ABSTRACT Background Schizophrenia is characterized by positive symptoms, negative symptoms, and cognitive impairment and is primarily treated with antipsychotic medications. However, a subset of patients responds inadequately to treatment and is classified as having treatment‐resistant schizophrenia (TRS). The prevalence of TRS among patients with schizophrenia remains insufficiently characterized. This study aimed to determine the prevalence of TRS using nationwide data and standardized diagnostic criteria. Methods This study included patients with schizophrenia who were discharged between 2016 and 2024 from 205 institutions participating in the Effectiveness of Guidelines for Dissemination and Education in Psychiatric Treatment (EGUIDE) project and authorized to prescribe clozapine. TRS was defined according to standardized diagnostic criteria used in Japan. The prevalence of TRS was calculated among patients who underwent a TRS examination by their treating psychiatrist. Results Among 18 914 patients, 9870 (52.2%) underwent a TRS examination. Among these 9870 patients, 2819 were classified as having TRS, corresponding to a prevalence of 28.6%. Among the 2819 patients with TRS, 1307 were prescribed clozapine at discharge, corresponding to a clozapine treatment rate of 46.4%. Conclusions This study had the largest sample size among single‐cohort studies investigating the prevalence of TRS. The prevalence of TRS was 28.6% among patients with schizophrenia who underwent a TRS examination and was nearly identical to the pooled prevalence reported in studies at low risk of bias in a previous meta‐analysis. These findings may provide important evidence regarding the prevalence of TRS in routine clinical practice.
Introduction Atypical auditory processing is a core characteristic of autism spectrum disorder (ASD), potentially stemming from disrupted thalamocortical circuits and frontal modulation. This study investigated whether individual differences in cortical microstructure, as measured by neurite orientation dispersion and density imaging, are associated with auditory brainstem responses (ABR) and whether these ABR measures are associated with autism traits and atypical sensory processing. Methods We recruited 15 adults with ASD (9 males, 6 females; mean age 26.9 ± 6.7 years) and 12 typically developing controls (12 males; mean age 37.1 ± 8.0 years) and assessed microstructural properties in the thalamus, temporal cortex, and orbitofrontal cortex (OFC). Auditory processing was evaluated via ABR recorded under forward-masking conditions. Results In this preliminary, exploratory analysis, mediation models suggested that the amplitude of wave PVII mediated the association between the orientation dispersion index in the temporal cortex and autism traits, as measured by the Autism-Spectrum Quotient. Similarly, the ΔVI amplitude (peak-to-peak potential between NVI and PVI) mediated the relationship between the neurite density index in the OFC and atypical sensory behaviors, assessed using the Adolescent/Adult Sensory Profile. In the ASD group, reduced PVII amplitude was linked to difficulties in attention switching and imagination, while increased ΔVI amplitude was associated with sensory avoidance. Discussion/conclusion Our preliminary and exploratory findings tentatively suggest that microstructural variability in the temporal cortex and OFC may relate to auditory neural responses and to sensory and cognitive features of ASD. However, given the small and demographically imbalanced sample, these results should be regarded as hypothesis-generating rather than confirmatory. These candidate brain–behavior pathways should be tested in larger, demographically matched cohorts before any mechanistic interpretation regarding sensory dysfunction in autism can be drawn.
N. Kashida, Kazuhiko Yamamuro, K. Matsuoka et al.· Frontiers in Psychiatry· 0 citations
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