Depression, also known as major depressive disorder, is a common mental health disorder that can significantly impact an individual's quality of life. It is classified in the Diagnostic and Statistical Manual of Mental Disorders (DSM) as a mood disorder.

The signs and symptoms of depression can include persistent feelings of sadness, hopelessness, and emptiness, as well as a loss of interest or pleasure in activities that were once enjoyable. Individuals with depression may also experience changes in appetite and sleep patterns, fatigue, difficulty concentrating, feelings of worthlessness or guilt, and thoughts of self-harm or suicide.

Diagnosing depression typically involves a comprehensive evaluation by a mental health professional, who will assess the individual's history, symptoms, and any family history of mental health disorders. They may also use standardized rating scales to measure the severity of symptoms and impairment.

The causes of depression are complex and can involve a combination of genetic, environmental, and cultural factors. Imbalances in neurotransmitters such as serotonin, norepinephrine, and dopamine have also been linked to the development of depression. Environmental factors such as stress, trauma, or loss can trigger or worsen depressive symptoms.

Treatment for depression typically involves a combination of medication and therapy. Antidepressant medication, such as selective serotonin reuptake inhibitors (SSRIs) or serotonin-norepinephrine reuptake inhibitors (SNRIs), can be effective in reducing symptoms of depression. Psychotherapy, such as cognitive-behavioral therapy (CBT) or interpersonal therapy (IPT), can also be helpful in managing symptoms, improving coping skills, and addressing issues related to self-esteem and negative thought patterns.