Medical Comorbidities in Late-Life Depression

Late-life depression is both underrecognized and undertreated, and the impact of medical comorbidity may mask depressive symptoms. 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. In addition, chronic disabling disorders can be a contributory factor to suicide attempts and completions in the elderly, but timely, appropriate treatment of depression can reduce this risk.3 This review provides an update of current evidence in relation to late-life depression and its management in the presence of some common medical conditions: stroke, coronary heart disease, diabetes mellitus, Parkinson disease, and COPD. The relatively new concept of vascular depression is also briefly discussed.4,5 STROKE AND MOOD DISORDER Depression Because depression and stroke are common in later life, poststroke depression is also common. Depression develops in 20% to 50% of patients within the first year after a stroke: the peak prevalence of major depression occurs at 3 to 6 months poststroke.6-8 However, the risk may continue for up to 2 or 3 years depending on the effects of disability on the patient’s lifestyle. The variability in prevalence is probably the result of clinical heterogeneity of the sample, the timing of the evaluation, and the lack of a valid disease-specific screening questionnaire for poststroke depression.9 A recent systematic review reported that the predisposing factors for poststroke depression include older age, a history of depressive disorder, the size of infarct, female sex, severity of stroke sequelae, and language impairment.10 Poststroke depression has been shown to be a predictor of impaired quality of life and a risk factor for cognitive decline and poorer functional recovery. It is also associated with an elevated risk of morbidity and mortality.9,10 The literature is inconclusive about whether baseline depressive symptoms predict cerebrovascular events in older age. The Framingham Study examined the risk of developing cerebrovascular events in 2 cohorts of patients: one group was 65 years or younger and the other was older than 65 years.11 The study used the Center for Epidemiologic Studies Depression (CES-D) score of greater than 16 as a cutoff for significant depression.12 Those 65 years and younger who had a CES-D score of 16 or greater were 4 times more likely to experience a stroke or transient ischemic attack as the same age-group without depression, after controlling for risk factors such as smoking status and education. There was no significant difference in the rate at which cerebrovascular events occurred in those who were 65 years or older, with or without depression. In contrast, findings from another study indicate a positive association between the presence of depression and the risk of stroke across the entire adult age range.13 This study also demonstrated a gradient effect (the greater the depression, the greater the risk of stroke), which was most marked among black racial groups. The exact mechanisms of how depressive symptoms predispose to stroke are not fully known, but depression is known to affect autonomic function and platelet activation. Diagnosing depression after a stroke can be difficult, especially in patients with aphasia. In their review of existing instruments, Bennett and Lincoln14 found the 14-item observer-rated Stroke