Exploring the dimensional structure of the Thought and Language Disorder scale in acute psychiatric inpatients

To explore the dimensional structure of the Thought and Language Disorder scale (TALD) in a sample of acute psychiatric inpatients and to contribute to a characterization of the latent dimensions underlying formal thought disorder (FTD).

A total of 250 acute patients with psychotic and affective disorders were assessed at admission using the TALD. Exploratory factor analysis (EFA) with minimum residual extraction and promax rotation was conducted, followed by second-order EFA and Schmid-Leiman orthogonalization to evaluate the hierarchical organization of FTD.

Hierarchical EFA identified four first-order factors, Thought Disorganization, Schizophasia, Objective Negative FTD, and Subjective Negative FTD, accounting for 48.6% of the total variance. These factors converged into two higher-order dimensions representing Positive and Negative FTD. The second-order factors accounted for the largest proportion of common variance (64%). However, items loading on Schizophasia (h²_1st = 0.317; h²_2nd = 0.265) and Objective Negative FTD (h²_1st = 0.297; h²_2nd = 0.284) retained a substantial proportion of first-order specific variance.

While largely supporting the original TALD structure, two major differences emerged: Thought Disorganization and Schizophasia constituted two distinct yet correlated dimensions within the broader Positive FTD domain, whereas no independent Subjective Positive factor was identified. This may partly reflect the highly acute patient sample. These findings support a hierarchical conceptualization of FTD and the distinction of Positive FTD into two subdomains, which may help clarify the dimensional structure underlying FTD.