Auditory Processing Differences Correlate With Autistic Traits in Males

Autism spectrum disorder (ASD) has high prevalence among males compared to females but mechanisms underlying the differences between sexes are poorly investigated. Moreover, autistic symptoms show a continuity in the general population and are referred to as autistic traits in people without an ASD diagnosis. One of the symptoms of ASD is sensory processing differences both in sensitivity and perception. To investigate sensory processing differences in autistic traits, we examined auditory and visual processing in a healthy population. We recruited 75 individuals (39 females and 36 males, mean age = 23.01 years, SD = 3.23 years) and assessed autistic traits using the Autism Spectrum Quotient, and sensory sensitivity using the Sensory Sensitivity Scales. Sensory processing in the visual domain was examined with the radial motion stimulus and the auditory domain was assessed with the 1,000 Hz pure tone stimulus with electroencephalography-evoked potentials. The results showed that the auditory sensitivity scores of the males (r_aud (34) = 0.396, p_aud = 0.017) and the visual sensitivity scores of females were correlated with autistic traits (r_vis (37) = 0.420, p_vis = 0.008). Moreover, the P2 latency for the auditory stimulus was prolonged in the participants with a higher level of autistic traits (r_s (61) = 0.411, p = 0.008), and this correlation was only observed in males (r_s (31) = 0.542, p = 0.001). We propose that auditory processing differences are related to autistic traits in neurotypicals, particularly in males. Our findings emphasize the importance of considering sex differences in autistic traits and ASD.

Development of Sensory Sensitivity Scales (SeSS): Reliability and validity analyses

BACKGROUND

Although adults are known to have sensory sensitivity differences, existing sensitivity scales have been mostly developed for children. The limited number of adult scales measure social/emotional features and modalities together.

AIMS

To develop scales for adults that evaluate visual, auditory and somatosensory sensitivities as separate domains and independent of social/emotional features.

METHODS AND PROCEDURES

Two consecutive studies (visual-auditory part and somatosensory part) were conducted using the same methods. Both studies included a pilot (n₁ = 405 and n₂ = 294) and a main group (n₁ = 425 and n₂ = 603). An exploratory factor analysis produced a single-factor solution for the visual and auditory domains and a three-factor solution for the somatosensory domain (touch, pain, and itch) of Sensory Sensitivity Scales.

OUTCOMES AND RESULTS

A confirmatory factor analysis revealed good construct validity in the the visual (CFI = .973, TLI = .965, and RMSEA = .075) auditory (CFI = .943, TLI = .927, and RMSEA = .074) and somatosensory (CFI = .955, TLI = .946, and RMSEA = .048) scales. The categories were internally consistent (α_v = .86, α_a = .79, α_s = .69). As an indicator of convergent validity, higher autistic traits were related to higher sensitivity (r_s-v = .17, r_s-a = .25, r_s-s = .14).

CONCLUSIONS AND IMPLICATIONS

Sensory Sensitivity Scales (SeSS) can be used to screen sensory sensitivity variability or identify and follow up the outcome of sensory interventions in adults.

Right Anterior Theta Hypersynchrony as a Quantitative Measure Associated with Autistic Traits and K-Cl Cotransporter KCC2 Polymorphism

Our aim was to use theta coherence as a quantitative trait to investigate the relation of the polymorphisms in NKCC1 (rs3087889) and KCC2 (rs9074) channel protein genes to autistic traits (AQ) in neurotypicals. Coherence values for candidate connection regions were calculated from eyes-closed resting EEGs in two independent groups. Hypersynchrony within the right anterior region was related to AQ in both groups (p < 0.05), and variability in this hypersynchrony was related to the rs9074 polymorphism in the total group (p < 0.05). In conclusion, theta hypersynchrony within the right anterior region during eyes-closed rest can be considered a quantitative measure for autistic traits. Replicating our findings in two independent populations with different backgrounds strengthens the validity of the current study.