Genetic overlap of autism with intelligence Recent increases in sample sizes, extensions of target phenotypes analyzed, and developments in analytic methods for genome-wide association studies, have allowed the first robust tests of the sign and magnitude of genetic correlations, due to pleiotropy and linkage disequilibrium, between intelligence and other traits including risk of psychiatric conditions.
Brain size and growth Large brain size and head circumference, especially in childhood but also adulthood, represent some of the best-substantiated phenotypic correlates of autism e.
Brain connectivity Low global, relative to local, structural and functional connectivity of the brain has been demonstrated in autism by a large suite of studies reviews in Courchesne and Pierce, ; Maximo et al. Neuronal function Synaptic plasticity represents a core component of brain function, and, in principle, it underlies on a neuronal scale the long-term macroscopic changes in cortical thickness across childhood and adolescence that have been linked with intelligence e.
Sensory functions, attention, and special abilities As noted above, Galton and Spearman first described hypotheses and psychometric evidence that sensory abilities and sensory discrimination skills were strongly positively associated with high intelligence. Socioeconomic status Socioeconomic status, intelligence, and education level achieved have been demonstrated to exhibit strong positive correlations amongst themselves, although the reasons for these associations have remained unspecified Deary and Johnson, Assortative mating Positive assortative mating, the mating between individuals who are relatively-similar for a given phenotype or genotype, results in a disproportionate concentration of the relevant alleles among offspring, an increase in additive genetic variance for the trait, and a concomitant rise in heritability Plomin and Deary, Discussion Risk and expression of autism is mediated by alterations to adaptive, evolved cognitive systems, and human intelligence represents one of the most important and pervasive changes along the human lineage and a principal source of cognitive variation among individuals.
Figure 4. Author contributions BC conceived and wrote the paper. Conflict of interest statement The author declares that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.
References Adida M. Decision-making and schizophrenia. Encephale 37 Suppl. Eagle-eyed visual acuity: an experimental investigation of enhanced perception in autism. Psychiatry 65 , 17— Autism Dev. A comparison of neuroimaging findings in childhood onset schizophrenia and autism spectrum disorder: a review of the literature.
Psychiatry 4 : A preliminary longitudinal volumetric MRI study of amygdala and hippocampal volumes in autism. Psychiatry 48 , — The hyper-systemizing, assortative mating theory of autism. Psychiatry 30 , — Autism: the Empathizing—Systemizing E-S theory. Talent in autism: hyper-systemizing, hyper-attention to detail and sensory hypersensitivity. B Biol. Autism occurs more often in families of physicists, engineers, and mathematicians.
Autism 2 , — Parents of children with Asperger syndrome: what is the cognitive phenotype? Why are autism spectrum conditions more prevalent in males? PLoS Biol. Mathematical talent is linked to autism. Is there a link between engineering and autism?
Autism 1 , — The panmodal sensory imprecision hypothesis of schizophrenia: reduced auditory precision in schizotypy.
Autism and abnormal development of brain connectivity. Exceptional visuospatial imagery in schizophrenia; implications for madness and creativity. Psychiatry 19 , — Tactile sensitivity in Asperger syndrome. Brain Cogn. A synaptic trek to autism. Brief report: the relationship between visual acuity, the embedded figures test and systemizing in autism spectrum disorders. Reasoning on the Autism Spectrum: a dual process theory account.
Default-mode brain dysfunction in mental disorders: a systematic review. An atlas of genetic correlations across human diseases and traits. Familial linkage between neuropsychiatric disorders and intellectual interests. Early generalized overgrowth in autism spectrum disorder: prevalence rates, gender effects, and clinical outcomes.
Child Adolesc. Psychiatry 53 , — Tactile perception in adults with autism: a multidimensional psychophysical study. GWAS-based pathway analysis differentiates between fluid and crystallized intelligence.
Genes Brain Behav. Learning, plasticity, and atypical generalization in children with autism. Common polygenic risk for autism spectrum disorder ASD is associated with cognitive ability in the general population.
Psychiatry 21 , — Global connectivity of prefrontal cortex predicts cognitive control and intelligence. Human intelligence and brain networks. Dialogues Clin. An overabundance of prefrontal cortex neurons underlies early brain overgrowth in autism , in Neurostereology: Unbiased Stereology of Neural Systems , ed Mouton P. Hoboken, NJ: Wiley-Blackwell; , 73— Why the frontal cortex in autism might be talking only to itself: local over-connectivity but long-distance disconnection. Psychosis and autism as diametrical disorders of the social brain.
Brain Sci. The evolutionary etiologies of autism spectrum and psychotic-affective spectrum disorders , in Evolutionary Thinking in Medicine: From Research to Policy and Practice , eds Alvergne A.
The evolutionary biology of human neurodevelopment: evo-neuro-devo comes of age , in Evolutionary Developmental Anthropology , eds Boughner J. Hoboken, NJ: Wiley; , — Imagination in human social cognition, autism, and psychotic-affective conditions. Cognition , — Genome-wide association studies establish that human intelligence is highly heritable and polygenic. Psychiatry 16 , — DUF dosage is linearly associated with increasing severity of the three primary symptoms of autism.
PLoS Genet. DUF copy number is linearly associated with increased cognitive function as measured by total IQ and mathematical aptitude scores. The level and nature of autistic intelligence.
Overall brain size, and not encephalization quotient, best predicts cognitive ability across non-human primates. Brain Behav. Sensory discrimination and intelligence: testing Spearman's other hypothesis. Intelligence and education: causal perceptions drive analytic processes and therefore conclusions. The neuroscience of human intelligence differences. Explaining enhanced logical consistency during decision making in autism. Neuronal factors determining high intelligence.
DUFdomain copy number implicated in human brain-size pathology and evolution. Socioeconomic inequality in the prevalence of autism spectrum disorder: evidence from a US cross-sectional study. Brain surface anatomy in adults with autism: the relationship between surface area, cortical thickness, and autistic symptoms.
JAMA Psychiatry 70 , 59— Heterogeneity in perceptual category learning by high functioning children with autism spectrum disorder. Integrative Neurosci.
More is less: pitch discrimination and language delays in children with optimal outcomes from autism. Autism Res. Deprivation, ethnicity and the prevalence of intellectual and developmental disabilities. The role of personality and intelligence in assortative mating. Spanish J. How autism became autism: the radical transformation of a central concept of child development in Britain.
Human Sci. The Measurement of Intelligence. Berlin: Springer Science and Business Media. Enhanced visual temporal resolution in autism spectrum disorders. High-expanding cortical regions in human development and evolution are related to higher intellectual abilities.
Cortex 25 , 26— Epidemiology of pervasive developmental disorders. An auditory processing abnormality specific to liability for schizophrenia. Structural gray matter differences during childhood development in autism spectrum disorder: a multimetric approach.
Mendelian and polygenic inheritance of intelligence: a common set of causal genes? Using next-generation sequencing to examine the effects of intellectual disability genes on normal-range intelligence. Intelligence 49 , 10— Intact prototype formation but impaired generalization in autism. Autism Spectr. Head circumference and body growth in autism spectrum disorders.
Brain Dev. London: JM Dent and Company. Genetic relationship between five psychiatric disorders estimated from genome-wide SNPs. Cognitive abilities in siblings of children with autism spectrum disorders. Brain Res. Autism-related deficits via dysregulated eIF4E-dependent translational control.
Nature , — Three-dimensional brain growth abnormalities in childhood-onset schizophrenia visualized by using tensor-based morphometry. The weak coherence account: detail-focused cognitive style in autism spectrum disorders.
Time to give up on a single explanation for autism. A preliminary longitudinal magnetic resonance imaging study of brain volume and cortical thickness in autism.
Psychiatry 66 , — An MRI study of increased cortical thickness in autism. Psychiatry , — Superior fluid intelligence in children with Asperger's disorder.
Superior discrimination of speech pitch and its relationship to verbal ability in autism spectrum disorders. Age-dependent pleiotropy between general cognitive function and major psychiatric disorders. Association between extreme autistic traits and intellectual disability: insights from a general population twin study. Proficiency of individuals with autism spectrum disorder at disembedding figures: a systematic review.
Savant skills in autism: psychometric approaches and parental reports. Evidence of common genetic overlap between schizophrenia and cognition. Neuroanatomical differences in brain areas implicated in perceptual and other core features of autism revealed by cortical thickness analysis and voxel-based morphometry. Brain Mapp. Enhanced synapse remodelling as a common phenotype in mouse models of autism. Brain development parameters and intelligence in Chilean high school graduates.
Intelligence 32 , — Sensory processing in schizophrenia: neither simple nor intact. When doors of perception close: bottom-up models of disrupted cognition in schizophrenia. Constructive replication of the visual—perceptual-image rotation model in Thurstone's battery of 60 tests of mental ability. Intelligence 33 , — The structure of human intelligence: it is verbal, perceptual, and image rotation VPR , not fluid and crystallized.
Sex differences in mental abilities: g masks the dimensions on which they lie. Intelligence 35 , 23— Linking abilities, interests, and sex via latent class analysis. Career Assess.
Genetic and environmental influences on the Verbal-Perceptual-Image Rotation VPR model of the structure of mental abilities in the Minnesota study of twins reared apart. Intelligence 35 , — Placing inspection time, reaction time, and perceptual speed in the broader context of cognitive ability: the VPR model in the Lothian Birth Cohort Intelligence 39 , — Cognitive abilities independent of IQ correlate with regional brain structure.
Intelligence 36 , 18— Autistic disturbances of affective contact. Nervous Child. Acta Paedopsychiatr. Early infantile autism. North Am. Endogenous testosterone concentration, mental rotation, and size of the corpus callosum in a sample of young Hungarian women. Skills , — Cortical thickness correlates of specific cognitive performance accounted for by the general factor of intelligence in healthy children aged 6 to Neuroimage 55 , — Resting-state networks in schizophrenia.
Structural dynamics of dendritic spines in memory and cognition. Trends Neurosci. The case for DUF domain dosage as a primary contributor to anthropoid brain expansion. The autistic neuron: troubled translation? Cell , — Cognitive processing speed in older adults: relationship with white matter integrity.
Cognitive styles and fluid intelligence: are they related? Children's intellectual ability is associated with structural network integrity. Neuroimage , — Socioeconomic status and the increased prevalence of autism in California. Early infantile autism: relation to schizophrenia. Child Psychiatry 14 , — Development of the brain's structural network efficiency in early adolescence: a longitudinal DTI twin study.
Genetic link between family socioeconomic status and children's educational achievement estimated from genome-wide SNPs. Intellectual asymmetry and genetic liability in first-degree relatives of probands with schizophrenia. The dendritic tree and brain disorders. Based on the test results, people come to the conclusion that autistic children cannot learn, when perhaps they do not learn the same way other people do.
The hidden potential of autistic people seems to fall in common areas—tasks that involve pattern recognition, logical reasoning and picking out irregularities in data or arguments. Soulieres describes working with an autistic woman in her lab who can pick out the slightest flaws in logic.
Recognizing these talents , rather than pushing them aside to focus on the drawbacks of autism, could benefit not just autistic people, but everyone else as well. Mottron chronicles how much better his science got by working with his autistic lab partner. I got far higher marks on my homework than I would have without Alex, even though his corrections were sometimes infuriating.
And many think their potential extends beyond science to all professions, if given the right chances. Just because a test says someone has potential, that does not mean it is easy to realize. But in class, he often falls behind when trying to listen to instructions and gets frustrated when trying to catch up.
More and more people are starting to wonder what gems might lie hidden in the autistic brain. And if my brothers are any indication, if we keep looking, we will find them. She's the creator and host Flash Forward, a podcast about possible and not so possible futures, and has covered everything from fake tumbleweed farms to million dollar baccarat heists.
Follow Rose Eveleth on Twitter. Already a subscriber? Sign in. Thanks for reading Scientific American. Create your free account or Sign in to continue. See Subscription Options. Discover World-Changing Science. Rose Eveleth is a writer and producer who explores how humans tangle with science and technology. Get smart. Sign up for our email newsletter. Sign Up. Support science journalism. Knowledge awaits. See Subscription Options Already a subscriber? The researchers looked for telltale patterns of brain activity that reflect the extent to which an individual recognizes the pictures and associates them with the correct words.
In the auditory cortex, a brain region that processes words, both groups showed a peak in activity, called the auditory P1, about milliseconds after they heard a word. And in the visual cortex, which processes images, both groups again showed a brief spike in brain activity, called the visual P1, about milliseconds after each picture appeared.
Both spikes occurred slightly later in the autistic children, indicating that sensory processing is in place, albeit slightly delayed. Benasich and her colleagues saw more significant differences arise later in the sensory processing, however. In the visual cortex, the control group showed a longer-lasting boost in brain activity, called the positive slow wave, about milliseconds after an image appeared. The autistic children did not show this wave, suggesting that their brains may not connect the pictures they see to related information.
The controls also showed a large change in brain activity, called the N, about milliseconds after hearing a mismatched word. Some of the autistic children showed less of a difference in the N after hearing a mismatched word versus a matching one. The smaller gap suggests that their brain has trouble relating the pictures they see to the words they hear, or that they simply do not understand the words.
Alternatively, they may use other parts of the brain to process the information. These differences might help researchers understand why some autistic children do not speak.
Kedar says his inability to speak more than a few words may be due to apraxia, a disconnect between speech plans in the brain and the motor plans needed to execute them. He was almost 7 before his mother, Tracy, first recognized how much he understood. The two were writing out invitations to his 7 th birthday party — with her hand over his on the pen. She was spelling out loud every letter he should write.
At one point, she noticed that she had omitted a word. Before she could tell her son, though, she says she felt his hand moving the pen to write the missing letters.
But before such tests replace standardized ones, researchers would need to validate their results with hundreds, if not thousands, of people. That may be tricky because the techniques are more expensive and less portable than traditional cognitive tests, says Aaron Kaat , research assistant professor of medical social sciences at Northwestern University in Chicago. Kaat is part of a team that has created a series of tests of cognitive and other abilities called the NIH Toolbox for tablets.
The toolbox is being validated in people with Down syndrome, intellectual disability and an autism-related condition called fragile X syndrome. It is designed to be used even outside the confines of a lab. Given the concerns the eye-tracking and EEG studies raise about the inaccuracy of conventional intelligence tests, some researchers say it is imperative to develop techniques for testing cognitive abilities in autistic people.
That might be the only way to reach children who can understand language and read, but who cannot communicate. This article was republished in The Atlantic. By joining the discussion, you agree to our privacy policy. Spectrum: Autism Research News. All News Conference News Collections of articles from conferences. All Opinion Viewpoint Expert opinions on trends and controversies in autism research. All Features Deep Dive In-depth analysis of important topics in autism. About Subscribe.
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