Treatment-resistant depression

Treatment-resistant depression
Classification and external resources
MeSH	D061218
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Treatment-resistant depression (TRD) or treatment-refractory depression is a term used in clinical psychiatry to describe cases of major depressive disorder (MDD) that do not respond adequately to appropriate courses of at least two antidepressants. The term was first coined with the development of the concept in 1974. Inadequate response has traditionally been defined as no response whatsoever. However, many clinicians consider a response inadequate if the patient does not achieve full remission of symptoms. Cases of treatment-resistant depression in which the course of treatment was not adequate are sometimes referred to as pseudoresistant. Some factors that contribute to inadequate treatment are: early discontinuation of treatment, insufficient dosage of medication, patient noncompliance, misdiagnosis, and concurrent psychiatric disorders. Cases of treatment-resistant depression may also be referred to by which medications they are resistant to (i.e.: SSRI-resistant).

Treatment-resistance is relatively common in cases of MDD. Rates of total remission following antidepressant treatment are only 50.4%. In cases of depression treated by a primary-care physician, 32% of patients partially responded to treatment and 45% did not respond at all.

Comorbid psychiatric disorders commonly go undetected in the treatment of depression. If left untreated, the symptoms of these disorders can interfere with both evaluation and treatment. Anxiety disorders are one of the most common disorder types associated with treatment-resistant depression. The two disorders commonly co-exist, and have some similar symptoms. Some studies have shown that patients with both MDD and panic disorder are the most likely to be nonresponsive to treatment. Substance abuse may also be a predictor of treatment-resistant depression. It may cause depressed patients to be noncompliant in their treatment, and the effects of certain substances can worsen the effects of depression. Other psychiatric disorders that may predict treatment-resistant depression include personality disorders, obsessive compulsive disorder, and eating disorders.

Some patients who are diagnosed with treatment-resistant depression may have an underlying undiagnosed health condition that is causing or contributing to their depression. Endocrine disorders like hypothyroidism, Cushing's disease, and Addison's disease are among the most commonly identified as contributing to depression. Others include diabetes, coronary artery disease, cancer, HIV, and Parkinson's disease. Another factor is that medications used to treat comorbid medical disorders may lessen the effectiveness of antidepressants or cause depression symptoms.

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