A 5-year-old girl with Autism Spectrum Disorder is referred for assessment of behavioural difficulties. Her parents report that she becomes extremely distressed during transitions between activities, insists on wearing only certain clothing textures, and covers her ears when exposed to loud sounds. She has average intelligence and can read fluently but struggles with understanding implied meanings in conversations. Which of the following best explains her sensory and communication difficulties?

Explanation

## Neurobiological Basis of ASD Symptoms ### Sensory Processing in ASD **Key Point:** Sensory abnormalities are now recognized as a core feature of ASD, not merely an associated feature. They reflect atypical neural processing of sensory input. ### Sensory Manifestations in This Case | Sensory Domain | Presentation | Mechanism | |---|---|---| | **Tactile** | Insists on specific clothing textures | Sensory hypersensitivity (hyperacusis equivalent for touch) | | **Auditory** | Covers ears to loud sounds | Auditory hypersensitivity; abnormal filtering of background noise | | **Proprioceptive/vestibular** | Distress with transitions | Difficulty with sensorimotor integration and change | **Clinical Pearl:** Sensory hypersensitivity (rather than hyposensitivity) is more common in ASD and may manifest as avoidance, distress, or self-protective behaviours. ### Pragmatic Language Deficits **High-Yield:** Despite average intelligence and fluent reading (intact phonological/decoding skills), this child struggles with **implied meanings**—a hallmark of pragmatic language impairment in ASD. **Mnemonic: PRAG** — **P**ragmatic deficits (implied meaning, context, tone), **R**eciprocal communication failure, **A**bnormal prosody/non-verbal cues, **G**eneral social-cognitive impairment ### Why Sensory + Pragmatic Deficits Co-occur in ASD ```mermaid flowchart TD A["Atypical Neural Connectivity in ASD"]:::outcome --> B["Abnormal Sensory Gating & Integration"]:::outcome A --> C["Impaired Theory of Mind & Social Cognition"]:::outcome B --> D["Sensory Hypersensitivity<br/>Texture/Sound Aversion"]:::outcome C --> E["Pragmatic Language Deficit<br/>Literal interpretation<br/>Difficulty with implied meaning"]:::outcome D --> F["Behavioural Avoidance<br/>Distress with transitions"]:::action E --> G["Social Communication Failure"]:::action ``` **Key Point:** Both sensory and pragmatic difficulties stem from the same underlying neurodevelopmental differences in ASD—not separate disorders. [cite:DSM-5 Sensory Features in ASD; Kaplan & Sadock's Synopsis of Psychiatry 12e Ch 37]