Differential diagnosis and comorbidity of ADHD and anxiety in adults

Objectives: The aim of the present study was to examine symptom profiles of people diagnosed with ADHD and/or anxiety in order to determine the validity of widely used ADHD and anxiety rating scales for differential diagnostic use and to develop modified measures that take symptom overlap into account.
Design: A cross sectional design was used to assess differences in rating scale scores between a clinical (n=52) and control (n=74) sample as well as differences among subgroups of the clinical sample (22 ADHD; 16 ADHD+ANX; 14 ANX).
Method: Participants completed an online questionnaire where they responded to the Conners’ Adult ADHD Rating Scale (CAARS; Conners et al., 1999) and State Trait Anxiety Inventory scales (STAI; Spielberger et al., 1983).
Results: Results showed that the CAARS and STAI had limited sensitivity and specificity, and may lack in ability to differentially diagnose ADHD and/or anxiety. Cluster analysis was used to guide the proposal of modifications for the two scales, which were to use inattentive items only for the CAARS and to exclude state anxiety-present items on the STAI for use in differential diagnosis. Further parametric analysis supported these proposed modifications.
Conclusions: Clinicians should be made aware of the limitations of the CAARS and STAI scales in terms of specificity, when used to inform differential diagnosis of ADHD and anxiety. Further analysis on the psychometric properties of these modified scales is needed in order to confirm that they are valid and reliable scales.