Cognitive processes of inattention in attention deficit hyperactivity disorder subtypes

The primary objective of this study was to compare and evaluate attention in children with attention deficit hyperactivity disorder, predominantly inattentive (ADHD/IA) and combined (ADHD/C) types and comparison controls on the Attention Networks Test (ANT), a computer task designed to assess cognitive processes of alerting, orienting, and conflict, associated with three anatomically distinct networks of attention. A secondary aim was to examine the utility of sluggish cognitive tempo (SCT) as a classification variable for identifying a more cognitively homogeneous subgroup of children with ADHD/IA. Performance results on the ANT demonstrated an attentional distinction between the subtypes, a greater alerting effect ADHD/IA relative to ADHD/C groups. This finding suggests that the cognitive functioning of ADHD subtypes can be distinguished by the efficiency of the alerting network of attention. Groups did not differ on measures of orienting or conflict. Findings for the utility of SCT as a classification variable in this sample were mixed. Several items presumed to measure this construct did not distinguish between the ADHD subtypes. High SCT in ADHD/IA, as determined by scores on a two-item composite, was associated with slower task performance and a greater alerting effect, though these effects were nonsignificant and small. Results provide support for the neurocognitive distinction of ADHD/IA and ADHD/C subtypes and suggest further consideration of SCT symptoms in subtype classification.