Depression
Depression is more than a temporary feeling of sadness; it is a disease. This mood disorder can arise seemingly unexpectedly due to a setback or personal loss, causing persistent feelings of sadness, worthlessness, hopelessness, helplessness, pessimism, or guilt.
During a depressive episode, a person experiences a depressed mood (sadness, irritability, emptiness) or a loss of interest in daily enjoyable activities for at least two weeks. Other symptoms may also be present, including difficulty concentrating, excessive guilt or low self-esteem, hopelessness about the future, thoughts of death or suicide, physical pain, sleep disturbances, changes in appetite or weight, and particularly fatigue or low self-esteem.
During depression, a person experiences significant difficulties in personal, family, social, educational, occupational, and/or other important areas of functioning.
A depressive episode can be classified as mild, moderate, or severe, depending on the number and severity of symptoms, as well as the impact on the person’s functioning.
Mood disorders have various patterns, including:
- Single episode depressive disorder: This means the person’s first and only episode.
- Recurrent depressive disorder: This means the person has had at least two depressive episodes.
- Bipolar disorder: This means depressive episodes alternate with periods of manic symptoms, which include euphoria or irritability, increased activity or energy, and other symptoms such as increased talkativeness, racing thoughts, heightened self-esteem, decreased need for sleep, distractibility, impulsiveness, and reckless behavior.
What causes depression?
There is no single answer to what causes depression. Rather, it likely results from a combination of genetic, biological, environmental, and psychological factors. Negative experiences such as trauma, the loss of a loved one, a difficult relationship, or any stressful situation that exceeds one’s coping abilities can trigger a depressive episode. Subsequent depressive episodes may occur with or without an obvious trigger.
However, depression is not an inevitable consequence of negative life events. Research increasingly shows that mood declines only when such events trigger negative thinking patterns, especially about oneself.
Studies using brain imaging technologies, such as magnetic resonance imaging (MRI), show that the brains of people with depression look different. Specifically, the parts of the brain responsible for regulating mood, thinking, sleep, appetite, and behavior appear to function abnormally. It is unclear which changes visible in the brain might be the cause of depression and which are the result.
Some types of depression tend to run in families, suggesting that there may be a genetic predisposition to the disorder.
Variations of depression
Depression symptoms can vary greatly among individuals. While one person with depression may experience sadness, hopelessness, and helplessness, another may feel angry, irritable, and frustrated.
Depression symptoms can seem like personality changes (such as irritability in situations that previously did not cause irritation). The symptoms can also change over the course of the illness (from sadness to anger and irritability).
When depression is severe, people may experience psychotic symptoms (hallucinations and delusions). Hallucinations are sensations that seem real but are not caused by actual things in the environment. Hallucinations can occur in any sensory modality (including vision, hearing, taste, smell, and touch) and can be very convincing. The most common form of hallucination is auditory, involving hearing voices of people who are not actually present.
Delusions are very strongly held false beliefs that cause a person to misinterpret events and relationships. They can vary widely. One might feel that someone is spying on or following them, that television shows contain special messages, or that some part of their body has changed or is injured. There can also be religious beliefs or the belief that one is famous.
When someone is depressed and has psychotic symptoms, the content of the hallucinations and delusions is usually consistent with the depressed mood and focuses on themes of guilt, personal inadequacy, or illness.
For example, people with depression may truly believe they are incapable of performing their job or parental duties because they are inadequate (a feeling that may be reinforced by voices telling them they are inadequate) and that everyone is laughing at them. A depressive episode with psychotic symptoms can be particularly problematic because the person may lose the ability to distinguish between real and imagined experiences.
How common is depression?
According to the World Health Organization, depression is a common illness worldwide, affecting an estimated 3.8% of the population, including 5.0% of adults and 5.7% of adults over 60 years old. Approximately 280 million people worldwide have depression. Depression differs from usual mood fluctuations and short-term emotional responses to challenges in everyday life. Especially when recurrent and with moderate or severe intensity, depression can become a serious health condition. It can cause significant suffering and impaired functioning at work, school, and within the family. At its worst, depression can lead to suicide. More than 700,000 people die by suicide every year. Suicide is the fourth leading cause of death among 15-29 year-olds.
