Autism Foundation of America
Loading pageCompare what research shows, how certain the evidence is, who was actually studied, where evidence gaps remain, and what concerns deserve attention.
Choose Two Supports
Quick Comparison
Communication
Strongest Evidence
Functional communication and requesting
Certainty Pattern
Low certainty for most measured outcomes
Biggest Evidence Gap
Adults, long term outcomes, and quality of life
Last Reviewed
August 2026
Behavior & Learning
Strongest Evidence
Language and some adaptive, daily living, and targeted behavior outcomes in young children
Certainty Pattern
Mostly Low certainty and highly dependent on the outcome and intervention
Biggest Evidence Gap
Harms, long term quality of life, adolescents, and adults
Last Reviewed
August 2026
Evidence Bottom Line
AAC
The strongest and most consistent evidence supports AAC for helping autistic children with complex communication needs communicate wants, needs, and other functional messages. Evidence for broader language development is promising but less certain. Research does not support the common concern that AAC prevents speech development. However, the evidence base is much stronger for children than adults and often focuses on structured requesting tasks rather than long term, real world communication and quality of life.
ABA
ABA based interventions can help some autistic children develop language, adaptive skills, daily living abilities, and specific functional behaviors. The evidence is strongest in young children and is considerably less certain for adolescents and adults. Confidence is limited by inconsistent intervention definitions, small or nonrandomized studies, risk of bias, differences in outcome measurement, and limited long term follow up. Research also does not adequately establish the frequency or magnitude of adverse effects. The goals, methods, intensity, provider quality, individual preferences, and respect for autonomy can substantially change what an ABA program actually involves.
Evidence by Outcome
Different supports may target different outcomes. A higher certainty rating for one outcome does not make one support universally better than another.
Aided AAC and speech generating device interventions generally improve functional communication, particularly requesting, in autistic children with complex communication needs.
AAC may support broader expressive language development, especially when integrated into developmental or communication focused intervention, but the evidence base is smaller and more variable than for requesting.
Available research does not indicate that AAC prevents speech development. Some studies report improvements in speech production alongside AAC use.
AAC can support communication beyond requesting, but evidence for sustained, generalized, diverse communication across people and settings remains limited.
AAC is used by autistic adults and qualitative research describes important benefits related to communication access and autonomy, but there is not enough intervention research to confidently estimate effects on adult communication outcomes or quality of life.
Some ABA based early interventions improve language and communication outcomes in autistic children, but results differ across intervention types and studies.
ABA based early interventions may improve adaptive functioning and daily living skills for some autistic children, although confidence in the size and consistency of the benefit remains limited.
Behavioral interventions can improve some targeted social emotional or behaviors of concern outcomes, but confidence decreases when studies with greater risk of measurement bias are excluded.
Some studies of intensive early behavioral intervention report improvements on standardized intellectual or developmental measures, but substantial methodological limitations make the size of this effect uncertain.
Research is inconsistent on whether ABA based interventions substantially change broad measures of autism characteristics, and reducing an autism severity score is not itself the same as improving quality of life.
There is not enough reliable evidence to determine the long term effects of ABA on quality of life, mental health, autonomy, or the frequency of adverse experiences.
Who Was Actually Studied?
Age and life stage
Research is strongest in preschool and school age children. Adolescent evidence is smaller, and adult evidence is limited.
Intellectual disability
People with intellectual and developmental disabilities appear in parts of the AAC literature, but reporting is inconsistent across studies.
High support / profound autism
People with substantial communication support needs are represented, including minimally speaking participants, but the specific category of profound or high support autism is rarely characterized consistently.
Minimal or no spoken language
Yes. Minimally speaking and nonspeaking autistic children are an important population within the AAC evidence base.
Adults
Poorly represented in intervention effectiveness research. Adult lived experience research exists but remains limited.
Settings
Studies include school, clinic, home, and structured intervention environments. Real world generalization is less consistently studied.
Age and life stage
The strongest effectiveness research involves young children, particularly preschool age children receiving early intervention. Evidence becomes much thinner for adolescents and adults.
Intellectual disability
Autistic children with developmental and intellectual disabilities are represented in parts of the ABA literature, but intellectual disability is not consistently reported or analyzed separately.
High support / profound autism
Children with substantial support needs are represented in early behavioral intervention research, but modern definitions of high support or profound autism are rarely applied consistently and subgroup outcomes are limited.
Minimal or no spoken language
Minimally speaking and nonspeaking autistic children are included in parts of the behavioral intervention literature, particularly communication focused research, but results are not consistently reported separately for this population.
Adults
Adults are poorly represented in controlled ABA effectiveness research. Adult research more often examines personal experiences, service history, attitudes, or specific behavioral supports rather than comprehensive childhood style ABA programs.
Settings
ABA based interventions have been studied in clinics, homes, schools, and community settings. Implementation, treatment intensity, staff qualifications, caregiver involvement, and opportunities for generalization vary widely.
AAC
ABA
AAC
ABA
Go Deeper
