Depression is a state of low mood and aversion to activity that can have a negative effect on a person’s thoughts, behaviour, feelings, world view and physicalwell-being. Depressed people may feel sad, anxious, empty, hopeless, worried, helpless, worthless, guilty, irritable, hurt or restless. They may lose interest in activities that once were pleasurable, experience loss of appetite or overeating, have problems concentrating, remembering details, or making decisions and may contemplate or attempt suicide. Insomnia, excessive sleeping, fatigue, loss of energy, or aches, pains or digestive problems that are resistant to treatment may also be present.
Depressed mood is not necessarily a psychiatric disorder. It is a normal reaction to certain life events, a symptom of some medical conditions and a side effect of some medical treatments. Depressed mood is also a primary or associated feature of certain psychiatric syndromes such as clinical depression.
Certain medications are known to cause depressed mood in a significant number of patients. These include Hepatitis C drug therapy and some drugs used to treat high blood pressure, such as beta-blockers or reserpine.
Depressed mood can be the result of a number of infectious diseases and physiological problems including hypoandrogenism (in men), Addison’s disease, Lyme disease, multiple sclerosis, sleep apnea and disturbed circadian rhythm. It is often one of the early symptoms of hypothyroidism (reduced activity of the thyroid gland). Chronic pain causes depression. For a discussion of non-psychiatric conditions that can cause depressed mood, see Depression (differential diagnoses).
A number of psychiatric syndromes feature depressed mood as a main symptom. The mood disorders are a group of disorders considered to be primary disturbances of mood. These include major depressive disorder (MDD; commonly called major depression or clinical depression) where a person has at least two weeks of depressed mood or a loss of interest or pleasure in nearly all activities; and dysthymia, a state of chronic depressed mood, the symptoms of which do not meet the severity of a major depressive episode. Another mood disorder, bipolar disorder, features one or more episodes of abnormally elevated energy levels, cognition and mood, but may also involve one or more depressive episodes. When the course of depressive episodes follows a seasonal pattern, the disorder (major depressive disorder, bipolar disorder, etc.) may be described as a seasonal affective disorder.
Outside the mood disorders: borderline personality disorder commonly features depressed mood; adjustment disorder with depressed mood is a mood disturbance appearing as a psychological response to an identifiable event or stressor, in which the resulting emotional or behavioral symptoms are significant but do not meet the criteria for a major depressive episode; and posttraumatic stress disorder, an anxiety disorder that sometimes follows trauma, is commonly accompanied by depressed mood.
Main article: Rating scales for depression
A full patient medical history, physical assessment and thorough evaluation of symptoms helps determine the cause of the depression. Standardized questionnaires can be helpful such as the Hamilton Rating Scale for Depression, and the Beck Depression Inventory.
A doctor generally performs a medical examination and selected investigations to rule out other causes of symptoms. These include blood tests measuring TSHand thyroxine to exclude hypothyroidism, basic electrolytes and serum calcium to rule out a metabolic disturbance and a full blood count including ESR to rule out a systemic infection or chronic disease. Adverse affective reactions to medications or alcohol misuse are often ruled out, as well. Testosterone levels may be evaluated to diagnose hypogonadism, a cause of depression in men. Subjective cognitive complaints appear in older depressed people, but they can also be indicative of the onset of a dementing disorder, such as Alzheimer’s disease.Cognitive testing and brain imaging can help distinguish depression from dementia. A CT scan can exclude brain pathology in those with psychotic, rapid-onset or otherwise unusual symptoms. No biological tests confirm major depression. Investigations are not generally repeated for a subsequent episode unless there is a medical indication.
Depression in young adults
Depression in young adults is a common health problem and a growing public concern. In 2006, 1 in 20 U.S. adults had experienced a major depressive episode with severe impairment. The Center for Disease Control and Prevention (CDC) reported that among ages 18–24, 2.8% met the criteria for major depression, 8.1% met the criteria for other depression (DSM-IV category Depressive Disorder, Not Otherwise Specified – minor or subthreshold depression, or Dysthymia) and 10.9% met the criteria for current depression. Forty-four percent of American college students report feeling symptoms of depression. This data suggests that traditional college aged students may be at high risk for depression or depressed mood.
Each year 44 colleges and universities use random sampling to administer the American College Health Association’s (ACHA) National College Health Assessment (NCHA) survey to 28,000 students. This assessment surveys students’ health status and behavior, including depression and depressive symptoms, for their previous academic year. Based on the findings, the rates of students reporting having been diagnosed with depression have increased from 10% in 2000 to 21% in 2011. In 2011, female students reported depressive symptoms, including 22% feeling that things were hopeless, 23% feeling lonely and 26% feeling very sad within the preceding two weeks to 21% in 2011. Women are at higher risk than men to experience depression.
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