FACT: The prevalence of those diagnosed with ASD has gone up about tenfold since the mid-1980s, but it is important to note the increase is largely associated with changes in the diagnostic criteria and a greater awareness in the medical community of how autism presents at different ages. There is no evidence that there is any environmental factor that might account for the increase in prevalence.
FACT: It is very clear that autism is not caused by vaccines. The initial paper published on this topic has been disproved. This claim has now been recognized as fraudulent and biased by the pursuit of class action lawsuits. In fact, there are several communities where the ingredients that were reported to cause autism have been removed from the vaccine and yet within those communities the diagnosis of autism continues to rise.
A genetic basis for at least some forms of autism has been demonstrated by family studies. Approximately 3 % of families with an autistic child will produce another child with autism, a prevalence rate which equals 50 to 100 times that of the general population. In addition, the concordance rate for autism in monozygotic twins has been found to range from 40 to 96%. Further support for genetic involvement is found in studies of characteristics in families of autistic children. Siblings of autistic children may be more likely to show superiority in visuospatial over verbal abilities (analogous to the autistic profile), cognitive difficulties such as language disorder, and social disengagement. A few studies have found that some parents of autistic children may be more likely to show unusual social behaviors. The search for specific genetic markers for autism thus far has uncovered two prospects: a marker for a gene that regulates neuron development, and abnormalities of chromosome 15.
The biggest fears of a parent are disorders or behavioural issues their children may have. It is both inspiring and astounding for me to see parents coping with their kids’ Autism.
Analyses. We examined the association of demographic covariates with ASD case status to assess possible confounding. To calculate odds ratios (ORs) for ASD associated with exposure to specific pollutants, we fit separate logistic regression models with ASD case status as the dependent variable and quintiles of each pollutant as the independent variable, both adjusted for child’s sex and stratified by sex. To test a linear dose–response relationship of pollutant exposure with ASD while reducing the influence of outliers, we assigned to each child the median pollutant concentration for his or her quintile and conducted logistic regression with these concentrations entered as a continuous independent variable. To test for sex differences in the association of pollutant quintile with ASD, we multiplied a continuous term for pollutant quintile (1–5) by an indicator of male sex and included this term in models with pollutant quintile, male sex, and demographic covariates. To adjust for multiple tests of significance, we calculated p-values adjusted for false discovery rate using the SAS Multtest procedure (SAS Institute Inc., Cary, NC).
The autistic child’s language profile is arguably the syndrome’s most distinctive cognitive feature, which has earned it a central position in some theories of the etiology of autism. Many aspects of verbal functioning are impaired in autistic children, as many as 40 to 50% of whom are mute, although this figure is declining with the advent of aggressive early intervention. Those with speech often display echolalia, difficulties with prepositions and pronouns, and inappropriate conversational behaviors. Verbal autistic children generally are able to acquire normal grammatical morphology and syntax, although onset and development are delayed. Some autistic children learn grapheme-phoneme correspondence, leading to early decoding of words; comprehension, however, lags far behind. Comprehension of oral language is significantly impaired relative to expression, and deficits in the semantic and pragmatic aspects of language are common. They are also deficient in interactive communication, including conversational behavior, nonverbal communication and speech prosody. In general, the more linguistic aspects of communication, including especially phonology and syntax, are spared relative to the pragmatic aspects; pragmatic deficits can be seen in the failure to use language functionally to share or request information, or perform other speech functions that serve social, rather than instrumental, functions.
Autism spectrum disorder (ASD) is a developmental disorder with increasing reported prevalence worldwide (). Although genetics plays a strong role in ASD, evidence suggests that environmental exposures, particularly in utero or during early life, also affect ASD risk (; ; Quaak et al. 2013). However, no specific environmental toxicant has been consistently associated with increased risk of ASD.
Overall cognitive level, or presence of mental retardation, is an important feature of the individual autistic child, and powerfully predicts the functional outcome that can be expected for the child. Recent work by several research groups, such as the group headed by Rapin (see Bibliography) suggests that high- and low-functioning autism may be significantly different in behavioral manifestations, history, and prognosis, that approximately half of the autistic population falls into each group, and that an IQ cutoff of about 65 makes the most appropriate division between highand low-functioning autism. Beyond studies of overall cognitive level, many investigators have examined typical cognitive profiles in autism, that is, areas of relative sparing and impairment. Some autistic children, both those with severe impairment and those who are higher functioning, display unusual gifts, especially in rote memory, calculations, and music. A majority of autistic children are known to have relative strengths in visuospatial abilities, while tasks requiring verbal reasoning, social cognition, or flexibility pose relative difficulty for the autistic child. Although this description suggests a typical cognitive profile, studies have shown that there is great heterogeneity in the autistic population, and that no single cognitive deficit is universal in autistic individuals.
NICHD is interested in applications that focus on environmental exposures that occurred prenatally during critical windows of fetal development and that impact early child development. Examples of exposures include medications used during pregnancy, prenatal infections, maternal immune or inflammatory conditions, other medical conditions of the mother, specific nutrient or dietary exposures, and psychosocial factors. Specifically, NICHD is interested in studies focusing on prenatal exposures that alter the genetic or epigenetic profile and predispose to autism susceptibility; factors that alter the maternal or offspring microbiome and affect infant development; prenatal exposures to maternal disease, condition(s), or medication(s); and the presence of significant inflammation in utero and how it might be quantitatively related to altered cellular function and development in the offspring. NICHD is also interested in specific gene-environment interactions influenced by prenatal exposures. Applicants are strongly encouraged to contact NICHD Scientific/Research staff prior to submission to determine if their project meets the interests of the NICHD.
NIMH is interested in research projects that seek to elucidate the role of genetic and epigenetic mechanisms modulated by environmental exposure(s) on gut microbiome in patients with ASD and control populations with the goal of identifying genetic pathways associated with ASD. Investigators are strongly encouraged to leverage existing longitudinal exposure data and detailed phenotypic assessments available on patients with ASD to evaluate the effect of environment on host gut microbiome and its role in autism.
NIMH is also interested in studies elucidating the relationship of environmental factors to genetic or epigenetic signatures that have been implicated in ASD, and in the identification and analysis of gene-environment interactions in the context of Genome-Wide Association Studies (GWAS) or other large scale genetic studies. Such analyses should leverage existing genetic and epigenomic data for characterization of phenotypes. Also of interest are projects that would utilize the National Database for Autism Research (NDAR) to develop methods to provide data on environmental exposures to the research community, without revealing the exact geospatial location of a research subject.