Comorbidity in psychology refers to the presence of two or more distinct illnesses or disorders in an individual at the same time. These illnesses or disorders could be physical or mental. Comorbidity is a common phenomenon in mental health, where individuals with one type of mental disorder often develop other types of mental disorders across their lifespan. Comorbidity is defined in epidemiological terms as the relative risk of a person with one disorder to receive the diagnosis of another disorder. Comorbidities might include social anxiety, depression, and substance abuse, among others. Comorbidity psychology is when one or more diseases or conditions coexist in the same patient.