Continuous performance tests (CPT) are often considered the gold standard for the diagnosis attention-deficit/hyperactivity disorder (ADHD), particularly when parent and teacher rating scales are inconclusive. Prior work has indicated that CPT can also help differentiate between ADHD subtypes. However, the ability of CPT to differentiate ADHD subtype has not been examined among youth with comorbid ADHD and anxiety (ADHD+A). This is particularly concerning as the extant literature suggests that anxiety symptoms may exacerbate deficits associated with ADHD (e.g.. , working memory, attention) and attenuate others (e.g., inhibition); thus, anxiety may influence expected patterns on the CPT. This study therefore seeks to examine the role of ADHD subtype on the relationship between ADHD+A and performance on a CPT among youth with ADHD+A.

Participants included 54 children ranging from 6 to 20 years old (Mage=11.83, 54% female) who were diagnosed with ADHD+A via neuropsychological evaluation. In terms of ADHD subtype, 51.9% (n=28) were diagnosed with ADHD combined or ADHD primarily hyperactive and 48.1% (n=26) were diagnosed with ADHD primarily inattentive. Approximately 46.30% (N=25) of participants were medication naive. Analyses were conducted using data from the Conners Kiddie Continuous Performance Test -Second Edition (KCPT-2), Conners Continuous Performance - Second Edition (CPT-2) and the Conners Continuous Performance - Third Edition (CPT-3), which are part of the same family of performance-based attention measures. Independent samples t-tests were conducted to examine performance differences in aspects of attention (e.g., inattentiveness, sustained attention) and hyperactivity (e.g., impulsivity, inhibition).

ADHD subtype was not significantly related to measures of inattentiveness. This includes the number of targets missed (omissions; (t(39)=-.532, p=.59)) and variability in response time (variability; (t(39)=-0.30, p=.77)). In terms of sustained attention, ADHD subtype was not related to variability in response speed across blocks (Hit SEBC/HRT Block Change; (t(39)=-0.26, p=.79)). Importantly, these results were consistent regardless of ADHD medication status. ADHD subtype was also not significantly related to impulsivity. This includes responses to nontargets (commissions; (t(39)=-1.05, p=.30)), random or anticipatory responding (perseverations; (t(39)=-0.19, p=.85)), and mean response speed of correct responses (HR; (t(39)=-0.72, p=.48)).

The extant literature suggests that CPT can help clinicians differentiate between ADHD subtypes. However, the results of this study indicate that there are no performance differences on the CPT among youth with comorbid ADHD and anxiety. There are several limitations to consider. First, this study had a relatively small sample size, which also limited the ability to examine ADHD primarily hyperactive/impulsive as a distinct subtype. Additionally, this study did not examine the effect of individual anxiety disorders (i.e., generalized anxiety disorder, specific phobias). Finally, these findings may not generalize to other standardized measures of attention or more ecologically valid measures. Despite these limitations, this study is an important step in understanding the relationship between ADHD+A and performance on attention measures. Clinicians should be cautious in using results from CPT to distinguish between ADHD subtype among children with comorbid anxiety.