The truth is that there is no correlation between mental illness and violence. Sure, some disorders may make the sufferer irritable and easily angered because it may be difficult to cope with life's daily trials. When the patient is highly involved in the treatment, most mental illness can be dealt with in short order. Some may have to take medication the rest of their lives to keep the illness from recurring. This is similar to those who must take medication for their heart condition, or insulin for diabetes.
Mental illness is contagious.
Mental illness is not a communicable disease and cannot be transmitted from one person to another. Schizophrenics have multiple personalities. It's not true. Both deserve care and support, but clinical depression is an illness that needs medical and psychological treatment and support. Mental illnesses all stem from childhood trauma.