Innovations In Clinical Neuroscience

MAR-APR 2018

A peer-reviewed, evidence-based journal for clinicians in the field of neuroscience

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29 ICNS INNOVATIONS IN CLINICAL NEUROSCIENCE March-April 2018 • Volume 15 • Number 3–4 R E V I E W (MADRS). 10–12 Insomnia is seen in more than 90 percent of patients with clinical depression. Insomnia as a symptom has a 60- to 70-percent positive predictive value in diagnosing MDD 13,14 More than 50 percent of patients presenting to sleep disorder clinics have insomnia, and those who present with insomnia have a higher prevalence of MDD. 15 There is a bidirectional relationship between insomnia and depression. 16 Insomnia can be a risk factor for subsequent development of depression. In a 40-year longitudinal follow-up of medical students, it was noted that those who had baseline insomnia were at higher risk for the subsequent development of MDD (relative risk [RR] 2.0, confidence interval [Cl] 1.2–3.3)] (Figure 1). 17 Patients with insomnia but without depression displayed an odds ratio of 6.2 for developing depression later in life, while patients with depression but without insomnia had an odds ratio of 6.7 of developing insomnia later in life. 12 In addition, in patients with insomnia and mood disorders, the insomnia preceded the mood disorder in 41 percent of patients, mood disorder preceded insomnia in 29 percent, and the symptoms appeared simultaneously in 29 percent. 18 Insomnia is a marker for increased risk of suicidal thinking. Higher levels of insomnia and depression, as recorded with the HAM-D, corresponded to significantly greater intensity of suicidal thinking (p<0.01, p<0.001, respectively). 19 Furthermore, the relation between suicidality and sleep disturbances has been shown even in the absence of mental disorders. 20 Insomnia is also a risk factor for relapse in patients treated for depression. 21 It has been shown that treatment of insomnia with cognitive behavior therapy in patients with depression resulted in a significantly greater decrease in depression scores, decreased relapse, and improved remission rates. 22 Table 1 summarizes these implications. INSOMNIA AND PSYCHOTIC DISORDERS Insomnia is common in patients with schizophrenia. 23 Sleep problems might emerge during any stage of the illness, including the prodrome, first episode, acute recurrence, and even during remission stages. Severe insomnia is a hallmark of the prodromal phase of psychosis. Insomnia is also a major risk factor for impending relapse of psychosis. Sleep abnormalities might play an important role in identifying at-risk patients (i.e., those in the prodromal phase). 21 Treatment of insomnia might play a role in prevention and treatment of psychosis. 24 Although a number of patients with schizophrenia might report longer and better sleep on antipsychotics, many continue to report significant sleep difficulties, including early and middle insomnia. 25 Sleep problems have been correlated with cognitive dysfunction in schizophrenia. 28 Patients with schizophrenia tend to have circadian rhythm dysfunctions. 26,27 These circadian rhythm abnormalities might be caused by decreased exposure to light due to psychotic symptoms, abnormalities in melatonin, and dysfunction of the suprachiasmatic nucleus. 28 FIGURE 1. Cumulative incidence of depression in 1,045 men according to sleep complaints in medical school—a) insomnia ( ) versus no insomnia (D); b) difficulty sleeping under stress ( ) versus no difficulty (D). The numbers below each Kaplan-Meier plot are the numbers of men included in the analysis at each time point. Reproduced with permission. Chang et al. Insomnia in young men and subsequent depression: The Johns Hopkins Study Precursors. Am J Epidemiol. 1997;146(2):105–114.

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