Differential Diagnoses and Assessment of Depression in Elderly Patients
Gary W. Small, MD
Memory and Aging Center, Semel Institute for Neuroscience and Human Behavior, and the Geriatric Division of the Department of Psychiatry and Biobehavioral Sciences, David Geffen School of Medicine, University of California, Los Angeles
Depression is a common but underdiagnosed and undertreated condition in older adults. Prevalence estimates for current DSM-IV MDD in adults aged 65 to 100 years in the community have been reported to be 3% in men and 4% in women.1 In the primary care setting, about 5% to 10% of older patients have MDD. However, MDD goes unrecognized by primary care providers in as many as half of depressed elderly patients2; the same is true in long-term care facilities. A large study3 of nursing home residents identified 11% of the residents as depressed, but only 55% of the diagnosed patients were receiving antidepressant treatment.
The consequences of depression in older people extend from lower quality of life4 to higher mortality rates from both medical illness and suicide.5,6 For example, depression was a significant predictor of mortality in a study5 that followed patients (mean age, 60 years) for 6 months after hospitalization for myocardial infarction. Additionally, the suicide rate for those 75 years of age or older is greater than for any other age group (AV 1).6 While physical illness and functional impairment are also associated with an increased risk of suicide in late life, depression confers the greatest risk.7
Geriatric Depression Vs Younger Adult Depression
Depressive symptoms may differ between geriatric patients and younger adults. In younger adults, the mood is often depressed, anhedonic, and accompanied by suicidal thoughts,8 whereas, in the geriatric population, the mood may be one of weariness, hopelessness, anger, or anxiety,9 with thoughts of death rather than outright suicidal ideation (AV 2).10
In younger adults, somatic symptoms such as disruption of sleep, appetite, and psychomotor patterns may occur with depression, but older adults often have pain and somatic symptoms that overlap with the effects of medication and comorbid medical illness. Decreased concentration and indecisiveness are seen in younger adults with depression, whereas cognitive complaints in the elderly with depression may include selective attention, problems in working memory and retrieval, and difficulties in learning, processing speed, and executive functioning (AV 2).11
The differential diagnosis of late-life depression includes consideration of bereavement/adjustment disorder, bipolar disorder, substance use disorders, anxiety disorders, personality disorders, psychosis, and a variety of other major psychiatric conditions. In addition, clinicians should consider medical problems that can lead to mood disorders, including cardiopulmonary disorders, neurologic conditions, and endocrine and metabolic disorders, as well as medication toxicities, nutritional deficiencies, sleep disorders, infections, and neoplasms.
A major consideration in diagnosing late-life depression is differentiating MDD from Alzheimer's disease and other neurodegenerative disorders (AV 3).12 For example, patients with Alzheimer's disease often do not have a prior psychiatric history of depression and their recognition memory is impaired. However, patients with the dementia syndrome of depression may have had a brief symptom duration, have a prior psychiatric history, and have intact recognition memory.
Investigators have also described a condition known as vascular depression.11,13 The first onset of depression in patients with this syndrome is at or after age 60 years, and the patient has hypertension and/or transient ischemic attacks or has had surgery for vascular disease. Vascular depression is associated less with depressive thinking than with psychomotor retardation and cognitive dysfunction, which is characterized by impaired fluency in naming, lack of insight, and executive dysfunction. In patients with vascular depression, MRI scans show left frontal and left putamen deep white matter hyperintensities.14
Assessing Late-Life Depression
In assessing patients for late-life depression, an informant is often helpful when obtaining a psychiatric history, as an older patient may not be able to report details if cognitive deficits are present. Formal depression and cognitive screening instruments such as the HAM-D,15 GDS, MADRS,16 MMSE, MoCA,17 and tests of executive function can be useful. Although not routine, neuroimaging studies are especially helpful when cognitive deficits are present. Any patient with dementia as part of the differential diagnosis should have a structural imaging study (eg, MRI), and, often, functional studies such as PET imaging can be helpful as well.
A medical history and a physical examination of the patient are essential components in evaluating older adults for MDD. Physicians should address the patient’s cardiopulmonary and cerebrovascular status, conduct a neurologic examination, and assess the patient’s sleep history. The patient’s medications, treatment adherence, and use of any additional nonprescription medicines or supplements should be comprehensively reviewed.
A thorough examination of the patient’s mental status should be conducted. This examination should include a standardized cognitive assessment, a description of the appearance and self-care of the patient, and notation of mood presentations, including withdrawal, weariness, and comorbid anxiety. Somatic symptoms and pain should be assessed, and the patient’s cognitive complaints should be compared with observed cognitive problems. Psychosocial factors should also be considered.
Laboratory assessment is necessary to rule out any underlying medical cause for depression, and data should include complete blood count, urinalysis, and appropriate chemistry values.
Depression is a common but underdiagnosed and undertreated problem in geriatric patients. Mortality from both suicide and medical illnesses is greater in older patients with MDD than in those without. Physicians should be aware of the varying presentations of depression in older adults. In the differential diagnosis, clinicians should rule out psychiatric diagnoses, such as bereavement or adjustment disorder or substance use disorder; psychosocial factors, nutrition, sleep patterns, and current medications should also be reviewed. A thorough evaluation can also determine if an older patient’s depression is caused by an underlying medical or neurologic condition, such as vascular disease or Alzheimer’s disease. Depression rating scales, cognitive screening instruments, and structural and functional neuroimaging studies may be implemented as the situation requires. Greater recognition and more aggressive treatment of depression in older patients are needed.
DSM-IV-TR = Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision, GDS = Geriatric Depression Scale, HAM-D = Hamilton Rating Scale for Depression, MADRS = Montgomery-Asberg Depression Rating Scale, MDD = major depressive disorder, MMSE = Mini-Mental State Examination, MoCA = Montreal Cognitive Assessment, MRI = magnetic resonance imaging, PET = positron emission tomography
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