Depression (major depressive disorder) is a common and serious mental disorder. It involves a depressed mood or loss of pleasure or interest in activities for long periods of time. Depression is different from regular mood changes and feelings about everyday life.

Common Types of Depression

• Major Depressive Disorder (MDD)

When people use the term clinical depression, they are generally referring to major depressive disorder (MDD). Major depressive disorder is a mood disorder characterized by a number of key features: 1. Depressed mood 2. Lack of interest in activities normally enjoyed 3. Changes in weight 4. Changes in sleep 5. Fatigue 6. Feelings of worthlessness and guilt

• Persistent Depressive Disorder (PDD)

Dysthymia, now known as persistent depressive disorder, refers to a type of chronic depression present for more days than not for at least two years. It can be mild, moderate, or severe. People might experience brief periods of not feeling depressed, but this relief of symptoms lasts for two months or less. While the symptoms are not as severe as major depressive disorder, they are pervasive and long-lasting. PDD symptoms include: 1. Feelings of sadness 2. Loss of interest and pleasure 3. Anger and irritability 4. Feelings of guilt 5. Sleeping too much

• Bipolar Disorder

Bipolar disorder is a mood disorder characterized by periods of abnormally elevated mood known as mania. These periods can be mild (hypomania) or they can be so extreme as to cause marked impairment with a person's life, require hospitalization, or affect a person's sense of reality. The vast majority of those with bipolar disorder also have episodes of major depression. In addition to depressed mood and markedly diminished interest in activities, people with depression often have a range of physical and emotional symptoms which may include: 1. Fatigue, insomnia, and lethargy 2. Unexplained aches, pains, and psychomotor agitation 3. Hopelessness and loss of self-esteem

• Postpartum Depression (PPD)

Pregnancy can bring about significant hormonal shifts that can often affect a woman's moods. Depression can have its onset during pregnancy or following the birth of a child. Currently classified as depression with peripartum onset, postpartum depression (PPD) is more than that just the "baby blues." Mood changes, anxiety, irritability, and other symptoms are not uncommon after giving birth and often last up to two weeks. PPD symptoms are more severe and longer-lasting. Such symptoms can include: 1. Low mood, feelings of sadness 2. Severe mood swings 3. Social withdrawal 4. Trouble bonding with your baby 5. Thoughts of hurting yourself or your baby PPD can range from a persistent lethargy and sadness that requires medical treatment all the way up to postpartum psychosis, a condition in which the mood episode is accompanied by confusion, hallucinations, or delusions. If left untreated, the condition can last up to a year. Fortunately, research has found that treatments such as antidepressants, counseling, and hormone therapy can be effective.

• Premenstrual Dysphoric Disorder (PMDD)

Among the most common symptoms of premenstrual syndrome (PMS) are irritability, fatigue, anxiety, moodiness, bloating, increased appetite, food cravings, aches, and breast tenderness. PMDD symptoms may include: 1. Extreme fatigue 2. Severe feelings of stress or anxiety 3. Mood swings, often with bouts of crying 4. Irritability 5. Food cravings or binging

• Seasonal Affective Disorder (SAD)

If you experience depression, sleepiness, and weight gain during the winter months but feel perfectly fine in spring, you may have a condition known as seasonal affective disorder (SAD), currently called major depressive disorder with seasonal pattern. SAD is believed to be triggered by a disturbance in the normal circadian rhythm of the body. Light entering through the eyes influences this rhythm, and any seasonal variation in night/day pattern can cause a disruption leading to depression.

• Atypical Depression

Do you experience signs of depression (such as overeating, sleeping too much, or extreme sensitivity to rejection) but find yourself suddenly perking up in face of a positive event? Based on these symptoms, you may be diagnosed with atypical depression (current terminology refers to this as depressive disorder with atypical features), a type of depression that doesn't follow what was thought to be the "typical" presentation of the disorder. Atypical depression is characterized by a specific set of symptoms related to:

Risk Factors for Depression

• Biochemical

Differences in certain chemicals in the brain (such as the neurotransmiters serotonin, dopamine and norepinephrine) may contribute to symptoms of depression.

• Genetic

Depression can run in families. For example, if one identical twin has depression, the other has a 70 percent chance of having the illness sometime in life.

• Personality

People with low self-esteem, who are easily overwhelmed by stress, or who are generally pessimistic may be more likely to experience depression.

• Environmental

Continuous exposure to violence, neglect, abuse or poverty can also pose risks for developing depression.

Symptoms of depression

• Feeling sad, irritable, empty and/or hopeless.

• Losing interest or pleasure in activities you once enjoyed.

• A significant change in appetite (eating much less or more than usual) and/or weight (notable loss or gain unrelated to dieting).

• Sleeping too little or too much.

• Decreased energy or increased tiredness or fatigue

• Increase in purposeless physical activity (e.g., inability to sit still, pacing, handwringing)

• Slowed movements or speech that are severe enough to be observable by others.

• Feeling worthless or excessively guilty.

• Difficulty thinking or concentrating, forgetfulness, and/or difficulty making minor decisions.

• Thoughts of death, suicidal ideation, or suicide attempts.