Autism may begin with sensory changes well before social signs appear

Our bodies meet the sensory world long before our minds can make sense of it. Scientists now argue that what we feel, hear, and see in those first hidden months may lay the tracks for later behavior, including the hallmarks of autism spectrum disorder (ASD).

Carissa Cascio of the University of Kansas Life Span Institute helped assemble the evidence and calls it the “cascading effects model.”

Early sensory patterns in autism

ASD touches about one in 36 eight-year-olds in the United States, a figure that keeps inching upward.

Since 2013 the Diagnostic and Statistical Manual has listed atypical responses to light, sound, or touch right alongside social traits, confirming that sensory quirks are not side-notes.

Those quirks can lean both ways. Some toddlers barely blink at loud noises, while others recoil from a shirt tag, yet both patterns predict later communication hurdles.

Touch develops early body awareness

Research tracing fetal physiology shows the sense of touch forming as early as eight weeks of gestation, long before hearing or vision join the party.

That early tactile scaffold gives a fetus its first map of “me versus not-me,” a map that guides newborn rooting, grasping, and self-soothing.

At birth the world suddenly grows brighter, colder, and louder, forcing the newborn brain to stitch together sight, sound, and touch in swift multisensory integration.

If any one strand lags or fires too fiercely, later strands, language, joint attention, play, may knot in unexpected ways.

Sensory changes before autism signs

A landmark eye-tracking study found that infants who would later be diagnosed with ASD began life looking at caregivers’ eyes as much as other babies but shifted away between two and six months.

That tiny change in visual preference predates any obvious social difference, hinting that a developing brain already feels mismatched input.

Brain scans echo the behavior. Infants who went on to an autism diagnosis showed faster-than-typical cortical surface growth in sensory areas between six and twelve months, a burst linked to later social scores.

Autism may begin with small differences

“Our work is rooted in the idea that brain differences in autism are starting much earlier than the age at which we use complex social interactions to diagnose autism,” said Cascio.

“We’re hopeful that the ideas in this paper will help researchers formulate and test questions about early sensory development,” said Cascio.

By framing sensory pathways as the first domino, the model explains why some children flap, spin, or crave noise: repetitive actions may be self-chosen ways to tame unpredictable signals.

It also clarifies why others seem distant, if touch or sound barely registers, the wider world offers fewer hooks for connection, so social skills have less raw material.

Sensory signs may help detect autism sooner

Follow-up studies show that higher sensory hyporesponsiveness at twelve months foretells lower expressive language at two years. Caregivers usually notice the silence, not the missing “aha” moments humble touch and sound should have sparked months before.

Yet plasticity cuts both ways. A 2025 randomized trial found that a parent-led program called Project ImPACT eased social hyporesponsiveness and, for some infants, boosted later language.

Not all sensory experiences are created equal, and not all babies grow up in the same sensory environments. Cultural norms, parenting styles, and household dynamics can all shape how infants respond to sounds, touch, and movement in those critical early months.

A baby raised in a quiet, low-stimulus setting may adapt differently than one growing up in a louder, more chaotic home, even if both develop along typical lines.

These early differences matter. For example, eye contact and physical touch carry different meanings across cultures.

What one family sees as normal affection, another may view as intrusive. If a child with ASD is raised in a context where reduced touch or gaze is common, it may mask or complicate early signs.

That’s why researchers like Cascio emphasize the need for broader studies that account for diverse families and developmental contexts.

Improving autism screening and support

Screening tools that focus only on gestures or words may miss children whose first signals are sensory.

Pediatric check-ups that include simple tests, does a four-month-old turn toward a rattle, settle with gentle stroking, blink at bright light, could flag risk while brains remain highly neurodevelopmental and adaptable.

Interventions might then start with the senses themselves: patterned touch, predictable light, graded sound, and caregiver coaching to read a baby’s comfort zone.

By tuning the earliest circuits, therapists hope to widen each child’s window for curiosity, play, and later learning.

The study is published in Psychological Review.

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