Exploring the interplay between language use and cognitive function in schizophrenia spectrum disorders: Insights from patients, first degree relatives, and healthy controls.

Background: For people with schizophrenia spectrum disorders (SSD), communication characterized by disrupted language use is common. However, the role of cognitive function in everyday language disruptions in SSD remains unclear. Family studies help control for confounding factors such as symptom burden, medication use and environment, offering insight into the interplay between language and cognition in SSD. Study design: We examined linguistic features in naturalistic speech from 176 individuals (51 with SSD, 77 first-degree relatives [50 parents, 27 siblings], and 48 healthy controls). Tasks included conversations, picture descriptions, story narration, reading and recall. We assessed cognitive domains: attention, verbal/visual memory, working memory, executive function, processing speed, motor dexterity, and theory of mind. We then studied associations between cognition and language. Results: Different patterns emerged across groups. In controls, longer speech and fewer pronouns were linked to better cognition. In SSD, greater adposition use and fewer pronouns related to better memory, executive function, and IQ. Among parents, more coordinating conjunctions during narration correlated with better visual memory and motor dexterity. Siblings showed the strongest, broadest associations: better cognition predicted richer language and fewer pronouns, especially tied to global and motor function. Story narration revealed the richest cognitive-linguistic links. Conclusions: In people with SSD and their relatives, specific cognitive deficits are reflected in everyday speech, regardless of content. These findings highlight the role of discourse context in shaping language-cognition relationships and support future research using language markers in psychosis.