Prevalence of Autism Spectrum Disorder and Co-morbidities in Children and Adolescents: A Systematic Literature Review

Abstract

Objective: Individuals with autism spectrum disorder often present somatic and/or psychiatric co-morbid disorders. The DSM-5 allows for consideration of additional diagnoses besides ASD and may have impacted the prevalence of co-morbidities as well as being limited in capturing the true differences in prevalence observed between males and females. We describe the prevalence of ASD and frequently observed co-morbidities in children and adolescents (<18 years) in the United States and five European countries.Methods: Two systematic literature reviews were conducted in PubMed and Embase for the period 2014–2019 and focusing on the prevalence of ASD and nine co-morbidities of interest based on their frequency and/or severity: Attention Deficit Hyperactivity Disorder (ADHD), anxiety, depressive disorders, epilepsy, intellectual disability (ID), sleep disorders, sight/hearing impairment/loss, and gastro-intestinal syndromes (GI).Results: Thirteen studies on prevalence of ASD and 33 on prevalence of co-morbidities were included. Prevalence of ASD was 1.70 and 1.85% in US children aged 4 and 8 years respectively, while prevalence in Europe ranged between 0.38 and 1.55%. Additionally, current evidence is supportive of a global increase in ASD prevalence over the past years. Substantial heterogeneity in prevalence of co-morbidities was observed: ADHD (0.00–86.00%), anxiety (0.00–82.20%), depressive disorders (0.00–74.80%), epilepsy (2.80–77.50%), ID (0.00–91.70%), sleep disorders (2.08–72.50%), sight/hearing impairment/loss (0.00–14.90%/0.00–4.90%), and GI syndromes (0.00–67.80%). Studies were heterogeneous in terms of design and method to estimate prevalence. Gender appears to represent a risk factor for co-morbid ADHD (higher in males) and epilepsy/seizure (higher in females) while age is also associated with ADHD and anxiety (increasing until adolescence).Conclusion: Our results provide a descriptive review of the prevalence of ASD and its co-morbidities in children and adolescents. These insights can be valuable for clinicians and parents/guardians of autistic children. Prevalence of ASD has increased over time while co-morbidities bring additional heterogeneity to the clinical presentation, which further advocates for personalized approaches to treatment and support. Having a clear understanding of the prevalence of ASD and its co-morbidities is important to raise awareness among stakeholders.

Discrete Wavelet Transform Analysis of the Electroretinogram in Autism Spectrum Disorder and Attention Deficit Hyperactivity Disorder

“…The co-occurrence of neurodevelopmental conditions is high with approximately 1:3 children with ASD also meeting diagnostic criteria for ADHD ( Berenguer-Forner et al, 2015 ). ASD and ADHD often present as co-occurrence in children ( Russell et al, 2014 ; Mansour et al, 2017 ) as well as other co-occurrences of conditions such as anxiety, epilepsy, and sleep disorders ( Bougeard et al, 2021 ). Visual perception in ASD shows superiority in visual search ( Constable et al, 2020a ) and abnormal electrophysiological cortical differences in global motion perception ( van der Hallen et al, 2019 ), motion onset ( Constable et al, 2012 ), and coherence thresholds perception ( Robertson et al, 2014 ).…”

Analysis of Faecal Microbiota and Small ncRNAs in Autism: Detection of miRNAs and piRNAs with Possible Implications in Host–Gut Microbiota Cross-Talk

“…Autism spectrum disorders (ASD) refers to a group of complex neurodevelopmental conditions whose core symptoms are a deficit in communication and social interaction, restricted interests, and repetitive behaviours ( , accessed on 26 November 2021). Comorbidities, such as mental retardation, epilepsy, anxiety, sensory, sleep, and gastrointestinal disorders, as well as food selectivity often occur in ASD [ 1 , 2 , 3 ]. ASD manifests during the first years of age, and in the last decades, its prevalence has continued to increase, reaching the frequency of one in 54 children aged eight years in the USA in the 2016 [ 4 ].…”

Health Preferences in Childhood Autism Spectrum Disorder (ASD): A Discrete Choice Experiment using the Childhood Autism Rating Scale (CARS2)

“…A recent review found the male/female ratio in ASD is approximately 4 or 5 to 1. (31) Our study approaches the lower end of this ratio, with 78-79% (ratio 3.7-3.9 to 1) of children being male. Among clinicians, medical doctors appear overrepresented (ST=66%, HF=75%), and psychologists underrepresented (ST=6%, HF=11%).…”