Neurocognitive Dysfunction in Children and Adolescents with Mental Illness

Introduction Robust evidence from adult samples indicates that neurocognitive dysfunction is a hallmark of many mental illnesses, contributing to the loss of daily function and quality of life that these illnesses cause. However, it is still unclear whether neurocognitive deficits associated with mental illnesses begin to manifest well before adulthood. The current study addresses this gap by evaluating neurocognitive function in four groups of children and adolescents with different mental illnesses compared to their matched healthy peers. Methods We evaluated the neurocognitive performance of four samples of youth diagnosed with ADHD (N=343), Anorexia (N=40), First-onset psychosis (N=25), and Conversion Disorder (N=56) with age-matched healthy controls. Performance was assessed using an objective assessment battery designed for use across diagnoses and settings and validated for its correlations with underlying brain structure and function. The resulting analyses assessed accuracy and reaction time performance for neurocognitive domains well established in the adult literature, such as cognitive flexibility, executive function, response inhibition, verbal fluency, verbal memory, visual memory, sustained attention, and working memory. Clinical and healthy group performance was compared using non-parametric testing. Results Distinct profiles of neurocognitive dysfunction were detected for each diagnosis. Particularly, children and adolescents with ADHD diffusely performed worse than their healthy counterparts, with exceptional impairment in working memory. Children and adolescents with anorexia displayed more specific impairments limited to response inhibition and verbal memory. While youth with ADHD had the most cognitive domains affected, youth with first-onset psychosis displayed the most severe impairments compared to healthy controls. Finally, deficits in conversion disorder were limited to cognitive flexibility, executive function, decision making, response inhibition, and working memory. These findings suggest that neurocognitive impairment in mental illness is transdiagnostic and can be detected as early as childhood or adolescence with standardized computerized testing. ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement The data are drawn from Stanford BRAINnet, which includes data acquired with support to LMW from the National Health and Medical Research Council (Project Grants 1004822, 457424), Australian Research Council (Discovery Projects DP120104496, DP077394, DP0345481), and a Pfizer Foundation Senior Research Fellowship. ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: The data used in the present work was downloaded from Stanford BRAINnet, a large database for mental health research ([www.stanfordbrainnet.com][1]). I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines and uploaded the relevant EQUATOR Network research reporting checklist(s) and other pertinent material as supplementary files, if applicable. Yes The data used in the present work was downloaded from and is available within Stanford BRAINnet, a large database for mental health research ([www.stanfordbrainnet.com][1]). [1]: https://www.stanfordbrainnet.com