This study investigates whether reduced syntactic complexity in speech is unique to schizophrenia spectrum disorder (SSD) or also present in major depressive disorder (MDD). Thirty-four SSD patients, 38 MDD patients, and 40 healthy controls described pictures. SSD patients showed significantly reduced syntactic complexity and diversity compared to MDD and control groups. Cluster analysis revealed four transdiagnostic clusters with varying syntactic complexity, with lower syntax associated with more severe psychopathology and poorer neuropsychological performance. Network analyses showed stronger associations between syntax, neuropsychology, and psychopathology in more complex speech.

Katharina Schneider, Katrin Leinweber, Hamidreza Jamalabadi, Lea Teutenberg, Katharina Brosch, Julia-Katharina Pfarr, Florian Thomas-Odenthal, Paula Usemann, Adrian Wroblewski, Benjamin Straube, Nina Alexander, Igor Nenadić, Andreas Jansen, Axel Krug, Udo Dannlowski, Tilo Kircher, Arne Nagels, Frederike Stein