Symptoms of Anxiety in Adults with ADHD: A Systematic Review and Meta-Analysis of Case-Control Studies

Abstract

Objective: Research suggests there is a higher prevalence of anxiety in individuals with ADHD compared to those without ADHD. However, estimated prevalence rates vary greatly due to differences in methodologies used across studies. This study is the first meta-analysis investigating differences in anxiety measure scores between adults with and without ADHD, and possible moderators of this effect. Method: Our analysis included 58 studies that compared anxiety scores in adults with/without ADHD (N = 18,821; k = 112). Results: The average effect size (Hedges’s g) of anxiety scores in those with ADHD relative to controls was 0.77 (SE = 0.066); a medium effect. The only significant moderator was the type of comparison group used, with comparisons to non-clinical control groups (g = 0.954, SE = 0.08) yielding significantly larger effects than comparisons to clinical control groups (g = 0.437, SE = 0.09). None of the other moderator variables examined (Method of characterising ADHD, Anxiety Measure Type, Anxiety Measure Focus, Age or Gender) moderated the effect. There was some evidence of publication bias, therefore results should be interpreted with this in mind. Conclusion: Overall, this study indicates that ADHD is associated with higher levels of anxiety symptomology. This has important implications in the diagnosis and treatment of individuals presenting with ADHD or anxiety, including the consideration and screening of each of these conditions as potentially co-occurring with the other. Adaptions made to clinical practice in line with this would better support this population, improve symptom management and overall quality of life. Suggestions for future research are discussed.