Differential Associations Between Positive and Negative Formal Thought Disorder and Social Functioning in Schizophrenia

Formal thought disorder (FTD) is a core feature of schizophrenia characterized by disturbances in the form and organization of thought as reflected in speech and communication. While research has established that FTD is associated with impaired social functioning, previous work has treated FTD as a unitary construct, potentially obscuring important dimensional differences. Marggraf et al. (2020) conducted a comprehensive meta-analysis examining the relationship between FTD and social functioning in schizophrenia, finding a small-to-medium inverse correlation (r = -0.23, p < .001) across 13 studies. However, this foundational work combined all FTD manifestations without distinguishing between positive and negative dimensions. Positive FTD includes symptoms such as derailment, tangentiality, incoherence, and illogicality (manifestations characterized by an excess or distortion of normal thought processes. Negative FTD encompasses poverty of speech, poverty of content of speech, and alogia) representing a deficit or reduction in normal thought and verbal output. Given that broader negative symptoms of schizophrenia have more profound effects on functioning than positive symptoms, a similar dissociation may exist within FTD dimensions. Critically, unlike broader negative symptoms where construct overlap with social withdrawal and lack of motivation is inevitable, negative FTD features are conceptually distinct from functional outcomes, making this investigation particularly valuable for understanding independent contributions to disability.