Rapid reportPrevalence of autism spectrum disorders in a semiurban community in south India
Introduction
Autism spectrum disorder (ASD), also known as pervasive developmental disorder, is a complex neurodevelopmental disorder characterized by impairments in social interaction and communication, restricted repertoire of interests and stereotyped activities [1]. It is often diagnosed by the age of 3 years and generally four times more frequent in men than in women, although a recent study with a better case ascertainment has estimated the male-to-female prevalence ratio as 2.3:1 [2]. The current prevalence of ASD in world population is estimated to be ∼1% [2]. The prevalence is ∼1.5% in United States [3], 1% in the United Kingdom [4], and slightly higher in Asian countries, ranging from 1.81% to 2.6% [5], [6]. Prevalence estimates of ASD have shown a steady increase during the last five decades. The first epidemiologic survey conducted by Lotter in the United Kingdom estimated a prevalence of 4.1/10,000 [7]. Since then, especially since 2000, an increase in the prevalence of ASD has been observed in the epidemiologic surveys carried out in different countries worldwide. In 2012, the global mean prevalence of ASD was estimated to be 61.9/10,000 [8].
Epidemiologic surveys of ASD have been useful in providing time trends of the prevalence of this disorder and its main correlates across different countries. By comparing prevalence estimates of ASD in different ethnic groups, in special populations (e.g., genetically isolated), and in populations exposed to peculiar environmental conditions (e.g., pollution, malnutrition), it would be possible to get a better understanding of the risk factors leading to autism. Autism Speaks, in collaboration with the US Center for Disease Control (CDC), has launched the International Autism Epidemiology Network (http://www.autismepidemiology.net) to monitor the prevalence rates of ASD globally [8]. Prevalence studies for ASD are ongoing in Australia, Mexico, Finland, Portugal, Iceland, India, Vietnam, Taiwan, South Africa, and Uganda [8].
In developing countries, systematic multicentre epidemiologic studies of ASD would help to ascertain the nature of the problem and to assess the social and economic burden. However, there have been very few studies on the prevalence of ASD in developing countries, including India. We conducted a community-based survey to assess the prevalence of ASD in a semi-urban population from south India, and report a prevalence of 23.3/10,000 in the age group 1-30 years.
Section snippets
Materials and methods
The study was prospectively reviewed and approved by a duly constituted Institutional Ethics Committee. Informed consent was obtained from all individual participants included in the study.
The staff at Institute for Communicative and Cognitive Neurosciences (ICCONS) conducted a community-based survey in 2011–2012 to assess the prevalence of ASD in a semiurban community of Kerala, a south Indian state. The survey was carried out in Shoranur (32.28 km2; 10.77°N 76.28°E), a semiurban municipality
Results
During phase I screening, 43 individuals were diagnosed with ASD in a questionnaire-based survey of the community (n = 43,000). The age of affected individuals ranged from 1 to 30 years with a male-to-female ratio of 2.1:1. The total number of individuals in the age group of 1–30 years was 18,480. The prevalence of ASD was thus estimated as 23.3/10,000. On age group–specific classification, a larger number of affected individuals were found to be in the age group of 6–10 years and 16–20 years.
Discussion
Given current epidemiologic estimates, there are approximately 1.7 million individuals with autism in India (https://www.autismspeaks.org/science/grants-program/special-international-autism-epidemiology-project). In this survey, we report an ASD prevalence of 23.3/10,000 in a semiurban community from the south Indian state of Kerala. Previously, in a state-wide systematic sample survey based on Anganwadis (a public health care system in India) in Kerala, 2.5%–3.4% of children were diagnosed
Acknowledgments
All authors have made substantial contributions to conception and design of the study, acquisition of data, analysis and interpretation of data, and drafting of the article. All the authors have given final approval of the submitted version.
References (21)
- et al.
Prevalence of pervasive developmental disorders in the British nationwide survey of child mental health
J Am Acad Child Adolesc Psychiatry
(2001) - et al.
Prevalence and early signs of autism spectrum disorder (ASD) among 18-36 month-old children of Tianjin in China
Biomed Environ Sci
(2014) Diagnostic and statistical manual of mental disorders
(2013)- et al.
Changes in prevalence of autism spectrum disorders in 2001-2011: findings from the Stockholm youth cohort
J Autism Dev Disord
(2015) Prevalence of autism spectrum disorder among children aged 8 years—Autism and Developmental Disabilities Monitoring Network, 11 Sites, United States, 2010
MMWR Surveill Summ
(2014)- et al.
Epidemiology of autism spectrum disorders in adults in the community in England
Arch Gen Psychiatry
(2011) - et al.
Reevaluating the incidence of pervasive developmental disorders: impact of elevated rates of detection through implementation of an integrated system of screening in Toyota, Japan
Psychiatry Clin Neurosci
(2008) - et al.
Prevalence of autism spectrum disorders in a total population sample
Am J Psychiatry
(2011) Epidemiology of autistic conditions in young children
Soc Psych
(1966)- et al.
Global prevalence of autism and other pervasive developmental disorders
Autism Res
(2012)
Cited by (42)
Characteristics and treatment patterns of autism spectrum disorder in China, 2020
2022, Psychiatry ResearchCitation Excerpt :However, in areas, such as Africa and the Middle Eastern region, the ASD surveys are mostly under-represented (Zeidan et al., 2022). Currently, the available evidence mostly focused on the ASD characteristics for children, and only a few of them involved ASD prevalence in adults aged 18 years old and above (Kočovská et al., 2012; Poovathinal et al., 2016). In China, due to the lack of national investigation dataset, there is very limited evidence about the characteristics of ASD.
Implementing and evaluating Social Attention and Communication Surveillance (SACS) to prospectively identify autism in very young children in Nepal
2021, Research in Developmental DisabilitiesCitation Excerpt :The current international estimates are much higher, being 1–2% (Lord et al., 2018). However, the estimated prevalence (0.26 %) in the current study is similar to recent prevalence estimates of 0.3 % in Nepal (Heys et al., 2018), and is higher than those from other LMICs, including India (0.09−0.23%; Poovathinal et al., 2016; Raina et al., 2015) and Bangladesh (0.15 %; Non Communicable Diseases Control Programme et al., 2013). These lower prevalence rates (compared to the global prevalence rates of ASD) can be attributed to the low referral rates of children, and a high likelihood of missing a group of children with milder behavioural presentations, including those without associated cognitive delays, who tend to have delayed diagnosis (Daniels & Mandell, 2014).
Analysis of neurotransmitters validates the importance of the dopaminergic system in autism spectrum disorder
2023, World Journal of Pediatrics
This study has no funding source.
The authors have no conflicts of interest to declare.