Magnitude of the problem
Prevalence estimates for clinically significant depression in later life range from about 10 percent for elderly persons living independently in the community to about 25 percent for those with chronic illness, especially persons with ischemic heart disease, stroke, cancer, chronic lung disease, arthritis, Alzheimer's disease, and Parkinson's disease (
1,
2,
3,
4,
5,
6,
7). These data underscore the inseparability of mental and physical health in aged persons. They also point to the need for clinical trials using agents likely to be safe and well tolerated by elderly depressed patients who are heavily burdened with chronic medical illnesses and depletion of psychosocial resources.
Certainly the most compelling consequence of depression in later life is increased mortality from both suicide and medical illness. Elderly persons have the highest suicide rate of any age group. This high rate is largely accounted for by older white males, with rates rising to 67.6 suicides per 100,000 among white males age 85 and older, more than 5.5 times the overall national rate of 12 per 100,000 (
8). Suicide among elderly persons is most likely to be a result of depression. Indeed, among patients 75 years of age and older, 60 to 75 percent of those committing suicide have diagnosable depression (
9). Hopelessness is strongly linked to the presence of suicidal ideation and tends to persist, even during periods of clinical remission, among those with a history of suicide attempts (
10).
These data underscore the need to develop effective and efficient disease management strategies for the prevention of suicide among elderly patients attending primary care clinics. This need has become a priority of the National Institute of Mental Health in its recent initiative in suicide prevention; its feasibility is supported by the work of Katon and associates (
11) and Meyers (
12).
In addition, the relationship between geriatric depression and nonsuicidal mortality is well supported for myocardial infarction, where depression elevates mortality risk by a factor of 5 (
13,
14). In nursing home patients, major depression has been found to increase the likelihood of mortality by 59 percent independent of physical health measures (
15). Hence the selection of treatment modalities for the short- and long-term management of geriatric depression may be, literally, a matter of life and death.
Some 800,000 older Americans are widowed each year. Grief following the death of a loved one is an important risk factor for both major and minor depression. At least 10 to 20 percent of widows and widowers develop clinically significant depression during the first year of bereavement (
16). Without treatment, such depressions tend to persist, becoming chronic and leading to further disability and impairments in general health.
Bereavement depression often coexists with another dimension of emotional distress, which has been termed traumatic grief (
17). The symptoms of traumatic grief appear to be a mixture of both separation and traumatic distress; such symptoms are extremely disabling and are associated with functional and health impairment and with persistent suicidal ideation. Appropriate treatments for traumatic grief need to be developed and tested.
Persistent insomnia, which occurs among 5 to 10 percent of elderly persons, is a known risk factor for the subsequent onset of new cases of major depression among both middle-aged and elderly persons (
18). Longitudinal fluctuation in sleep complaints among elderly persons residing in the community covaries with the intensity of depressive symptoms after health status, gender, and age are controlled for (
19). Sleep disturbances in older men and women have also been recently linked to poor health, depression, angina, limitations in activities of daily living, and the chronic use of benzodiazepines (
20). Persistent or residual sleep disturbance among elderly patients with prior depressive episodes augurs a less successful maintenance response to either pharmacotherapy (
21) or to interpersonal psychotherapy (
22).
The estimated prevalence of chronic, primary insomnia among elderly persons is 5 to 10 percent (
23). Relatively little is known about the etiology or pathophysiology of chronic primary insomnia and about why it constitutes a risk factor for depression among adults and geriatric subjects. An important and promising area for further research is whether effective treatment for chronic insomnia would serve to prevent the subsequent development of clinical depression in midlife and later life.
A final pathway to geriatric depression, suggested by computed tomography and magnetic resonance imaging studies, may involve structural neuroanatomic factors. Enlarged lateral ventricles, cortical atrophy, increased white matter hyperintensities, decreased caudate size, and vascular lesions in the caudate nucleus appear to be especially prominent in late-life depression associated with vascular risk factors (
23). These findings have generated the vascular hypothesis of geriatric depression, which states that even in the absence of a clear stroke, disorders that cause vascular damage, such as hypertension, coronary artery disease, and diabetes mellitus, may induce cerebral pathology that constitutes a vulnerability factor for depression (
24).
Clinical issues
A recent review by the Geriatric Psychiatry Alliance concluded that depression is widely linked to increased utilization of health care services (
25). For example, Luber and associates (
26) reported that depressed patients required almost twice the number of medical appointments required by nondepressed patients, with almost half of the depressed patients making five or more office visits yearly. Luber and colleagues (
26) also observed far more frequent use of multiple medications by depressed patients. In addition, they found the frequency of lengths of stay per hospital admission that were over diagnosis-related-group norms to be twice as great among depressed patients as among control subjects. These findings could be due to a greater burden of medical disease among depressed patients, to depression itself, or to the interaction of depression and other medical diseases.
Depression amplifies the disability of medical disease. After controlling for the effects of medical comorbidity, Unutzer and colleagues (
27) found that outpatient visits by depressed primary care patients increased in proportion to the severity of depression, with total median annual health care costs twice as high for those with severe depression compared with nondepressed control subjects. In the nursing home environment, Fries and colleagues (
28) found that depression significantly increased demands on nursing home time.
Presenters at the 1991 National Institutes of Health (NIH) consensus development conference on the diagnosis and treatment of late-life depression confirmed that one of six elderly patients seen in primary care is affected by depression, but only one in six of those is diagnosed and treated appropriately (
29). Because older persons obtain most of their medical and mental health care from the general medical sector, data such as these underscore the need for more effective and efficient treatment of depression in primary care and for studies showing that antidepressant treatment for elderly patients works in geriatric primary care settings. The fundamental problem in the primary care treatment of geriatric depression is undertreatment (
26,
27). The most common errors are underdosing and discontinuation of medication too quickly. Recent demonstration research in this area includes the Hartford-MacArthur minor depression study and the Hartford depression management study.
Our recent reviews of 30 years of treatment studies of chronic insomnia among nonelderly subjects (
30) and elderly subjects (
31) have shown only short-term clinical trials evaluating the efficacy of benzodiazepines and other sedative hypnotics. Clinicians' concerns about benzodiazepine dependence have led to a 30 percent decrease in benzodiazepine prescription and a 100 percent increase in the use of antidepressants as hypnotics over the past decade, despite the absence of efficacy data from controlled clinical trials (
32). It is clearly a priority to inform geriatric practice clinicians about such data and to determine if appropriate long-term management of insomnia can reduce the incidence of geriatric depression.
Treatment issues
The hallmark of depression among older people is its comorbidity with medical illness (
25). There are many pathways to depression in later life, including medical illness and its attendant disability, psychosocial stressors such as bereavement, chronic insomnia, and genetic liability. At the same time, geriatric depression has many costs and consequences, including suicide, anxiolytic dependence and alcoholism, cognitive impairment, disability, medical symptoms, increased health care utilization, and excess mortality.
Researchers consistently find that elderly patients, even the very old, respond to antidepressant medication (
33). Patients 75 years old and older typically have a high prevalence of medical comorbidity, and physicians are often reluctant to add another medication to an already complex regimen for a frail individual. However, because very old patients are also at high risk for adverse medical outcomes of depression, risk-benefit considerations favor treatment. Selective serotonin reuptake inhibitors (SSRIs) have become the first-line treatment for depression in later life because of their favorable side-effect profile and safety in case of overdose. In standard controlled studies, SSRIs appear to be as effective as tricyclic antidepressants in the treatment of elderly depressed patients.
Response to acute and continuation treatment with combined nortriptyline and interpersonal psychotherapy is similar between so-called "young old" patients (primarily in their 60s and early 70s) and patients in their 30s and 40s, with 80 percent success rates in samples of patients who completed treatment in both age groups (
34). However, the time to remission is about two weeks longer among elderly patients, and elderly patients have twice the rate of relapse during continuation treatment than do younger patients, about 15 percent versus 7 percent.
We have estimated the rate of treatment resistance to combined treatment with nortriptyline and interpersonal psychotherapy to be about 18 percent among elderly patients with recurrent nonpsychotic unipolar depression (
35). Finally, we have shown that nortriptyline and interpersonal psychotherapy both singly and in combination are effective maintenance treatments for late-life depression over a three-year period and that the combined treatment is more effective than either alone in preventing recurrence. The value of combined antidepressant medication and psychotherapy is particularly apparent among patients aged 70 and above (
36).
A related issue is that although 80 percent of elderly patients with moderate to severe unipolar depression can be expected to respond well to antidepressant treatment—especially combined treatment with medication and psychotherapy—the clinical response to antidepressant treatment in later life follows a variable temporal response trajectory, with a median time to remission of 12 weeks. In addition, reliable prediction of whether elderly patients have responded to antidepressant medication is generally not possible before four to five weeks of treatment.
The delayed onset of clinical antidepressant activity among elderly patients is particularly problematic, prolonging the duration of suffering and disability, potentially reducing compliance (and thus diminishing ultimate recovery rates), not infrequently shifting therapy from pharmacotherapy to electroconvulsive therapy, and increasing the risk for attempted or completed suicide. Thus the development of strategies to accelerate treatment response and to improve the early recognition of patients who are not responding to antidepressant treatment would be an important advance.
The determinants of the temporal profile of the response trajectory in late-life depression are the subject of much current research interest. We have found that the determinants of slower and more brittle response include older age, the presence of acute and chronic stressors, higher levels of pretreatment anxiety, lower levels of perceived social support, and greater biologic dysregulation as evidence by higher levels of rapid eye movement sleep (
37). The temporal profile of the initial response trajectory may also provide important clues about which patients are likely to remain well on maintenance treatment and which are likely to have a brittle treatment response and a stormy course of long-term illness.
A recent update of the NIH consensus development conference on the diagnosis and treatment of late-life depression underscored the still unmet need for more data to guide long-term treatment planning, especially in the treatment of patients with major depression who are older than age 70 (
38). The question is whether there is any difference in speed and rate of remission, relapse, recovery, and recurrence between patients age 60 to 69 and those age 70 and above.
To address this question, we recently analyzed a data set on 180 patients available through the Pittsburgh study of maintenance therapies in late-life depression, funded by the National Institute of Mental Health (NIMH). The two groups of patients —those age 60 to 69 (N=113) and those age 70 and older (N=67)—showed comparable times to remission and recovery, as well as similar absolute rates of remission during acute therapy, relapse during continuation therapy, and recovery. However, patients age 70 and older experienced a significantly higher rate of recurrence during the first year of maintenance therapy—60.5 percent (23 of 38 patients), compared with 30.4 percent (21 of 69 patients) for patients age 60 to 69. Thus, although response to acute and continuation treatment with combined nortriptyline and psychotherapy was strikingly similar among patients in the two age groups, those age 70 and older showed a much more brittle long-term treatment response, as evidenced by a higher rate of recurrence during the first year of maintenance therapy (
39). This observation poses the major therapeutic and public health challenge of how best to protect those age 70 and older from recurrence of major depression.
Data from naturalistic studies have identified several predictors of relapse and recurrence among patients with geriatric depression, including a history of frequent episodes, first episode after age 60, supervening medical illness, a history of myocardial infarction or vascular disease, high pretreatment severity of depression and anxiety, and cognitive impairment, especially frontal-lobe dysfunction. These factors appear to interact with a low level of treatment intensity in determining more severe courses of illness.
Despite the evidence that a high level of treatment intensity is effective in preventing relapse and recurrence (
36), naturalistic studies have shown that the intensity of treatment prescribed by psychiatrists begins to decline within 16 weeks of patients' entry into treatment and about ten weeks before recovery (
40). In this context, also, residual symptoms of excessive anxiety and worrying among elderly depressed patients predict early recurrence after continuation treatment is tapered (
12).