High Comorbidity Rate of Bipolar Disorder and ADHD “Not by Chance”
(Part 1 of 2)
Co-occurrence of adult bipolar disorder (BD) and attention/deficit-hyperactivity disorder (ADHD) is heterogenous and “much higher than expected by chance,” according to a meta-analysis published online in Neuroscience & Biobehavioral Reviews. Clinicians should be aware of this overlap, which can have important implications for diagnosis and potentially treatment, researchers wrote.
Here, lead author Carmen Schiweck, PhD, Goethe University Frankfurt, Germany, explains the motivation for the study, the methods, and critical findings. In Part 2 of this Q&A, she discusses surprising outcomes, practical applications for clinicians, and further research.
Q: What led you and your colleagues to investigate the comorbidity between ADHD and adult bipolar disorder?
A: ADHD and adult BD are frequent disorders and do share some symptoms, but are also frequently comorbid, which is not only important for clinical presentation, but also for treatment choices. Quite a few studies have tried to quantify the magnitude of comorbidity for ADHD and childhood-onset bipolar disorder. However, since ADHD is a neurodevelopmental disorder and typically diagnosed during childhood or adolescence, its comorbidity with adult BD may often be overlooked. Having an indication of how often both disorders occur may increase awareness and potentially help treat both conditions.
Q. Please briefly describe the study method and participants.
A: To investigate the comorbidity between ADHD and adult bipolar disorder, we relied on published studies which assessed either the prevalence of ADHD in patients with BD, or vice versa, the prevalence of BD in patients with ADHD. We used a previously piloted data extraction form to extract all relevant information and then used meta-analysis to quantify the results. Diagnoses for ADHD were permitted without any age restriction, whereas samples of BD patients had to be 15 or older.
Q: Please briefly describe the most significant finding(s).
A: What struck us most is the magnitude of prevalence; of course, clinicians are already aware that psychiatric comorbidities are present in diverse patient groups, but to see that around 1 in 6 patients with BD and 1 in 13 patients with ADHD has the other disorder, shows just how frequently this occurs. In terms of population estimates this amounts to roughly 0.4% of the population, which is considerable. Another interesting aspect was that in this adult population, age of onset for BD in patients who had comorbid ADHD was considerably younger than those with “pure” BD. What should also be mentioned is that heterogeneity of results was very high in the included studies, which points to a large influence of other factors that contribute to comorbidity rates.
Reference
Dr. Carmen Schiweck has studied psychology and neurosciences in Paris, France, Maastricht, and the Netherlands. She holds a PhD in Biomedical Sciences from KU Leuven University, Belgium, and has a research interest in neurobiological processes in affective and psychotic disorders. Dr. Schiweck is currently working at Goethe University in Frankfurt, Germany, where she works in the lab of Professor Andreas Reif.
