Teresa Tavassoli

Talent in autism: hyper-systemizing, hyper-attention to detail and sensory hypersensitivity

We argue that hyper-systemizing predisposes individuals to show talent, and review evidence that hyper-systemizing is part of the cognitive style of people with autism spectrum conditions (ASC). We then clarify the hyper-systemizing theory, contrasting it to the weak central coherence (WCC) and executive dysfunction (ED) theories. The ED theory has difficulty explaining the existence of talent in ASC. While both hyper-systemizing and WCC theories postulate excellent attention to detail, by itself excellent attention to detail will not produce talent. By contrast, the hyper-systemizing theory argues that the excellent attention to detail is directed towards detecting ‘if p, then q’ rules (or [input–operation–output] reasoning). Such law-based pattern recognition systems can produce talent in systemizable domains. Finally, we argue that the excellent attention to detail in ASC is itself a consequence of sensory hypersensitivity. We review an experiment from our laboratory demonstrating sensory hypersensitivity detection thresholds in vision. We conclude that the origins of the association between autism and talent begin at the sensory level, include excellent attention to detail and end with hyper-systemizing.

Insulin-like growth factor-1 rescues synaptic and motor deficits in a mouse model of autism and developmental delay

BackgroundHaploinsufficiency of SHANK3, due to either hemizygous gene deletion (termed 22q13 deletion syndrome or Phelan-McDermid syndrome) or to gene mutation, accounts for about 0.5% of the cases of autism spectrum disorder (ASD) and/or developmental delay, and there is evidence for a wider role for SHANK3 and glutamate signaling abnormalities in ASD and related conditions. Therapeutic approaches that reverse deficits in SHANK3-haploinsufficiency may therefore be broadly beneficial in ASD and in developmental delay.FindingsWe observed that daily intraperitoneal injections of human insulin-like growth factor 1 (IGF-1) over a 2-week period reversed deficits in hippocampal α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) signaling, long-term potentiation (LTP), and motor performance that we had previously reported in Shank3-deficient mice. Positive effects were observed with an IGF-1 peptide derivative as well.ConclusionsWe observed significant beneficial effects of IGF-1 in a mouse model of ASD and of developmental delay. Studies in mouse and human neuronal models of Rett syndrome also show benefits with IGF-1, raising the possibility that this compound may have benefits broadly in ASD and related conditions, even with differing molecular etiology. Given the extensive safety data for IGF-1 in children with short stature due to primary IGF-1 deficiency, IGF-1 is an attractive candidate for controlled clinical trials in SHANK3-deficiency and in ASD.

Sensory over-responsivity in adults with autism spectrum conditions:

Anecdotal reports and empirical evidence suggest that sensory processing issues are a key feature of autism spectrum conditions. This study set out to investigate whether adults with autism spectrum conditions report more sensory over-responsivity than adults without autism spectrum conditions. Another goal of the study was to identify whether autistic traits in adults with and without autism spectrum conditions were associated with sensory over-responsivity. Adults with (n = 221) and without (n = 181) autism spectrum conditions participated in an online survey. The Autism Spectrum Quotient, the Raven Matrices and the Sensory Processing Scale were used to characterize the sample. Adults with autism spectrum conditions reported more sensory over-responsivity than control participants across various sensory domains (visual, auditory, tactile, olfactory, gustatory and proprioceptive). Sensory over-responsivity correlated positively with autistic traits (Autism Spectrum Quotient) at a significant level across groups and within groups. Adults with autism spectrum conditions experience sensory over-responsivity to daily sensory stimuli to a high degree. A positive relationship exists between sensory over-responsivity and autistic traits. Understanding sensory over-responsivity and ways of measuring it in adults with autism spectrum conditions has implications for research and clinical settings.

The Sensory Perception Quotient (SPQ): development and validation of a new sensory questionnaire for adults with and without autism

BackgroundQuestionnaire-based studies suggest atypical sensory perception in over 90% of individuals with autism spectrum conditions (ASC). Sensory questionnaire-based studies in ASC mainly record parental reports of their child’s sensory experience; less is known about sensory reactivity in adults with ASC. Given the DSM-5 criteria for ASC now include sensory reactivity, there is a need for an adult questionnaire investigating basic sensory functioning. We aimed to develop and validate the Sensory Perception Quotient (SPQ), which assesses basic sensory hyper- and hyposensitivity across all five modalities.MethodsA total of 359 adults with (n = 196) and without (n = 163) ASC were asked to fill in the SPQ, the Sensory Over-Responsivity Inventory (SensOR) and the Autism-Spectrum Quotient (AQ) online.ResultsAdults with ASC reported more sensory hypersensitivity on the SPQ compared to controls (P < .001). SPQ scores were correlated with AQ scores both across groups (r = .-38) and within the ASC (r = -.18) and control groups (r = -.15). Principal component analyses conducted separately in both groups indicated that one factor comprising 35 items consistently assesses sensory hypersensitivity. The SPQ showed high internal consistency for both the total SPQ (Cronbach’s alpha = .92) and the reduced 35-item version (alpha = .93). The SPQ was significantly correlated with the SensOR across groups (r = -.46) and within the ASC (r = -.49) and control group (r = -.21).ConclusionsThe SPQ shows good internal consistency and concurrent validity and differentiates between adults with and without ASC. Adults with ASC report more sensitivity to sensory stimuli on the SPQ. Finally, greater sensory sensitivity is associated with more autistic traits. The SPQ provides a new tool to measure individual differences on this dimension.

A pilot controlled trial of insulin-like growth factor-1 in children with Phelan-McDermid syndrome

[This corrects the article DOI: 10.1186/2040-2392-5-54.].

Taste Identification in Adults with Autism Spectrum Conditions

Sensory issues are widely reported in Autism Spectrum Conditions (ASC). Since taste perception is one of the least studied senses in ASC we explored taste identification in adults with ASC (12 males, 11 females) compared to control participants (14 males, 12 females). ‘Taste strips’ were used to measure taste identification overall, as well as bitter, sour, sweet and salty tastes. Results revealed lower taste scores overall in the ASC group, as well as for bitter, sour and sweet tastes. Salty taste scores did not differ between the groups. Examining error types showed that adults with ASC more often misidentified a taste as salty or as no taste. Future studies should investigate underlying mechanisms of taste identification difficulties in ASC.

Variation in the autism candidate gene GABRB3 modulates tactile sensitivity in typically developing children

BackgroundAutism spectrum conditions have a strong genetic component. Atypical sensory sensitivities are one of the core but neglected features of autism spectrum conditions. GABRB3 is a well-characterised candidate gene for autism spectrum conditions. In mice, heterozygous Gabrb3 deletion is associated with increased tactile sensitivity. However, no study has examined if tactile sensitivity is associated with GABRB3 genetic variation in humans. To test this, we conducted two pilot genetic association studies in the general population, analysing two phenotypic measures of tactile sensitivity (a parent-report and a behavioural measure) for association with 43 SNPs in GABRB3.FindingsAcross both tactile sensitivity measures, three SNPs (rs11636966, rs8023959 and rs2162241) were nominally associated with both phenotypes, providing a measure of internal validation. Parent-report scores were nominally associated with six SNPs (P <0.05). Behaviourally measured tactile sensitivity was nominally associated with 10 SNPs (three after Bonferroni correction).ConclusionsThis is the first human study to show an association between GABRB3 variation and tactile sensitivity. This provides support for the evidence from animal models implicating the role of GABRB3 variation in the atypical sensory sensitivity in autism spectrum conditions. Future research is underway to directly test this association in cases of autism spectrum conditions.

Altered tactile processing in children with autism spectrum disorder

Although tactile reactivity issues are commonly reported in children with autism spectrum disorder (ASD), the underlying mechanisms are poorly understood. Less feed‐forward inhibition has been proposed as a potential mechanism for some symptoms of ASD. We tested static and dynamic tactile thresholds as a behavioral proxy of feed‐forward inhibition in 42 children (21 children with ASD and 21 typically developing [TD] children). Subthreshold conditioning typically raises the dynamic detection threshold, thus comparison of the dynamic to the static threshold generates a metric that predicts gamma‐aminobutyric acid (GABA) mediated feed‐forward inhibition. Children with ASD had marginally higher static thresholds and a significantly lower ratio between thresholds as compared with TD children. The lower ratio, only seen in children with ASD, might be indicative of less inhibition. Static thresholds were correlated with autism spectrum quotient scores, indicating the higher the tactile threshold, the more ASD traits. The amount of feed‐forward inhibition (ratio between dynamic/static) was negatively correlated with autism diagnostic observation schedule repetitive behavior scores, meaning the less inhibition the more ASD symptoms. In summary, children with ASD showed altered tactile processing compared with TD children; thus measuring static and dynamic thresholds could be a potential biomarker for ASD and might be useful for prediction of treatment response with therapeutics, including those that target the GABAergic system. Autism Res 2016, 9: 616–620.

Spatial localisation in autism: evidence for differences in early cortical visual processing

BackgroundVision in people with autism spectrum conditions (ASC) is reported to be different from people without ASC, but the neural level at which the differences begin to occur is not yet known. Here we examine two variants of a vernier acuity task to determine if differences are evident in early visual processing.FindingsAbutting and separated vernier acuity was assessed in 16 people with ASC and 14 matched controls. In controls, abutting and separated thresholds were unrelated (r = 0.13, p = 0.65), suggesting thresholds are determined by two separate mechanisms. In contrast, the abutting and separated thresholds of ASC observers were strongly correlated (r = 0.88, p < 0.0001), with separated thresholds tending towards being superior to those of controls [t(28) = −2.46, p = 0.02].ConclusionsThe findings suggest the mechanisms employed by ASC observers in separated vernier tasks are different to those of controls. This psychophysical evidence suggests that visual differences in ASC may begin at an early cortical stage of visual processing.

the role of sensorimotor difficulties in autism spectrum Conditions

In addition to difficulties in social communication, current diagnostic criteria for autism spectrum conditions (ASC) also incorporate sensorimotor difficulties, repetitive motor movements, and atypical reactivity to sensory input (1). This paper explores whether sensorimotor difficulties are associated with the development and maintenance of symptoms in ASC. First, studies have shown difficulties coordinating sensory input into planning and executing movement effectively in ASC. Second, studies have shown associations between sensory reactivity and motor coordination with core ASC symptoms, suggesting these areas each strongly influence the development of social and communication skills. Third, studies have begun to demonstrate that sensorimotor difficulties in ASC could account for reduced social attention early in development, with a cascading effect on later social, communicative and emotional development. These results suggest that sensorimotor difficulties not only contribute to non-social difficulties such as narrow circumscribed interests, but also to the development of social behaviors such as effectively coordinating eye contact with speech and gesture, interpreting others’ behavior, and responding appropriately. Further research is needed to explore the link between sensory and motor difficulties in ASC and their contribution to the development and maintenance of ASC.