Sleep and obesity-known interactions and open questions.

Patients with schizophrenia commonly exhibit impairments in executive function, which contribute substantially to poor functional outcome []. The Wisconsin Card Sorting Test (WCST) has been widely used to assess executive dysfunction in schizophrenia, particularly cognitive inflexibility, impaired rule maintenance, and perseverative responding [, ]. Importantly, successful WCST performance requires not only maintaining an abstract sorting rule but also continuously using feedback from recent trials to guide subsequent choices []. Thus, trial‐by‐trial adaptation to positive and negative feedback is a central cognitive process underlying WCST performance. Cognitive inflexibility is one of the most robust neuropsychological findings in schizophrenia, but schizophrenia is highly heterogeneous, and it remains unclear whether distinct cognitive phenotypes can be identified within this diagnostic category []. This question may be especially relevant in treatment‐resistant schizophrenia (TRS), a clinically important subtype associated with poorer clinical and functional outcomes as well as marked heterogeneity [, ]. Previous studies have suggested that patients with TRS may show greater neurocognitive impairment than those with non‐TRS []. However, most prior studies have evaluated WCST performance using conventional subject‐level summary indices, such as total errors, perseverative errors, or number of categories achieved [, ]. Although these aggregate measures capture overall task performance, they provide limited information about how patients dynamically adjust their behavior after recent success or failure. Therefore, a trial‐level analysis of WCST performance may capture cognitive alterations that are obscured by conventional summary measures. In particular, examining how the outcome of the immediately preceding trial influences the next response allows us to assess feedback‐guided behavioral adjustment during the WCST. In the present study, we examined whether recent trial outcome modulates subsequent responding differently between patients with TRS and non‐TRS.