According to the World Health Organization, depression is a common illness worldwide, with more than 264 million people affected. Depression is different from usual mood fluctuations and short-lived emotional responses to challenges in everyday life. Especially when long-lasting and with moderate or severe intensity, depression may become a serious health condition. It can cause the affected person to suffer greatly and function poorly at work, at school and in the family. At its worst, depression can lead to suicide. Close to 800 000 people die due to suicide every year. Suicide is the second leading cause of death in 15-29-year-olds.
Although there are known, effective treatments for mental disorders, between 76% and 85% of people in low- and middle-income countries receive no treatment for their disorder. Barriers to effective care include a lack of resources, lack of trained health-care providers and social stigma associated with mental disorders. Another barrier to effective care is inaccurate assessment. In countries of all income levels, people who are depressed are often not correctly diagnosed, and others who do not have the disorder are too often misdiagnosed and prescribed antidepressants. The burden of depression and other mental health conditions is on the rise globally. A World Health Assembly resolution passed in May 2013 has called for a comprehensive, coordinated response to mental disorders at the country level.
Types and symptoms
There are different types of depressive disorders, and while there are many similarities among them, each depressive disorder has its own unique set of symptoms.
Major Depressive Disorder
The most commonly diagnosed form of depression is Major Depressive Disorder. In 2015, around 16.1 million adults aged 18 years or older in the U.S. had experienced at least one major depressive episode in the last year, which represented 6.7 percent of all American adults. Depression is the leading cause of disability in the United States among people ages 15-44. View the NIMH website for statistics from the 2016 National Survey on Drug Use and Health
Major depression is characterized by at least five of the diagnostic symptoms of which at least one of the symptoms is either an overwhelming feeling of sadness or a loss of interest and pleasure in most usual activities. The other symptoms that are associated with major depression include decrease or increase in appetite, insomnia or hypersomnia, psycho motor agitation or retardation, constant fatigue, feelings of worthlessness or excessive and inappropriate guilt, recurrent thoughts of death and suicidal ideation with or without specific plans for committing suicide, and cognitive difficulties, such as, diminished ability to think, concentrate and take decisions. The symptoms persist for two weeks or longer and represent a significant change from previous functioning. Social, occupational, educational, or other important functioning is also impacted. For instance, the person may start missing work or school, or stop going to classes or their usual social activities.
Persistent depressive disorder (dysthymia)
Another type of depression is called Persistent depressive disorder (dysthymia). The essential feature of this mood disorder is a low, dark or sad mood that is persistently present for most of the day and on most days, for at least 2 years (children and adolescents may experience predominantly irritability and the mood persist for at least 1 year). For the individual to receive the diagnosis of persistent depressive disorder they should also have two of the diagnostic symptoms which include poor appetite or overeating, insomnia or hypersomnia, low energy or fatigue, low self-esteem, poor concentration, difficulty making decisions, or feelings of hopelessness. During this period, any symptom-free intervals last no longer than two months. The symptoms are not as severe as with major depression. Major depression may precede persistent depressive disorder, and major depressive episodes may also occur during persistent depressive disorder.
Premenstrual dysphoric disorder
Premenstrual dysphoric disorder is another manifestation of depression which is a severe and sometimes disabling extension of premenstrual syndrome (PMS). Although regular PMS and Premenstrual dysphoric disorder (PMDD) both have physical and emotional symptoms, the mood changes in PMDD are much more severe and can disrupt social, occupational, and other important areas of functioning. In both PMDD and PMS, symptoms usually begin seven to 10 days before the start of a menstrual period and continue for the first few days of the period. Both PMDD and PMS may also cause breast tenderness, bloating, fatigue, and changes in sleep and eating habits. PMDD is characterized by emotional and behavioral symptoms that are more severe, such as sadness or hopelessness, anxiety or tension, extreme moodiness, irritability or anger.
Recurrent depressive disorder
This disorder involves repeated depressive episodes. During these episodes, the person experiences depressed mood, loss of interest and enjoyment, and reduced energy leading to diminished activity for at least two weeks. Many people with depression also suffer from anxiety symptoms, disturbed sleep and appetite, and may have feelings of guilt or low self-worth, poor concentration and even symptoms that cannot be explained by a medical diagnosis.
Depending on the number and severity of symptoms, a depressive episode can be categorized as mild, moderate or severe. An individual with a mild depressive episode will have some difficulty in continuing with ordinary work and social activities but will probably not cease to function completely. During a severe depressive episode, it is unlikely that the sufferer will be able to continue with social, work or domestic activities, except to a limited extent.
Bipolar affective disorder
This type of depression typically consists of both manic and depressive episodes separated by periods of normal mood. Manic episodes involve elevated or irritable mood, over-activity, pressure of speech, inflated self-esteem and a decreased need for sleep.
Some medical conditions can trigger depressive symptoms in individuals. This is called depressive disorder due to another medical condition. Endocrine and reproductive system disorders are commonly associated with depressive symptoms. For example, people with low levels of the thyroid hormone (hypothyroidism) often experience fatigue, weight gain, irritability, memory loss, and low mood. When the hypothyroidism is treated it usually reduces the depression. Cushing’s syndrome is another hormonal disorder caused by high levels of the hormone cortisol which can also cause depressive symptoms. Other conditions that have been found to cause depression include conditions such as HIV/AIDS, diabetes, strokes, Parkinson’s disease etc.
Adjustment Disorder with Depressed Mood is diagnosed when symptoms of depression are triggered within 3 months of onset of a stressor. The stressor usually involves a change of some kind in the life of the individual which he/she finds stressful. Sometimes the stressor can even be a positive event such as a new job, marriage, or baby which is nevertheless stressful for the individual. The distress is typically out of proportion to the expected reaction and the symptoms cause significant distress and impairment in functioning. The symptoms typically resolve within 6 months when the person begins to cope and adapt to the stressor or the stressor is removed. Treatment tends to be time limited and relatively simple since some additional support during the stressful period helps the person recover and adapt.
Another type of depression is related to changes in the length of days or seasonality. This type of depression is called Seasonal affective disorder (SAD). People with SAD suffer the symptoms of a Major Depressive Disorder only during a specific time of year, usually winter. This appears to be related to the shorter days of winter, and the lack of sunlight in many parts of the country.
Contributing factors and prevention
Depression results from a complex interaction of social, psychological and biological factors. People who have gone through adverse life events (unemployment, bereavement, psychological trauma) are more likely to develop depression. Depression can, in turn, lead to more stress and dysfunction and worsen the affected person’s life situation and depression itself.There are interrelationships between depression and physical health. For example, cardiovascular disease can lead to depression and vice versa.
Prevention programmes have been shown to reduce depression. Effective community approaches to prevent depression include school-based programmes to enhance a pattern of positive thinking in children and adolescents. Interventions for parents of children with behavioural problems may reduce parental depressive symptoms and improve outcomes for their children. Exercise programmes for the elderly can also be effective in depression prevention.
Depression and Anxiety Disorders: Not the Same
Depression and anxiety disorders are different, but people with depression often experience symptoms similar to those of an anxiety disorder, such as nervousness, irritability, and problems sleeping and concentrating. But each disorder has its own causes and its own emotional and behavioral symptoms.
Many people who develop depression have a history of an anxiety disorder earlier in life. There is no evidence one disorder causes the other, but there is clear evidence that many people suffer from both disorders.