Changes in Autism and Co-Occurring Conditions from Preschool to Adolescence: Considerations for Precision Monitoring and Treatment Planning.

Purpose: To describe retention of an autism spectrum disorder (ASD) diagnosis from preschool to adolescence and the most common co-occurring diagnoses among children with ASD in preschool and adolescence. A second objective was to identify co-occurring diagnoses more likely to emerge between preschool and adolescence among children with ASD vs. another developmental or mental health diagnosis in preschool.

Methods: Children completed a case-control study when they were between 2 and 5 years of age. Caregivers reported their child's diagnoses of ASD and attention deficit hyperactivity disorder (ADHD), any developmental delay (DD), epilepsy/seizure disorder, obsessive-compulsive disorder, sensory integration disorder, and speech/language disorder when the child was preschool age and, separately, during adolescence. Any anxiety and depression/mood disorder, intellectual disability (ID), and learning disability (LD) were considered only in adolescence.

Results: 85.5% of preschool children retained their ASD diagnosis in adolescence. DD, sensory integration disorder, and speech-language disorder co-occurred in over 20% of preschool age children with ASD. These same conditions, along with anxiety disorders, ADHD, ID, and LD, co-occurred in over 20% of adolescents with ASD. Significantly more children with ASD vs. another developmental or mental health diagnosis in preschool gained diagnoses of ADHD, DD, sensory integration disorder, and speech-language disorder by adolescence.

Conclusion: ASD is a highly stable diagnosis and co-occurring conditions are common. The prevalence of co-occurring diagnoses may depend on age, with some persisting from preschool to adolescence and others emerging over time. Health and education providers can use these findings to inform precision monitoring and treatment planning.