User:Llj2/Epidemiology of autism

United States
According to a report by the CDC in 2020, 1 in 36 children have ASD (27.6 in every 1,000). The number of diagnosed cases of autism grew dramatically in the U.S. in the 1990s and have continued in the 2000s. For the 2006 surveillance year, identified ASD cases were an estimated 9.0 per 1000 children aged 8 years (95% confidence interval [CI] = 8.6–9.3). These numbers measure what is sometimes called "administrative prevalence", that is, the number of known cases per unit of population, as opposed to the true number of cases. This prevalence estimate rose 57% (95% CI 27%–95%) from 2002 to 2006.

COVID-19
The COVID-19 pandemic may have impacted the current number of diagnoses. More assessments for ASD occurred among 4-year-olds than the current 8-year-olds when they were 4 years of age prior to the pandemic. After the pandemic, the rate of current assessments has dropped, leading to possible delayed identification of ASD.

Vaccines and Autism
A common misconception is that vaccinations are the cause of children developing ASD. This is partly due to the concern of a former ingredient called thimerosal, which is a substance that contains mercury. Scientific literature demonstrates that there is no causal link between thimerosal and ASD. Though the ingredient is not as prevalent in vaccines anymore, there is still concern about the link between autism and vaccinations, but there is no evidence to support this notion.

Environmental Chemical Exposure
One theory behind autism is exposure to environmental chemicals before the age of two months. Human studies have mainly focused on particulate matter or mercury. Other studies investigated the effects of pollutants in the air or lead. Additionally, studies involving rodent animal models also investigated the effects of chlorpyrifos. Research suggests that environmental chemicals can be targeted and impacted by pollutants. Some systemic reviews have indicated that while significant correlations between mercury exposure and autism have been found, more research is needed.

Other Findings
There exists behavioral differences and differences in brain structures between males and females with autism. Females often either mask their symptoms more (called camoflaging) or need to display more prominent symptoms to receive a diagnosis. Males tend to demonstrate common symptoms of autism such as repetitive and restricted behaviors more so than females. This difference is hypothesized to be part of why females are more likely to be underdiagnosed.

Differences in brain structures also exist between males versus females with autism. There are known differences between male and female brain structures in neurotypical individuals; however, among those with autism, there exists a separate set of difference between biological males and females. It was found that the patterns of gray matter in regions of the brain relating to motor function can distinguish males with autism from females with autism. (results from their own research at Stanford- remove bc cannot trace?)

Related Brain Structures
Key symptoms of autism spectrum disorder are impaired social and communication abilities and having a narrow scope of interest and repeated behaviors. An impairment of language used to be a key diagnostic factor, but research has lead to categorizing this symptom as a specifier. One scoping review has determined multiple brain structures that appear to play a role in language related symptoms in autism spectrum disorder. For example, having a larger sized right inferior frontal gyrus is correlated with those diagnosed with autism, specifically categorized in the language impairment subgroup (but not in those without). Some research yields conflicting results however related to different structures and total language scores, in which a possible factor for this could be age.

As for temporal regions, increased rightward radial diffusivity might have an association with receptive language scores. Research concerning the planum temporale and its role in language has been inconclusive. The cerebellum may also be a factor in whether a person has language impairment or not.

Biomarkers
https://www.frontiersin.org/journals/neuroscience/articles/10.3389/fnins.2023.1269880/full

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6989979/

There are no known methods of diagnosing ASD such as blood tests (ncbi). Yet there are different biomarkers that professionals can look for. These can be determined as early as the prenatal stages or during the pre-symptomatic period.

It appears that different kinds of auditory stimuli can change the amplitude

Australia
Approximately 1 in 100 people in Australia have been reported to have autism.

Updated stats- my change in bold

Frequency estimates[edit]
Estimates of the prevalence of autism vary widely depending on diagnostic criteria, age of children screened, and geographical location. Most recent reviews tend to estimate a prevalence of 1–2 per 1,000 for autism and close to 27.6 per 1,000 for ASD ; PDD-NOS is the vast majority of ASD, Asperger syndrome is about 0.3 per 1,000 and the atypical forms childhood disintegrative disorder and Rett syndrome are much rarer.

** aspergers? cannot find

Canada[edit]
'''The Canadian government reported in 2019 that 1 in 50 children were diagnosed with autism spectrum disorder. . ''However, preliminary results of an epidemiological study conducted at Montreal Children's Hospital in the 200–2004 school year found a prevalence rate of 0.68% (or 1 per 147). <-- not relevant, cannot find equivalent (asked about on talk page).'

Symptom Management
Much research centered around those with ASD that have impaired communication and seeking improvement in social interaction often investigate the use of psychosocial interventions. However, other research looks to pharmacology for treatment. Therapy is also a common treatment that appears most impactful when treatment begins while they are younger(cite https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6989979/) (changed directly on article). Overall however, treatment options are still in development.