Abstract
Thought disorder (TD) is one of the main symptom domains of schizophrenia. TD is a construct that can be seen in both acute and chronic periods in patients with schizophrenia. It is associated with a poor prognosis and relapses, and it disrupts social-occupational functioning. TD also shows a strong familial aggregation and increases the risk of transition to schizophrenia in subjects with ultra-high risk. Although TD was once thought to be pathognomonic to schizophrenia, now it is known that it is a transdiagnostic symptom that is seen not only in schizophrenia but also in other psychiatric disorders. This article reviews the concept of thought disorder in terms of its history, clinical evaluation, neurocognitive features and clinical course in patients with schizophrenia.