Some views, summarized by Mann (1998), are that suicidal intent represents a special form of depression, or an important variant of it, and that certain individuals are by nature susceptible as a result of biologic factors. In other words, suicide is not simply a cognitive response to extreme stress or despondency. Certainly impulsivity, a frontal lobe phenomenon, seems to be an element of the suicidal act in many cases but this also is difficult to anticipate and prevent. There is no way for the authors to judge these views, but proponents have pointed to particular indices of serotonin function that differ between depressed individuals who attempt suicide and those who do not. It has also been observed that the inception of modern antidepressant medications has not greatly altered the rate of suicide among depressed patients. Bipolar illness, endogenous depression, depression resulting from a debilitating disease (particularly Huntington disease, cancer, and HIV), pathologic grief, and depression in an alcoholic or schizophrenic, all carry the risk of suicide. In bipolar disease and endogenous depression, the risk of suicide over the lifetime of the patient is approximately 15 percent (Guze and Robins). In Robins’ series of 134 patients who committed suicide, 47 percent had a known depressive illness and 25 percent were alcoholic. Other series have recorded even higher rates of depression, alcoholism, and drug abuse (see Andreasen and Black).
Despite the above comments regarding impulsivity, most suicides are planned. Furthermore, the intention of committing suicide is more often than not communicated to someone significant in the patient’s life. The message may be in the form of a direct verbal statement of intent, or it may be indirect, such as giving away a treasured possession or revising a will. It is known that successful suicide is 3 times more common in men than in women and particularly common among men older than 40 years of age. Patients with a history of suicide in either mother or father carry a higher risk than those without such a history. A previous suicide attempt adds to the risk. As alluded to earlier, important deterrents to suicide are devout Catholicism or comparable religious belief against suicide, concern about the suffering it would cause the family, and fear of death sincerely expressed by the patient. However, no single one of these attributes stands out as entirely predictive of suicide. As a consequence, one is left with clinical judgment and an index of suspicion as the main guides. The only rule of thumb is that all suicidal threats are to be taken seriously and all patients who threaten to kill themselves should be evaluated quickly by a psychiatrist.
In our experience, the following are some of the common and troublesome clinical situations in which it may prove difficult to recognize an underlying depression: 1. Patients with chronic pain. The association of chronic pain and depression has long been appreciated. This is far from a homogeneous group. The special case of chronic headache, confronted often by neurologists, is discussed below and in Chap. 9. In some patients with chronic pain, the symptoms and signs of depression are quite apparent. If the pain has been present for less than 1 year and had its onset at the same time as other depressive symptoms, response to antidepressant treatment is likely to be favorable. Far more difficult to understand, and to manage, are patients with persistent pain as the only complaint; the head, face, and lower back are the most common loci. Weeks or months of unremitting daily tension-type headaches in the context of a normal examination are highly suggestive of depression at any age. If an exhaustive search for the source of the pain proves unsuccessful, the conclusion is finally reached that the pain is “psychogenic.” This attribution of pain to some obscure psychologic mechanism is hardly helpful. Nevertheless, in a fair proportion of such patients, that pain will be alleviated by antidepressant drugs is suggestive of a linkage of the pain and depression. The problem may have been made even more difficult by repeated surgical operations as well as dependency on analgesic drugs, which in themselves deplete energy and have other adverse effects. Such patients are to be found among those disabled after multiple operations for ruptured intervertebral disc or arthritic hips or those with atypical facial pain.