Definition

Mental depression is a psychiatric disorder distinguished from normal sadness and grief by severity and duration of the mood disturbances and by the presence of fatigue, loss of appetite, and insomnia.

Incidence and prevalence

Depression is the most common psychiatric disorder, affecting 2% to 4% of the population.

Pathophysiology

Pathophysiologic causes of major mental depression are unknown, although abnormalities of amine neurotransmitter pathways are the most likely etiologic factors. Cortisol hypersecretion is present in many of these patients.

Clinical manifestations

Diagnosis of major mental depression is based on the persistent presence of at least five characteristics and the exclusion of organic causes or a normal emotional reaction. Alcoholism and major depression often occur together, and it is presumed that toxic effects of alcohol on the brain are responsible. As stated earlier, this disease is characterized by mood disturbances and by the presence of fatigue, loss of appetite, and insomnia.

Treatment

Treatment of mental depression can be initiated using with antidepressant drugs, electroconvulsive therapy (ECT), or both. Common drug therapies include selective serotonin reuptake inhibitors, tricyclic antidepressants, and monoamine oxidase inhibitors (MAOIs). ECT is indicated for treating severe mental depression in patients who are unresponsive to drugs or who become acutely suicidal. Increased ICP is a contraindication to ECT.

Anesthetic considerations

Treatment with tricyclic antidepressants need not be discontinued before administration of anesthesia for elective operations. Increased availability of neurotransmitters in the patient’s CNS can result in increased anesthetic requirements. An increased level of norepinephrine at postsynaptic receptors in the peripheral sympathetic nervous system can be responsible for exaggerated systemic blood pressure responses after administration of indirect-acting vasopressors. Long-term treatment with tricyclic antidepressants may alter the responses to pancuronium, and the combination has been associated with tachyarrhythmias.

Anesthesia can be safely conducted despite earlier recommendation that these drugs be discontinued 14 to 21 days before elective operations. Careful consideration is needed when selecting drugs and administering doses.

During anesthesia and surgery, it is important to avoid stimulating the sympathetic nervous system, so as to decrease the incidence of systemic hypertension and cardiac dysrhythmias.

Although uncommon, adverse interactions between MAOIs and opioids have been observed. Systemic hypertension, hypotension, hyperthermia, depression of ventilation, seizures, and coma may follow administration of opioids with these agents. Meperidine has been the opioid most often incriminated, but the same syndrome can occur with other opioids.