Depression

Various forms of clinical depression are defined by the American Psychiatric Association's Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM IV). According to this classification scheme, five or more symptoms (see Table 1) must be present during the same two-week period, and they must represent a change from previous functioning, in order for a person to receive a diagnosis of major depressive disorder (MDD). At least one of these symptoms must be either depressed mood or loss of interest or pleasure (i.e., anhedonia). The symptoms must cause distress or impairment in social, occupational, or other important areas of functioning, and they must not be clearly and fully accounted for by the direct physiological effects of a substance or a general medical condition. The average episode Table 1 SOURCE: Author length for major depression is approximately seven months.

In addition to major depressive disorder, dysthymic disorder is a less severe, but more chronic form of depression. Dysthymia is indicated by the presence of a depressed mood occurring on most days for a period of at least two years. Average episode length is approximately ten years, and the disorder often lasts for up to twenty or thirty years. To meet criteria for dysthymic disorder, a person must display, in addition to depressed mood, at least two of the following symptoms: poor appetite or overeating, insomnia or hypersomnia, low energy or fatigue, low self-esteem, poor concentration or difficulty making decisions, and feelings of hopelessness. The person must have these symptoms for more than two months to meet the criteria for diagnosis. As with major depression, these symptoms must cause distress or impairment in social, occupational, or other important areas of functioning, and must not be clearly and fully accounted for by the direct physiological effects of a substance or a general medical condition.

Individuals who do not meet criteria for a major depressive episode or dysthymic disorder may nonetheless display symptoms of depression. Estimates in the late 1990s indicated that approximately 10 percent of elderly primary-care patients display such subsyndromal depression. Research in the late 1990s and early 2000s suggests that subsyndromal depression among elderly persons is best viewed as a less intense form of major depressive disorder. That is, elderly persons with subsyndromal depression experience distress and impairment, but to a lesser degree than those who meet the full criteria for MDD. Two symptoms that may distinguish MDD from subsyndromal depression among elderly persons are suicidal thoughts and feelings of guilt or worthlessness.

A specific category of subsyndromal depression, bereavement, may be particularly likely to occur among elderly individuals due to higher mortality rates among this population. Bereavement is a normal reaction to the loss of a loved one. Bereaved individuals frequently display symptoms characteristic of MDD, although a diagnosis of MDD should not be made unless the symptoms persist for more than two months after the loss. The presence of any of the following symptoms may be indicative of MDD, as opposed to bereavement: guilt unrelated to actions taken at the time of death; thoughts of death other than a desire to have died with the deceased person; marked feelings of worthlessness; marked psychomotor retardation; marked functional impairment; and hallucinations that do not involve the deceased person.

One-year prevalence rates of depression among elderly persons vary depending on where they live and if they have a medical condition. For adults age sixty-five and older who live in the community and do not have a medical condition, the prevalence rate of MDD ranges from 1 to 6 percent. This prevalence rate is less than that for younger adults. However, when considering the prevalence rate for those that experience depressive symptoms but do not meet criteria for diagnosis, the rate for older adults increases to 20 to 30 percent. The one-year prevalence rate for individuals with dysthymia averages between 1 and 2 percent.

The one-year prevalence rates of MDD is higher for elder persons who live in nursing homes, compared to those who live in the community. For older adults who live in a nursing home, the prevalence rate for MDD ranges from 6 to 25 percent. When just considering depressive symptoms, the prevalence rate increases to between 16 and 30 percent. The one-year prevalence rate for older adults in nursing homes with dysthymia ranges from 16 to 30 percent, which is substantially higher than the rate for older adults in the community.

Depressive symptoms are common among individuals with medical conditions. One-year prevalence rates for elderly persons with medical conditions range from 6 to 44 percent. The rates can be higher among individuals with severe illnesses, such as cancer, or with more functional disabilities.

Depression can be usefully conceptualized within a diathesis-stress framework, where an individual will have certain factors that predispose him or her to depression. When these predisposing factors combine with a stressor, depression can result. There are various factors that can predispose someone to depression, some of which are biological. For example, having low or dysregulated levels of certain neurotransmitters, such as serotonin or norepinephrine, has been associated with depression. It has also been found that as people get older their levels of norepinephrine, as well as other neurochemicals, decrease. Another biological factor associated with depression is brain abnormalities similar to those seen with Alzheimer's disease or dementia. These brain abnormalities include enlargement of the ventricle areas and changes in white matter. Thus, changes in the neurochemistry, neurophysiology, and neuroanatomy can make one more vulnerable to depressive symptoms.

Other factors that can predispose an individual to depression are social and psychological in nature. Depressed individuals tend to have thought patterns that can distort reality and emphasize negative aspects of a situation. In addition, depressed individuals may view themselves, their future, and others in a negative light. These thought patterns produce behaviors that can predispose and exacerbate the individual's depression. For example, depressed individuals might seek reassurance or positive feedback from others. However, due to their negative views about themselves, they do not believe the feedback they receive and seek it again. This leads into a cycle of continuously seeking feedback, which eventually tires the other person and leads the depressed individual to eventually receive negative feedback. This pattern of thoughts and behaviors not only predisposes individuals to depression, but also helps maintain the depression.

Stressors and negative life events can also trigger and impact the severity of depression. Elderly persons may encounter various stressors in their lives, such as the death of loved ones, loss of physical agility and ability, loss of ability to work, caregiving for other individuals, physical disability, and medical illness. Diagnosing depression in the presence of physical disability and medical illness can be difficult. Numerous medical conditions, including cardiovascular, pulmonary, endocrine, infectious, malignant, metabolic, and neurological disorders, may lead elderly persons to present with symptoms of depression. For instance, hypothyroidism often presents as sadness, disinterest, fatigue, decreased appetite, and poor concentration. Certain medications may also produce side effects mimicking depressive symptoms. For example, cancer treatments may induce depression-like symptoms of fatigue, insomnia, and decreased appetite. Such disorders and medications should be ruled out before a mood-disorder diagnosis is made and treatment is implemented.

Older adults with medical illnesses and physical disabilities are more susceptible to depression, even when taking into account those symptoms that overlap. Approximately 60 to 85 percent of depressed older persons report a physical illness that preceded their depression. However, not all medically ill older adults suffer from depression. Other factors, such as social support and coping styles, can prevent older adults from having depression.

Three methods of treatment have been demonstrated to be effective among elderly persons: antidepressant medications, psychosocial interventions, and electroconvulsive therapy (ECT). Antidepressant medications can be divided into four classes. The first class, heterocyclic antidepressants (HCAs), includes medications such as nortriptyline (Pamelor, Aventyl), desipramine (Norpramin), bupropion (Wellbutrin), and trazedone (Desyrel). HCAs tend to produce unpleasant side effects such as dry mouth, constipation, and mild cognitive impairments. Moreover, they sometimes lead to orthostatic hypotension (low blood pressure that occurs when an individual stands upright) and cardiotoxic affects, which may be especially problematic among individuals with existing heart or blood pressure conditions. In general, bupropion and trazedone produce fewer adverse side effects than other HCAs.

Monoamine oxidase inhibitors (MAOIs) are the second class of antidepressant medications. Similar to HCAs, these medications often produce a number of unpleasant side effects. Moreover, they have potentially lethal interactions with other medications and foods, which may make treatment more difficult among persons who take other medications or who have trouble maintaining dietary restrictions. As a result, MAOIs are rarely used among elderly individuals. Examples of MAOIs include moclobemide (Aurorix), phenelzine (Nardil), and selegiline (Eldepryl).

The third class of antidepressants, serotonin reuptake inhibitors (SRIs), include medications such as paroxetine (Paxil), fluoxetine (Prozac), and sertraline (Zoloft). SRIs typically produce fewer side effects than HCAs and MAOIs, are less reactive with other medicines, and are less lethal in overdose. Consequently, they may be preferable to the other classes. Evidence suggests that HCAs, SRIs, and MAOIs are comparably effective, producing improvement in 50 to 80 percent of depressed, elderly persons.

The fourth group of antidepressant medications is referred to as atypical because their chemical properties do not fit into any of the other classes. These medications have not yet been adequately studied among depressed, elderly persons. Thus, it is not currently known how effective they may be for this population. Examples of atypical antidepressants include nefazodone (Serzone) and venlafaxine (Effexor).

The duration of antidepressant treatment must be considered when treating depressed, elderly persons. Elderly persons typically respond to antidepressant medications more slowly than younger persons; twelve weeks of treatment may be required to achieve maximum response. Furthermore, treatment should be continued at the same dosage for a minimum of six months after remission to prevent relapse.

In addition to antidepressant medications, five psychosocial interventions have demonstrated efficacy for treating depressed, elderly persons: cognitive-behavioral therapy (CBT), brief psychodynamic therapy, interpersonal psychotherapy (IPT), reminiscence therapy, and psychoeducational approaches. A brief description of these therapies is presented in Table 2. CBT, IPT, and brief psychodynamic therapy all appear to be comparably effective to antidepressant medications, with improvement rates near 70 percent. Reminiscence therapy has been shown to be effective for mild and moderate cases of depression, but does not appear to be as effective as CBT for more severe cases of depression. Psychoeducational interventions are effective in reducing depressive symptoms among elderly persons with subsyndromal depression. Psychosocial interventions may be superior to antidepressants and electroconvulsive therapy at reducing the risk of future depression.

Electroconvulsive therapy (ECT) is a third form of treatment for depressed, elderly individuals. ECT involves passing electrical current through an individual's brain, and is typically used only in severe cases of depression that have not responded to other treatments. ECT appears to be as effective (and perhaps more effective) than antidepressant medications for the short-term treatment of MDD, particularly in severe and psychotic cases of depression. It typically produces a more rapid response than either antidepressants or psychosocial interventions. Nevertheless, the majority of individuals who receive ECT relapse into depression if they do not receive additional treatment. In addition, roughly one-third of elderly persons who receive ECT experience complications such as memory impairment, delirium, and arrythmias.

Although combinations of the three forms of treatment have not been researched thoroughly, a limited amount of data and common clinical practice indicate that antidepressant treatment combined with psychosocial interventions may be superior to either form of treatment administered alone. If the increased cost associated with a second form of treatment is feasible, and if combined treatment is not contraindicated for medical reasons, combined antidepressant and psychosocial interventions may provide the optimal treatment for depression among older adults.