Sudden Gains in Day-to-Day Change: Revealing Nonlinear Patterns of Individual Improvement in Depression

• Published in: Journal of consulting and clinical psychology 2020-02, Vol.88 (2), p.119-127
• Main Authors: Helmich, Marieke A, Wichers, Marieke, Olthof, Merlijn, Strunk, Guido, Aas, Benjamin, Aichhorn, Wolfgang, Schiepek, Günter, Snippe, Evelien
• Format: Article
• Language: English
• Subjects: Adult; Affect; Affective Disorders; Changes; Complaints; Depressive Disorder - diagnosis; Depressive Disorder - psychology; Depressive Disorder - therapy; Emotional disorders; Female; Health Complaints; Human; Humans; Major Depression; Male; Mental depression; Middle Aged; Questionnaires; Rating; Remission (Disorders); Remission (Medicine); Self evaluation; Severity; Severity (Disorders); Severity of Illness Index; Surveys and Questionnaires; Treatment; Treatment Outcome; Women
• ISSN: 0022-006X; 1939-2117
• DOI: 10.1037/ccp0000469

Objective: We examined individual overall trajectories of change and the occurrence of sudden gains in daily self-rated problem severity and the relation of these patterns to treatment response. Method: Mood disorder patients (N = 329, mean age = 44, 55% women) completed daily self-ratings about the severity of their complaints as a standard part of treatment, using the Therapy Process Questionnaire (TPQ). Per individual, the best-fitting defined (linear, log-linear, 1-step) trajectory was tested for significance: for change over time, and for specificity of the best-fitting trajectory. Two-hundred and three cases had ICD-10 Symptom Rating (ISR) depression scores posttreatment: a score ≤1 identified 114 treatment responders. Relation to response was examined for sudden gains and type of change trajectory. Results: 138 cases (42%) had a significant decrease in problem severity, of which 54 cases (16%) had a defined trajectory: 50 cases with one-step improvement, and 4 with a linear improvement in daily problem severity. Sudden gains occurred in 28% of the total sample, and within 58% of improvement patterns. Specifically, sudden gains occurred in 68% of significant 1-step trajectories and 25% of the linear cases. Sudden gains and nonspecific change trajectories were significantly more frequent for treatment responders. Conclusions: At the day-level, patterns of improvement are nonlinear for most patients. Sudden gains occur within various forms of overall change and are associated with treatment response. Clinically relevant improvements in depression occur both gradually and abruptly, and this finding allows for the possibility that the remission process functions according to dynamical systems principles. What is the public health significance of this article? Mapping individual changes in depressive problem severity with daily measurements during treatment reveals that most mood disorder patients show a nonspecific, nonlinear improvement trajectory overall, and clinically relevant jumps (sudden gains) occur as a part of the improvement process for most patients. This study shows that these patterns are related to treatment response, and thereby highlights the clinical relevance of monitoring the pattern of change in individual patients during treatment.