Over 70% of schizophrenia patients who are “treatment resistant” have apparently developed dopamine supersensitivity psychosis from long-term use of antipsychotic medications, according to a study in Psychiatry Research.
Researchers from Chiba University in Japan examined 611 patients from three hospitals, and identified 147 patients who met the criteria for “treatment-resistant schizophrenia” (TRS). Of these, they found that 106 (72.1%) seemed to have dopamine supersensitivity psychosis (DSP).
The researchers defined DSP in this way: “Briefly, the criteria focus on three factors as follows; (1) rebound psychosis, (2) developed tolerance to antipsychotic effect, (3) presence of TD [tardive dyskinesia]. If the patient experienced at least one of these three criteria at any time during the treatment, the patient was judged as the presence [sic] of DSP episode.”
“Of the DSP patients, 42% and 56% experienced rebound psychosis and tolerance to antipsychotic effects, respectively,” wrote the researchers. “The present study revealed that approximately 70% of TRS patients experienced one or more DSP episodes, which may have a strong impact on the long-term prognosis of patients with schizophrenia.”
Suzuki, Tomotaka, Nobuhisa Kanahara, Hiroshi Yamanaka, Masayuki Takase, Hiroshi Kimura, Hiroyuki Watanabe, and Masaomi Iyo. “Dopamine Supersensitivity Psychosis as a Pivotal Factor in Treatment-Resistant Schizophrenia.” Psychiatry Research 0, no. 0. Accessed April 10, 2015. doi:10.1016/j.psychres.2015.02.021. (Abstract)