Identification of biotypes in Attention-Deficit/Hyperactivity Disorder, a report from a randomized, controlled trial

Area of Science:

• Neuroscience
• Psychiatry
• Computational Biology

Background:

• Attention-Deficit/Hyperactivity Disorder (ADHD) is recognized as a heterogeneous condition.
• Current ADHD subtypes demonstrate limited longitudinal stability and prognostic value.
• There is a need for biologically-grounded classifications of ADHD.

Purpose of the Study:

• To identify data-driven ADHD biotypes using a comprehensive cognitive battery.
• To validate these identified biotypes using electroencephalogram (EEG), electrocardiogram (ECG), and clinical response to atomoxetine.
• To explore distinct neurophysiological and clinical profiles within ADHD.

Main Methods:

• Employed unsupervised machine learning on a cognitive battery of 20 measures from 116 children with ADHD and 56 controls.
• Utilized a double-blind, randomized, placebo-controlled crossover trial of atomoxetine.
• Validated biotypes using baseline EEG, ECG, ADHD Rating Scale, and cognitive change correlations.

Main Results:

• Identified two distinct ADHD biotypes: 'impulsive cognition' (more errors of commission, faster reaction time, higher theta/delta EEG, higher heart rate) and 'inattentive cognition' (more errors of omission, slower/variable reaction time, lower beta EEG, normal heart rate).
• The 'inattentive cognition' biotype showed a significant correlation between atomoxetine response and verbal memory improvement (r = -0.447, p < 0.001).
• EEG and ECG measures differentiated the identified biotypes, suggesting distinct underlying arousal mechanisms.

Conclusions:

• ADHD comprises at least two distinct biotypes that transcend current subtype criteria.
• These biotypes may reflect different arousal mechanisms.
• Cognitive biotype investigation offers a promising path for developing biologically-based ADHD diagnostics and interventions.