29735
Simple Reaction Time and Postural Control in Autism Spectrum Disorder Subjects
Reaction Time (RT) has been used as biomarker of cognitive performance and of trans-diagnostic phenotype in Autism Spectrum Disorders (ASD). It is also well known that RT is an important component of effective postural control and balance. In this regard few studies have examined the relationship between static and dynamic balance and Simple Reaction Time (SRT) in neurotypical (NT) children and adolescents. No studies are available in this regard in ASD subjects.
Objectives: The three aims of this study are: 1) to assess SRT in a ASD sample 2) then measure the correlation between lower limb SRT and sway tests (ST), maximal balance range test (MBRT) and coordinated stability test (CST) in ASD children; 3) to compare the results with the same data obtained in a sample of 243 NT subjects.
Methods:
The study sample included 12 ASD subjects (10 males). The ASD subjects were diagnosed with autism according to the DSM V criteria, confirmed through ADOS-2 and under observation at our Institute. SRT was measured in milliseconds using a hand-held electronic timer and a light as the stimulus and the activation of a foot lever for responses. We conducted all the postural control tests using a sway meter that measures displacements of the body at waist level. ST is the evaluation of anterioposterior and mediolateral sway as the subject attempts to stand as still as possible for 30 seconds; ST was performed in four different conditions: on the floor with open- eyes, on floor with their eyes closed, on a foam rubber mat with open-eyes and on a foam rubber mat with their eyes closed. MBRT measures the maximum distance traveled from the total forward and backward excursion. CST is the evaluation of errors made by the subject in moving the pen of the sway meter on a predefined track. All the tests employed have been validated for the study of sensorimotor components of balance into the Fall Screen Assessment System.
Results:
The mean age of ASD subjects was 11.67y (SD 4.08y; range 5-18y). Seven out of 12 ASD subjects (58,3%) showed SRT values above the Reference Intervals age related of NT children; four ASD subjects (33,3%) were in and those of 1 subject (8,3%) was lower. We found no significant correlations between SRT and ST values in all the four conditions and between SRT and both MBRT and CST values, while in the NT reference group there was a significant correlation between SRT and ST in 3 of 4 conditions. In the same group SRT performance significantly correlated also with MBRT (R Pearson=-0.245; p=0.000) and with CST (R Pearson=0.644; p=0.000).
Conclusions: This is the first study that analyses correlation between lower limb SRT and postural control performance in ASD subjects. In contrast with results obtained in NT subjects, lower limb SRT are not correlated with sway tests, MBRT and CST values. These findings confirm the presence of deficits of sensorimotor integration and therefore impairment in postural control in ASD children.