A discrepancy between processing speed and verbal ability in gifted youth is genetically and diagnostically associated with autism

BackgroundHigh cognitive ability is an almost universally positive prognostic indicator in the context of neurodevelopmental, neuropsychiatric, and neurodegenerative conditions. However, "twice-exceptional" individuals, those who demonstrate exceptionally high cognitive ability (gifted) and exhibit profound behavioral and mental health challenges, are a striking exception to this rule. MethodsWe digitized the clinical records of N=1,074 clients from a US-based specialty clinic serving gifted students. This included a broad array of diagnostic, cognitive, achievement, and behavioral data, including self, teacher, and parent reported items. We conducted both hypothesis-driven and unsupervised learning analyses to 1) identify characteristics whose association with full-scale IQ (FSIQ) was dependent on autism diagnosis and 2) identify cognitive archetypes associated with autism diagnosis and related behaviors. We tested the generalization of our findings using data from the SPARK (N=17,634) and ABCD studies (N=10,602). ResultsAutistic individuals with IQ >= 120 were nearly 15 times more likely to enter adulthood undiagnosed compared to lower-IQ (IQ < 70) counterparts. Self-reported sense of inadequacy was most strongly associated with increasing FSIQ specifically among autistic clients (beta=0.3, 95% CI:[0.15,0.45], p=7.1x10-5). Similarly, self, parent, and teacher reports of anxiety increased with FSIQ (all p<0.05) in autistic individuals, in striking opposition to the ameliorating effect of FSIQ seen in non-autistic individuals. We uncovered a pattern of decreased processing speed (PS) coupled with very high verbal comprehension (VC), a PS/VC discrepancy, that was associated with autism, inattention, and internalizing problems. Similar cognitive-behavioral links were also observed in the ABCD study. Finally, we found a significant association between the PS/VC discrepancy and polygenic risk for autism in the ABCD sample (t=2.9, p=0.004). ConclusionsOur results suggest that autistic individuals with exceptional ability are underserved and suffer disproportionately from high anxiety and low self-worth. In addition, elevated IQ with a significant PS/VC discrepancy appears to be a clinically and genetically meaningful biotype linked to autism.