Overview of Mental Disorders in Older Adults
Older adults are encumbered by many of the same mental disorders as are other adults; however, the prevalence, nature, and course of each disorder may be very different. This section provides a general overview of assessment, diagnosis, and treatment of mental disorders in older people. Its purpose is to describe issues common to many mental disorders. Subsequent sections of this chapter provide more detailed reviews of late-life depression and Alzheimers disease. Also, to shed light on the range and frequency of disorders that impair the mental well-being of older Americans, the chapter reviews the impact on older adults of anxiety, schizophrenia, and alcohol and substance abuse.
Assessment and diagnosis of late-life mental disorders are especially challenging by virtue of several distinctive characteristics of older adults. First, the clinical presentation of older adults with mental disorders may be different from that of other adults, making detection of treatable illness more difficult. For example, many older individuals present with somatic complaints and experience symptoms of depression and anxiety that do not meet the full criteria for depressive or anxiety disorders. The consequences of these subsyndromal conditions may be just as deleterious as the syndromes themselves. Failure to detect individuals who truly have treatable mental disorders represents a serious public health problem (National Institutes of Health [NIH] Consensus Development Panel on Depression in Late Life, 1992).
Detection of mental disorders in older adults is complicated further by high comorbidity with other medical disorders. The symptoms of somatic disorders may mimic or mask psychopathology, making diagnosis more taxing. In addition, older individuals are more likely to report somatic symptoms than psychological ones, leading to further underidentification of mental disorders (Blazer, 1996b).
Primary care providers carry much of the burden for diagnosis of mental disorders in older adults, and, unfortunately, the rates at which they recognize and properly identify disorders often are low. With respect to depression, for example, a significant number of depressed older adults are neither diagnosed nor treated in primary care (NIH Consensus Development Panel on Depression in Late Life, 1992; Unutzer et al., 1997b). In one study of primary care physicians, only 55 percent of internists felt confident in diagnosing depression, and even fewer (35 percent of the total) felt confident in prescribing antidepressants to older persons (Callahan et al., 1992). Physicians were least likely to report that they felt very confident in evaluating depression in other late-life conditions (Gallo et al., in press). Researchers estimate that an unmet need for mental health services may be experienced by up to 63 percent of adults aged 65 years and older with a mental disorder, based on prevalence estimates from the Epidemiologic Catchment Area (ECA) study (Rabins, 1996).
The large unmet need for treatment of mental disorders reflects patient barriers (e.g., preference for primary care, tendency to emphasize somatic problems, reluctance to disclose psychological symptoms), provider barriers (e.g., lack of awareness of the manifestations of mental disorders, complexity of treatment, and reluctance to inform patients of a diagnosis), and mental health delivery system barriers (e.g., time pressures, reimbursement policies).
Stereotypes about normal aging also can make diagnosis and assessment of mental disorders in late life challenging. For example, many people believe that senility is normal and therefore may delay seeking care for relatives with dementing illnesses. Similarly, patients and their families may believe that depression and hopelessness are natural conditions of older age, especially with prolonged bereavement.
Cognitive decline, both normal and pathological, can be a barrier to effective identification and assessment of mental illness in late life. Obtaining an accurate history, which may need to be taken from family members, is important for diagnosis of most disorders and especially for distinguishing between somatic and mental disorders. Normal decline in short-term memory and especially the severe impairments in memory seen in dementing illnesses hamper attempts to obtain good patient histories. Similarly, cognitive deficits are prominent features of many disorders of late life that make diagnosis of psychiatric disorders more difficult.
Prevention in mental health has been seen until recently as an area limited to childhood and adolescence. Now there is mounting awareness of the value of prevention in the older population. While the body of published literature is not as extensive as that for diagnosis or treatment, investigators are beginning to shape new approaches to prevention. Yet because prevention research is driven, in part, by refined understanding of disease etiologyand etiology research itself continues to be rife with uncertaintyprevention advances are expected to lag behind those in etiology.
There are many ways in which prevention models can be applied to older individuals, provided a broad view of prevention is used (Lebowitz & Pearson, in press). Such a broad view entails interventions for reducing the risk of developing, exacerbating, or experiencing the consequences of a mental disorder. Consequently, this section covers primary prevention (including the prevention of depression and suicide), treatment-related prevention, prevention of excess disability, and prevention of premature institutionalization. However, many of the research advances noted in this section have yet to be translated into practice. Given the frequency of memory complaints and depression, the time may soon arrive for older adults to be encouraged to have mood and memory checkups in the same manner that they are now encouraged to have physical checkups (N. Abeles, personal communication, 1998).
The largest body of primary prevention research focuses on late-life depression, where some progress has been documented. With other disorders, primary prevention research is in its infancy. Prevention in Alzheimers disease might target individuals at increased genetic risk with prophylactic nutritional (e.g., vitamin E), cholinergic, or amyloid-targeting interventions. Prevention research on late-onset schizophrenia might explore potential protective factors, such as estrogen.
Prevention of Depression and Suicide
One approach to preventing depression is through grief counseling for widows and widowers. For example, participation in self-help groups appears to ameliorate depression, improve social adjustment, and reduce the use of alcohol and other drugs of abuse in widows (Constantino, 1988; Lieberman & Videka-Sherman, 1986). The efficacy of self-help groups approximates that of brief psychodynamic psychotherapy in older bereaved individuals without significant prior psychopathology (Marmar et al., 1988). The battery of psychosocial and pharmacological treatments to prevent recurrences of depression (i.e., secondary prevention) is discussed later in this chapter under the section on depression.
Depression is a foremost risk factor for suicide in older adults (Conwell, 1996; Conwell et al., 1996). Older people have the highest rates of suicide in the U.S. population: suicide rates increase with age, with older white men having a rate of suicide up to six times that of the general population (Kachur et al., 1995; Hoyert et al., 1999). Despite the prevalence of depression and the risk it confers for suicide, depression is neither well recognized nor treated in primary care settings, where most older adults seek and receive health care (Unutzer et al., 1997a). Studies described in the depression section of this chapter have found that undiagnosed and untreated depression in the primary care setting plays a significant role in suicide (Caine et al., 1996). This awareness has prompted the development of suicide prevention strategies expressly for primary care. One of the first published suicide prevention studies, an uncontrolled experiment conducted in Sweden, suggested that a depression training program for general practitioners reduces suicide (Rihmer et al., 1995). Suicide interventions, especially in the primary care setting, have become a priority of the U.S. Public Health Service, with lead responsibility assumed by the Office of the Surgeon General and the National Institute of Mental Health.
Depression and suicide prevention strategies also are important for nursing home residents. About half of patients newly relocated to nursing homes are at heightened risk for depression (Parmelee et al., 1989).
Prevention of medication side effects and adverse reactions also is an important goal of treatment-related prevention efforts in older adults. Comorbidity and the associated polypharmacy for multiple conditions are characteristic of older patients. New information on the genetic basis of drug metabolism and on the action of drug-metabolizing enzymes can lead to a better understanding of complex drug interactions (Nemeroff et al., 1996). For example, many of the selective serotonin reuptake inhibitors compete for the same metabolic pathway used by beta-blockers, type 1C antiarrhythmics, and benzodiazepines (Nemeroff et al., 1996). This knowledge can assist the clinician in choosing medications that can prevent the likelihood of side effects. In addition, many older patients require antipsychotic treatment for management of behavioral symptoms in Alzheimers disease, schizophrenia, and depression. Although doses tend to be quite low, age and length of treatment represent major risk factors for movement disorders (Saltz et al., 1991; Jeste et al., 1995a). Recent research on older people suggests that the newer antipsychotics present a much lower risk of movement disorders, highlighting their importance for prevention (Jeste et al., in press). Finally, body sway and postural stability are affected by many drugs, although there is wide variability within classes of drugs (Laghrissi-Thode et al., 1995). Minimizing the risk of falling, therefore, is another target for prevention research. Falls represent a leading cause of injury deaths among older persons (IOM, 1999).
Prevention of Excess Disability
Prevention of Premature Institutionalization
The growing importance of avoiding premature institutionalization is illustrated by its use as one measure of the effectiveness of pharmacotherapy in older individuals. For example, clinical trials of drugs for Alzheimers disease have begun using delay of institutionalization as a primary outcome (Sano et al., 1997) or as a longer-term outcome in a followup study after the double-blind portion of the clinical trial ended (Knopman et al., 1996).
Treatment of mental disorders in older adults encompasses pharmacological interventions, electroconvulsive therapy, and psychosocial interventions. While the pharmacological and psychosocial interventions used to treat mental health problems and specific disorders may be identical for older and younger adults, characteristics unique to older adults may be important considerations in treatment selection.
The aging process leads to numerous changes in physiology, resulting in altered blood levels of certain medications, prolonged pharmacological effects, and greater risk for many side effects (Kendell et al., 1981). Changes may occur in the absorption, distribution, metabolism, and excretion of psychotropic medications (Pollock & Mulsant, 1995).
As people age, there is a gradual decrease in gastrointestinal motility, gastric blood flow, and gastric acid production (Greenblatt et al., 1982). This slows the rate of absorption, but the overall extent of gastric absorption is probably comparable to that in other adults. The aging process is also associated with a decrease in total body water, a decrease in muscle mass, and an increase in adipose tissue (Borkan et al., 1983). Drugs that are highly lipophilic, such as neuroleptics, are therefore more likely to be accumulated in fatty tissues in older patients than they are in younger patients.
The liver undergoes changes in blood flow and volume with age. Phase I metabolism (oxidation, reduction, hydrolysis) may diminish or remain unchanged, while phase II metabolism (conjugation with an endogenous substrate) does not change with aging. Renal blood flow, glomerular surface area, tubular function, and reabsorption mechanisms all have been shown to diminish with age. Diminished renal excretion may lead to a prolonged half-life and the necessity for a lower dose or longer dosing intervals.
Pharmacodynamics, which refers to the drugs effect on its target organ, also can be altered in older individuals. An example of aging-associated pharmacodynamic change is diminished central cholinergic function contributing to increased sensitivity to the anticholinergic effects of many neuroleptics and antidepressants in older adults (Molchan et al., 1992).
Because of the pharmacokinetic and pharmacodynamic concerns presented above, it is often recommended that clinicians start low and go slow when prescribing new psychoactive medications for older adults. In other words, efficacy is greatest and side effects are minimized when initial doses are small and the rate of increase is slow. Nevertheless, the medication should generally be titrated to the regular adult dose in order to obtain the full benefit. The potential pitfall is that, because of slower titration and the concomitant need for more frequent medical visits, there is less likelihood of older adults receiving an adequate dose and course of medication.
Increased Risk of Side Effects
Tardive dyskinesia is a frequent and persistent side effect that occurs months to years after initiation of neuroleptics. In older adults, tardive dyskinesia typically entails abnormal movements of the tongue, lips, and face. In a recent study of older outpatients treated with conventional neuroleptics the incidence of tardive dyskinesia after 12 months of neuroleptic treatment was 29 percent of the patients. At 24 and 36 months, the mean cumulative incidence was 50.1 percent and 63.1 percent, respectively (Jeste et al., 1995a). This study demonstrates the high risk of tardive dyskinesia in older patients even with low doses of conventional neuroleptics. Studies of younger adult patients reveal an annual cumulative incidence of tardive dyskinesia at 4 to 5 percent (Kane et al., 1993).
Unlike conventional neuroleptics, the newer atypical ones, such as clozapine, risperidone, olanzapine, and quetiapine, apparently confer several advantages with respect to both efficacy and safety. These drugs are associated with a lower incidence of extrapyramidal symptoms than conventional neuroleptics are. For clozapine, the low risk of tardive dyskinesia is well established (Kane et al., 1993). The incidence of tardive dyskinesia with other atypical antipsychotics is also likely to be lower than that with conventional neuroleptics because extrapyramidal symptoms have been found to be a risk factor for tardive dyskinesia in older adults (Saltz et al., 1991; Jeste et al., 1995a). The determination of exact risk of tardive dyskinesia with these newer drugs needs long-term studies.
Despite the relative paucity of research, psychosocial interventions may be preferred for some older patients, especially those who are unable to tolerate, or prefer not to take, medication or who are confronting stressful situations or low degrees of social support (Lebowitz et al., 1997). The benefits of psychosocial interventions are likely to assume greater prominence as a result of population demographics: as the number of older people grows, progressively more older people in need of mental health treatmentespecially the very oldare expected to be suffering from greater levels of comorbidity or dealing with the stresses associated with disability. Psychosocial interventions not only can help relieve the symptoms of a variety of mental disorders and related problems but also can play more diverse roles: they can help strengthen coping mechanisms, encourage (and monitor) patients compliance with medications, and promote healthy behavior (Klausner & Alexopoulos, in press).
New approaches to service delivery are being designed to realize the benefits of established psychosocial interventions. Many older people are not comfortable with traditional mental health settings, partially as a result of stigma (Waters, 1995). In fact, many older people prefer to receive treatment for mental disorders by their primary care physicians, and most older people do receive such care in the primary care setting (Brody et al., 1997; Unutzer et al., 1997a). Since older people show willingness to accept psychosocial interventions in the primary care setting, new models are striving to integrate into the primary care setting the delivery of specialty mental health services. The section of this chapter on service delivery discusses new models in greater detail.
Gap Between Efficacy and Effectiveness