Chapter 5: Mood Disorders

INTRODUCTION

Depression in the general population is a major public health problem, its most severe form (major depression [MDD]) affecting almost 7% of American adults.¹ Depressive spectrum disorders are sufficiently common in oncology that clinicians of all specialties working in the field can expect to encounter patients with presentation of these states on a daily basis. Because of the negative emotional valence associated with cancer, depression may be overlooked or ignored as a "normal" consequence of the cancer experience, not requiring or unlikely to respond to treatment (therapeutic nihilism).² Depressive disorders adversely affect quality of life and appear to increase medical morbidity and symptom burden in cancer patients.^3,4,5 Depression predicts desire for hastened death in terminally ill patients, as does hopelessness.⁶ There is increasing evidence that depression predicts early mortality from malignancy, although some studies have not found this to be the case.^{7,8,9,10,11,12} Familiarity with differential diagnosis and treatment options for depressive disorders is an essential component of comprehensive care and can do much to palliate emotional distress of patients and caregivers. Diagnosis and treatment of mood disorders can be time intensive and thus potentially problematic for clinicians with busy practices or with understandable preoccupation with therapeutic decisions or focus on more acute symptoms (ie, pain, dyspnea). However, to the extent that depressive states interfere with or complicate treatment, identification and treatment of symptoms could also make care more efficient and, possibly, less stressful for clinicians.

Diagnosis of depression in oncology can be difficult. The term "depression" is nonspecific, with meanings ranging from a nonpathological emotional state common to everyday experience to so-called "reactive depressions" (adjustment disorders [AD]), to a formally defined neuropsychiatric disorder with possible organic and/or "functional" etiologies (major depressive disorder). Here we focus on the most significant depressive spectrum disorders: AD and MDD, the former being the most common presentations that clinicians will encounter.¹³ Patients so affected will experience troubling persistent dysphoria or anhedonia (most likely to bring them to attention and most obviously associated with the term "depression") and may also experience thoughts of suicide and physical symptoms of consequence, including change in sleep patterns, appetite, fatigue, and cognitive function. Some symptoms of MDD are similar to those caused by malignant disease itself or its treatment. Currently there is much interest and increasing evidence to suggest that symptom clusters (ie, fatigue, anorexia, cognitive impairment, pain) common to oncology can have common biological (ie, inflammatory, neuroendocrine) etiologies.^14,15,16

Patients with mood disorders may also present with mania. Present in the general population at rates of about 2.5%, patients with symptoms of mania present with elevated, expansive, or irritable mood, speech that is rapid to the point of being pressured, racing thoughts, grandiosity, decreased need for sleep, variable psychomotor agitation, and impulsivity or poor judgment resulting in risk-taking behaviors.^1...