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Definition and Diagnostic EvolutionASD is a group of early-onset neurodevelopmental disorders, primarily characterized by social communication deficits, restricted interests, and repetitive behaviors. The diagnostic criteria have evolved significantly, from Leo Kanner's initial description of "early infantile autism" in 1943 to the unified classification under ASD in the DSM-5 (2013), which merged previously separate diagnoses such as pervasive developmental disorders and Asperger syndrome. This shift reflects a growing recognition of the spectrum nature and heterogeneity of the disorder, emphasizing the continuum of symptom severity.

EtiologyCurrent research indicates that ASD is driven by a complex interplay between genetic and environmental factors, with heritability estimates ranging from 50% to 95%. Multiple risk genes have been identified, including SHANK3 and CHD8. Neurobiological studies have revealed structural and functional abnormalities in the brains of individuals with ASD, particularly in regions such as the prefrontal cortex and amygdala.

Prevalence and Gender DistributionGlobally, the diagnosis rate of ASD has shown a significant upward trend. The WHO estimates a global prevalence of approximately 1 in 100, with rates in developed countries reaching up to 1.5%. The U.S. CDC reported a prevalence of 1 in 36 among 8-year-old children in the United States in 2022. In China, the reported prevalence is approximately 0.7%, which may be due to diagnostic awareness and access to medical resources. The male-to-female ratio is approximately 4:1, but females may be underdiagnosed.

Symptoms and ComorbidityASD symptoms typically appear before the age of 2–3, with early signs observable as early as 12 to 18 months. Comorbidity is common, with approximately 70% of individuals with ASD having at least one additional psychiatric condition, the most prevalent being ADHD.

Risk FactorsEnvironmental risk factors include advanced parental age, maternal infections during pregnancy, and exposure to certain medications. Every 10-year increase in parental age is associated with an approximately 20% increase in the risk of ASD.

DiagnosisASD diagnosis is primarily based on behavioral observations and standardized clinical assessments, as there are currently no reliable biological markers for definitive diagnosis. Common diagnostic tools include the M-CHAT and ADOS. The AAP recommends initial ASD screening at 18 months of age.

TreatmentTreatment typically follows a multidisciplinary approach, involving behavioral interventions, speech and language therapy, and occupational therapy. Pharmacological treatment is mainly used to address comorbid symptoms, but there is currently no effective medication targeting the core symptoms of ASD.

Family Support and Educational InterventionsFamily support and educational interventions play a vital role, particularly in training for social skills and daily living abilities. Early intervention, especially before the age of 6, can lead to significant improvements in long-term outcomes.

Research and Treatment AdvancementsResearch and treatment of ASD are advancing toward precision medicine. Progress in genomic research and biomarker development is paving the way for early risk prediction and more objective diagnosis. Targeted therapies for specific genetic mutations and emerging technologies such as AI-assisted diagnostic systems are showing promising prospects.

Preventive Research and Future DirectionsPreventive research, especially early intervention strategies for high-risk populations, is gaining attention. Improving social support systems, including specialized rehabilitation centers and community-based support services, is a key area for future development. The application of big data analytics and artificial intelligence is expected to play a transformative role in designing personalized intervention plans.

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