The psychological disorder that is characterized by extreme alterations in thoughts, perceptions, and consciousness is schizophrenia.
Schizophrenia is a severe mental disorder that affects how a person thinks, feels, and behaves. People with schizophrenia may experience a range of symptoms, including delusions (false beliefs), hallucinations (seeing or hearing things that aren't there), disordered thinking, and altered perceptions of reality. They may also experience disruptions in their emotions, motivation, and ability to communicate effectively.
While bipolar disorder, obsessive-compulsive disorder, and depressive disorder can also involve alterations in thoughts and emotions, schizophrenia is the disorder that is most strongly associated with extreme alterations in thoughts, perceptions, and consciousness.