Yes. Mental illnesses are definable, diagnosable and treatable. In fact, psychiatry has a higher success rate than many other branches of medicine. For example, the treatment success rate is 85% for major depression; 80% for panic disorder and bipolar (manic depressive) illness; and 60% for schizophrenia. By contrast, success rates for common heart treatments, such as angioplasty and atherectomy, are only 41% and 52%.