Is impaired set-shifting an endophenotype of anorexia nervosa?

Set-shifting difficulties have been reported in subjects with anorexia nervosa and appear to persist after recovery; therefore, they may be endophenotypic traits. The goals of this study were to investigate whether set-shifting difficulties are familial by examining discordant sister-pairs in comparison with healthy unrelated women and to replicate, with a broader battery, the lack of influence of an acute illness state on neuropsychological performance.

Forty-seven pairs of sisters discordant for anorexia nervosa and 47 healthy unrelated women who were comparable in age and IQ completed neuropsychological tasks selected to assess set-shifting ability. Analyses of variance with standard errors that are robust against correlations within family clusters were used to compare the groups. Results were adjusted for obsessive-compulsive, anxiety, and depression symptoms. Subjects with acute (N=24) and fully remitted (N=23) anorexia nervosa were compared to assess state versus trait effects.

Sisters with and without anorexia nervosa took significantly longer than unrelated healthy women to shift their cognitive set (CatBat task) and demonstrated greater perceptual rigidity (Haptic Illusion task) but did not differ significantly from each other. Women with anorexia nervosa were slower than other groups on Trail Making tasks. Women who had fully recovered from anorexia nervosa made significantly fewer errors than those with acute anorexia nervosa on the Trail Making alphabet task, but these subgroups did not differ on other measures.

Both affected and unaffected sisters had more set-shifting difficulties than unrelated healthy women. This finding, together with the replicated finding that set-shifting difficulties persist after recovery, suggests that set-shifting difficulties are trait characteristics and may inform the search for the endophenotype in anorexia nervosa.