An investigation of set shifting in anorexia nervosa and clinical research portfolio

Background: Recent research has examined the possibilities that deficits in cognitive processes, in particular set shifting, might contribute to the development and maintenance of anorexia nervosa (AN). Results of studies of set shifting have been mixed. There has been considerable variability in tests used to measure set shifting and a lack of homogeneity of populations sampled. Methods: This study investigated set shifting abilities within a restrictive sub type AN population using the intra-extra dimensional set shift (IED) sub-test of the Cambridge Neuropsychological Test Automated Battery (CANTAB) and the Brixton Spatial Anticipation Test (BSAT). Participants with AN were matched with healthy controls. Results: There was no significant difference found between the groups on the BSAT or the number of stages that were completed on the IED. The AN group made significantly more errors on the IED. Anxiety scores for the AN group were significantly correlated with this error measure The two measures of set shifting were not significantly correlated. Conclusion: Possible explanations were considered for the significant difference on only one of the measures, including that the IED may be a more difficult test or that the tests may be measuring different cognitive abilities. The role of anxiety on the results was also acknowledged. The possibility that previous, contradictory, research has captured aspects from different AN subgroups and the usefulness of the diagnosis of AN was discussed. Whilst it appears that patients with AN made significantly more errors on the IED, there is not currently enough conclusive evidence to support the idea that this is indicative of a deficit in set shifting.