Do thoughts actually drive symptoms? Testing cognitive theories of posttraumatic stress with natural language processing in daily diaries

Cognitive theories are among the leading conceptualizations of posttraumatic stress disorder (PTSD). The core perspective shared by these theories is that distorted thinking (e.g., “no one can be trusted”) is involved in maintaining symptoms. However, the proximal mechanisms linking cognition and PTSD symptoms remains unclear due to two major methodological limitations: 1) lack of research on cognition-symptom dynamics at the daily level, and 2) reliance on self-reported thought distortions, which is a method ill-suited for capturing biases that people often do not have insight into or are outside of their awareness. The present study helps address these limitations in a sample of trauma-exposed patients (N=510) who completed daily video diaries and symptom ratings for 90 days (n=30,958 days). We used two natural language processing techniques to assess cognitive distortions from the diary transcripts: a lexica-based and large language model (LLM) approach. We then established the day-to-day sequencing of cognitive distortion and symptom fluctuations using dynamic structural equation models. Across the lexical and LLM models, distorted thinking did not predict worsening symptoms (bs=-.02–.01). Instead, worsening symptoms predicted more distorted thinking (bs=.03–.07). Also, symptoms and cognitive distortions tended to fluctuate together (bs=.08–.41). The current findings suggest that cognitive distortions do not precede PTSD symptoms as many theories have assumed, but may instead be a consequence or correlate of them. If replicated, our results could help refine cognitive and related models of PTSD.