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PubMed2003

Behavioral relationship between autism and fragile x syndrome.

Previous researchers have reported autistic features in children with fragile X syndrome. We compared 21 children with pervasive developmental disorders (autism group) to 15 with fragile X syndrome on the Childhood Autism Rating Scale and the Reiss Scales for Children's Dual Diagnosis. The 7 children (47%) with fragile X who scored above the Childhood Autism Rating Scale cut-off (fragile X-autism group) were more impaired than the remaining children (fragile X-no autism) on Childhood Autism Rating Scale subscales related to emotion, visual and listening responses, and communication. The autism group's Reiss scores were higher than fragile X-no autism group, but not fragile X-autism group. Although the Childhood Autism Rating Scale identified almost 50% of children with fragile X as having autism, qualitative differences may exist in specific autistic-like behaviors between children with autism and children with fragile X.

Adolescent↗

PubMed2007

Infection in the first 2 years of life and autism spectrum disorders.

OBJECTIVE: The purpose of this work was to investigate the association between infections in the first 2 years and subsequent diagnosis of autism spectrum disorders. METHODS: We conducted a case-control study among children born at Kaiser Permanente Northern California from 1995 to 1999. Case subjects (n = 403) were children with an autism diagnosis recorded in Kaiser Permanente databases. Control subjects (n = 2100) were randomly sampled from the remaining children without autism and frequency matched to case subjects on gender, birth year, and birth hospital. Information on infections and covariates were obtained from Kaiser Permanente and birth certificate databases. RESULTS: Overall, infection diagnoses in the first 2 years of life were recorded slightly less often for children with autism than control children (95.0% vs 97.5%). Among specific diagnoses, upper respiratory infections were significantly less frequently diagnosed and genitourinary infections more frequently diagnosed in children with autism. In the first 30 days of life, the frequency of having an infection was slightly higher among children with autism (22.6% vs 18.7%). CONCLUSIONS: Children with subsequent diagnoses of autism do not have more overall infections in the first 2 years of life than children without autism. Data suggest that children with autism may have modestly elevated rates of infection in the first 30 days and that, during the first 2 years, children with autism may be at higher risk for certain types of infections and lower risk for others. Additional studies that explore the associations between prenatal and early childhood infections and autism may help clarify the role of infection and the immune system in the etiology of autism spectrum disorder.

Autistic Disorder↗

PubMed2001

Autism and measles-mumps-rubella vaccination: controversy laid to rest?

It has been suggested that vaccination, particularly with measles-mumps-rubella (MMR) vaccine, may be related to the development of autism. The main evidence for a possible association is that the prevalence of autism has been increasing at the same time that infant vaccination coverage has increased, and that in some cases there is an apparent temporal association in which autistic characteristics are first noted shortly after vaccination. Although the prevalence of autism and similar disorders appears to have increased recently, it is not clear if this is an actual increase or the result of increased recognition and changes in diagnostic criteria. The apparent onset of autism in close proximity to vaccination may be a coincidental temporal association. The clinical evidence in support of an association derives from a series of 12 patients with inflammatory bowel conditions and regressive developmental disorders, mostly autism. The possibility that measles vaccine may cause autism through a persistent bowel infection has generated much interest, since it provides a possible biological mechanism. Epidemiological studies, however, have not found an association between MMR vaccination and autism. The epidemiological findings are consistent with current understanding of the pathogenesis of autism, which has a strong genetic component and in which the neurological defects probably occur early in embryonic development. It seems unlikely that a vaccination that is given after birth could cause autism. A minority of cases of autism may have onset after 1 year of age (regressive autism), but the single epidemiological study that included such cases did not find an association with MMR vaccination. Currently, the weight of the available epidemiological and related evidence does not support a causal association between MMR vaccine, or any other vaccine or vaccine constituent, and autism.

Autistic Disorder↗

PubMedDate not supplied

A comparison of the performance of children with and without autism on the Sensory Profile.

OBJECTIVE: The purpose of this study was to determine whether the Sensory Profile discriminates between children with and without autism and which items on the profile best discriminate between these groups. METHOD: Parents of 32 children with autism aged 3 to 13 years and of 64 children without autism aged 3 to 10 years completed the Sensory Profile. A descriptive analysis of the data set of children with autism identified the distribution of responses on each item. A multivariate analysis of covariance (MANCOVA) of each category of the Sensory Profile identified possible differences among subjects without autism, with mild or moderate autism, and with severe autism. Follow-up univariate analyses were conducted for any category that yielded a significant result on the MANCOVA: RESULTS: Eight-four of 99 items (85%) on the Sensory Profile differentiated the sensory processing skills of subjects with autism from those without autism. There were no group differences between subjects with mild or moderate autism and subjects with severe autism. CONCLUSION: The Sensory Profile can provide information about the sensory processing skills of children with autism to assist occupational therapists in assessing and planning intervention for these children.

Adolescent↗

PubMed2003

[Clinical features of epilepsy in autism spectrum disorders].

Autism is a rare disease, but is currently in vogue. An incidence of 1/1,000 has been estimated for early childhood autism, but in autism spectrum the incidence can reach 30/1,000. The clinical characteristics of autism are cognitive language disorders, lack of social interaction, obsessive behaviours with stereotypic movements and epilepsy. For some authors it is an associated symptom while for others it is a cardinal symptom of the disease. Epilepsy in autism, as an association, was reported as early as 1944 by Leo Kanner, in describing his initial work involving 11 cases and how one of them suffered from epilepsy. In 1960, the prevalence of epilepsy among autistic patients was evaluated and found to be much higher than in the normal population. The figures differ from author to author, but really they depend on age: the higher the age, the greater the prevalence of epilepsy. It was in fact this detail that drew our attention to this issue, and triggered the first questions in our research into autism and epilepsy. The series vary from 4 to 86%, depending on the methodology used to confirm the epilepsy. In our casuistics, between the ages of 1 and 18 years, 20% of these children with autism spectrum disorders suffer some kind of epileptic seizures, and 80% suffer what other researchers call subclinical seizures . In this paper, the symptomatology of the most important subclinical seizures that have been observed in these children is presented; the diseases associated with autism are commented on; the concept of primary and secondary autism is discussed; we explain why seizures occur in autism and their consequences as a neurodevelopmental disorder, and we put forward an interesting hypothesis within our general theory of autism. We also comment on the importance that the use of functional magnetic images in the study of autism has in our research.

Adolescent↗

PubMed2004

Autism as early expression of catatonia.

BACKGROUND: Reports indicate that catatonia often occurs in autism. The association lacks a conceptual basis. Modern classificatory schemes define autism and catatonia separately and are not conducive to study areas of overlap. The exploration of the relation between autism and catatonia may be important because autism is increasingly recognized but effective treatments are lacking. Catatonia, on the other hand, is thought to be treatable, but is poorly recognized. MATERIAL/METHODS: The literature on autism and catatonia are reviewed to identify areas of overlap. A hypothesis is formulated that, in some cases, autism may the early expression of catatonia. RESULTS: Several areas of overlap between autism and catatonia are found. Catatonic symptoms are common in autism. Effects of anti-catatonic treatments on autistic symptoms are unknown. Abnormal gamma-aminobutyric acid (GABA) function has been implicated in both disorders. Neuroimaging studies show small cerebellar structures in both disorders. There is genetic evidence that susceptibility genes for autism and catatonia are located on the long arm of chromosome 15. Differences between autism and catatonia of age-of-onset, symptoms, and illness course, do not exclude a common genetic etiology. CONCLUSIONS: Focused research is needed to further evaluate the phenomenological, biological, and genetic overlap between autism and catatonia and to test the hypothesis that a subgroup of autism is early-onset catatonia.

Adolescent↗

PubMed2006

Amygdala volume and nonverbal social impairment in adolescent and adult males with autism.

BACKGROUND: Autism is a syndrome of unknown cause, marked by abnormal development of social behavior. Attempts to link pathological features of the amygdala, which plays a key role in emotional processing, to autism have shown little consensus. OBJECTIVE: To evaluate amygdala volume in individuals with autism spectrum disorders and its relationship to laboratory measures of social behavior to examine whether variations in amygdala structure relate to symptom severity. DESIGN: We conducted 2 cross-sectional studies of amygdala volume, measured blind to diagnosis on high-resolution, anatomical magnetic resonance images. Participants were 54 males aged 8 to 25 years, including 23 with autism and 5 with Asperger syndrome or pervasive developmental disorder not otherwise specified, recruited and evaluated at an academic center for developmental disabilities and 26 age- and sex-matched community volunteers. The Autism Diagnostic Interview-Revised was used to confirm diagnoses and to validate relationships with laboratory measures of social function. MAIN OUTCOME MEASURES: Amygdala volume, judgment of facial expressions, and eye tracking. RESULTS: In study 1, individuals with autism who had small amygdalae were slowest to distinguish emotional from neutral expressions (P=.02) and showed least fixation of eye regions (P=.04). These same individuals were most socially impaired in early childhood, as reported on the Autism Diagnostic Interview-Revised (P<.04). Study 2 showed smaller amygdalae in individuals with autism than in control subjects (P=.03) and group differences in the relation between amygdala volume and age. Study 2 also replicated findings of more gaze avoidance and childhood impairment in participants with autism with the smallest amygdalae. Across the combined sample, severity of social deficits interacted with age to predict different patterns of amygdala development in autism (P=.047). CONCLUSIONS: These findings best support a model of amygdala hyperactivity that could explain most volumetric findings in autism. Further psychophysiological and histopathological studies are indicated to confirm these findings.

Adolescent↗

PubMed2004

Language-association cortex asymmetry in autism and specific language impairment.

Language deficits are among the core impairments of autism. We previously reported asymmetry reversal of frontal language cortex in boys with autism. Specific language impairment (SLI) and autism share similar language deficits and may share genetic links. This study evaluated asymmetry of frontal language cortex in a new, independent sample of right-handed boys, including a new sample of boys with autism and a group of boys with SLI. The boys with autism were divided into those with language impairment (ALI) and those with normal language ability (ALN). Subjects (right-handed, aged 6.2-13.4 years) included 22 boys with autism (16 ALI and 6 ALN), 9 boys with a history of or present SLI, and 11 normal controls. MRI brain scans were segmented into grey and white matter; then the cerebral cortex was parcellated into 48 gyral-based divisions per hemisphere. Group differences in volumetric asymmetry were predicted a priori in language-related regions in inferior lateral frontal (Broca's area) and posterior superior temporal cortex. Language impaired boys with autism and SLI both had significant reversal of asymmetry in frontal language-related cortex; larger on the right side in both groups of language impaired boys and larger on the left in both unimpaired language groups, strengthening a phenotypic link between ALI and SLI. Thus, we replicated the observation of reversed asymmetry in frontal language cortex reported previously in an independent autism sample, and observed similar reversal in boys with SLI, further strengthening a phenotypic link between SLI and a subgroup of autism. Linguistically unimpaired boys with autism had similar asymmetry compared with the control group, suggesting that Broca's area asymmetry reversal is related more to language impairment than specifically to autism diagnosis.

Adolescent↗

PubMed1999

Autism and measles, mumps, and rubella vaccine: no epidemiological evidence for a causal association.

BACKGROUND: We undertook an epidemiological study to investigate whether measles, mumps, and rubella (MMR) vaccine may be causally associated with autism. METHODS: Children with autism born since 1979 were identified from special needs/disability registers and special schools in eight North Thames health districts, UK. Information from clinical records was linked to immunisation data held on the child health computing system. We looked for evidence of a change in trend in incidence or age at diagnosis associated with the introduction of MMR vaccination to the UK in 1988. Clustering of onsets within defined postvaccination periods was investigated by the case-series method. FINDINGS: We identified 498 cases of autism (261 of core autism, 166 of atypical autism, and 71 of Asperger's syndrome). In 293 cases the diagnosis could be confirmed by the criteria of the International Classification of Diseases, tenth revision (ICD10: 214 [82%] core autism, 52 [31%] atypical autism, 27 [38%] Asperger's syndrome). There was a steady increase in cases by year of birth with no sudden "step-up" or change in the trend line after the introduction of MMR vaccination. There was no difference in age at diagnosis between the cases vaccinated before or after 18 months of age and those never vaccinated. There was no temporal association between onset of autism within 1 or 2 years after vaccination with MMR (relative incidence compared with control period 0.94 [95% CI 0.60-1.47] and 1.09 [0.79-1.52]). Developmental regression was not clustered in the months after vaccination (relative incidence within 2 months and 4 months after MMR vaccination 0.92 [0.38-2.21] and 1.00 [0.52-1.95]). No significant temporal clustering for age at onset of parental concern was seen for cases of core autism or atypical autism with the exception of a single interval within 6 months of MMR vaccination. This appeared to be an artifact related to the difficulty of defining precisely the onset of symptoms in this disorder. INTERPRETATION: Our analyses do not support a causal association between MMR vaccine and autism. If such an association occurs, it is so rare that it could not be identified in this large regional sample.

Autistic Disorder↗

PubMed2004

The brain response to personally familiar faces in autism: findings of fusiform activity and beyond.

Past functional MRI (FMRI) studies of autism have reported reduced activation in response to the faces of strangers primarily in the 'fusiform face area' (FFA). An alternative and potentially stronger test of FFA function in autism is one that attempts to affect levels of FFA activity using factors believed to modulate function in this brain region, such as face familiarity and the perception of face identity. The current study presented personally meaningful faces, such as mother and co-worker, as well as stranger faces in a rapid event-related FMRI design. Seven autistic and nine normal control adults participated and pressed a button in response to all female faces. A deconvolution analysis revealed significant FFA activity in response to familiar and stranger faces in both autism and normal control groups. Individuals with autism also showed greater fusiform activity in response to familiar faces than stranger faces, as well as the prototypical right hemisphere dominance in response to both types of faces. Normal subjects showed additional activation to familiar faces in the posterior cingulate, amygdala and medial frontal lobes, including the anterior cingulate. Subjects with autism showed a similar, but more limited, network in response to familiar faces. This network included the amygdala and implies that this structure, involved in multiple socio-emotional functions, can be responsive in autism in the presence of stimuli that represent high reward value, such as mother's face. Furthermore, the presence of a distinct network to process familiar faces in autism, one that included limbic structures and was not found in response to the faces of strangers, suggests socio-emotional processing in autism. A potentially noteworthy trend, however, was evidence for a reduction in medial frontal lobe function in the autism group. The main finding of FFA activity in autism stands in contrast to most past FMRI studies of face processing in this disorder. This positive result may reflect the use of personally significant faces that enhanced attention and motivation in the autistic participants. Furthermore, given the proposed role of the FFA in establishing person identity, the use of almost a dozen different personally familiar faces for each participant (totalling 32 non-repeating faces) may have additionally maximized FFA involvement. Therefore, dysfunction in the FFA found in other studies of autism may reflect defects in systems that modulate the FFA, rather than the FFA itself.

Adolescent↗

PubMed2005

Continuity and change from early childhood to adolescence in autism.

BACKGROUND: This longitudinal study of 48 children diagnosed with autism at 2-5 years of age was designed to test the hypothesis that diagnosis would remain stable for most of the sample but that there would be improvements in symptom severity, adaptive behavior, and emotional responsiveness in adolescence. METHODS: A sample of children with autism assessed in both early and middle childhood were observed in late adolescence with the Autism Diagnostic Observation Scale (ADOS) and their parents were administered the Autism Diagnostic Interview-Revised (ADI-R) and the Vineland Adaptive Behavior Scale. RESULTS: All but 2 adolescents (46 of 48) met lifetime criteria for autism according to the ADI-R, and all but 4 adolescents (40 of 44) met criteria for autism spectrum disorder on the ADOS. In contrast to the continuity in diagnosis, parents described improvements in social interactions, repetitive/stereotyped behaviors, adaptive behaviors, and emotional responsiveness to others' distress in adolescence compared to middle childhood. High-functioning adolescents with autism showed more improvement in these domains than low-functioning adolescents with autism. The extent to which the adolescents were observed to be socially engaged with their peers in school in middle childhood predicted adaptive behavior skills even when intelligence level was statistically constrained. CONCLUSIONS: The developmental trajectory of children with autism appears to show both continuity and change. In this sample, most individuals continued to be diagnosed in the autism spectrum but parents reported improvements in adolescence. The results suggest that social involvement with peers improves adaptive behavior skills, and this argues for focusing intervention programs in this area. In addition, it is clear that high-functioning adolescents improve more than low-functioning individuals not only in cognitive abilities but also in social interaction skills. Thus, any early intervention that impacts the cognitive abilities of young children with autism is likely to have a parallel influence on their social skills as they mature into late adolescence and early adulthood.

Adaptation, Psychological↗

PubMed2001

Mumps, measles, and rubella vaccine and the incidence of autism recorded by general practitioners: a time trend analysis.

OBJECTIVE: To estimate changes in the risk of autism and assess the relation of autism to the mumps, measles, and rubella (MMR) vaccine. DESIGN: Time trend analysis of data from the UK general practice research database (GPRD). SETTING: General practices in the United Kingdom. SUBJECTS: Children aged 12 years or younger diagnosed with autism 1988-99, with further analysis of boys aged 2 to 5 years born 1988-93. MAIN OUTCOME MEASURES: Annual and age specific incidence for first recorded diagnoses of autism (that is, when the diagnosis of autism was first recorded) in the children aged 12 years or younger; annual, birth cohort specific risk of autism diagnosed in the 2 to 5 year old boys; coverage (prevalence) of MMR vaccination in the same birth cohorts. RESULTS: The incidence of newly diagnosed autism increased sevenfold, from 0.3 per 10 000 person years in 1988 to 2.1 per 10 000 person years in 1999. The peak incidence was among 3 and 4 year olds, and 83% (254/305) of cases were boys. In an annual birth cohort analysis of 114 boys born in 1988-93, the risk of autism in 2 to 5 year old boys increased nearly fourfold over time, from 8 (95% confidence interval 4 to 14) per 10 000 for boys born in 1988 to 29 (20 to 43) per 10 000 for boys born in 1993. For the same annual birth cohorts the prevalence of MMR vaccination was over 95%. CONCLUSIONS: Because the incidence of autism among 2 to 5 year olds increased markedly among boys born in each year separately from 1988 to 1993 while MMR vaccine coverage was over 95% for successive annual birth cohorts, the data provide evidence that no correlation exists between the prevalence of MMR vaccination and the rapid increase in the risk of autism over time. The explanation for the marked increase in risk of the diagnosis of autism in the past decade remains uncertain.

Age Distribution↗

PubMed2005

What is known about autism: genes, brain, and behavior.

Autism is a neurodevelopmental disorder of genetic origins, with a heritability of about 90%. Autistic disorder is classed within the broad domain of pervasive developmental disorders (PDD) that also includes Rett syndrome, childhood disintegrative disorder, Asperger syndrome, and PDD not otherwise specified (PDD-NOS). Prevalence estimates suggest a rate of 0.1-0.2% for autism and 0.6% for the range of PDD disorders. There is considerable phenotypic heterogeneity within this class of disorders as well as continued debate regarding their clinical boundaries. Autism is the prototypical PDD, and is characterized by impairments in three core domains: social interaction, language development, and patterns of behavior (restricted and stereotyped). Clinical pattern and severity of impairment vary along these dimensions, and the level of cognitive functioning of individuals with autism spans the entire range, from profound mental retardation to superior intellect. There is no single biological or clinical marker for autism, nor is it expected that a single gene is responsible for its expression; as many as 15+ genes may be involved. However, environmental influences are also important, as concordance in monozygotic twins is less than 100% and the phenotypic expression of the disorder varies widely, even within monozygotic twins. Multiple susceptibility factors are being explored using varied methodologies, including genome-wide linkage studies, and family- and case-control candidate gene association studies. This paper reviews what is currently known about the genetic and environmental risk factors, neuropathology, and psychopharmacology of autism. Discussion of genetic factors focuses on the findings from linkage and association studies, the results of which have implicated the involvement of nearly every chromosome in the human genome. However, the most consistently replicated linkage findings have been on chromosome 7q, 2q, and 15q. The positive associations from candidate gene studies are largely unreplicated, with the possible exceptions of the GABRB3 and serotonin transporter genes. No single region of the brain or pathophysiological mechanism has yet been identified as being associated with autism. Postmortem findings, animal models, and neuroimaging studies have focused on the cerebellum, frontal cortex, hippocampus, and especially the amygdala. The cerebello-thalamo-cortical circuit may also be influential in autism. There is evidence that overall brain size is increased in some individuals with autism. Presently there are no drugs that produce major improvements in the core social or pragmatic language deficits in autism, although several have limited effects on associated behavioral features. The application of new techniques in autism research is being proposed, including the investigation of abnormal regulation of gene expression, proteomics, and the use of MRI and postmortem analysis of the brain.

Animals↗

PubMed2006

Mental health in the United States: parental report of diagnosed autism in children aged 4-17 years--United States, 2003-2004.

Autism is a lifelong neurodevelopmental disorder characterized by early onset of impairments in social interaction and communication and unusual, stereotyped behaviors. Autism (i.e., autistic disorder) often is classified with two related, although less severe, developmental disorders: Asperger disorder and pervasive developmental disorder--not otherwise specified. These three constitute the autism spectrum disorders (ASDs). Diagnosis of ASDs is based exclusively on developmental pattern and behavioral observation. Two population-based studies conducted by CDC in selected U.S. locations reported ASD prevalence of 3.4 and 6.7 per 1,000 children, respectively. CDC also conducts two nationally representative surveys, the National Health Interview Survey (NHIS) and the National Survey of Children's Health (NSCH), in which parents are asked whether their child ever received a diagnosis of autism. Because of similarities in methodology used by the two surveys, CDC analyzed 2003-2004 data from NHIS and data from the first-ever NSCH (collected during January 2003-July 2004) to 1) estimate the population-based prevalence of parental report of diagnosed autism in the United States and 2) assess parental reporting of child social, emotional, and behavioral strengths and difficulties and special-health care needs among children with and without reported autism. This report describes the results of that analysis, which indicated that the prevalence of parent-reported diagnosis of autism was 5.7 per 1,000 children in NHIS and 5.5 per 1,000 children in NSCH. Prevalence estimates in the two studies were similar across age, sex, and racial/ethnic populations. The consistency in estimates between the two surveys suggests high reliability for parental report of autism. These estimates suggest that, as of 2003-2004, autism had been diagnosed in at least 300,000 U.S. children aged 4-17 years. In addition, parental reports of autism were associated with reported social, emotional, and behavioral symptoms and specialized needs. Thus, these surveys might be useful to assess health, education, and social service needs of children with autism.

Adolescent↗

PubMed2002

Symptom domains in autism and related conditions: evidence for familiality.

Heterogeneity in autism impairs efforts to localize and identify the genes underlying this disorder. As autism comprises severe but variable deficits and traits in three symptom domains (social interaction, communication, and repetitive behaviors) and shows variability in the presence and emergence of useful phrase speech, different genetic factors may be associated with each. The affected cases (n=457) in multiply affected siblingships (n=212), including a proband with autism and one or more siblings with either autism or marked deficits in autism symptom domains, were assessed using the Autism Diagnostic Interview, Revised. Symptom domain scores and language features were examined to determine their similarity within siblingships. The variance within siblingships was reduced for the repetitive behavior domain and for delays in and the presence of useful phrase speech. These features and the nonverbal communication subdomain provided evidence of familiality when we considered only the diagnosis of autism to define multiply affected siblingships (cases: n=289; siblingships: n=136). In addition, the same familial features identified also appeared familial for those with autism-related conditions. Finally, the level of severity of almost all of the familial features varied within multiplex siblingships independently. The features identified as familial replicate the combined set suggested in earlier, smaller studies. Furthermore, the familiality of these features extend to related conditions of milder severity than autism and appear to be independent. Making distinctions among families by the severity of these features may be useful for identifying more genetically homogeneous subgroups in studies targeted at genes for specific autism-related symptom domains.

Autistic Disorder↗

PubMed2025

Polygenic and developmental profiles of autism differ by age at diagnosis.

Although autism has historically been conceptualized as a condition that emerges in early childhood1,2, many autistic people are diagnosed later in life3-5. It is unknown whether earlier- and later-diagnosed autism have different developmental trajectories and genetic profiles. Using longitudinal data from four independent birth cohorts, we demonstrate that two different socioemotional and behavioural trajectories are associated with age at diagnosis. In independent cohorts of autistic individuals, common genetic variants account for approximately 11% of the variance in age at autism diagnosis, similar to the contribution of individual sociodemographic and clinical factors, which typically explain less than 15% of this variance. We further demonstrate that the polygenic architecture of autism can be broken down into two modestly genetically correlated (rg = 0.38, s.e. = 0.07) autism polygenic factors. One of these factors is associated with earlier autism diagnosis and lower social and communication abilities in early childhood, but is only moderately genetically correlated with attention deficit-hyperactivity disorder (ADHD) and mental-health conditions. Conversely, the second factor is associated with later autism diagnosis and increased socioemotional and behavioural difficulties in adolescence, and has moderate to high positive genetic correlations with ADHD and mental-health conditions. These findings indicate that earlier- and later-diagnosed autism have different developmental trajectories and genetic profiles. Our findings have important implications for how we conceptualize autism and provide a model to explain some of the diversity found in autism.

Humans↗

PubMed2025

Polygenic and developmental profiles of autism differ by age at diagnosis.

Although autism has been historically conceptualised as a condition that emerges in early childhood, many autistic people are diagnosed later in life. It is unknown whether earlier and later diagnosed autism have different developmental trajectories and genetic profiles. Using longitudinal data from four independent birth cohorts, we demonstrate that two different socioemotional and behavioural trajectories are associated with age at diagnosis. In independent cohorts of autistic individuals, common genetic variants account for approximately 11% of the variance in age at autism diagnosis, comparable to the contribution of individual sociodemographic and clinical factors, which typically explain less than 15% of this variance. We further demonstrate that the polygenic architecture of autism can be decomposed into two modestly genetically correlated (rg = 0.38, SE = 0.07) autism polygenic factors. One of these factors is associated with earlier autism diagnosis, and lower social and communication abilities in early childhood but is only modestly genetically correlated with ADHD and mental health conditions. Conversely, the second factor is associated with later autism diagnosis, increased socioemotional and behavioural difficulties in adolescence, and has moderate to high positive genetic correlations with Attention-Deficit/Hyperactivity Disorder and mental health conditions. These findings indicate that earlier and later diagnosed autism have different developmental trajectories and genetic profiles. Our findings have important implications for how we conceptualise autism and provide one model to explain some of the diversity within autism.

Journal Article↗

PubMed2006

Parental report of health conditions and health care use among children with and without autism: National Survey of Children's Health.

OBJECTIVE: To compare parent-reported prevalence of health conditions and health care use between children with and without autism. DESIGN: Cross-sectional analysis of the 2003 to 2004 National Survey of Children's Health. SETTING: Population-based sample across the United States. PARTICIPANTS: More than 100 000 parents. The main exposure was "autism" (not further defined), from response to the question: "Has a doctor or health professional ever told you that your child has autism?" MAIN OUTCOME MEASURES: Medical and mental health conditions and measures of health care use. RESULTS: Autism prevalence among children aged 3 to 17 years was 53 per 10 000 (95% confidence interval, 45-61 per 10,000), equating to a national estimate of 324 000 children (95% confidence interval, 274,000-375,000 children). Children with autism had a significantly (P<.001) higher prevalence of depression or anxiety problems (38.9% vs 4.2%) and behavioral or conduct problems (58.9% vs 5.2%) than children without autism. Respiratory, food, and skin allergies were reported by parents more often for children with autism, with food allergies having the strongest relative difference between the groups (odds ratio, 4.5; 95% confidence interval, 3.0-7.0). Children with autism had significantly (P<.001) higher mean physician visits over 12 months for preventive care, nonemergency care, and hospital emergency care, and were far more likely than children without autism to receive physical, occupational, or speech therapy (76.0% vs 6.3%), to need treatment or counseling for an emotional, developmental, or behavioral problem (75.4% vs 7.0%), and, among those taking a prescribed medication, to be using a medication long-term (51.4% vs 14.5%). CONCLUSION: We found markedly higher reports of concurrent conditions and health care use associated with childhood autism in this study.

Adolescent↗