The Issue of Prevalence of Autism/ASD (original) (raw)
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The epidemiology of autism spectrum disorder and factors contributing to the increase in its prevalence, 2022
Autism spectrum disorder (ASD) is a multifactorial neurodevelopmental disorder which has attracted the interest of researchers in many scientific fields. The prevalence of a disease or a disorder is important for healthcare and socioeconomic reasons. According to the World Health Organization (WHO), currently, 1 in 160 children is born with ASD (0.63%), possibly a conservative estimate, as many studies have reported a prevalence higher than 1%. Even so, the WHO rate is approximately 14 times higher than that reported in the first epidemiological study on ASD, which was conducted in the UK 50 years ago. It is currently estimated that approximately 60 million people worldwide have ASD. Diagnosis and documentation of these individuals is challenging, due to the nature of the disorder and its broad spectrum. Many countries have no epidemiological data on ASD and several epidemiological studies on ASD record significant methodological limitations, but the currently available data indicate that the prevalence of ASD has risen over the years. The interpretation of this trend remains uncertain, but several factors have been documented that may have contributed to this apparent increase, including revision of the diagnostic criteria, overdiagnosis, scientific advances, accessibility to services, increase in social awareness, and improvement in the methodology applied in the epidemiological studies, in addition to environmental and other factors.
Global Prevalence of Autism and Other Pervasive Developmental Disorders
Autism Research, 2012
We provide a systematic review of epidemiological surveys of autistic disorder and pervasive developmental disorders (PDDs) worldwide. A secondary aim was to consider the possible impact of geographic, cultural/ethnic, and socioeconomic factors on prevalence estimates and on clinical presentation of PDD. Based on the evidence reviewed, the median of prevalence estimates of autism spectrum disorders was 62/10 000. While existing estimates are variable, the evidence reviewed does not support differences in PDD prevalence by geographic region nor of a strong impact of ethnic/cultural or socioeconomic factors. However, power to detect such effects is seriously limited in existing data sets, particularly in low-income countries. While it is clear that prevalence estimates have increased over time and these vary in different neighboring and distant regions, these findings most likely represent broadening of the diagnostic concets, diagnostic switching from other developmental disabilities to PDD, service availability, and awareness of autistic spectrum disorders in both the lay and professional public. The lack of evidence from the majority of the world's population suggests a critical need for further research and capacity building in low-and middle-income countries. Autism Res 2012, ••: ••-••.
Global prevalence of autism: A systematic review update
Autism Research, 2022
Prevalence estimates of autism are essential for informing public policy, raising awareness, and developing research priorities. Using a systematic review, we synthesized estimates of the prevalence of autism worldwide. We examined factors accounting for variability in estimates and critically reviewed evidence relevant for hypotheses about biological or social determinants (viz., biological sex, sociodemographic status, ethnicity/race, and nativity) potentially modifying prevalence estimates of autism. We performed the search in November 2021 within Medline for studies estimating autism prevalence, published since our last systematic review in 2012. Data were extracted by two independent researchers. Since 2012, 99 estimates from 71 studies were published indicating a global autism prevalence that ranges within and across regions, with a median prevalence of 100/10,000 (range: 1.09/10,000 to 436.0/10,000). The median male-to-female ratio was 4.2. The median percentage of autism cases with co-occurring intellectual disability was 33.0%. Estimates varied, likely reflecting complex and dynamic interactions between patterns of community awareness, service capacity, help seeking, and sociodemographic factors. A limitation of this review is that synthesizing methodological features precludes a quality appraisal of studies. Our findings reveal an increase in measured autism prevalence globally, reflecting the combined effects of multiple factors including the increase in community awareness and public health response globally, progress in case identification and definition, and an increase in community capacity. Hypotheses linking factors that increase the likelihood of developing autism with variations in prevalence will require research with large, representative samples and comparable autism diagnostic criteria and case-finding methods in diverse world regions over time. Lay Summary We reviewed studies of the prevalence of autism worldwide, considering the impact of geographic, ethnic, and socioeconomic factors on prevalence estimates. Approximately 1/100 children are diagnosed with autism spectrum disorder around the world. Prevalence estimates increased over time and varied greatly within and across sociodemographic groups. These findings reflect changes in the definition of autism and differences in the methodology and contexts of prevalence studies.
The Prevalence of Autism Spectrum Disorder in Europe
Autism Spectrum Disorders - Recent Advances and New Perspectives [Working Title]
This chapter set out to present a comprehensive review on the prevalence of autism spectrum disorder (ASD) among 5–18-year-olds living in Europe. The review was based on studies published between 2015 and 2020. Separate meta-analyses were conducted for population studies and register-based studies to determine the random effects pooled prevalence rate (REPPR) for ASD. The European REPPR for ASD among young people was estimated at 0.8% based on register-based studies and 1.4% based on population. Comparative analysis was carried out to identify trends of prevalence rates across countries, gender, and level of education. The prevalence among primary school children was four times that of secondary school children. A male: female ratio of 3.5:1 was obtained. A range of challenges toward young people with ASD are portrayed, including diagnostic limitations, poor awareness on ASD, and socioeconomic inequality. Nationwide screening, early intervention services, and further research on gen...
Epidemiological surveys of autism and other pervasive developmental disorders: an update
Journal of autism and developmental disorders, 2003
This paper was commissioned by the committee on the Effectiveness of Early Education in Autism of the National Research Council (NRC). It provides a review of epidemiological studies of pervasive developmental disorders (PDD) which updates a previously published article (The epidemiology of autism: a review. Psychological Medicine 1999; 29: 769-786). The design, sample characteristics of 32 surveys published between 1966 and 2001 are described. Recent surveys suggest that the rate for all forms of PDDs are around 30/10,000 but more recent surveys suggest that the estimate might be as high as 60/10,000. The rate for Asperger disorder is not well established, and a conservative figure is 2.5/10,000. Childhood disintegrative disorder is extremely rare with a pooled estimate across studies of 0.2/10,000. A detailed discussion of the possible interpretations of trends over time in prevalence rates is provided. There is evidence that changes in case definition and improved awareness expla...
Epidemiology of Autism Spectrum Disorders: A Review of Worldwide Prevalence Estimates Since 2014
Brain Sciences, 2020
The prevalence of Autism Spectrum Disorder (ASD) has increased dramatically in recent decades, supporting the claim of an autism epidemic. Systematic monitoring of ASD allows estimating prevalence and identifying potential sources of variation over time and geographical areas. At present, ASD prevalence estimates are available worldwide, coming either from surveillance systems using existing health and educational databases or from population studies specifically performed. In the present article, we present a review of the ASD prevalence estimates published since 2014. Data confirm a high variability in prevalence across the world, likely due to methodological differences in case detection, and the consistent increase of prevalence estimates within each geographical area.
Two-fold increase in the prevalence of autism in Israel between 2017 and 2021
medRxiv (Cold Spring Harbor Laboratory), 2023
The prevalence of autism spectrum disorder (ASD) has increased steadily in most highincome countries over the last decade. Estimates of ASD prevalence among 8-year-old children in the U.S. have increased from 1.47% in 2010 to 2.3% in 2018, and up to 3.5% among 3-17-year-old children in 2020. In Israel, estimates have been lower, with the prevalence of ASD in 8-year-old children increasing from 0.3% in 2009 to 0.64% in 2018. Here, we examined data from the entire population of Israel (~3 million 1-17-year-old children) and quantified changes in their ASD prevalence between 2017 and 2021. We analyzed consecutive annual reports acquired from the Israeli National Insurance Institute (NII), which monitors all children with ASD in Israel who receive welfare services, and Clalit Health Services (CHS), the largest Health Maintenance Organization (HMO) in Israel that services ~50% of the population. Both data sources revealed a nearly twofold increase in the ASD prevalence of 1-17-year-old children during this five-year period. Rates differed across age groups with 2-3-year-old (day-care) children exhibiting a ~4.4-fold increase in prevalence from 0.27% to 1.19% and 4-6-year-old (pre-school) children exhibiting a ~2.3fold increase from 0.80% to 1.83%. These results demonstrate that ASD prevalence in Israel is increasing at unprecedented rates and shifting towards diagnosis at earlier ages. These findings highlight the challenge facing health and education service providers in meeting the needs of a rapidly growing ASD population that is being diagnosed at earlier ages. NOTE: This preprint reports new research that has not been certified by peer review and should not be used to guide clinical practice.
International Journal of Special Education, 2014
The prevalence of autism is increasing globally. While most of the published works are done in the Western and European countries, the trend in autism research is shifting towards the Asian continent recently. In this review, we aimed to highlight the current prevalence, diagnosis, treatment and research on Autism Spectrum Disorders (ASD) in Singapore and Malaysia. Based on database searches, we found that the awareness about autism among lay and professional public is higher in Singapore compared to Malaysia. The special education system and approach towards autism treatment is also different between both societies although the culture is similar and the geographic location is close. Main findings and implications were discussed in this review. The lack of study on autism prevalence in this part of the world commands a critical need for further research. Perhaps more collaborative work between both countries could be done to expand the knowledge in autism. Autistic Spectrum Disorder (ASD) is a type of neurodevelopmental disorder affecting the mental, emotion, learning and memory of a person (McCary et al., 2012). According to the Diagnostic and Statistical Manual of Mental Disorders Fourth Edition (DSM-IV) (American Psychiatric Association, 2000), ASD is characterized by three features. Firstly, impairment of social interaction, which includes but not limited to impairment in the use of multiple nonverbal behaviours such as eye-to-eye gaze, facial expression, body postures and gestures to regular social interaction. Secondly, impairment in communication, which includes but not limited to delay in or total lack of the development of spoken language, or impairment in the ability to initiate or sustain a conversation with others. Thirdly, there is restricted, repetitive and stereotyped pattern of behaviour, interests, and activities, which include but not limited to inflexible adherence to specific, nonfunctional routines or rituals (APA, 2000). Many official health reports on ASD have shown that there is an increase in the number of ASD cases over the years. One of the most comprehensive ASD prevalence study done so far is the one done by the US Centers for Disease Control and Prevention (CDC)"s Autism and Developmental Disabilities Monitoring (ADDM) Network (Autism and Developmental Disabilities Monitoring Network, 2012). In its latest study in 2008, the rate of US cases rose from one in 110 in 2006 to about one in 88 children in 2008. In fact, the autism numbers skyrocketed since 2002(Autism Spectrum Disorders-Data & Statistics, 2014). This number has caused a public health concern worldwide. Health officials attribute the increase in autism cases through greater awareness, wider screening and better diagnosis (Weintraub, 2011). But the numbers increase at a rate so fast that researchers start to question if these are the true factors that justify the increase (Weintraub, 2011). Growing evidences have shown that environmental and epigenetic factors could contribute towards autism incidence (Persico & Bourgeron, 2006),which include possible causal factors such as genetic mutations (Freitag, 2007) and various environmental agents that would cause birth defects (Arndt, Stodgell, & Rodier, 2005). Yet in all its efforts to understand the underlying cause of ASD which knows no bounds in affecting children across racial, ethnic and socioeconomic groups,
Journal of Developmental and Physical Disabilities, 2016
Many different studies have been conducted to determine the prevalence rates of Autism Spectrum Disorder (ASD) in the United States. The methodologies of these studies have varied, resulting in a multitude of publications with differing prevalence rates. Because there is such a wide range in the results of prevalence studies, it may be difficult for individual states to determine their rates. Accurate prevalence rates are important to obtain for many different reasons including increasing advocacy and awareness, increasing funding, and proper allocation of services for individuals with ASD and their families. Additionally, prevalence studies can be used to assess which groups are more at risk for ASD based off location and environmental factors. This paper describes different methodologies that can be utilized to determine ASD prevalence rates, the strengths and weaknesses of each method, and the challenges to determining accurate rates. Implications for future prevalence studies will be addressed and recommendations will be provided.