Differences in Cognition and Behaviour in Multiplex and Simplex Autism: Does Prior Experience Raising a Child with Autism Matter?
Multiplex autism kids think a bit faster, but it is not because their parents already raised an autistic sibling.
01Research in Context
What this study did
Berends et al. (2019) compared kids from two kinds of autism families.
Multiplex families have more than one child with autism. Simplex families have only one.
The team asked: do parents in multiplex homes raise the younger child differently because they already practiced with the older one? They tested cognition, autism symptoms, and daily living skills.
What they found
Kids from multiplex homes scored higher on thinking tests, no matter how much parent practice they had.
Autism symptoms and daily skills looked the same in both groups.
Parent experience did not explain the cognitive edge.
How this fits with other research
Stephens et al. (2018) found a similar pattern in theory-of-mind. Older siblings helped only in simplex families, not multiplex ones. Both papers show that extra siblings do not boost multiplex kids further.
Peristeri et al. (2024) tracked IQ over four years. They saw wide, messy paths—some kids rose, some fell. The multiplex snapshot gain is real, but it may not hold steady as children grow.
Meuret et al. (2001) showed that genetic risk for autism stays equal across IQ levels. Daniel’s work sharpens that view: within autism, family type, not parent know-how, drives small cognitive differences.
Why it matters
When you read an assessment, note if the child comes from a multiplex home. Expect slightly higher IQ scores, but plan for the same autism teaching needs. Do not assume parents already have extra skills; offer the same caregiver training you give simplex families.
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02At a glance
03Original abstract
Previous research has found multiplex (MPX) children have an advantage in cognition compared to simplex (SPX) children. However, MPX parent's previous experience with older diagnosed siblings has not been considered. We used a large database sample to investigate the MPX advantage and contribution of birth order. Children from the Autism Genetic Resource Exchange (AGRE) were stratified into first- (MPX1, n = 152) and second-affected MPX (MPX2, n = 143), SPX (n = 111), and only-child SPX (SPXOC, n = 23) groups. Both MPX groups had higher cognitive scores compared to SPX groups, with no differences between MPX1 and MPX2 groups. No differences were found for autism symptoms or adaptive behaviour. These results suggest parent experience due to birth order is an unlikely contributor to the MPX cognitive advantage.
Journal of autism and developmental disorders, 2019 · doi:10.1007/s10803-019-04052-7