Verbal working memory and processing speed: Correlations with the severity of attention deficit and emotional dysregulation in adult ADHD

OBJECTIVES The Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5), emphasizes symptoms severity with regard to the diagnosis of attention deficit hyperactivity disorder (ADHD). Many clinicians use neuropsychological test results as objective measures of cognitive functions as part of the diagnostic work-up. The aim of this study was to investigate whether the psychometric test results regarding verbal working memory and processing speed are useful as indicators of the severity of attention deficits and emotional dysregulation in adults with ADHD. METHODS This observational cross-sectional clinical study included 418 adults diagnosed with ADHD according to the DSM-5. Attention deficit severity was defined based on the inattentive subscale of the Adult ADHD Self-Report Scale. Emotional dysregulation was assessed with the Deficient Emotional Self-Regulation scale. Verbal working memory was measured with the Working Memory Index (WMI), and processing speed was measured with the Processing Speed Index (PSI) from the Wechsler Adult Intelligence Scale, third edition. RESULTS The full-scale intelligence quotients of the participants were in the normal range, with expected reductions in verbal working memory and processing speed. Only processing speed was associated with attention deficits (β = -.056, p = .003). The association between the psychometric test result for verbal working memory and processing speed and that between the severity of attention deficits and emotional dysregulation were weak (R2  < .1) and mostly non-significant. CONCLUSION The psychometric index scores for verbal working memory (WMI) and processing speed (PSI) seem to have limited utility as indicators of the severity of attention deficits and emotional dysregulation in adult ADHD patients.