# Psychotherapy Process Dynamics and Their Relation to Treatment Success Do Not Differ Across Diagnoses

## TL;DR

Psychotherapy process dynamics and their link to treatment success are similar across depression, PTSD, dissociative disorders, and personality disorders.

## Contribution

This study shows that psychotherapy process dynamics and their relation to improvement are consistent across different psychiatric diagnoses.

## Key findings

- Psychotherapy process dynamics like variability and instability do not differ significantly between patients with different diagnoses.
- Clinical improvement is linked to rising positive emotions, mindfulness, insight, and motivation, with decreasing variability.
- High-frequency monitoring can track recovery progress in a transdiagnostic way.

## Abstract

Psychotherapy process research increasingly uses intensive longitudinal monitoring to capture dynamic patterns of change in patients. In this study, 283 psychiatric inpatients diagnosed with depression (n = 70), PTSD (n = 148), dissociative disorders (n = 26) or personality disorders (n = 39) completed the Therapy Process Questionnaire each evening over an average of 81.5 days per patient, yielding a total of 23,074 assessment days. We computed eight dynamic process characteristics, including variability, autocorrelation, instability and complexity, for each TPQ scale, both on average per patient and in a moving‐window approach. Then, the diagnostic groups were compared via one‐way ANOVAs with Bonferroni–Holm correction. No significant differences emerged across diagnoses in any average process characteristics or their change over time, indicating that idiosyncratic within‐person process dynamics overshadow diagnostic distinctions. Further, patients' clinical improvement was associated with rising mean levels and declining variability in positive emotions, mindfulness, insight and motivation. Again, these predictions of improvement were not moderated by patients' diagnoses. Our results support a transdiagnostic approach to measurement‐based care that leverages individual process characteristics to guide interventions, rather than relying on diagnostic categories to predict therapy trajectories.

Day‐to‐day psychotherapy process dynamics (e.g., variability, instability and complexity) do not differ meaningfully between inpatients with depression, PTSD, dissociative or personality disorders.Across all diagnoses, clinical improvement was associated with increasing mean levels and decreasing variability of positive emotions, mindfulness, insight and motivation for change.High‐frequency routine monitoring with the Therapy Process Questionnaire can be used in everyday practice to track both levels and fluctuations in these processes, providing early indications of whether a patient is moving toward recovery or remaining unstable.Since process–outcome relations did not differ across diagnostic groups, measurement‐based, process‐focused care and feedback systems may be implemented in a largely transdiagnostic way.

Day‐to‐day psychotherapy process dynamics (e.g., variability, instability and complexity) do not differ meaningfully between inpatients with depression, PTSD, dissociative or personality disorders.

Across all diagnoses, clinical improvement was associated with increasing mean levels and decreasing variability of positive emotions, mindfulness, insight and motivation for change.

High‐frequency routine monitoring with the Therapy Process Questionnaire can be used in everyday practice to track both levels and fluctuations in these processes, providing early indications of whether a patient is moving toward recovery or remaining unstable.

Since process–outcome relations did not differ across diagnostic groups, measurement‐based, process‐focused care and feedback systems may be implemented in a largely transdiagnostic way.