Mental illnesses are medical conditions that disrupt a person's thinking, feeling, mood, ability to relate to others and daily functioning. There are many different conditions that are recognized as mental illnesses. Serious mental illnesses include major depression, schizophrenia, bipolar disorder, obsessive compulsive disorder (OCD), panic disorder, post traumatic stress disorder (PTSD) and borderline personality disorder. The cause of mental disorders varies and in some cases it remains unclear. Genes and family history may play a role in mental illness. Life experiences may also be the reason. Other factors such as use of inappropriate drugs and medical conditions such as cancer may also increase the chance of getting mental illness. Mostly mental disorders are treatable. Psychotherapy and psychiatric medication are two major treatment options.