Depression is a serious medical condition that affects emotions, thoughts, and actions. It can result from alcohol and drug abuse, serious physical and mental illnesses, lack of social support, close friendships, lack of good coping skills in dealing with stress or ongoing problems or conflicts, among many others. It can affect anyone at any age. Symptoms vary from mild to severe, but usually includes feelings of sadness, tearfulness, emptiness or hopelessness; loss of interest or pleasure in activities once enjoyed; insomnia or sleeping too much; severe tiredness and lack of energy to perform even the smallest tasks; suicidal thoughts and suicide attempts; reduced appetite and weight loss; increased food and weight gain; angry outbursts, irritability or frustration, even over small matters; trouble thinking, concentrating, making decisions and remembering things. Depression also manifests as physical symptoms, such as moving or speaking slower than usual, unexplained aches and pains, constipation, and changes in menstrual cycle. Symptoms must persist for a minimum of two weeks before it is considered clinical depression or major depressive disorder. The risk factors of depression are many, such as biochemistry (chemicals in the brain), genetics, personality (people with low self-esteem, easily overwhelmed by stress, or are generally pessimistic), and environmental factors (excessive exposure to violence, neglect, abuse or poverty). Diagnosis is done by a health professional who conducts an interview, a physical examination, and in some cases a blood test to rule out underlying health conditions. Medication is usually an antidepressant drug, over a long-term period. Psychotherapy (talk therapy) is also used to depression, and sometimes used in combination with antidepressant medications. The types of psychotherapy used are Cognitive behavioral therapy (CBT) - aims to change patterns of thinking or behavior that causes people emotional difficulties. The number of therapy sessions required depends on the severity of the depression; Electroconvulsive Therapy (ECT) - for people with severe major depression who have not responded to other treatments, involving brief electrical stimulation of the brain while the patient is under anesthesia. A patient typically receives ECT two to three times a week for a total of six to 12 treatments.