Task-switching deficits and repetitive behaviour in genetic neurodevelopmental disorders: Data from children with Prader–Willi syndrome chromosome 15 q11–q13 deletion and boys with Fragile X syndrome

Abstract

Prader–Willi syndrome (PWS) and Fragile X syndrome (FraX) are associated with distinctive cognitive and behavioural profiles. We examined whether repetitive behaviours in the two syndromes were associated with deficits in specific executive functions. PWS, FraX, and typically developing (TD) children were assessed for executive functioning using the Test of Everyday Attention for Children and an adapted Simon spatial interference task. Relative to the TD children, children with PWS and FraX showed greater costs of attention switching on the Simon task, but after controlling for intellectual ability, these switching deficits were only significant in the PWS group. Children with PWS and FraX also showed significantly increased preference for routine and differing profiles of other specific types of repetitive behaviours. A measure of switch cost from the Simon task was positively correlated to scores on preference for routine questionnaire items and was strongly associated with scores on other items relating to a preference for predictability. It is proposed that a deficit in attention switching is a component of the endophenotypes of both PWS and FraX and is associated with specific behaviours. This proposal is discussed in the context of neurocognitive pathways between genes and behaviour.

Keywords:

• Fragile X syndrome
• Prader-Willi syndrome
• Task switching
• Behavioural phentotype
• Executive functioning

Notes

¹ The effect of gender on TEACh performance was examined within PWS and TD groups with an additional between-subjects gender (male, female) factor. However, there were no significant main effects of gender or interactions involving gender.

² The effect of gender on performance in single task blocks of the Simon task was examined within PWS and TD groups with an additional between-subjects gender (male, female) factor. However, there were no significant main effects of gender or interactions involving gender.

³ The effect of gender on performance in mixed task blocks of the Simon task was examined within PWS and TD groups with an additional between-subjects gender (male, female) factor. However, there were no significant main effects of gender or interactions involving gender.

⁴ Across FraX and TD groups, the Group × Switch × Congruency interaction showed a trend towards significance, F(1, 52) = 2.69, p = .107. Similar to the PWS group (see Figure 1), boys with FraX showed increased problems with switching to congruent trials, F(1, 52) = 2.30, p = .135, than to noncongruent trials when compared to the TD group, F(1, 52) = 0.374, p = .543. Interestingly, when only chronological age and not WISC Vocabulary was used as a covariate, the Switch × Congruency × Group interaction was significant in both PWS versus TD, F(1, 53) = 9.18, p = .004, and FraX versus TD comparisons, F(1, 53) = 12.84, p = .001.