Innovations In Clinical Neuroscience

MAR-APR 2018

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

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28 ICNS INNOVATIONS IN CLINICAL NEUROSCIENCE March-April 2018 • Volume 15 • Number 3–4 R E V I E W I Insomnia affects 25 million people in the United States annually and leads to an estimated $100 billion health care burden. Insomnia has also been shown to be a causal factor in other medical and psychiatric disorders, cognitive impairments, accidents, absenteeism, and reduced quality of life. 1 The cost of not treating insomnia is more than the cost of treating insomnia. 2 Insomnia as a symptom is seen in up to one third of the United States population, while the disorder is seen in up to 20 percent. 3 The diagnostic criteria of insomnia have been updated in the International Classification of Sleep Disorders, Third Edition (ICSD-3) and the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5). The distinction between primary and secondary insomnia was removed from both classifications. Insomnia is a disorder unto itself that needs independent clinical attention. Viewing insomnia mainly as a symptom of another disorder prompted many clinicians to direct the bulk of their treatment efforts at the so-called primary disorder. Studies have shown that treating insomnia leads to better outcomes and improvement in co-existing psychiatric disorders. To achieve optimal treatment outcomes in people with comorbid psychiatric illness and insomnia, the clinician should target both disorders. 4–7 NEUROBIOLOGICAL CORRELATES OF INSOMNIA AND PSYCHIATRIC DISORDERS AND THEIR IMPLICATIONS IN TREATMENT Monoaminergic neuronal regions promote wakefulness. These regions include basal forebrain (producing acetylcholine); locus ceruleus (located beneath floor of fourth ventricle), producing norepinephrine; dorsal raphe nucleus (located in brainstem), producing serotonin; tuberomammilary nucleus (located at the base of posterior hypothalamus), producing histamine; and ventral tegmental area, producing dopamine. Orexin and hypocretin are excitatory neuropeptides produced by neurons in the lateral and posterior hypothalamus that promote wakefulness. Gamma-aminobutyric acid (GAB) and glycine, which are produced in preoptic areas (particularly in the ventrolateral preoptic area [VLPO]), produce sleep. 8 Conditions that induce high aminergic output and medications that increase central aminergic states can cause insomnia. Also, conditions that decrease inhibitory neurotransmission can cause insomnia. Anxiety and cognitive distortions seen in various psychiatric disorders can also contribute to hyperarousal seen in insomnia and perpetuate chronic insomnia. 9 The same pathophysiological mechanisms that cause psychiatric disorders, such as depression, anxiety, and psychosis, can also cause insomnia or hypersomnia. Medications that increase serotonergic activity (e.g., selective serotonin reuptake inhibitors [SSRIs]) can cause insomnia. Increased dopaminergic states that are implicated in causation of psychosis can cause insomnia. This can also be true for drug- induced psychosis—the prototypical example is cocaine-induced psychosis and insomnia. INSOMNIA AND DEPRESSION Insomnia is a diagnostic criterion of MDD (MDD). Insomnia is also rated on one or more items on various rating scales for depression, such as Patient Health Questionnaire (PHQ-9), Hamilton Depression Rating Scale (HAM-D), and Montgomery Asberg Depression Rating Scale A B S T R A C T Insomnia is a clinical problem of significant public health importance. Insomnia can be a symptom or harbinger of other psychiatric disorders. Insomnia can also be comorbid with other psychiatric disorders, thereby adding to the medical burden and increasing the risk of psychiatric relapse. Insomnia can also be associated with medical and neurological disorders. Some medications can also cause insomnia. Treatment of insomnia can lead to positive outcomes, not only by alleviating symptoms and moderating these comorbid disorders, but by preventing new episodes. Therefore, it is vital to be aware of the relationship between insomnia and psychiatric illness. This article reviews this relationship and provides recommendations for management. Keywords: Insomnia, sleep disorder, psychiatric disorder, depression, psychosis, schizophrenia, anxiety disorder Comorbid Insomnia and Psychiatric Disorders: An Update by KHURSHID A. KHURSHID, MD, FAASM Dr. Khurshid is Clinical Associate Profressor and Chief of the Neuromodulation and Sleep Disorders Program in the Department of Psychiatry at the University of Florida College of Medicine in Gainsville, Florida. Innov Clin Neurosci. 2018;15(3–4):28–32 FUNDING: No funding was received for the preparation of this article. DISCLOSURES: The author has no conflicts of interest relevant to the content of this article. CORRESPONDENCE: Khurshid A Khurshid, Email: khurshid@ufl.edu

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