Mechanisms of Change in Digital Health Interventions for Mental Disorders in Youth: Systematic Review

Background Digital health interventions (DHIs) are efficacious for several mental disorders in youth; however, integrated, evidence-based knowledge about the mechanisms of change in these interventions is lacking. Objective This systematic review aims to comprehensively evaluate studies on mediators and mechanisms of change in different DHIs for common mental disorders in children and adolescents. Methods A systematic literature search of the electronic databases Cochrane Central Register of Controlled Trials, Embase, MEDLINE, and PsycINFO was conducted, complemented by backward and forward searches. Two independent reviewers selected studies for inclusion, extracted the data, and rated the methodological quality of eligible studies (ie, risk of bias and 8 quality criteria for process research). Results A total of 25 studies that have evaluated 39 potential mediators were included in this review. Cognitive mediators were the largest group of examined intervening variables, followed by a broad range of emotional and affective, interpersonal, parenting behavior, and other mediators. The mediator categories with the highest percentages of significant intervening variables were the groups of affective mediators (4/4, 100%) and combined cognitive mediators (13/19, 68%). Although more than three-quarters of the eligible studies met 5 or more quality criteria, causal conclusions have been widely precluded. Conclusions The findings of this review might guide the empirically informed advancement of DHIs, contributing to improved intervention outcomes, and the discussion of methodological recommendations for process research might facilitate mediation studies with more pertinent designs, allowing for conclusions with higher causal certainty in the future.

Morphology of the Prefrontal Cortex Predicts Body Composition in Early Adolescence: Cognitive Mediators and Environmental Moderators in the ABCD Study

Morphological features of the lateral prefrontal cortex (PFC) in late childhood and early adolescence may provide important clues as to the developmental etiology of clinical conditions such as obesity. Body composition measurements and structural brain imaging were performed on 11,226 youth at baseline (age 9 or 10) and follow-up (age 11 or 12). Baseline morphological features of the lateral PFC were examined as predictors of body composition. Findings revealed reliable associations between mid-frontal gyrus volume, thickness and surface area and multiple indices of body composition. These findings were consistent across both time points, and remained significant after covariate adjustment. Cortical thickness of the inferior frontal gyrus and lateral orbitofrontal cortex were also reliable predictors. Morphology effects on body composition were mediated by performance on a non-verbal reasoning task. Modest but reliable moderation effects were observed with respect to environmental self-regulatory demand after controlling for sex, race/ethnicity, income and methodological variables. Overall findings suggest that prefrontal cortex morphology is a reliable predictor of body composition in early adolescence, as mediated through select cognitive functions and partially moderated by environmental characteristics.

Cognitive mediators of US—China differences in early symbolic arithmetic

Chinese children routinely outperform American peers in standardized tests of mathematics knowledge. To examine mediators of this effect, 95 Chinese and US 5-year-olds completed a test of overall symbolic arithmetic, an IQ subtest, and three tests each of symbolic and non-symbolic numerical magnitude knowledge (magnitude comparison, approximate addition, and number-line estimation). Overall Chinese children performed better in symbolic arithmetic than US children, and all measures of IQ and number knowledge predicted overall symbolic arithmetic. Chinese children were more accurate than US peers in symbolic numerical magnitude comparison, symbolic approximate addition, and both symbolic and non-symbolic number-line estimation; Chinese and U.S. children did not differ in IQ and non-symbolic magnitude comparison and approximate addition. A substantial amount of the nationality difference in overall symbolic arithmetic was mediated by performance on the symbolic and number-line tests.

An investigation of the efficacy and cognitive mechanisms of two brief interventions for anxiety sensitivity

Anxiety Sensitivity (AS) is the fear of normal, arousal-related bodily sensations due to the belief that they have negative consequences. AS is a transdiagnostic construct, and high AS is associated with psychopathology, including panic disorder, social anxiety disorder, generalized anxiety disorder, depression, and alcohol-use disorders. There is research and clinical interest in developing brief and transdiagnostic interventions to streamline treatment. Targeting AS through brief interventions may be one way to accomplish this goal. Therefore, the purpose of this dissertation was to advance the literature on AS by examining the efficacy and transdiagnosticity of two brief interventions for AS. Cognitive mediators of change in AS were also examined. Target variables were psychopathology symptoms and cognitive processes, including interpretation biases, attentional biases, and perceived control. Study 1 investigated the immediate and short-term efficacy of a brief intervention that included a single session of psychoeducation and daily interoceptive exposure practices. Participants with high AS were randomly assigned to the intervention (n = 19) or health education control condition (n = 16). Participants in the intervention condition appeared to demonstrate reductions in AS, one facet of interpretation bias, social anxiety symptoms, and motivation to consume alcohol. Methodological issues, however, limited conclusions about the efficacy of the intervention. Finally, the three potential cognitive mediators did not mediate change in AS. Study 2 investigated the efficacy of a computerized cognitive bias modification (CBM) program. Participants with high AS were randomly assigned to 4 sessions of CBM (n= 24) or 4 sessions of sham training (n= 24). Sessions occurred over a 2-week period. At the end of the intervention period, the CBM condition appeared to show reductions in AS, interpretive biases, and almost all facets of psychopathology. However, similar changes were found in the control condition. Again, the three potential cognitive mediators did not mediate change in AS. Taken together, these findings provide limited support for the efficacy of psychoeducation and CBM as brief, transdiagnostic interventions. However, both studies must be interpreted in light of major limitations, which include limited homework completion in Study 1 and a control training task that induced training effects in Study 2.

An investigation of the efficacy and cognitive mechanisms of two brief interventions for anxiety sensitivity

Anxiety Sensitivity (AS) is the fear of normal, arousal-related bodily sensations due to the belief that they have negative consequences. AS is a transdiagnostic construct, and high AS is associated with psychopathology, including panic disorder, social anxiety disorder, generalized anxiety disorder, depression, and alcohol-use disorders. There is research and clinical interest in developing brief and transdiagnostic interventions to streamline treatment. Targeting AS through brief interventions may be one way to accomplish this goal. Therefore, the purpose of this dissertation was to advance the literature on AS by examining the efficacy and transdiagnosticity of two brief interventions for AS. Cognitive mediators of change in AS were also examined. Target variables were psychopathology symptoms and cognitive processes, including interpretation biases, attentional biases, and perceived control. Study 1 investigated the immediate and short-term efficacy of a brief intervention that included a single session of psychoeducation and daily interoceptive exposure practices. Participants with high AS were randomly assigned to the intervention (n = 19) or health education control condition (n = 16). Participants in the intervention condition appeared to demonstrate reductions in AS, one facet of interpretation bias, social anxiety symptoms, and motivation to consume alcohol. Methodological issues, however, limited conclusions about the efficacy of the intervention. Finally, the three potential cognitive mediators did not mediate change in AS. Study 2 investigated the efficacy of a computerized cognitive bias modification (CBM) program. Participants with high AS were randomly assigned to 4 sessions of CBM (n= 24) or 4 sessions of sham training (n= 24). Sessions occurred over a 2-week period. At the end of the intervention period, the CBM condition appeared to show reductions in AS, interpretive biases, and almost all facets of psychopathology. However, similar changes were found in the control condition. Again, the three potential cognitive mediators did not mediate change in AS. Taken together, these findings provide limited support for the efficacy of psychoeducation and CBM as brief, transdiagnostic interventions. However, both studies must be interpreted in light of major limitations, which include limited homework completion in Study 1 and a control training task that induced training effects in Study 2.

Mechanisms of Change in Digital Health Interventions for Mental Disorders in Youth: Systematic Review (Preprint)

BACKGROUND Digital health interventions (DHIs) are efficacious for several mental disorders in youth; however, integrated, evidence-based knowledge about the mechanisms of change in these interventions is lacking. OBJECTIVE This systematic review aims to comprehensively evaluate studies on mediators and mechanisms of change in different DHIs for common mental disorders in children and adolescents. METHODS A systematic literature search of the electronic databases Cochrane Central Register of Controlled Trials, Embase, MEDLINE, and PsycINFO was conducted, complemented by backward and forward searches. Two independent reviewers selected studies for inclusion, extracted the data, and rated the methodological quality of eligible studies (ie, risk of bias and 8 quality criteria for process research). RESULTS A total of 25 studies that have evaluated 39 potential mediators were included in this review. Cognitive mediators were the largest group of examined intervening variables, followed by a broad range of emotional and affective, interpersonal, parenting behavior, and other mediators. The mediator categories with the highest percentages of significant intervening variables were the groups of affective mediators (4/4, 100%) and combined cognitive mediators (13/19, 68%). Although more than three-quarters of the eligible studies met 5 or more quality criteria, causal conclusions have been widely precluded. CONCLUSIONS The findings of this review might guide the empirically informed advancement of DHIs, contributing to improved intervention outcomes, and the discussion of methodological recommendations for process research might facilitate mediation studies with more pertinent designs, allowing for conclusions with higher causal certainty in the future.