Gesture Impairments in Schizophrenia: Distinct Roles of Negative Symptoms and Formal Thought Disorder

Background and Hypothesis Gesture impairments are increasingly recognized as a core feature of schizophrenia, apparent across different domains and gesture categories. However, the potential differential effects of specific symptom domains on distinct types of gestures are unknown. The current study aimed to investigate whether specific domains of negative symptoms (NS) and formal thought disorder (FTD) relate to different aspects of gesture performance in patients with schizophrenia. Study Design Gesture accuracy was assessed using the well-established test of upper limb apraxia, which examines performance across 2 domains and 3 semantic categories in 87 patients with schizophrenia and 57 age- and gender-matched controls. Further, we used standardized clinical rating scales to assess NS and FTD across their different subdomains. Study Results Patients performed worse than controls in both domains and all gesture categories. Further, both NS and FTD were associated with gesture impairments, yet the associations were distinct. Negative symptoms, particularly avolition and affective flattening, as well as Objective Negative FTD, were specifically linked to reduced performance of pantomime meaningless gestures. Conversely, Objective Positive FTD was associated with a broader range of gesture deficits, impacting both imitation and pantomime domains, including intransitive and transitive gestures. Conclusions Our findings reveal that gesture impairments in schizophrenia vary across distinct symptom domains, indicating that NS and FTD contribute differently to motor and cognitive dysfunctions suggesting different underlying neural mechanisms. These insights can guide targeted interventions to address specific gesture deficits based on underlying psychopathology.