The progression of severe behavior disorder in young children with intellectual and developmental disabilities.
Frequency of self-injury predicts later severity, while severity of aggression predicts later frequency—act early on whichever comes first.
01Research in Context
What this study did
Medeiros et al. (2013) tracked the toddlers with delays for one year. All kids had IQ scores under 70. Parents filled out a behavior checklist every three months.
The team used numbers called SEMs to see if the amount of a behavior came first, or if how bad it was came first.
What they found
Self-injury stayed the same year over year. The big news: more frequent head-hitting now meant worse wounds later. For aggression, the story flips. Harder hits now predicted more hits later, not the other way around.
Stereotypy stayed flat too. Diagnosis label did not change these patterns.
How this fits with other research
Marcell et al. (1988) showed that matching treatment to the reason behind SIB works. Kristen’s data say you must act while the behavior is still just frequent, not yet severe.
Waizbard-Bartov et al. (2022) found that autism severity can move up or down through age 11. Together, the two papers warn us that early paths are not set in stone; early action can shift them.
Matson et al. (2008) reviewed dozens of SIB studies and said we lack head-to-head trials. Kristen’s finding gives us a timeline reason to run those trials in toddlers, not older kids.
Why it matters
If you see a two-year-old tapping her head often, do not wait for bruises. Start a brief functional analysis and teach a replacement like asking for a break. If you see hard bites, expect the count to rise; add protective equipment and teach communication fast. Use the first six months of service to cut frequency, not just react to severity.
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02At a glance
03Original abstract
Behavior disorders, such as self-injurious, stereotypic, and aggressive behavior are common among individuals with intellectual or developmental disabilities. While we have learned much about those behaviors over the past few decades, longitudinal research that looks at developmental trajectory has been rare. This study was designed to examine the trajectory of these three forms of severe behavior disorders over a one year time period. The behaviors were measured on two dimensions: frequency of occurrence and severity. Participants were 160 infants and toddlers at risk for developmental delays in Lima, Peru. Using structural equation modeling, we found that the frequency of self-injury and stereotypic behavior and the severity of aggressive behavior remained stable over the 12-month period. Uni-directional structural models fit the data best for self-injurious and aggressive behavior (with frequency being a leading indicator of future severity of self-injury and severity being a leading indicator of future frequency for aggression). For stereotypic behavior, a cross-lagged autoregressive model fit the data best, with both dimensions of frequency and severity involved as leading indicators of each other. These models did not vary significantly across diagnostic groups, suggesting that toddlers exhibiting behavior disorders may be assisted with interventions that target the specific frequencies or severities of behaviors, regardless of diagnostic category.
Research in developmental disabilities, 2013 · doi:10.1017/S0954579498001667