Abstract
Autism spectrum disorders (ASDs) are a range of neurodevelopmental disorders whose aetiologies are largely unknown. In the past few decades, studies have demonstrated that ASDs occur globally, and that the numbers of recorded cases are rising; however, determining the true prevalence figures is still a major challenge, especially in developing nations. Also, subtle differences in cultural norms might impede timely/accurate diagnosis and categorisation of patients. In this review, we examine the globally-available data on the prevalence of ASD and discuss some of the challenges of data acquisition, with reference to how these may impact the reliability of figures obtained. Some of the facts, fallacies and limitations relating to the presently-available figures are also highlighted.
Highlights
Epidemiology is concerned with patterns of disease occurrence within human populations, but it is concerned with the factors that determine or influence development of disease, or maintenance of health
Epidemiological investigations of neuropsychiatric diseases begin with cross-sectional surveys, which help to determine the prevalence of the disease condition, patterns of risk factors, as well as the possible correlates between disease and risk factors among representative samples [1]
The first epidemiological survey of autism was initiated in England in the early to mid-1960s [2, 3], while the first hospital-based survey in sub-Saharan Africa was conducted in five countries in the late 1970s [4]
Summary
Epidemiology is concerned with patterns of disease occurrence within human populations, but it is concerned with the factors that determine or influence development of disease, or maintenance of health. Autism surveys have since become global, with different countries conducting surveys to determine the prevalence and risk factors in their communities [1, 5], and thereby propose strategies to improve identification, diagnosis, management as well as promote policy reforms that bring awareness to the plight of the autistic child. Results from epidemiological surveys indicate that the global prevalence of ASDs is on the rise; data from sub-Saharan Africa and a number of other developing countries still show numbers that are generally lower than those from the developed countries [9,10,11] Whether this reflects an absolute low prevalence, deficits in diagnostic skills, mal-adaptation of diagnostic criteria as it relates to cultural differences in behaviour, or under-sampling is still being studied. We summarise how these factors impact strategies to improve identification, diagnosis and management; as well as promote policy reforms
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