Mental health, or the idea of being mentally healthy, is a broad and general concept that has to do with feeling well, thinking clearly, functioning well in life and tolerating the challenges and inevitable hard times that come along. A medical practitioner who specializes in mental health may treat any number of psychiatric conditions—anything from schizophrenia, bipolar disorder, depression, eating disorders to substance abuse. Practitioners often specialize further, working primarily with people struggling with addictions, for example. Certain addictions are understood as mental illnesses and classified as such by medical professionals. Just as a person may be diagnosed with more than one mental illness, such as depression and anxiety, many people who suffer from addictions may also meet criteria for additional diagnoses such bipolar disorder or post-traumatic stress disorder (PTSD). The mental health treatment that a person with multiple diagnoses receives needs to take into account the nature of each illness and the way in which the illnesses and treatments interact. Many addiction treatment facilities are staffed with both addiction and mental health specialists and interdisciplinary treatment teams commonly provide treatment. This means the client has someone who focuses on the addiction issues planning and implementing treatment along with a specialist who may help diagnose and treat underlying depression.