Occupational therapy guidelines - instruments for practice, teaching, and science. Improve practice, increase quality of care, save costs, and increase client satisfaction: The demands on therapeutic health professionals are high. Practice guidelines provide information and interventions that are systematic and evidence-based. Volume 4: People with serious mental illness. Diagnosis, functional impairment, and illness duration are typically the elements used to clarify the concept of a "serious mental illness." Classically, the following mental illnesses are classified as severe: schizophrenia and schizoaffective disorder, bipolar disorder, and major (unipolar) depression. For people with severe mental illness, methods that proceed from the approach of the recovery model are suitable. The occupational therapy H.