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.