Just like with any mental health condition, people with depression or who are going through a depressive episode (also known as major or clinical depression) experience symptoms differently. But for most people, depression changes how they function day-to-day.
- Changes in sleep. Many people have trouble falling asleep, staying asleep or sleeping much longer than they used to. Waking up early in the morning is common for people with major depression.
- Changes in appetite. Depression can lead to serious weight loss or gain when a person stops eating or uses food as a coping mechanism.
- Lack of concentration. A person may be unable to focus during severe depression. Even reading the newspaper or following the plot of a TV show can be difficult. It becomes harder to make decisions, big or small.
- Loss of energy. People with depression may feel profound fatigue, think slowly or be unable to perform normal daily routines.
- Lack of interest. People may lose interest in their usual activities or lose the capacity to experience pleasure. A person may have no desire to eat or have sex.
- Low self esteem. During periods of depression, people dwell on losses or failures and feel excessive guilt and helplessness. Thoughts like “I am a loser” or “the world is a terrible place” or “I don’t want to be alive” can take over.
- Hopelessness. Depression can make a person feel that nothing good will ever happen. Suicidal thoughts often follow these kinds of negative thoughts—and need to be taken seriously.
- Changes in movement. People with depression may look physically depleted or they may be agitated. For example, a person may wake early in the morning and pace the floor for hours.
- Physical aches and pains. Instead of talking about their emotions or sadness, some people may complain about a headache or an upset stomach.
Depression does not have a single cause. It can be triggered, or it may occur spontaneously without being associated with a life crisis, physical illness or other risk. Scientists believe several factors contribute to cause depression:
- Trauma. When people experience trauma at an early age, it can cause long-term changes in how their brains respond to fear and stress. These brain changes may explain why people who have a history of childhood trauma are more likely to experience depression.
- Genetics. Mood disorders and risk of suicide tend to run in families, but genetic inheritance is only one factor. Identical twins share 100% of the same genes, but will both develop depression only about 30% of the time. People who have a genetic tendency to develop depression are more likely to show signs at a younger age. While a person may have a genetic tendency, life factors and events seem to influence whether he or she will ever actually experience an episode.
- Life circumstances. Marital status, financial standing and where a person lives have an effect on whether a person develops depression, but it can be a case of “the chicken or the egg.” For example, depression is more common in people who are homeless, but the depression itself may be the reason a person becomes homeless.
- Brain structure. Imaging studies have shown that the frontal lobe of the brain becomes less active when a person is depressed. Brain patterns during sleep change in a characteristic way. Depression is also associated with changes in how the pituitary gland and hypothalamus respond to hormone stimulation.
- Other medical conditions. People who have a history of sleep disturbances, medical illness, chronic pain, anxiety, and attention-deficit hyperactivity disorder (ADHD) are more likely to develop depression.
- Drug and alcohol abuse. Approximately 30% of people with substance abuse problems also have depression.