One-year follow-up of the effectiveness and mediators of cognitive behavioural therapy among adults with attention-deficit/hyperactivity disorder: secondary outcomes of a randomised controlled trial

Abstract

Abstract Background The long-term effectiveness of cognitive behavioural therapy (CBT) in medicated attention-deficit/hyperactivity disorder (ADHD) adults with residual symptoms needs to be verified across multiple dimensions, especially with respect to maladaptive cognitions and psychological quality of life (QoL). An exploration of the mechanisms underlying the additive benefits of CBT on QoL in clinical samples may be helpful for a better understanding of the CBT conceptual model and how CBT works in medicated ADHD. Methods We conducted a secondary analysis of a randomised controlled trial including 98 medicated ADHD adults with residual symptoms who were randomly allocated to the CBT combined with medication (CBT + M) group or the medication (M)-only group. Outcomes included ADHD-core symptoms (ADHD Rating Scale), depression symptoms (Self-rating Depression Scale), maladaptive cognitions (Automatic Thoughts Questionnaire and Dysfunctional Attitude Scale), and psychological QoL (World Health Organization Quality of Life-Brief Version-psychological domain). Mixed linear models (MLMs) were used to analyse the long-term effectiveness at one-year follow-up, and structural equation modeling (SEM) was performed to explore the potential mechanisms of CBT on psychological QoL. Results ADHD patients in the CBT + M group outperformed the M-only group in reduction of ADHD core symptoms (d = 0.491), depression symptoms (d = 0.570), a trend of reduction of maladaptive cognitions (d = 0.387 and 0.395, respectively), and improvement of psychological QoL (d = − 0.433). The changes in above dimensions correlated with each other (r = 0.201 ~ 0.636). The influence of CBT on QoL was mediated through the following four pathways: 1) changes in ADHD core symptoms; 2) changes in depressive symptoms; 3) changes in depressive symptoms and then maladaptive cognitions; and 4) changes firstly in depressive symptoms, maladaptive cognitions, and then ADHD core symptoms. Conclusions The long-term effectiveness of CBT in medicated ADHD adults with residual symptoms was further confirmed. The CBT conceptual model was verified in clinical samples, which would be helpful for a deeper understanding of how CBT works for a better psychological QoL outcome. Trial registration ChiCTR1900021705 (2019-03-05).