Mental Fatigue in Individuals with Psychiatric Disorders: A Scoping Review

Objective: The aim of this study was to complete a scoping review of the published literature describing the relationship between mental fatigue and various psychiatric disorders, to better understand its frequency and clinical impact, and to provide recommendations for future clinical research. Methods: A scoping review using PubMed/MEDLINE, Cochrane and PsychArticles databases was conducted using the keywords ‘mental fatigue’, ‘mental tiredness’ or ‘mental exhaustion’, and completed in accordance with the Preferred Reporting Items for Systematic Review and Meta-Analysis Protocols Extension for Scoping Reviews 2018 checklist. Results: We extracted 10 studies fulfilling our inclusion criteria from a total of 2937 publications. Mental fatigue was studied within mood disorders, anxiety disorders, obsessive compulsive disorder and obsessive-compulsive personality disorder. A commonly used tool to measure mental fatigue in these samples was the Multidimensional Fatigue Inventory-20. Specific cognitive factors (unhelpful beliefs about sleep, symptom-focussed rumination) and personality risk factors (harm avoidance, self-directedness, cooperativeness, persistence) were relevant to predicting mental fatigue symptoms and rates of mental fatigue may vary with gender and diagnosis. Conclusion: Research into mental fatigue in adult psychiatric sample was limited to a few psychiatric disorders and requires further investigation.Key points A commonly used tool to measure mental fatigue was the Multidimensional Fatigue Inventory-20. However, more research into the validity and reliability for illness specific instruments to measure mental fatigue in psychiatric population is required. Reduction of mental fatigue was associated with improvement on quality of life. Specific cognitive factors (unhelpful beliefs about sleep, symptom-focussed rumination) and personality risk factors (harm avoidance, self-directedness, cooperativeness, persistence) were relevant to predicting mental fatigue symptoms and rates of mental fatigue may vary with gender. Reviewed articles indicated that mental fatigue presence was associated with lower odds of OCD. In addition, the results suggested that mental fatigue symptoms were more common in individuals with OCPD rather than OCD. Research into mental fatigue in adult psychiatric sample was limited to a few psychiatric disorders and requires further investigation to prevent potential misattribution as mental fatigue symptoms overlap between different psychiatric disorders.