Autism spectrum disorders

ASD is diagnosed based on DSM-5 criteria requiring: (1) persistent deficits in social communication and social interaction across multiple contexts (deficits in social-emotional reciprocity, nonverbal communicative behaviors, and developing/maintaining relationships), and (2) restricted, repetitive patterns of behavior, interests, or activities (stereotyped movements, insistence on sameness, highly restricted fixated interests, hyper/hyporeactivity to sensory input). Symptoms must be present in early developmental period (though may not fully manifest until social demands exceed capacity) and cause clinically significant impairment.

Etiology is multifactorial with strong genetic component (high concordance in monozygotic twins ~60-90%); associated with fragile X syndrome, tuberous sclerosis, and other genetic syndromes. Advanced parental age is a risk factor. No causal link to vaccines (thoroughly debunked - Wakefield study retracted).

Clinical presentation often includes delayed language development, poor eye contact, difficulty with joint attention, lack of interest in peer relationships, repetitive behaviors (hand-flapping, lining up objects), intense narrow interests, and need for routine/sameness. Intellectual disability co-occurs in ~30-50% of cases; some individuals have average or above-average intelligence (previously termed Asperger syndrome, now folded into ASD spectrum in DSM-5).

Diagnosis is clinical, typically made by age 2-3, using screening tools (M-CHAT) and standardized diagnostic instruments (ADOS, ADI-R). Early intervention (applied behavior analysis, speech therapy, occupational therapy) improves outcomes significantly. No cure exists; pharmacotherapy (e.g., risperidone, aripiprazole) may target associated irritability/aggression but does not treat core symptoms. Comorbidities include ADHD, anxiety, epilepsy, and GI issues.

For boards: know DSM-5 criteria, distinguish from intellectual disability alone, recognize associated genetic syndromes (Fragile X most common single-gene cause), and understand there is no vaccine link (high-yield ethics/public health point).