Depression is frequently encountered in the context of many cardiovascular diseases. The epidemiology, pathophysiology, clinical presentation, and course of the depression vary in each of these medical conditions. They are therefore discussed separately in this chapter. However, the treatment of depression in the context of these various cardiovascular diseases differs very little and thus is covered in a single section at the end.

EPIDEMIOLOGY

Coronary heart disease (CHD) results from narrowing of the arteries that supply blood to the heart, leading to acute myocardial infarction (MI), angina pectoris, and other ischemic heart disease. The American Heart Association estimates that 15 million Americans have CHD, a prevalence of 6.4% among adults aged 20 or older.¹ Approximately 700,000 Americans have a new or recurrent MI each year.¹ While rates of hospitalization and death due to MI decreased from 1999 to 2009, CHD was still the cause of one in six deaths in 2009.¹ The 5-year mortality rate following a first MI is 36% for men and 47% for women aged 45 and older. Additionally, CHD is estimated to cost $195 billion per year in the United States in direct and indirect costs (Figs. 7-1 to 7-3).¹

CHD is associated with elevated rates of depression. Prevalence of major depressive disorder (MDD) is approximately 17% to 27% among patients with CHD,² compared to an estimated lifetime prevalence of 16% in the general population.³ An additional 20% to 30% of patients with CHD experience minor depression or subsyndromal depressive symptoms following MI.^4–6 Patients undergoing coronary artery bypass graft surgery (CABG) due to CHD demonstrate rates of depression of about 20% to 25%, and rates as high as 38% are reported when minor depression is included.^7,8 CHD is also associated with an increased risk of suicide, particularly within the first month of an MI, although the elevated risk may persist for several years.⁹

In addition to co-occurrence in individuals with already established CHD, depression is also an independent risk factor for the subsequent development of initial and recurrent cardiovascular disease in healthy men and women.² A large prospective study of individuals with a history of depression but without prior CHD revealed a 2.7-fold increase in subsequent CHD mortality.¹⁰ In a prospective study of women without prior CHD, depressive symptoms were correlated with increased risk of MI, fatal CHD, and sudden cardiac death.¹¹ Depression confers a relative risk of 1.64 for the development of CHD,¹² and relative risk of about 1.5 for death due to cardiovascular disease.^13,14

The risk of developing depression in CHD is related to biological, social, and psychological factors (Box 7-1a). Family history of depression is a known risk factor for MDD,¹⁵ as well as for depression in the setting of CHD,¹⁶ and heritability studies in twins also indicate that there are genetic risk factors for MDD.¹⁵ However, it is unclear if MDD and CHD share any genetic risk factors. One study did demonstrate that the co-occurrence of depression and cardiovascular disease was partly explained by shared genetic factors.¹⁷

A number of demographic factors are associated with risk of depression after MI (Box 7-1b). Depressed patients with CHD are younger than nondepressed CHD patients.^18–20 A proposed explanation for this interaction is that younger patients experience more change in their physical mobility and lifestyle following MI than older patients.² Female gender is also associated with an increased rate of depression in CHD.^18,19,21,22 Women may also have an elevated risk of suicide after MI compared to men.²³ It is unclear whether depression imparts different risks for mortality or recurrent MI in women compared to men.²

Medical comorbidity may moderate the relationship between depression and CHD. The presence of other comorbidities, such as diabetes and obesity, are associated with depression in CHD.²⁴ These may in turn affect cardiovascular outcomes and partly account for the impact of depression on CHD risk.²

The role of social isolation has been studied in patients with depression and CHD.^25,26 Living alone is a risk factor for depression in the setting of MI,²⁷ and lack of social support in general predicts CHD mortality.²⁶ Social isolation also predicts persistent depression at 1 year follow-up for patients who were depressed at the time of MI.²⁵

Psychological factors are also predictive of depression in CHD or following MI. Thus, “Type D” personality, a tendency toward negative affective states and social inhibition, predicts persistent depression over 1 year.²⁸ An individual’s beliefs about heart disease may predict the development of post-MI depression; belief in the curability of heart disease is associated with reduced incidence of depression after MI, while belief that one will have a lengthy illness is associated with increased incidence of depression after MI (Fig. 7-4).²⁹

As with depression in medically healthy populations, a history of prior depressive episodes predicts recurrence of depression following acute MI, both in the hospital and after discharge.^27,30 Up to half of patients with post-MI depression have a history of depression before the MI.³¹

It is unclear whether increasing severity of CHD increases risk of depression. Most studies do not find correlations between the severity of depressive symptoms and measures of MI severity, including left ventricular ejection fraction,^7,8 serial CPKs, and Killip class (a classification of mortality risk following MI).^32–34 Likewise, significant associations have not been found between depressive symptoms and systolic and diastolic function, exercise-induced ischemia, and cardiac wall motion abnormalities.³³ However, a minority of studies have found that depression risk is correlated with CHD severity, specifically left ventricular dysfunction,²⁸ higher Killip class,^31,33,35 and poorer exercise tolerance.²⁷

PATHOPHYSIOLOGY

Several pathophysiological mechanisms have been examined as biological mediators of the association between depression and CHD (Box 7-2). Depression is accompanied by increased sympathetic nervous system activation and/or decreased parasympathetic function. Elevated levels of plasma norepinephrine, which may reflect increased sympathetic activity, are observed in depressed patients with CHD.^18,36 Resting heart rates are elevated in depressed CHD patients,^36,37 and elevated resting heart rate is associated with increased risk of MI and other cardiovascular diseases.³⁸ Additionally, depressed patients demonstrate decreased heart rate variability, another measure of cardiac autonomic function that is a risk factor for mortality following MI.³⁹ This finding is most consistent among patients with depression and CHD, but has also been observed among patients with depression and no medical comorbidities.³⁸

Dysregulation of the hypothalamic–pituitary–adrenal (HPA) axis is another proposed biological mechanism to account for the association between depression and CHD. Elevated cortisol levels have been associated with depression, both in patients with CHD⁴⁰ and in medically healthy populations.⁴¹ Elevated cortisol is also associated with CHD, and may impact release of vasodilators and vasoconstrictors from the endothelium.⁴⁰ It is unclear whether increased cortisol levels result from depression or cause depression. Patients with high levels of cortisol due to Cushing syndrome have elevated rates of depression and cardiovascular disease, suggesting that cortisol may have a causal influence on both of these disorders.⁴⁰

Inflammation is proposed as an important mediator between depression and CHD. Levels of inflammatory cytokines, such as interleukin-1 beta (IL-1 beta), interleukin-6 (IL-6), C-reactive protein (CRP), and tumor necrosis factor (TNF) are elevated in patients with depression who are otherwise healthy.^42,43,44 These inflammatory markers are also associated with increased risk of CHD and MI.^42,45 They may contribute to the rupture of atherosclerotic plaques or impact myocardial contractility.⁴⁵ Interleukin-6, for example, is known to increase levels of CRP and to stimulate platelet aggregation.⁴⁵

Altered platelet function may contribute to the association between depression and CHD. More than 99% of the body’s serotonin is stored in platelets,⁴⁶ and platelets secrete serotonin upon activation, leading to platelet aggregation and coronary vasoconstriction.⁴⁷ There is increased sensitivity of platelets to serotonergic activation in patients with depression.⁴⁶ However, selective serotonin reuptake inhibitors have been found to reduce platelet aggregation,⁴⁸ perhaps by blocking signaling pathways in the clotting response that are mediated by serotonin transporters.⁴⁹

A number of genetic factors may contribute to the connection between depression and CHD, although evidence is equivocal thus far. Recent research examining the 5-HTTLPR gene, a serotonin transporter gene promoter region finds that the short allele of this gene is associated with depressive symptoms and cardiac events.^42,50 Several other genes are also preliminary candidates for the link between depression and CHD. Single nucleotide polymorphisms in the gene for a clotting factor, the von Willebrand factor, are correlated with levels of depressive symptoms.⁵¹ In addition, linkage studies identify several loci shared by depression and CHD.⁵²

Reduced omega-3 levels may also link depression and CHD, though limited evidence is available. Patients with depression appear to have lower levels of serum omega-3 fatty acids, which are believed to be protective against CHD.⁴⁵ However, further studies are needed to determine whether omega-3 fatty acids have a causal role in the association between depression and CHD.

CLINICAL PRESENTATION

The clinical presentation of depression often differs in patients with CHD compared to medically healthy patients (Box 7-3). Patients with depression and CHD or a previous MI may be more likely to report the somatic symptoms of depression and less likely to report cognitive or affective symptoms.^53,54 Thus patients with depression and a recent MI had lower levels of cognitive/affective symptoms, including depressed mood, anhedonia, guilt, and concentration difficulties when compared to patients with depression and no MI, but had similar levels of somatic symptoms⁵⁵ including appetite/weight changes, sleep disturbances, psychomotor changes, and fatigue. Depressed patients with CHD may be more likely to report physical symptoms, such as shortness of breath and chest pain, and symptoms of irritability and anxiety.⁵ Some research indicates that somatic symptoms of depression are more predictive of cardiovascular mortality and recurrent MI than cognitive/affective symptoms, but other studies have not confirmed this.^53,56

Given the prominent somatic nature of depressive symptoms in CHD, it is often unclear to what degree these symptoms are due to depression itself and to what degree they result from CHD. Fatigue and sleep disturbance are the primary symptoms shared by depression and CHD.⁵ This overlap may make depression more difficult to identify in patients with CHD. Both patients and clinicians may attribute fatigue to the patient’s medical condition, leading clinicians to overlook the possibility of depression. Similarly, reduced activity level could be due either to impaired cardiovascular function, or to depressive anhedonia. To distinguish these symptoms of depression from symptoms of cardiovascular disease, it may be helpful to focus on the presence of cognitive symptoms of depression, such as hopelessness, difficulty concentrating, or suicidal ideation. Routine medical evaluation for causes of fatigue and sleep disturbance may also assist in determining the etiology of a patient’s somatic symptoms.

Qualitative studies have explored the emotional consequences of CHD. A recent study found that about half of male patients with depression and CHD felt that the two were related, and described feeling a loss of masculinity and shame over not being able to support their families financially.⁵⁷ In the year following an MI, about 25% of patients reported uncertainty about the future due to their medical condition and 20% reported reduced activity levels due to their cardiac condition.²⁰

Depression also affects the experience and reporting of cardiac symptoms, such as chest pain. Post-MI patients with depressive symptoms have increased rates of angina compared to post-MI patients without depressive symptoms.^35,58,59

Depression in CHD and following MI is associated with poorer quality of life, and greater physical limitations and disability.^35,60 Patients with post-MI depression have a four- to fivefold increase in rates of complete and partial disability compared to patients following MI without depression; this is true even after controlling for past history of depression and cardiac function.⁶¹ Depression is also associated with decrements in quality of life and lower satisfaction with cardiovascular care.⁵⁹

COURSE AND NATURAL HISTORY

Depressive symptoms seem to be highest during hospitalization for MI and in the month following MI,^20,35 and then begin to remit over time. Approximately 30% to 65% of cases of depression may remit by 1 month following MI.^35,62 One study with a longer follow-up period found that approximately 31% of patients with recurrent MI were depressed at baseline, of whom 62% continued to be depressed at the 6-month time point.²⁰

The preponderance of the evidence suggests that depression is associated with increased cardiovascular events and mortality in both patients with stable CHD and following MI.^18,22,63,64 Frasure-Smith and colleagues found that MDD was an independent risk factor for death within 6 months after MI.²² In outpatients with stable CHD, the Heart and Soul Study reported that depressive symptoms were correlated with a 31% higher rate of cardiovascular events over an average follow-up period of 5 years.¹⁸ A meta-analysis disclosed a twofold increase in mortality over a 2-year follow-up in depressed compared to nondepressed CHD patients (adjusted hazard ratio 1.76).⁶³ Although even mild levels of depressive symptoms may worsen outcome, the risk of mortality increases with severity of depression.⁶⁴ As noted, however, not all studies show an increase in mortality in patients with depression after MI.^62,65

Depression is also associated with an increased frequency of cardiac interventions following MI, such as cardiac catheterization and angioplasty.⁶² This may reflect a more complicated illness course or may result from higher reported symptom levels in patients with depression. Depression correlates with frequency of angina after MI³⁵ and frequency of chest pain is associated with increased risk of depression 1 year after MI.²⁵ The timing of depressive episodes is relevant for risk of recurrent cardiovascular events so that new-onset depressive episodes after MI may be particularly predictive of mortality and adverse cardiovascular events, whereas preexisting depression does not carry the same risk.^10,25,31,32 Patients whose first lifetime episode of MDD follows an MI may be at a greater risk of adverse cardiovascular outcomes than patients with a recurrent episode of MDD following MI.^66,67

Certain depressive symptoms are more associated with poorer cardiovascular prognosis. The somatic symptoms of depression, but not cognitive/affective symptoms, predict worse cardiovascular outcomes and mortality rates, but the significance of this association is unclear, because somatic symptoms may reflect the presence of more severe cardiac disease rather than more severe depression.^53,68,69 One study specifically reports that anhedonia predicts adverse cardiovascular outcomes even after controlling for severity of depressive symptoms, while depressed mood does not.⁷⁰

Adverse health-related behaviors, such as smoking, physical activity level, and medication adherence, may underlie some of the association between depression and poor outcomes in CHD (Figs. 7-5 and 7-6). When behavioral and biological risk factors for CHD are compared in depressed and nondepressed individuals, depressed patients differed more on behavioral risk factors than on biological risk factors.⁷¹

The interaction of smoking with depression and CHD has been closely examined. Depression is associated with increased rates of smoking and less success with smoking cessation in CHD patients¹⁹ as well as in healthy populations.^2,24,72

Depression is associated with lower levels of physical activity in both medically healthy populations^73,74 and patients with CHD,¹⁹ and levels of physical inactivity do contribute to the association between depression and recurrent cardiovascular events following MI.¹⁸ Depression also affects utilization of cardiac rehabilitation.^19,20,75 Persistently depressed patients with CHD are approximately 50% less likely to attend a cardiac rehabilitation program than nondepressed patients with CHD,¹⁹ and complete fewer sessions even when they do enroll.²⁰ Depression may also diminish the level of cardiovascular benefit from rehabilitation.⁷⁵ This suggests that modifiable behavioral factors, such as activity level, could influence rates of cardiovascular events in patients with depression.¹⁸

Medication adherence is also affected by depression and has itself been linked to the risk of rehospitalization and mortality rates. Patients with CHD and depression are significantly less likely to adhere to baby aspirin prophylaxis than nondepressed CHD patients.^76,77 In patients with stable CHD, the rate of medication noncompliance is 14% in those with MDD compared to 5% in those without MDD.⁷⁸

Depression may alter the CHD patient’s perception of his/her illness, generating increased feelings of hopelessness or pessimism about recovery. Such feelings may in themselves predict poorer cardiovascular outcomes. Thus hopelessness is an independent predictor of mortality from cardiovascular events even after adjusting for depression.⁷⁹ Men with high levels of hopelessness are twice as likely to have a first MI and nearly four times as likely to die of cardiovascular causes compared to men with low levels of hopelessness.⁷⁹ Similarly, some evidence suggests that pessimistic expectations about recovery and return to normal life after MI are associated with increased mortality rates, even after controlling for cardiovascular disease severity and depressive symptoms.⁸⁰

ASSESSMENT AND DIFFERENTIAL DIAGNOSIS

Differential diagnosis of depression in patients with CHD can be broad (Box 7-4). Medically, it includes hypothyroidism and other endocrine disorders, sleep disorders, nutritional deficiencies, and medication reactions. Among psychiatric disorders, the differential includes MDD, minor depression or subsyndromal depression, bipolar disorder, dementia, delirium, and personality disorders. Two other conditions that deserve special consideration are demoralization and adjustment disorders.

Demoralization is a syndrome of existential distress that occurs in patients facing medical illness. It includes feelings of hopelessness, helplessness, and a loss of meaning or purpose in life.⁸¹ Demoralization occurs in approximately 33% of cardiac patients, and frequently overlaps with major depression.⁸² It is distinguished from depression in that demoralized patients may experience happiness and pleasure in other aspects of their lives but feel unable to cope with their medical situation and uncertainty about their future.⁸¹ Adjustment disorders are also a common diagnosis in this medically ill population, and may be difficult to differentiate from depression. Adjustment disorders are characterized by an excessive or maladaptive response to a stressful life event, such as acute medical illness, and occur within 3 months of the stressor. Adjustment disorders are self-limited and resolve within 6 months of the stressor ending. Finally, individuals with adjustment disorders do not meet full criteria for a major depressive episode.

Routine depression screening is recommended in CHD patients,⁸³ and the American Heart Association recommends use of the Patient Health Questionnaire-2 (PHQ-2), an abbreviated form of the Patient Health Questionaire-9 (PHQ-9). This instrument has high sensitivity for depressive symptoms in cardiovascular disease although it lacks sensitivity for MDD.^42,84 The PHQ-2 consists of two questions: “During the past month, have you often been bothered by feeling down, depressed, or hopeless?” and “During the past month, have you often been bothered by little interest or pleasure in doing things?”.⁸⁵ If a patient answers “yes” to either question, follow-up with a more comprehensive screening tool, such as the PHQ-9 or diagnostic clinical interview is recommended. A PHQ-9 score of 10 or greater can be used as a basis for initiating depression treatment.⁸⁵ (See “Treatment of Depression in the Context of Cardiovascular Disease” below).

It may be helpful to initiate depression assessment with open-ended questions about the level of interest in daily activities and social engagement, as some patients may deny feeling depressed due to fear of stigmatization.⁵ Clinicians may also wish to guard against their tendency to consider a patient’s depressive symptoms as a natural and understandable response to medical illness, thereby overlooking the possibility of a treatable major depression. Primary care physicians may sometimes normalize clinical depression as a perfectly natural response to a serious medical condition, which can lead to reduced exploration and assessment of depression as a treatment target.⁸⁶

SUMMARY

The prevalence of depression is higher among individuals with CHD or following MI than in the general population. Depression is both a risk factor for the onset of CHD, and also a predictor of poorer cardiovascular outcomes in individuals with pre-existing CHD. The extent to which this association is explained by shared pathophysiology versus behavioral factors remains unclear. Among CHD patients with depression, those with depressive episodes preceding the onset of their CHD may differ from those with no prior history of depression; additional research is needed to compare the clinical characteristics and cardiovascular prognosis of these two groups. Further studies are also needed to identify the most efficacious treatments for depression in CHD.

EPIDEMIOLOGY

In congestive heart failure (CHF), the heart is unable to pump enough blood to meet the body’s demands. Currently, 5.7 million Americans are affected by CHF⁸⁷ and the prevalence is predicted to increase 25% over the next two decades as the population ages. Survival after heart failure diagnosis is improving; however, the mortality remains high and approximately 50% of heart failure patients die within 5 years of heart failure diagnosis.⁸⁸ Depression is a common comorbidity among CHF patients and carries important prognostic implications. Prevalence of depression in patients with CHF is between 9% and 60%, with an average of 21.5% in various studies.⁸⁹ Higher rates are reported in studies assessing depressive symptoms while lower rates are reported in patients assessed with a diagnostic clinical interview.⁸⁹

The incidence of depression in CHF increases with severity of heart failure, correlating with higher New York Heart Association (NYHA) functional class⁸⁹ and with proxy measures of illness severity, such as disability and lack of independence.⁹⁰ Depression is also more common in younger CHF patients, women, and in those with prior history of depression.⁹⁰ CHF increases the risk of developing new-onset depression, with health status and social factors, such as living alone and alcohol abuse contributing to this risk.⁹¹ Whether depression increases the risk of developing heart failure is less clear, though there may be some bidirectionality to this relationship. In patients 60 years or older with isolated systolic hypertension, depression is independently associated with development of heart failure over a 4.5-year follow-up.⁹² In elderly individuals free from heart failure at baseline, depression emerged as an independent risk factor for development of heart failure among women, but not among men, over a 14-year period.⁹³

PATHOPHYSIOLOGY

Potential mechanisms that link depression and CHF include autonomic nervous system dysfunction, inflammation, cardiac arrhythmias, hypercoagulability, and altered platelet functioning (Box 7-2). Sympathetic nervous system activation is increased in both major depression³⁶ and CHF,⁹⁴ norepinephrine levels are elevated in both conditions, and elevated plasma norepinephrine levels are an independent predictor of all-cause mortality in CHF.⁹⁴ Sympathetic activation from depression and heart failure may work synergistically to worsen outcome by increasing the risk for arrhythmia or sudden cardiac death. Little is known about whether treatment of depression reduces autonomic system dysfunction and impacts the course of CHF. In one trial, the antidepressant nefazodone not only improved depression scores, but reduced heart rate and plasma norepinephrine levels in patients with heart failure and depression.⁹⁵ In another trial, short-term treatment with sertraline significantly decreased norepinephrine appearance rates, correlating with a decrease in sympathetic nervous system activity.⁹⁶

The hypothalamic-pituitary-adrenal (HPA) axis is another potential link between depression and heart failure. Elevated levels of the adrenal hormones cortisol and aldosterone are associated with heart failure progression and are independent predictors of death in heart failure patients.⁹⁷ Increased activation of the HPA axis occurs in depression, and thus elevated levels of these adrenal hormones in patients with depression and heart failure may result in greater severity of CHF and worsened outcomes.

Inflammatory cytokines, including interleukin 1 beta (IL-1 beta), interleukin 6 (IL-6), and tumor necrosis factor alpha (TNF-alpha) are elevated in both depression and heart failure.^98–101 In heart failure, proinflammatory cytokines may initially play a beneficial role in cardiac remodeling, but when overexpressed, contribute to worsening of heart failure.¹⁰¹ It is unclear whether inflammation is a marker of depressed states or is a causal factor of depression. Depression may prospectively predict higher white blood cell count, which is a marker of systemic inflammation, in CHD patients.¹⁰²

Behavioral mechanisms likely play a significant role in the relationship of depression and heart failure. Medication adherence in heart failure is challenging, requiring a large number of medications to be taken multiple times a day. Patients with depression are at threefold higher risk for nonadherence with medication compared with nondepressed individuals.¹⁰³ Nonadherence in turn is associated with heart failure related hospitalization and is an independent risk factor for mortality.¹⁰⁴ Social supports also play a role, as family cohesion is positively associated with medication adherence¹⁰⁵ and patients with depression are less likely to have social supports. Depression is also associated with other adverse health-related behaviors, such as poor diet, physical inactivity, alcohol use, and tobacco use.

It has been suggested that there are areas of brain injury resulting from chronic heart failure that contribute to the pathogenesis of co-occurring depression. There appear to be differences in patterns of cerebral gray matter loss among patients with heart failure, including lateralized gray matter losses in the hippocampi, mammillary bodies, and frontal cortices.¹⁰⁶ Patients with heart failure and these patterns of gray matter loss were significantly more depressed and had poorer executive functioning than control subjects.¹⁰⁶

CLINICAL PRESENTATION

Depression is underrecognized in CHF patients (Box 7-3). This may relate to lack of comfort by nonmental health specialists in diagnosing depression, time constraints, lack of support for management and follow-up, belief that depression is a normative response to the illness, and diagnostic difficulties posed by the overlap of depressive and heart failure symptoms. Symptoms of fatigue, poor appetite, weight gain or loss, impaired concentration, and sleep disturbance are common features of both depression and heart failure. Patients who have both conditions report more physical symptoms than patients with heart failure who are not depressed. In a study of elderly patients with both heart failure and depression, 68% report a loss of appetite and 79% report sleeping difficulties, as compared with 40% and 51%, respectively, of patients with heart failure who were not depressed.¹⁰⁷ Although the risk of depression increases along with severity of heart failure, patients with advanced heart failure also experience a greater burden of physical symptoms as their illness progresses. Thus depression inventories with high proportions of somatic symptoms may have a lower specificity in patients with heart failure than other cardiac conditions.⁹⁰

Frequent psychiatric comorbidities in patients with heart failure include anxiety, panic disorder, alcohol abuse, and nicotine dependence. Anxiety and depression correlate highly with one another, with approximately 60% of depressed patients also having clinically significant levels of anxiety.¹⁰⁸ Rates of anxiety in CHF range from 20% to 54%,^108–110 with women having higher rates of anxiety than men.¹¹⁰ Panic disorder occurs in 9.3% of heart failure patients, of whom almost half have a comorbid depressive disorder. Although some studies show only depression predicts mortality in heart failure,¹⁰⁹ other studies suggest that anxiety is an independent risk, with the highest mortality risk carried by patients having both anxiety and depression.¹⁰⁸ Alcoholic cardiomyopathy is thought to be the cause of heart failure in 21% to 40% of patients with idiopathic dilated cardiomyopathy.^111,112 Although moderate consumption of alcohol is protective against heart failure, excessive alcohol intake is associated with cardiotoxicity. Mechanisms of alcoholic cardiomyopathy include myocyte loss, fibrosis, impaired cardiac contractility, altered calcium homeostasis, oxidative stress, and nutritional deficiencies. Alcohol use is common in depression, and in some individuals, may lead to a substance-induced depressive disorder. Alcohol use is associated with depression and unrecognized cognitive impairment in 58% of a population of veterans with CHF.¹¹³