A mental illness is a diagnosable disorder with a standard set of criteria. It can be caused by factors like genes, brain chemistry or trauma. Anyone can have a mental illness, regardless of age, socioeconomic class, sex or race. These disorders can also be called mental health conditions.
Mental illnesses complicate mental health by affecting the way a person feels, thinks, acts or experiences the world. Different mental illnesses have different symptoms, some of which take effort to work through.