Do ADHD subtypes change over time?

Attention Deficit Hyperactivity Disorder (ADHD) is a condition often diagnosed in childhood, characterized by symptoms like difficulty focusing, hyperactivity, and impulsive behavior. The Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5), recognizes three main subtypes of ADHD: Combined, Predominantly Inattentive, and Predominantly Hyperactive/Impulsive. This classification helps clinicians understand and treat the disorder more effectively.

Among children with ADHD, the Inattentive subtype is the most commonly diagnosed. A study focusing on Australian children aged 6 to 17 years found that the number of subjects with Inattentive ADHD was significantly higher compared to those with Hyperactive-Impulsive or Combined subtypes.

Children diagnosed with ADHD often experience shifts in their subtypes over time. Research has shown that a significant percentage of children with ADHD change subtypes, with the highest shift occurring in the Hyperactive-Impulsive type. This observation aligns with the earlier note that hyperactive children tend to become less hyperactive as they age, potentially developing into another subtype of ADHD.

The Hyperactive-Impulsive type (HT) in ADHD, observed mainly in younger children, represents a significant facet of the disorder. HT was incorporated into the DSM-IV to acknowledge children who predominantly display hyperactivity and impulsivity, as they were found to be as impaired as those with the combined type. This subtype is particularly prevalent in younger children, suggesting that it might be an early indicator of ADHD, which could evolve into the combined type with age.

A comprehensive literature review and meta-analysis encompassing 546 studies evaluated the stability of ADHD subtypes over time. This study supportedthe understanding that the vast majority of individuals with ADHD do not meet the same criteria over a prolonged period.

In adults with ADHD, the distribution of subtypes appears significantly different from that in children. A study revealed that 62% of adults with ADHD have the combined subtype, 31% are predominantly inattentive, and only 7% are predominantly hyperactive/impulsive. This data suggests a shift in the prevalence of ADHD subtypes as individuals age, with a notable increase in the combined subtype in the adult population.