Adult ADHD and Comorbid Somatic Disease
By Stephen V. Faraone, PhD
Although there has been much research documenting that ADHD adults are at risk for other psychiatric and substance use disorders, relatively little is known about whether ADHD puts adults at risk for somatic medical disorders. Given that ADHD people are disorganized and inattentive and that they tend to favor short-term over long term rewards, it seems logical that they should be at higher risk for adverse medical outcomes. But what do the data say? In a systematic review of the literature, Instanes and colleagues provide a thorough overview of this issue. Although they found 126 studies, most were small and were of “modest quality”. Thus, their results must be considered to be suggestive, not definitive for most of the somatic conditions they studied. Also, they excluded articles about traumatic injuries because the association between ADHD and such injuries is well established. Using qualitative review methods, they classified associations as being a) well-established; b) tentative or c) lacking sufficient data. Only three conditions met their criteria for being a well-established association: asthma, sleep disorders and obesity. They found tentative evidence implicating ADHD as a risk factor for three conditions: migraine headaches, celiac disease and diseases of the circulatory system. These data are intriguing but cannot tell us why ADHD people are at increased risk for somatic conditions. One possibility is that ADHD symptoms lead to an unhealthy lifestyle, which leads to increased medical risk. Another possibility is that the biological systems that are dysregulated in ADHD are also dysregulated in some medical disorders. For example, we know that there is some overlap between the genes that increase risk for ADHD and those that increase risk for obesity. We also know that the dopamine system has been implicated in both disorders. Instanes and colleagues also point out that some medical conditions might lead to symptoms that mimic ADHD. They give sleep disordered breathing as an example of a condition that can lead to symptom of inattention. But this seems to be the exception, not the rule. Other medical conditions co-occurring with ADHD seem to be true comorbidities rather than the case of one disorder causing the other. Thus primary care clinicians should be alert to the fact that many of their patients with obesity, asthma or sleep disorders might also have ADHD. By screening such patients for ADHD and treating that disorder, you may improve their medical outcomes indirectly via increased compliance with your treatment regime and an improvement in health behaviors. We don’t yet have data to confirm these latter ideas as the relevant studies have not yet been done.
Instanes, J. T., Klungsoyr, K., Halmoy, A., Fasmer, O. B. & Haavik, J. (2016). Adult ADHD and Comorbid Somatic Disease: A Systematic Literature Review. J Atten Disord.