In 2001, depressive disorders were the third leading cause of disability in Western industrialized countries.1 The cost of depression in the United States alone, in 2000, was estimated to be more than $83 billion.1 Of this, $26.1 billion were medically related costs, $51.5 billion were work-related costs, and $5.4 billion were related to suicidal mortality.2 The prevalence of depression is higher among persons with comorbid medical conditions than in those with no comorbidity. Some conditions that are common in older people, such as stroke, cardiac disease, chronic obstructive pulmonary disease (COPD), and diabetes mellitus, are associated with particularly high rates of depression comorbidity.3-5
Late-life depression is both underrecognized and undertreated. The impact of medical comorbidity may mask depressive symptoms. Social isolation, recent bereavement, and cognitive impairment as well as the stigma of depression and the belief that it is a normal part of aging, can also contribute to depression in the elderly.4-6 Untreated depression in older people impairs their quality of life and leads to a decreased ability for self-care, a decrease in social interaction, and an increase in health care use.7-9
Depression further complicates the prognosis of medical illness by increasing physical disability and decreasing motivation and adherence to prescribed medications and/or exercise or rehabilitation programs. These adverse associations apply to all types of depression in later life. In addition, older people make up about 12% of the US population but account for 16% of suicides. Chronic disabling disorders can be a contributing factor, but timely, appropriate treatment of depression can reduce this risk.10
This review provides an update of current evidence in relation to late-life depression and its diagnosis and treatment.
General etiological factors
The interaction between medical illness and depression in older patients is 2-way and self-perpetuating: physical illness increases susceptibility to depression and depression worsens medical outcomes. Lyness11 recently noted that depression and medical illnesses might have similar pathways that range from shared genetic vulnerabilities to the effects of personality or other enduring psychological or psychosocial constructs. The older patient’s own perception of his or her health plays a role in actual health: a poor perception is associated with increased depressive symptoms regardless of actual health impairment.3,5 A history of depression strongly predicts the development of depression after any major adverse health event.3
Many factors contribute to an increased risk of late-life depression. Sensory impairment and macular degeneration frequently affect older people and are also associated with high levels of depression.12 Physical disability is another strong predictor of late-life depression, although it may be modifiable: the patient who has poor transportation links and becomes isolated is at greater risk for depression.
Use of prescribed drugs and polypharmacy increases with age and can have an impact on depression. Drug-induced depression (along with depression caused by an occult illness, such as cancer, an endocrine disturbance, or early dementia) is an important differential diagnosis. A European study estimated the Population Attributable Risk percentage (PAR%)—depression associated with the use of certain medication—for a large number of medications.13 For nonselective b-blockers, the PAR% was 2.5%, for calcium antagonists it was 5%, and for benzodiazepines it was 15.42%.
Late-life depression is an umbrella term that covers a range of depressive symptoms from mild to severe in an older adult (usually defined as aged 65 years or older).4,7 The core symptoms are listed in Table 1. About half of late-life major depressive disorder (MDD) occurs in those with recurrent depressive disorder.4,7 It is harder to classify older individuals with disabling symptoms of depression who do not meet MDD criteria. The prevalence of this type of depression (variously labeled minor depression, subthreshold depression, or clinically relevant depressive symptomatology) exceeds that of MDD by a factor of 2 to –3. Therefore, the overall health burden is potentially as great or greater than for MDD.14
Somatic symptoms such as fatigue, sleep disturbance, decrease in social interaction, and loss of interest in pleasurable activities may be the result of physical illness, a depressive disorder, or both—especially in patients with physical comorbidity. Three symptoms may help with the diagnosis4:
• Depressed mood
• Mood worsening in the morning