Patients with chronic conditions often have to adjust their aspirations, lifestyle, and employment. Many grieve about their predicament before adjusting to it. But others have protracted distress and may develop psychiatric disorders, most commonly depression or anxiety. A prospective study of general medical admissions found that 13% of men and 17% of women had an affective disorder. The proportion of patients with conditions such as diabetes or rheumatoid arthritis who have an affective disorder is between 20% and 25%. Among patients admitted to the hospital for acute care and among patients with cancer, rates can exceed 30%3 compared with a prevalence of depression in the community of about 4%-8%.
It can be difficult to diagnose depression in the medically ill. Physical symptoms such as disturbed sleep, impaired appetite, and lack of energy may already exist as a result of the disease. Sometimes treatment for a medical condition (for example, the use of steroids) may affect the patient's mood, as may the disease process itself (for example hypoxia and infection in a patient with chronic respiratory disease may have a direct cerebral impact on mood). The functional limitations imposed by the disease may result in “understandable” distress, and some clinicians find it difficult to conceptualize such distress as a depressive disorder. Indeed, the distinction between an adjustment reaction and a depressive illness is often not clear. Clarification of the diagnosis may be aided by examining the patient's risk factors for depression—that is, whether they have a history of depression, a major functional disability, or pain. Other risk factors include adverse social circumstances, such as unemployment or financial strain, and a lack of emotional support. In elderly people in particular, there are clear links between physical illness, disability, and depression and increased use of hospital and medical outpatient services.
Despite these difficulties, it is essential to diagnose and treat depression in patients with chronic conditions. Even mild depression may reduce a person's motivation to gain access to medical care and to follow treatment plans. Depression and hopelessness also undermine the patient's ability to cope with pain and may exert a corrosive effect on family relationships. Although the patient with an incurable medical illness who commits suicide may seem to some people to have acted rationally, most of the patients who commit suicide are also suffering from a depressive ill-ness. Furthermore, the development of depression in people with a medical illness has been linked to adverse physical outcomes and substantial increases in disability. Patients who become depressed after a cerebrovascular accident have been found to have an increased risk of dying and to make significantly less recovery on measures of activities of daily living.The clinical course of heart disease is also influenced by depression, and 9 out of 10 studies have found an increase in mortality from cardiovascular disease among depressed patients.