Set shifting and central coherence as neurocognitive endophenotypes in eating disorders: A preliminary investigation in twins

OBJECTIVES: Weak central coherence and poor set shifting are risk markers for eating disorders that are present post recovery and in first degree relatives. The aim of this study was to examine these traits in twins with eating disorders. METHODS: Neuropsychological tests were administered to 114 female twins (n = 53 met lifetime DSM-IV eating disorder criteria, n = 19 non-eating disorder cotwins and n = 42 controls). Within pair correlations for monozygotic (MZ) and dizygotic (DZ) twins were calculated and generalised estimating equations (GEE) compared probands, with non-eating disorder cotwins and controls. RESULTS: The genetic basis was highest for the central coherence tasks (Rey-Osterrieth Complex Figure Task: MZ twins r = 0.44 [CI: 0.07-0.70, P = 0.01] and Group Embedded Figures Test: MZ twins r = 0.58 [CI: 0.26-0.79, P = 0.00]). Poor set shifting was related to obsessive compulsive symptoms in both individuals with eating disorders and their non-eating disorder cotwins (r = 0.2-0.5). CONCLUSION: Set shifting abilities and central coherence appear to be endophenotypes associated with eating disorders.