Sensorimotor Impairments Linked to Increased Autism Likelihood in ASD Individuals

Sensorimotor impairments observed in individuals with autism spectrum disorder (ASD) may serve as inherited markers of autism likelihood, according to findings published in Autism Research. 

While evidence of quantitative traits that are not directly observable have shed some light on the heritability of certain conditions, like autism, few of these findings have been replicated. In the current controlled study, researchers sought to assess the familial nature of sensorimotor deficits in ASD across different motor behaviors and effector systems.

Fifty-seven autistic individuals (probands), 109 of their biological parents, and 89 neurotypical control participants were included in the sample. Researchers examined manual motor and oculomotor control, differentiating between rapid, feedforward-driven movements and sustained actions requiring sensory feedback. They also confirmed autism diagnoses using the Autism Diagnostic Inventory-Revised; the Autism Diagnostic Observation Schedule, Second Edition; and expert clinical opinion. None of the parents in the study had a formal diagnosis of autism.

The primary outcome was to determine whether sensorimotor deficits in autism are familial and whether they vary based on the presence of broader autism phenotype (BAP) traits in parents. BAP+ parents exhibited subclinical autistic traits, while BAP− parents did not. Subgroup analyses compared sensorimotor performance between families with at least one BAP+ parent and those with 2 BAP− parents. 

Among autistic individuals, those with BAP− parents (BAP− probands) exhibited significant impairments in rapid oculomotor control, including increased saccade velocity (12° target: d=0.684; 24° target: d=0.680) and reduced saccade duration (d=0.364) compared to neurotypical controls. In contrast, BAP+ probands displayed impairments in sustained manual motor control, with increased grip force variability at higher force levels (85% maximum voluntary contraction [MVC]: d=0.407) compared to both neurotypical controls and BAP− probands. 

Similarly, BAP− parents demonstrated impaired rapid oculomotor control, showing increased saccade velocity (12° target: d=0.352; 24° target: d=0.347) and shorter saccade duration (12°: d=0.329; 24°: d=0.326) compared to neurotypical parents. In contrast, BAP+ parents showed greater sustained grip force variability, particularly at lower force levels (15% MVC: d=0.280), suggesting distinct familial motor traits. 

Familial analyses revealed that rapid oculomotor impairments, particularly increased saccade velocity, were highly correlated between autistic individuals and their parents (f²=0.848, P<.001), indicating a strong inherited component. However, sustained manual motor impairments did not show the same degree of familiality. 

At the behavioral level, BAP+ probands exhibited greater hyperactivity and impulsivity (t=−2.76, P=.01) compared to BAP− probands, but sensorimotor impairments were not directly correlated with core autism symptom severity.

“We found that hand and eye movement impairments in autistic children, and their parents were different depending on whether parents show autistic traits,” the researchers concluded.

Study limitations include a small sample size, lack of replication in larger groups, and an absence of analysis on whether familial sensorimotor traits predict autism in relatives.

One study author declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of disclosures.

This article originally appeared on Psychiatry Advisor