Aspects of Attention in Rett Syndrome

We sought to examine fundamental aspects of attention in children with Rett syndrome, a severely disabling neurodevelopmental disorder caused by spontaneous mutations in the X-linked MECP2 gene. To gauge their attention, we used eye tracking, which bypasses the profound impairments in expressive language and hand use in Rett syndrome. We report two aspects of attention-shifting and sustaining-basic abilities known to drive cognitive growth.

Two groups were compared: those with Rett syndrome (N = 20; 3-15 years) and a typically developing comparison group (N = 14; 3-16 years), using a task in which an attractive central stimulus was followed, after a short gap, by a dynamic target presented to one side. Time to shift to the target location (reactive and anticipatory saccades) and time fixating the target were assessed.

Children with Rett syndrome were consistently slower to shift (largely because of fewer anticipations); their reactive saccades were also slower than those of typically developing children, but not significantly so. The Rett syndrome group spent considerable time looking at the target (over 75% of available time), although significantly less so than the typically developing group.

These findings indicate that children with Rett syndrome could maintain attention on a stimulus and orient relatively quickly to the appearance of a target in the visual field. However, they had difficulty in anticipating predictable events, a difficulty in endogenous attention that is likely to have deleterious implications for executive functioning.