Factors relating to age of onset in autism.

Researchers asked parents when they first noticed autism signs in their child. They also scored each child's symptom severity and IQ.

The team wanted to see if earlier parent concern linked to more severe autism traits.

Three out of four parents spotted problems before the child's second birthday.

Kids whose parents spoke up earliest tended to have lower IQs and higher CARS autism scores.

Warnes et al. (2005) seems to disagree. They also used parent recall but found onset timing did NOT predict later IQ or severity. The clash fades when you see both studies used different age points and severity tools.

Eisenmajer et al. (1998) adds nuance. Early language delay predicted worse symptoms only in early childhood, not later. This warns us that early signs may matter most at preschool age, matching B et al.'s window.

Katz et al. (2003) backs parents as reliable reporters. Their survey showed parents can recall clear social, language, and motor red flags years before diagnosis, strengthening trust in the 1988 parent timestamps.

When parents say "something felt off before age two," take it seriously. Use their history as one cue for thorough assessment and plan for possibly higher support needs. Pair this clue with direct observation and current skill data rather than relying on timing alone.