Depression in the Elderly: When to Suspect

ABSTRACT: Depression could affect people at any age; however, it may have a different presentation in the elderly. It can be easily overlooked, misdiagnosed, or considered a natural consequence of aging, especially in those with co-occurring medical illnessor those with a recent loss of a loved one. Somatization, interpersonal communication difficulties, and cognitive decline can also hinder the identification of patients who are in need of treatment. Elderly patients may be unwilling to divulge their depressed feelings during the initial medical evaluation; thus, repeated evaluation may be required. Primary care providers may also be reluctant to question patients about sensitive emotional topics. These difficulties can be lessened by the use of appropriate screening scales. Failure to identify and treat depression in the elderly increases both morbidityand mortality; it also may lead to increased demands on family members and on health care and social services.

About 80% of mental health treatment for elderly patients is delivered in the primary care setting.¹ Depression, however, may often be unrecognized in this setting, where the focus is mainly on addressing physical complaints rather than emotional and psychological symptoms.

Elderly persons may be also reluctant to share their feelings of depression for fear of being a burden on others. Moreover, in the elderly, depression may present with symptoms that differ from the typical clinical presentation of depression in the general adult population. The treatment of depression in the elderly may also differ from that in younger adults because of the frequent presence of co-occurring medical conditions, in addition to many psychosocial and financial stressors. Depression in the elderly is a serious public health concern; its progression in the absence of treatment leads to needless suffering, impaired functioning, increased mortality, and
excessive, costly use of health care resources.

Here, in part 1 of this two-part article, the epidemiology and the diagnosis of depression in the elderly are summarized. In a coming issue, the treatment will be addressed.

EPIDEMIOLOGY

The prevalence of depression in the total US population is 1% (1.4% in women, 0.4% in men).² The estimated point prevalence of depression for those overthe age of 65 is 4.4% in women and 2.7% in men.³ The prevalence of depression in adults older than 65 years of age ranges from 7% to 36% in medical outpatients and increases to 40% in hospitalized elderly patients.⁴ The rate approaches 12% to 30% in patients who live in long-term care facilities.⁵ Up to 50% of patients with Alzheimer disease or Parkinson disease develop a depressive disorder.^6,7

Depression has been identified in 17% to 37% of elderly patients treated in primary care settings. Approximately 3% of physically healthy elderly persons living in the community have a depressive disorder, and 3% will initially present to a primary care setting.^1-3 The rate of recurrence of depression may be as high as 40%.^6,7

Suicide rates are nearly twice as high in depressed patients as in the general population.⁵ Depression is the most common diagnosis in elderly persons who commit suicide. Approximately 63% of those who commit suicide are white elderly men, and 85% of them have an associated psychiatric or physical illness.³ About 75% of those who commit suicide had visited a primary care provider within the preceding month, but their symptoms were not recognized or treated.^3-7

Early diagnosis and treatment of depression in the elderly improve quality of life and functional status, and may help prevent premature death. This issue will become even more significant within the next 30 years, when the elderly population is expected to double.⁸

OBSTACLES TO RECOGNIZING DEPRESSION IN THE ELDERLY

Because depressive symptoms are often attributed to “normal” aging or described as secondary to a physical illness, depression may be overlooked or misdiagnosed.⁹ Depression is often misdiagnosed as dementia, hypochondriasis, or somatization disorder.⁹ Although the symptoms of depression in the elderly are similar to those in the general adult population, the signs of depression that are more common in the elderly than in other populations include diminished self-care, irritability, and psychomotor retardation.¹⁰ Some of these differences are summarized in Table 1.

The stigma associated with mental illness^1-3 could also deter primary care providers from diagnosing depression, especially in the presence of coexisting medical conditions or co-occurring substance abuse, including prescription medication misuse and dependence. Time constraints, cost issues, and health insurance requirements could also lead to misdiagnosis of depression in the elderly. Low socioeconomic status, bereavement associated with the loss of loved ones, social isolation, and lack of family support can hinder access to mental health care, thereby delaying diagnosis and treatment. Clinical experiences in primary care settings have demonstrated that a comprehensive evaluation of depressive symptoms is more accurate than an elderly patient’s report of mood changes in diagnosing depression and monitoring treatment response.^9,10

CAUSES OF DEPRESSION IN THE ELDERLY

An earlier history of depression during adulthood is a risk factor for depression in the elderly. Elderly patients who experience their first episode of depression are less likely to have a family history of depression or other major mental disorder than patients whose first episode occurred earlier in life. This difference suggests that genetic or hereditary factors are less likely to play a role in precipitating depression in the elderly.^5,11 However, the biological, sociological, psychological, and spiritual changes that are associated with aging are important to consider when assessing the causes of depression in the elderly. The risk factors for depression in the elderly include:

•Female gender.

•Social isolation.

•Being single, widowed, divorced, or going through marital separation.

•Lower socioeconomic status.

•Co-occurring psychiatric and or substance abuse disorder.

•Co-occurring medical conditions such as coronary heart disease, stroke, and cancer.

•The development of uncontrolled or inadequately managed pain.

•Insomnia.

•Functional impairment due to neurodegenerative disease of the brain such as Parkinson disease or cerebrovascular diseases.

•Cognitive impairment due to Alz-heimer disease, vascular dementia, and other dementias.

•Medications that cause depression.

•Ongoing stressful financial, occupational, or interpersonal life events.

The loss of a lifelong spouse, retirement, social isolation, and separation from siblings and grown children also increase the risk of depression in the elderly.

The risk of suicide is nearly twice as high in depressed patients as in the general population. Being Caucasian, male gender, and elderly and having associated psychiatric or physical illness further increase that suicidal risk.¹² Previous suicidal attempts markedly increase the risk of future attempts. The co-occurrence of anxiety, agitation, insomnia, uncontrolled chronic pain, worsening of self-esteem, substance abuse, and the presence of psychotic features and personality disorders—especially if associated with aggressive and narcissistic tendencies—further contribute to an increased suicide risk in the elderly.^6-12

CLASSIFICATION OF DEPRESSION

It is important not to rely on categorical definitions of typesof depression, as these do not fit well when superimposed onthe variety of illnesses seen in a primary care setting. The conceptof a spectrum of symptoms and severity, ranging from no diseasethrough minor or sub-thresholddepressionto major depressivedisorder (MDD) is more applicable, and this model is becomingincreasinglyaccepted and reliable. The effects of age of onset, changes in the aging brain, and the presence of co-occurring medical conditions would influence the type and expression of depression as well as treatment responsiveness. Some patients may have clinically significant depressive symptoms but do not totally fulfill the criteria for MDD as defined by The Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision (DSM-IV-TR) nomenclature, which are summarized in Table 2.¹³ An overview of the main DSM-IV-TR depressive disorders categoriesis also outlined in Table 3.

Major depressive disorder. MDD is also known as recurrent depressive disorder, clinical depression, major depression, or unipolar depression. The DSM-IV-TR defines MDD as a condition characterized by the presence of depressed mood or loss of interest or pleasure. Associated symptoms include changes in appetite or weight (5% of total body weight), sleep, energy, concentration, and psychomotor activity, as well as feelings of inappropriate guilt or worthlessness, and recurrent thoughts of death or suicide.

Dysthymic disorder (dysthymia). This is characterized by depressed mood, more days than not, for at least 2 years and the absence of major depressive episodes during the first 2 years of the dysthymic disturbance.¹³ The classic term “depressive neurosis” used by Freud to describe this type of depression is seldom employed in the current psychiatric classification. Elderly patients with late-onset dysthymic disorder have a higher prevalence of medical conditions, particularly cardiovascular disease, but are otherwise similar to older patients with late-onset depression. Patients with dysthymic disorder are also at greater risk for major depression, which is clinically described as “double depression.”^6,7

Depression with psychotic features (psychotic depression). Psychotic depression, or at times called delusional depression, is one of the most serious types of depression that occur in the elderly.^13,14 Delusions tend to be mood congruent with themes of inadequacy and worthlessness, impoverishment, exaggerated guilt, and preoccupation with death and dying. Somatic delusions involve misperceptions of impaired or poorly functioning bodily systems. Paranoid, persecutory, or jealous delusions may also be present. Hallucinations are uncommon and tend to be transitory but consistent with the depressed themes. Patients may also have co-existing cognitive difficulties, thus complicating the identification and the treatment of depression.

Minor (subsyndromal) depression. In this category of depression, patients do not meet DSM-IV-TR criteria for major depression or dysthymic disorder because of fewer symptoms or limited duration of symptoms.¹⁴ This type of depression is particularly important in the elderly, since it carries disease burdens similar to those of major depression, and it is associated with poorer health and social outcomes, functional impairment, and higher health care utilization and treatment costs. In addition, affected patients are at high risk for subsequent development of major depression and may develop suicidal ideation. Minor depression is not currently recognized in the DSM-IV-TR; it would be diagnosed as a depressive disorder, not otherwise specified.¹³

Depression due to a general medical condition.In this category, the depression is caused by a general medical, surgical, or neurological condition. The diagnosis of MDD is not made if the major depressive–like episodes are all attributable to the direct physiological effects of a general medical condition.^13-15

Substance-induced mood disorder. This type of depression results from the direct physiological effects of a substance. The diagnosis of MDD is not made if the major depressive–like episodes are all attributable to the direct physiological effects of a substance (including medications, over-the-counter agents, herbal preparations, alternative medical agents, etc).¹³

Seasonal affective disorder. In this category, the episodes of depression occur every year during fall or winter, and symptoms improve in spring and summer.¹³ The symptoms usually build up gradually in the late fall and winter months. Less often, seasonal affective disorder causes depression in the spring or early summer.

Adjustment disorder with depressed mood. This disorder is characterized by depressive symptoms that occur in response to a stressor and do not meet the criteria for an MDD episode. The depressive symptoms usually subside within 6 months as a result of reversing the precipitating stressors.¹³ If the adjustment period lasts more than 6 months, then the condition will be termed chronic adjustment disorder with depressed mood.

Uncomplicated bereavement. This occurs in response to the loss of a loved one and is generally less severe than MDD. Its onset begins following the loss of a loved one; it persists for less than 2 months after the loss and is not characterized by marked functional impairment, morbid preoccupation with worthlessness, suicidal ideation, psychotic symptoms, or psychomotor retardation.^13,16

Dementia. The relationship between dementia and depression in the elderly can affect diagnostic accuracy because the two conditions can easily mimic each other and they can also co-exist.^13,17,18 Dementia of depression was traditionally recognized as pseudodementia or the dementia syndrome of depression. This condition refers to the reversible cognitive impairment seen in the setting of a depressive episode that improves with the treatment of that episode. Depression can also be an early-presenting symptom of dementia. It is, however, unclear whether depression is a risk factor for the development of dementia, or an independent event. It appears most likely that the relationship between depression and cognitive decline is patient-dependent. An accurate diagnosis is essential, since the treatment and prognosis of depression differ greatly from that of dementia and the treatment of depression could improve the overall management of dementia. Some of the differences between depression and dementia symptoms are summarized in Table 4.

EVALUATION AND DIAGNOSIS OF DEPRESSION IN THE ELDERLY

The presence of a dysphoric mood may be less reliable as an indicator of depression in the elderly (especially in those older than 85 years of age).¹⁹ When diagnosing depression in the frail elderly, emphasis should be focused on a change in mood or in interest in pleasurable activities of at least 2 weeks’ duration, non-physically related symptoms, social regression, or incapacity. Physical symptoms used to support the diagnosis of depression should occur with or worsen after mood symptoms, and they should be out of proportion to what is expected of the illness or usual treatments. Depression is less likely to be present if the elderly patients respond to affection from family and caregivers, are able to maintain their sense of humor, look forward to visits, and accept assistance and support.

Confounding factors.Assessment of patients for depression, especially the physically frail elderly, is challenging because of the presence of multiple factors that could complicate the accuracy of the diagnosis.²⁰ These may include some or all of the following:

•The concurrence of medical conditions, which could present with symptoms similar to those of depression, such as fatigue, psychomotor slowing, loss of appetite, sleep disturbances, lack of sexual interest, and complaints related to cognition, especially memory difficulties. A summary of some of the medical conditions associated with depression is provided in Table 5.

•Medications that may cause depression. Some of these are summarized in Table 6.

•Impairment in communication skills due to decreased visual, auditory, and tactile acuity.

•Initial presentation with multiple somatic symptoms and complaints.

•Initial complex medical issues that require an extended examination time, thus not allowing sufficient time to evaluate psychological problems.

•Patient, family, provider, and societal attitudes that regard depression as a natural consequence of aging.

•Patients’ fears and reluctance to acknowledge psychiatric conditions because of the perceived stigma of discrimination and denial of care for mental conditions.

Because of the various factors that affect the relationship between depression, cognitive function, and somatic complaints, it is recommended that any elderly patient with multiple unexplained medical complaints or cognitive decline be screened for depression.

Screening scales. Many screening scales have been developed and validated for use in assessing depression. The most widely used screening tools for this purpose include the Patient Health Questionnaire 2 (PHQ-2), which is outlined in Figure 1. This two-item self-report inquires about the frequency of depressed mood and anhedonia (loss of or little interest in enjoying pleasurable activities) over the past 2 weeks.²¹

Patients who have a positive screening result on the PHQ-2 can be further evaluated with the Patient Health Questionnaire-9 (PHQ-9).²² This nine-item depression scale consists of two components: an assessment of impairment to make a tentative diagnosis and the derivation of a severity score to help select and monitor treatment. The PHQ-9 is summarized in Figure 2.

The Geriatric Depression Scale (GDS) can also be used to screen for depression. It is a self-ratingscale that can also be given during an initial primary care interview, and it is outlined in Figure 3.²³ The GDS screens for seven characteristics of depression in the elderly: somatic concern, lowered affect, cognitive impairment, feelings of discrimination, impaired motivation, lack of future orientation, and lack of self-esteem. The yes-or-no questionnaire is administered orally, and one point is scored for each answer in parentheses. A score of 10 or more indicates depression. The GDS Short Form²⁴ can also be used as described in Figure 4. In that scale, a score of 0 to 5 is normal, and a score above 5 suggests depression.

The results of these scales should be considered as a component of a comprehensive diagnostic work-up, not as a substitute for such a work-up. In addition these scales could be administrated following treatment initiation to monitor patients’ progress.

DIFFERENTIAL DIAGNOSIS FOR MAJOR DEPRESSIVE DISORDER

Aging process. Some of the physical signs of aging, such as astooped posture and a linedface, may influence the perception of the elderly by othersand result in a tendency to consider them depressed. In addition, the symptoms of pain orfatigue may be attributed to the process of aging or to the presence of medical disorders rather than being considered as depressive symptoms.¹⁷

Somatization disorder. Patients with this chronic condition tend to experienceand communicate somatic distress and somatic symptoms that could not be accountedfor by relevant medical findings, as an attribute of a physical illness, which would require a medical intervention.^13,25 As a consequence, somatization disorder can lead to the development of other diseases from unnecessary investigationsand treatments. The DSM-IV-TR allows somatic symptoms to be counted toward the diagnosis of depression if there is any possibility of psychological causation rather than attributing them to either physicalor other psychiatric causes.¹³ Many health care providers tend to attribute difficult-to-diagnose symptoms in the elderly to somatization rather than conduct a comprehensive assessment to rule out medical and psychiatric disorders that primarily present with somatic complaints. Somatization disorder usually starts earlier during adulthood and is not a manifestation of aging.

Hypochondriasis. This differs from somatization in attributing normal bodily sensationsto illness, and in the persistent seeking of medical investigationsand reassurance.^25,26 It may be part of lifelong maladaptive behavior. In the elderly population, it has also been associated with anxiety disorders. Rigorous medical evaluation must be undertakento exclude underlying physical problems before attributing symptoms of hypochondriasisor somatization as being secondary to depression in the elderly.

Schizophrenia, delusional disorder, psychotic disorder not otherwise specified. In these conditions, depressive mood symptoms may be present. They are brief relative to the total duration of the psychotic disturbance. If major depressive episodes are superimposed on a psychotic disorder, these depressive episodes should be diagnosed as depressive disorder not otherwise specified.¹³

Bipolar I or bipolar II disorder. In these disorders, one or more manic, mixed, or hypomanic symptoms are present. The diagnosis of MDD cannot be made if a manic, mixed, or hypomanic episode has occurred in the past.¹³

Schizoaffective disorder. This condition is characterized by a period of at least 2 weeks of psychotic symptoms of delusions and/or hallucinations occurring in the absence of any prominent mood symptoms.¹³