Anticipatory oculomotor responses in parents of children with attention deficit hyperactivity disorder

Oculomotor Function in Children and Adolescents with Autism, ADHD or Co-occurring Autism and ADHD

Oculomotor characteristics, including accuracy, timing, and sensorimotor processing, are considered sensitive intermediate phenotypes for understanding the etiology of neurodevelopmental conditions, such as autism and ADHD. Oculomotor characteristics have predominantly been studied separately in autism and ADHD. Despite the high rates of co-occurrence between these conditions, only one study has investigated oculomotor processes among those with co-occurring autism + ADHD. Four hundred and five (n = 405; 226 males) Australian children and adolescents aged 4 to 18 years (M = 9.64 years; SD = 3.20 years) with ADHD (n = 64), autism (n = 66), autism + ADHD (n = 146), or neurotypical individuals (n = 129) were compared across four different oculomotor tasks: visually guided saccade, anti-saccade, sinusoidal pursuit and step-ramp pursuit. Confirmatory analyses were conducted using separate datasets acquired from the University of Nottingham UK (n = 17 autism, n = 22 ADHD, n = 32 autism + ADHD, n = 30 neurotypical) and University of Kansas USA (n = 29 autism, n = 41 neurotypical). Linear mixed effect models controlling for sex, age and family revealed that children and adolescents with autism + ADHD exhibited increased variability in the accuracy of the final saccadic eye position compared to neurotypical children and adolescents. Autistic children and adolescents demonstrated a greater number of catch-up saccades during step-ramp pursuit compared to neurotypical children and adolescents. These findings suggest that select differences in saccadic precision are unique to autistic individuals with co-occurring ADHD, indicating that measuring basic sensorimotor processes may be useful for parsing neurodevelopment and clinical heterogeneity in autism.

The Eyes Have It: A Meta-analysis of Oculomotor Inhibition in Attention-Deficit/Hyperactivity Disorder

BACKGROUND

Diminished inhibitory control is one of the main characteristics of attention-deficit/hyperactivity disorder (ADHD), and impairments in oculomotor inhibition have been proposed as a potential biomarker of the disorder. The present meta-analysis summarizes the effects reported in studies comparing oculomotor inhibition in ADHD patients and healthy control subjects.

METHODS

Inhibitory outcomes were derived from oculomotor experimental paradigms including the antisaccade (AS), memory-guided saccade, and prolonged fixation tasks. Temporal and spatial measures were also extracted from these tasks and from visually guided saccade tasks as secondary outcomes. Data were available from k = 31 studies (N = 1567 participants). Summary effect sizes were computed using random-effects models and a restricted maximum-likelihood estimator.

RESULTS

Among inhibitory outcomes, direction errors in AS, after correcting for publication bias, showed a moderate effect and large between-study heterogeneity (k = 18, n = 739, g = 0.57, 95% confidence interval [CI] [0.27, 0.88], I²= 74%); anticipatory saccades in memory-guided saccade showed a large effect and low heterogeneity (k = 11, n = 487; g = 0.86, 95% CI [0.64, 1.08], I² = 17.7%); and saccades during prolonged fixation evidenced large effect size and heterogeneity (k = 6, n = 325 g = 1.11, 95% CI [0.56, 1.65], I² = 79.1%) partially related to age. Among secondary outcomes, saccadic reaction time in AS (k = 22, n = 932, g = 0.34, 95% CI [0.06, 0.63], I² = 53.12%) and coefficient of variability in visually guided saccade (k = 5, n = 282, g = 0.53, 95% CI [0.28, 0.78], I² = 0.01%) indicated significant effects with small to moderate effects sizes.

CONCLUSIONS

ADHD groups commit more oculomotor inhibition failures than control groups. The substantial effects support the conclusion that oculomotor disinhibition is a relevant ADHD-related mechanism. Moderate effects observed in saccadic reaction time variability suggest that fluctuant performance in oculomotor tasks is another relevant characteristic of ADHD.