Research review : neuropsychological functioning in young anorexia nervosa : a meta-analysis

Background: Cognitive inflexibility and compulsive behaviours are commonly observed in patients with anorexia nervosa (AN) and are often considered to be caused by impairments in executive functioning and visuospatial processing. Despite an increasing number of young individuals presenting with AN, there is a lack of meta-analytic evidence on the neuropsychological functioning in this population. Our primary aim was to review and synthesize the differences in neuropsychological test performance between young people with AN and healthy controls, and to explore potential moderators. Methods: A database search following PRISMA guidelines of MEDLINE, PsycINFO, ISI Web of Science and Epistemonikos was conducted. Hedges' g served as an effect size indicating the standardized mean differences. We utilized mixed-effects meta-regression and machine learning meta-analyses to identify relevant moderators. Results: Sixteen studies met the inclusion criteria with a total of 1333 participants (665 with AN) and 59 effect sizes. Random-effects meta-analyses demonstrated a small and insignificant difference between young individuals with AN and controls ((Formula presented.) = −0.144, 95% CI [−0.328, 0.041]) in overall neuropsychological functioning. However, the difference was significant for the cognitive domains of memory, working memory and visuospatial abilities. Moderator and machine-learning analyses revealed a stronger negative effect in older participants and moderator effects of country and assessment quality. Conclusions: Our findings highlight the significant impact of age on neuropsychological test performance in patients with AN. There is a need for a more widespread inclusion of potentially confounding variables in primary studies as well as instruments specifically targeted at younger populations.