The term, depression, is commonly used to denote both simple depressed affect as well as the depressive syndrome, which is a clinical significant psychiatric condition that requires careful evaluation and treatment. Depressed affect refers to subjective feelings of sadness, feeling blue, feeling like crying, or being “down in the dumps,” which may be accompanied by a sad expression, tearfulness, and either psychomotor retardation or psychomotor agitation. Depressed affect is a normal response to loss and threatened loss. When such feelings persist, often without any obvious cause, and are accompanied by physiologic signs such as sleep disturbance (insomnia or hypersomnia), anorexia, fatigue, constipation, loss of libido, cognitive symptoms such as inability to concentrate or memory disturbance, low self-esteem, guilt feelings, hopelessness, helplessness, and suicidal ideations, then the depressive syndrome should be suspected, for which definitive treatment may be imperative (see Chap. 15). Suspected depression and/or suicidal ideation is the most common reason for psychiatric consultation request in a general hospital, followed by altered mental status (delirium).

Clouding of consciousness is characterized by impaired ability to think clearly and to perceive, respond to, and remember stimuli. Delirium is a state of disturbed and fluctuating consciousness with psychomotor changes, usually restlessness or drowsiness, and transient psychotic symptoms. Obtundation is a state in which patients are awake but not alert and exhibit psychomotor retardation. Stupor is the state in which the patient, although conscious, exhibits little or no spontaneous activity. Stuporous patients may be awakened with stimuli but have little motor or verbal activity once aroused. Coma is the state of unarousable unresponsiveness. A comatose patient does not exhibit purposeful movements. In light coma, patients may respond to noxious stimuli reflexively, but in deep coma, there is no response even to strongly noxious stimuli. The Glasgow Coma Scale (GCS) is commonly used in identifying the degree of impairment. A GCS score of 8 or below indicates coma (see Appendix 1 at the end of chapter).

Psychiatric consultation is often requested to evaluate altered mental states (AMS). As comatose and stuporous patients do not respond verbally, the immediate approach to such patients is to recognize and treat the underlying medical condition, and to provide physical protection and supportive measures. When the patient presents with delirium or improves to a delirious state, the psychiatric consultant may be of great service in evaluating and managing the condition (see Chap. 12).