Classifying ADHD subtypes/presentations considering the joint effect of three levels of investigation

Discriminant validity of the Attention Deficits/Hyperactive Disorders (ADHD) subtypes/presentations is not yet clear. The purpose of this study was to investigate joint contribution of the strongest factors of the three dimensions, namely psychopathology, neuropsychology and electrophysiology for subtyping of presentations.

A sample of 104 boys aged 7-12 years was subdivided into three groups with ADHD combined (n = 22), inattentive (n = 25) and hyperactive/impulsive subtype (n = 14), and 43 typically developing controls (TDC). Children were investigated regarding the Child Behavior Checklist (CBCL), the Integrated Visual and Auditory Test (IVA), and EEG spectral power during eyes closed resting state. Subsequently, statistical analysis included discriminant functional analysis and principle component analysis.

Neuropsychological parameters had the highest contribution in classifying of the groups. EEG parameters had no effect on differentiation of the groups, and among the psychopathological parameters, only the oppositional behavioral disorder score contributed to correctly classify 74.3% of the groups. Furthermore, we found four factors with eigenvalues higher than 1 in the ADHD and typical groups, with one factor characterized by four CBCL scales, another one by auditory and visual vigilance, speed and beta band power, the third by auditory and visual prudence, and forth by theta band power.

Our results demonstrated that ADHD subtypes/presentations can be differentiated from each other at different levels of investigation despite some clinical symptoms overlap. The results suggested that not only psychopathology but also the impairment of sensory processing should be assessed in children with ADHD in order to use this additional information for a jointly multilevel clinical intervention, which may improve treatment success.