Lower pattern recognition memory scores in anorexia nervosa

Johanna Keeler,Valentina Cardi,Sandrine Thuret,Miriam Olivola,Judith Owen,Janet Treasure,Jingjing Xia,Ellen Lambert,Hubertus Himmerich

doi:10.1186/s40337-021-00406-8

Abstract

BackgroundThere is extensive evidence for volumetric reductions in the hippocampus in patients with anorexia nervosa (AN), however the impact on function is unclear. Pattern separation and recognition are hippocampus-dependent forms of learning thought to underlie stimulus discrimination.MethodsThe present study used the Mnemonic Similarity Task to investigate pattern separation and recognition for the first time in patients with AN (N = 46) and healthy controls (N = 56). An Analysis of Covariance examined between-group differences, controlling for age, antidepressant use and method of task delivery (remote vs. in person).ResultsWhen controlling for covariates, pattern recognition memory scores were lower in the AN group with a medium effect size (d = 0.51). In contrast, there was a small effect whereby patients with AN had a greater pattern separation score than controls (d = 0.34), albeit this difference was not significant at the p = 0.05 threshold (p = 0.133). Furthermore, pattern separation and recognition memory abilities were not related to age, body mass index, eating disorder psychopathology or trait anxiety levels.ConclusionsThis preliminary study provides initial evidence for an imbalance in pattern separation and recognition abilities in AN, a hippocampus-dependent cognitive ability. Further studies should endeavour to investigate pattern separation and recognition performance further in AN, as well as investigate other hippocampus-dependent functions.

Highlights

Anorexia nervosa (AN) is a serious, complex psychiatric illness, with core characteristics including an avoidance of food, leading to severe dietary restriction and a significantly low body weight [1]
The hippocampus is an area of the brain that is vital for memory and learning, and it is not understood the extent to which its function is impaired in anorexia nervosa (AN)
This offers a possible explanation for our finding of reduced recognition memory in AN, since dietary restriction is characteristic of the disorder and is detrimental to both the survival of newly born cells in the dentate gyrus and pattern recognition performance

Summary

Introduction

Anorexia nervosa (AN) is a serious, complex psychiatric illness, with core characteristics including an avoidance of food, leading to severe dietary restriction and a significantly low body weight [1]. Many patients with AN have an enduring illness, with one study finding only a third recovered at a 9-year follow-up [2]. Treatment resistance in other forms of severe psychiatric illnesses such as Major Depressive Disorder and schizophrenia has been linked to abnormal hippocampal function [4, 5]. Preliminary evidence was found for a reduction in the hippocampal structure in AN [6]. There is extensive evidence for volumetric reductions in the hippocampus in patients with anorexia nervosa (AN), the impact on function is unclear. Pattern separation and recognition are hippocampusdependent forms of learning thought to underlie stimulus discrimination

Methods

Results

Discussion

Conclusion