A meta-analysis on neural changes of cognitive training for mental disorders in executive function tasks: increase or decrease brain activation?

Effects of virtual reality-based cognitive training for adolescents with depressive episodes: A pilot randomized controlled study

Cognitive impairment is a common symptom in depression, yet few intervention strategies target adolescents. This study investigated the effects of an attention and working memory cognitive training system based on virtual reality (VRCT) in adolescents with mild to moderate depressive episodes. Adolescents with depression were randomized into a VR training group (VRG, n = 47) or a waitlist control group (WT, n = 46). The VR training consisted of three 10-min tasks per session, conducted three sessions per week for 20 sessions over 7 weeks. Forty-four healthy adolescents participated as a comparison group for baseline cognitive assessment. Cognitive functions and depressive symptoms were assessed using the Das-Naglieri cognitive assessment system, driven by the Planning, Attention, Simultaneous, and Successive (PASS) processing theory, and the Hamilton Depression Rating Scale-24 at pre- and post-intervention. Baseline results indicated significantly lower cognitive scores in patients compared to healthy adolescents. Post-intervention, the VRG demonstrated significant improvements in all four cognitive scales (effect sizes 0.56 to 0.76) and a significant reduction in depressive symptoms compared to the WT. These findings suggest that VRCT holds potential for improving cognitive impairments and alleviating depressive symptoms in adolescents with depression. Further large-scale and follow-up studies are necessary to confirm long-term benefits.

A Systematic Review and Narrative Synthesis of Cognitive Training in the Treatment of Mental Illness and Substance Use Disorder

Introduction: The one unifying and distinguishing feature of all neuropsychiatric illnesses is the co-occurrence of cognitive dysfunction. Cognitive training (CT) was developed to enhance neural connectivity and cognition and improve day-to-day functioning. However, the benefits of CT are still debated. This current systematic review aimed to examine the efficacy of CT and to identify diagnostic and CT characteristics associated with superior outcomes across a range of psychiatric disorders. Method: Studies investigating CT in psychiatric illnesses were extracted from Embase, PubMed, CINAHL, PsycINFO, and PsycARTICLES up to 17 August 2023. Inclusion criteria were randomised control trials (RCT) and English language. The primary search strategy included terms relating to cognitive training, cognitive remediation, cognitive enhancement, or cognitive rehabilitation and randomised control trials, clinical trials, or experiments. Risk of bias was assessed using RevMan Web version 8.1.1. Narrative synthesis was used to analyse findings. Due to the heterogeneity of participant demographics, diagnoses, and interventions, meta-analyses were considered inappropriate. Results: Fifteen studies, including a total of 1075 participants, were identified. Approximately 67% of studies reported significant improvements in at least one trained domain of cognitive function after CT, and 47% observed improvements in psychiatric symptoms or function. Cognitive transfer effects were not observed. Sample sizes for studies were generally small, and most CT durations were 6 weeks or less. Conclusions: Findings suggest that CT can improve cognitive function in trained domains, though little evidence of cognitive transfer effects was observed. Due to the lack of standardisation in CT format and delivery, and inadequate measures of psychiatric symptoms or daily function, there is insufficient evidence to conclude whether or not this technique may benefit cognitive impairment in psychiatric disorders, or lead to subsequent improvement in disease symptomatology. Further studies of longer duration and using consistent methodologies must be conducted to identify the benefits of CT in psychiatric disorders.

Can we enhance working memory? Bias and effectiveness in cognitive training studies

Meta-analyses have found that working memory (WM) can be improved with cognitive training; however, some authors have suggested that these improvements are mostly driven by biases in the measurement of WM, especially the use of similar tasks for assessment and training. In the present meta-analysis, we investigated whether WM, fluid intelligence, executive functions, and short-term memory can be improved by cognitive training and evaluated the impact of possible sources of bias. We performed a risk of bias assessment of the included studies and took special care in controlling for practice effects. Data from 52 independent comparisons were analyzed, including cognitive training aimed at different cognitive functions. Our results show small improvements in WM after training (SMD = 0.18). Much larger effects were observed when the analysis was restricted to assessment tasks similar to those used for training (SMD = 1.15). Fluid intelligence was not found to improve as a result of training, and improvements in WM were not related to changes in fluid intelligence. Our analyses did however indicate that cognitive training can improve specific executive functions. Contrary to expectations, a set of meta-regressions indicated that characteristics of the training programme, such as dosage and type of training, do not have an impact on the effectiveness of training. The risk of bias assessment revealed some concerns in the randomization process and possible selective reporting among studies. Overall, our results identified various potential sources of bias, with the most significant being the choice of assessment tasks.