OCD is known to respond to serotonergic antidepressants. It is characterized by repetitive anxiety-provoking thoughts (obsessions) or repetitive behaviors aimed at reducing anxiety (compulsions). Clomipramine and several of the SSRIs are approved for the treatment of OCD, and they are moderately effective. Behavior therapy is usually combined with the antidepressant for additional benefits.
Social anxiety disorder is an uncommonly diagnosed but a fairly common condition in which patients experience severe anxiety in social interactions. This anxiety may limit their ability to function adequately in their jobs or interpersonal relationships. Several SSRIs and venlafaxine are approved for the treatment of social anxiety. The efficacy of the SSRIs in the treatment of social anxiety is greater in some studies than their efficacy in the treatment of MDD.
PTSD is manifested when a traumatic or life-threatening event results in intrusive anxiety-provoking thoughts or imagery, hypervigilance, nightmares, and avoidance of situations that remind the patient of the trauma. SSRIs are considered first-line treatment for PTSD and can benefit a number of symptoms including anxious thoughts and hypervigilance. Other treatments, including psychotherapeutic interventions, are usually required in addition to antidepressants.
C. Pain Disorders
Antidepressants possess analgesic properties independent of their mood effects. TCAs have been used in the treatment of neuropathic and other pain conditions since the 1960s. Medications that possess both norepinephrine and 5-HT reuptake blocking properties are often useful in treating pain disorders. Ascending corticospinal monoamine pathways appear to be important in the endogenous analgesic system. In addition, chronic pain conditions are commonly associated with major depression. TCAs continue to be commonly used for some of these conditions, and SNRIs are increasingly used. In 2010, duloxetine was approved for the treatment of chronic joint and muscle pain. As mentioned earlier, milnacipran is approved for the treatment of fibromyalgia in the USA and for MDD in other countries. Other SNRIs, eg, desvenlafaxine, are being investigated for a variety of pain conditions from postherpetic neuralgia to chronic back pain.
D. Premenstrual Dysphoric Disorder
Approximately 5% of women in the child-bearing years will have prominent mood and physical symptoms during the late luteal phase of almost every cycle; these may include anxiety, depressed mood, irritability, insomnia, fatigue, and a variety of other physical symptoms. These symptoms are more severe than those typically seen in premenstrual syndrome (PMS) and can be quite disruptive to vocational and interpersonal activities. The SSRIs are known to be beneficial to many women with PMDD, and fluoxetine and sertraline are approved for this indication. Treating for 2 weeks out of the month in the luteal phase may be as effective as continuous treatment. The rapid effects of SSRIs in PMDD may be associated with rapid increases in pregnenolone levels.
E. Smoking Cessation
Bupropion was approved in 1997 as a treatment for smoking cessation. Approximately twice as many people treated with bupropion as with placebo have a reduced urge to smoke. In addition, patients taking bupropion appear to experience fewer mood symptoms and possibly less weight gain while withdrawing from nicotine dependence. Bupropion appears to be about as effective as nicotine patches in smoking cessation. The mechanism by which bupropion is helpful in this application is unknown, but the drug may mimic nicotine’s effects on dopamine and norepinephrine and may antagonize nicotinic receptors. Nicotine is also known to have antidepressant effects in some people, and bupropion may substitute for this effect.
Other antidepressants may also have a role in the treatment of smoking cessation. Nortriptyline has been shown to be helpful in smoking cessation, but the effects have not been as consistent as those seen with bupropion.
F. Eating Disorders