Clustering of Behavioral Data for Identification of Presumptive Subtypes of Attention Deficit/Hyperactivity Disorder in Children

The objective of the present study was to investigate Amen's formulations of subtypes of AD/HD initially identified by brain imaging techniques, through the use of behavioral checklist data. And in testing Amen's theory of six separate subtypes of AD/HD, to identify and differentiate the subtypes based on symptom presentation. Data was obtained through retrospective chart reviews (N=161) of children between the ages of 5 and 12 who met the criteria for the major symptoms observed in AD/HD and were referred for a previous comprehensive AD/HD evaluation. Data from behavioral checklist (CBCL and DBRS-IV) were matched to Amen's Subtype Symptom Checklist and each subject was given a percentage score for six subtype symptoms. Cluster analysis reliably found six clusters and each subject was labeled according to their symptom presentation. The clusters found were labeled as AD/HD - Combined Type, AD/HD - Predominately Inattentive Type, AD/HD - Predominately Hyperactive-Impulsive Type, Ad/HD - Combined Type with Obsessive-Compulsive features, AD/HD - Combined Type with Obsessive/Compulsive and Conduct Disorder features and Undifferentiated AD/HD. However, the present study did not find evidence of subtypes that corresponded to Amen's Temporal Lobe ADD or Limbic ADD. Discriminant function analysis of the six clusters found that the variables in the model (symptom percentage scores) significantly discriminated the subtype classification. Also, 76% of all cases were correctly classified according to their symptom presentation. Potential limitations of the sample and the data used for interpretation were discussed. Limitations of the study warrant further investigation making use of multi-modal assessment tools which relate well with brain imaging techniques, such as neuropsychological measures of attention and concentration, laboratory based measures of activity, continuous performance tests measuring inattention and impulsivity, and QEEG data measuring brain wave information. A multi-modal approach to investigating symptom subtypes of AD/HD would likely provide increased reliability and validity of differential diagnosis, and therefore, more effective treatment of children with the presenting symptomology of AD/HD. The diagnostic and clinical implications' of each cluster subtype symptomology found in the present study was discussed as well