Schizophrenia. National Alliance on Mental Illness. https://www.nami.org/About-Mental-Illness/Mental-Health- Conditions /Schizophrenia. Accessed Jan. 18, 2024. What is schizophrenia? American Psychiatric Association. https://www.psychiatry.org/patients-families/schizophrenia/what-is-schizophrenia. Accessed Jan. 18, 2024. Schizophrenia. Explore comprehensive guides on hundreds of common and rare diseases and conditions from the experts at Mayo Clinic. Mental illness, also called mental health disorders, refers to a wide range of mental health conditions — disorders that affect your mood, thinking and behavior. Chronic conditions may increase the risk of influenza complications. Examples include asthma and other lung diseases, diabetes, heart disease, and nervous system diseases.