Causes of Rising Autism Prevalence

Causes Behind the Rise in Autism Diagnoses

The world of autism is a complex one, with new understandings and diagnoses on the rise. Autism Spectrum Disorder (ASD) is a neurological and developmental disorder that affects communication and behaviour, and it's more common than you might think.

In the United States, the prevalence of ASD is estimated between 1% and 3%, with about 1 in 44 eight-year-olds meeting the diagnostic criteria in 2018. This number is significantly higher compared to the past, with a 787% increase in diagnoses in the UK between 1998 and 2018. However, these numbers might not be a confirmation of a rise in incidence, but rather a result of better understanding, broader diagnostic criteria, and increased awareness.

Boys are four times more likely to be diagnosed with ASD than girls, but experts suggest that this could be due to girls exhibiting less obvious symptoms, which might lead to underdiagnosis. This gender bias is a concern, as an autism diagnosis can provide individuals with much-needed accommodations and community support.

The diagnostic process for ASD is based on observations of behaviour, not through blood tests or brain scans. Diagnostic questionnaires are based on childhood development, making it difficult for adults to be diagnosed. However, with increasing awareness, more adults are seeking and receiving diagnoses.

In some countries, there is little-to-no data about the prevalence of ASD, but globally, it's estimated that about 1 in 100 children have ASD, according to the World Health Organization (WHO). The WHO notes that the number of diagnoses varies across studies and could be higher.

The Diagnostic and Statistical Manual of Mental Disorders (DSM) has changed its definition of ASD over the years, broadening it and including Asperger syndrome. The latest version, the DSM-5-TR, allows people to be diagnosed with ASD and attention deficit hyperactivity disorder (ADHD) concurrently.

Clinicians' biases can affect how they interpret a patient's behaviour during diagnosis, and gender bias might prevent autistic women and girls from being diagnosed. The CDC's estimation of ASD prevalence is based on school and medical records, which might miss children with no records or children with less obvious signs.

Despite these challenges, health organizations are recommending earlier screenings for ASD. In the US, children are now being screened at 9, 18, and 30 months old. The 11th edition of the International Classification of Diseases (ICD-11) has expanded its definition of ASD to include Asperger's Syndrome, Childhood Disintegrative Disorder (CDD), and other developmental disorders.

As we continue to learn more about ASD, it's essential to remember that it is a spectrum disorder, with signs varying from one person to another. With increased awareness, early diagnosis, and appropriate support, individuals with ASD can lead fulfilling and productive lives.