Saccadic eye movement tasks assess central nervous system dysfunction and cognitive improvements in children with fetal alcohol spectrum disorders
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Background: The central nervous system (CNS) dysfunction resulting from prenatal alcohol exposure (PAE) is the most debilitating aspect of fetal alcohol spectrum disorders (FASDs). Affected children exhibit numerous cognitive and behavioural deficits which can severely affect quality of life. As the diagnosis of FASDs often requires specially trained physicians, there is a need for sensitive and specific tools that screen PAE-related CNS dysfunction in order to identify individuals who require further consultation. Additionally, objective measures of intervention end-points are critical to assess potential treatments for this population. As saccadic eye movement behaviours reflect the integrity of multiple brain structures, a battery of oculomotor tasks may serve both these functions. This study sought to test the hypothesis that oculomotor performance in FASD would differ from typically developing children and would allow the objective measure of cognitive improvements resulting from a strength-based motor skills intervention. Methods: A cohort of 31 children with FASD, and 31 age- and sex-matched controls completed prosaccade, antisaccade, delayed memory-guided sequential (DMS) and predictive eye movement tasks. Additionally, a selection of these children were involved in an intervention study and therefore tested on three separate occasions using the eye movement tasks and computerized neuropsychological tests. Results: Compared to controls, children with FASDs elicited increased direction and anticipatory errors in the antisaccade task, increased timing and sequence errors in the DMS task, and increased anticipatory and decreased express saccades in the predictive task. The FASD group also exhibited an increase in the error of saccade trajectories in the pro- and antisaccade tasks, in addition to increased velocities of visually-guided saccades in the predictive task. Furthermore, those involved in the intervention study improved in measures of response inhibition in the DMS task. Conclusion: This study indicates that frontostriatal and cerebellar dysfunction can be assessed in children with FASDs using a battery of eye movement tasks. In addition, children involved in the strength-based motor skills intervention improved in the ability to perform complex oculomotor tasks. These findings suggest that select eye movement tasks may be utilized to identify CNS dysfunction in FASD and to measure cognitive improvements resulting from behavioural interventions.