Depression is one of the most frequent psychiatric problems experienced by older adults. When measured by criteria established by the American Psychiatric Association, the prevalence of a major depressive disorder is 4-5% in the elderly. However, perhaps as many as 20% of the elderly living in the community have some symptoms of depressive symptomatology. Depression is even higher among the elderly in hospitalized or nursing home populations: 12 to 23% in acute care and 15-30% in nursing homes. Depression can result in poor recovery from other acute illnesses, impede the management of concomitant illnesses, and is associated with a high suicide rate. Furthermore, while depression is potentially treatable, the treatment modalities may be associated with significant side effects, making an accurate diagnosis imperative.

What are the Clinical Features of Depression in the Elderly?

Depression is easily overlooked in elderly patients in whom symptoms suggestive of depression are commonly due to physical illnesses. Although a dysphoric mood or sadness is key to diagnosing depression, the most important expression of depression may be anhedonia, the loss of ability to enjoy one's usual activities. Compared to younger adults, the depressed elderly are more likely to manifest somatic symptoms, hyperactive agitated behavior and delusions and are less likely to express feelings of guilt.

In diagnosing depression, the physician must recognize the presence of several categories of depressive disorders. In major depression, as defined by the American Psychiatric Association, fourth edition, patients will manifest a depressed mood or loss of interest or pleasure in all or most activates most of the day plus at least four of the following symptoms for a period of at least two weeks: loss of interest in usual activities, either increase or decrease in appetite and weight, increased or decreased sleep, agitation or retardation, inappropriate guilt or worthlessness, diminished concentration, and suicidal ideation. Other categories are bipolar disorder (depression in the context of at least one prior manic episode); organic depression secondary to a concomitant organic metabolic or toxic illness, adjustment disorders in which depressive symptoms occur in response to a known physical or psychosocial stress; and dysthymia in which only a few of the classic symptoms of a major depression are present.

What is Pseudodementia?

Although disturbed mood is the dominant characteristic of depression, patients may manifest cognitive deficits, suggestive of dementia or delirium. The combination of depression and cognitive impairments has sometimes been called pseudodementia or more recently, the dementia of depression, implying that the cognitive symptoms are secondary to depression. To distinguish dementia from pseudodementia, the physician must consider the pattern of onset and the level of severity of the cognitive versus the affective symptoms. In this case, one needs to determine whether the cognitive or affective deficits are dominant. Patients suffering from a bipolar disorder may simulate a hyperactive delirious state while in their manic phase but the presence of grandiosity and euphoria and the history of depression will help establish the correct diagnosis. True pseudodementia, that is cognitive deficits due to depression, is uncommon. More often, dementia and depression coexist, especially during early stages of dementia. Therefore, the task of the physician is not to choose between dementia and depression but to determine whether either or both exist.

What Are Some Common Causes of Depression in the Elderly?

Symptoms of depression such as fatigue, weakness, insomnia, and anorexia may be due to a variety of treatable physical illnesses and to other psychiatric diagnoses: Parkinson's disease, hyper and hypothyroidism, malnutrition, chronic obstructive lung disease, heart failure, malignancies, and stroke. Drugs are the most common cause of treatment-induced depression. Among the wide variety of drugs that can produce symptoms of depression, antihypertensive agents, particularly centrally acting alpha agents and beta blockers, and sedatives are probably the most common. Steroids, antiparkinsonism drugs, and narcotic analgesics are also common offenders.

What are the Elements of the Physical Examination of the Depressed Patient?

In addition to the mental status features described above, the physical examination of a patient suspected of depression must include a standard neurologic examination, focusing on focal neurological deficits, language, gait, incontinence and sensory impairment. Laboratory tests are necessary to establish the presence of medical illnesses associated with depression. The following tests are recommended: A complete blood count, tests of thyroid function, serum calcium, and liver and renal function tests. When used as screening tests of depression, head CT scanning, electroencephalography and chest radiography have seldom been shown to affect management. These tests should only be obtained when suggested by clinical symptoms or signs.

How should Depression in the Elderly Be Treated?

Several treatment modalities are important in managing depression. The choice of treatments will depend on the severity of the depression as indicated by its impact on functional status and the risks of suicide or death, (for example due to malnutrition or the interference of the depression with treatment of concomitant illnesses). As a general rule, physical illnesses in the depressed patient should be optimally treated before using antidepressant drugs or electroconvulsive therapy. However, the suicidal, delusional, or starving patient, requires treatment of the depressive disorder immediately. Supportive measures including exercise, environmental manipulation, involvement of families and friends, and social stimulation are crucial in combination with psychotherapy or electroconvulsive therapy.

Several types of drugs are used to treat depression in the elderly: tricyclic antidepressants, monoamine oxidase inhibitors (MAOIs), lithium, psychostimulants, and most recently, selective serotonin reuptake inhibitors (SSRIs). A full discussion of these drugs is beyond the scope of this review. However, several points are useful for the practicing physician. First, if the practitioner is uncertain of the diagnosis of depression, a psychiatrist should be consulted. Second, although efficacy has been demonstrated for most of the medications on the market, all these medications have potential side effects and therefore should only be used by practitioners familiar with their dosing and side effects. However, drugs have been less beneficial in elderly with psychotic symptoms than in other depressed groups. Last, elderly patients should be treated with lower than the standard doses used in middle aged and young adults because of the higher incidence of adverse effects.

What are the Adverse Effects of Antidepressants?

Selection of antidepressant therapy is largely dependent upon the side effect profile of the drugs. MAOIs can cause significant hypotension. Lithium has a narrow therapeutic ratio in the elderly, its blood levels are influenced by diuretics and angiotensin converting enzyme inhibitors, and its is unlikely to be useful in the treatment of acute depression. The principal side effects of the tricyclic antidepressants are sedation, postural hypotension, and anticholinergic side effects including possible delirium. Antidepressants with potent anticholinergic effects should be avoided if possible in patients with urinary retention or gastrointestinal symptoms of reflux or constipation. Whereas tricyclic antidepressants can be administered safely in patients with impaired myocardial contractility, they are contraindicated in patients with conduction disturbances, left or right bundle branch block. Among the cardiovascular side effects of the tricyclic antidepressants, orthostatic hypotension is often overlooked. Drugs with a high potential for orthostasis should be avoided in patients with a low blood pressure or those with postural hypotension prior to therapy.

The selective serotonin reuptake inhibitors (fluoxetine, sertraline, paroxetine, and fluvoxamine) have acquired a significant role in treating the elderly depressed patients because they are better tolerated in general than other agents. They have few to none of the anticholinergic side effects of other classes of antidepressants but they are associated with insomnia, nausea, and in some cases sexual dysfunction. They also generally require less dosage titration than do the tricyclics in order to reach the final dose.

Is Electroconvulsive Therapy Safe in the Elderly?

If drug treatment of depression fails or if treatment is required for rapid relief, electroconvulsive therapy (ECT) should be considered. Although ECT has a controversial past, it is relatively safe and can be highly effective in the elderly