Verbal fluency in individuals with attention deficit-hyperactivity disorder (ADHD): A meta-analysis

Verbal fluency, an important aspect of executive function, is often impaired in attention deficit-hyperactivity disorder (ADHD). However, findings across studies have been inconsistent regarding age groups and comorbid conditions. This meta-analysis examined verbal fluency in both children and adults with ADHD, including studies that reported common comorbidities (e.g., oppositional defiant disorder [ODD], conduct disorder [CD], and anxiety disorders), while excluding studies including autism spectrum disorder (ASD).

A systematic search of PubMed, ScienceDirect, PsycINFO, and Google Scholar (1994-April 2024) identified cross-sectional studies comparing verbal fluency performance between individuals with ADHD (children and adults) and healthy controls. Risk of bias was assessed using the Joanna Briggs Institute (JBI) checklist.

Sixteen studies (1167 participants; 566 with ADHD, 601 healthy controls; age range 4-55 years) showed consistent verbal fluency impairments in individuals with ADHD, Both phonemic (g=-0.44) and semantic (g=-0.51) fluency tasks indicated medium-sized deficits; however, the semantic task showed a slightly larger effect size. Gender moderated the observed outcomes, whereas age did not. Comorbid conditions also influenced verbal fluency performance.

Impairments in verbal fluency, with semantic fluency showing a comparatively larger deficit, suggest the presence of executive dysfunction among individuals with ADHD across the lifespan. Therefore, verbal fluency measures should be included in neuropsychological evaluations for both children and adults with ADHD.