Predominantly Hyperactive-Impulsive
The rarely isolated type
Characterized by hyperactive and impulsive behaviors without significant inattention. This is most commonly diagnosed in very young children. As cognitive demands increase with age (e.g., in school), most are re-diagnosed with the Combined presentation because underlying inattention becomes apparent.
The DSM-5 criteria — in plain language
6+ of the following in children (under 17); 5+ in adults. Present for 6+ months, in 2+ settings, causing impairment.
Constant physical movement. In adults, this often becomes internal restlessness or leg bouncing.
Struggles with meetings, dinners, or classroom settings that require sitting still.
In adolescents and adults, this may be limited to feeling restless.
Everything is done at high volume or high intensity.
Constant forward momentum; finds it deeply uncomfortable to just do nothing.
Often taking over conversations or unable to tolerate silence.
Impulsivity in social interactions.
In lines, in traffic, or in conversation.
Butting into conversations or games without meaning to be rude, driven by impulse.
The developmental pathway
Why this is rarely an adult diagnosis.
Young boys
This presentation is overwhelmingly diagnosed in young children, predominantly boys. It is the stereotypical "ADHD kid" profile.
Rare in adults
As the prefrontal cortex develops and societal demands increase, purely hyperactive individuals almost always begin to show inattentive symptoms, shifting their diagnosis to Combined type.
Internalized restlessness
For those who retain strong hyperactive traits into adulthood, the physical running and climbing usually transitions into a profound internal restlessness and chronic overworking.