Deficits in eye movement control in children with 22q11.2 deletion syndrome.
Kalwarowsky, Sarah Ann
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Background: The 22q11.2 deletion syndrome (22q11.2 DS) causes a wide variety of symptoms, but the central nervous system (CNS) dysfunction is the one most likely to affect the day-to-day life of those affected by this genetic disorder. In addition to affecting the educational needs of children with 22q11.2 DS, the neurological deficits in childhood and adolescence could be related to future psychosis and schizophrenia, which can affect 30% of these patients. Thus, the development of screening tools for CNS dysfunction could help identify children who are most at risk for developing later psychosis, allowing them to receive additional care. As saccadic eye movement behaviours reflect the integrity of multiple brain structures, a battery of oculomotor tasks could help identify neurological deficits. This study sought to test the hypothesis that children with 22q11.2 DS would have deficits in oculomotor performance compared to typically developing children. Methods: A cohort of 16 children with 22q11.2 DS, and 32 age- and sex-matched controls completed prosaccade, antisaccade, delayed memory-guided sequential (DMS) and predictive eye movement tasks. Results: Compared to controls, children with 22q11.2 DS exhibited increased direction errors in the antisaccade task, increased timing errors in the DMS task, as well as decreased predictive and increased regular saccades in the predictive task. The group of children with 22q11.2 DS also exhibited an increase in saccade amplitude in the prosaccade, antisaccade and predictive tasks, increased error in saccade trajectory in the prosaccade, antisaccade and DMS tasks and decreased saccade velocity in the predictive saccade tasks. Conclusion: This study showed that performance in the eye movement tasks could be used to assess injury to the frontostriatal circuitry and cerebellum in children with 22q11.2 DS.