will be an important area for future research. The literature on the treatment of comorbid insomnia also establishes that perhaps the most fundamental pillar of the secondary insomnia model, which has served as a guide to clinical practice, has crumbled. Because chronic insomnia was believed to be caused by psychiatric disorders, effective treatment of those underlying psychiatric disorders was expected to eliminate insomnia [3]. There is now clear evidence that treatment of major depression, GAD, and alcoholism frequently does not relieve the associated chronic insomnia. The case for the treatment of insomnia when comorbid with other psychiatric disorders is clear. Effective treatment for each of the most important comorbid psychiatric conditions often fails to alleviate the associated insomnia. When comorbid insomnia is associated with impairment in function or quality of life, treatment specifically for that insomnia is needed. One factor that seems likely to have obscured this issue and to have prevented the observation of residual insomnia in the past is that nearly all of the psychiatric disorders in question were routinely treated with sedating agents (tricyclic or other sedating antidepressants in major depression; benzodiazepines or tricyclic or other sedating antidepressants in anxiety disorders; tricyclic or other sedating antidepressants in alcoholism), and these medications probably were treating the associated insomnia. Over time these disorders increasingly have been treated with agents that are not sedating (SSRIs, serotonin-norepinephrine reuptake inhibitors, norepinephrine-dopamine reuptake inhibitors). The residual insomnia has been most clearly observed in studies that have included these agents. Although in some instances the insomnia may reflect a sleep-disruptive side effect, the observation that residual insomnia also is found in patients who respond to cognitive behavioral therapy suggests otherwise [21]. Nonetheless, the view that sedating single-agent therapies might be addressing insomnia that occurred in association with psychiatric disorders was supported by the studies in which improvements in sleep were noted with several benzodiazepine-related agents and trazodone. Studies of other single-agent sedating treatments, including tricyclic antidepressants, and mirtazapine, would help in making clinical decisions when an agent that addresses insomnia is indicated. These considerations also suggest that the treatment of comorbid insomnia with interventions that do not address insomnia, such as cognitive behavioral therapy, SSRIs, bupropion, or serotonin-norepinephrine reuptake inhibitors should be accompanied by adjunctive insomnia therapy, particularly in patients who have major depression and those at high risk or with greater impairment in function. Very few combinations of nonsedating treatments and insomnia therapies have been studied. Insomnia agents that have been combined with fluoxetine are eszopiclone, trazodone, zolpidem, and clonazepam. Bupropion also has been combined with trazodone. There is a need to investigate other combinations of medications both for the treatment of the insomnia and the associated psychiatric decision to provide an empiric basis for making the clinical decisions needed for optimal management of comorbid insomnia. © 2006 Elsevier Inc. All rights reserved.

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Author Andrew Darrell Krystal Psychiatry & Behavioral Sciences, Behavioral Medicine & Neur ...