Letter to Editor re.:

Pan, P., Jonsson, U., Şahpazoğlu Çakmak, S., Häge, A., Hohmann, S., Nobel Norrman, H., … Bölte, S. (2021). Headache in ADHD as comorbidity and a side effect of medications: A systematic review and meta-analysis. Psychological Medicine, 1–12. doi: 10.1017/S0033291721004141

Dear Editors,

In their comprehensive review on headache in attention-deficit/hyperactivity disorder (ADHD), Pan et al. (Reference Pan, Jonsson, Şahpazoğlu Çakmak, Häge, Hohmann, Nobel Norrman and Bölte2021) correctly assert that the pathophysiological links between ADHD and headache are currently unclear, and that consequently no evidence-based guidelines for the treatment of headache in ADHD exist. The authors elaborate on several potential pathophysiological mechanisms that may lead to headache in the context on ADHD, including sleep–wake cycle disturbances, genetic factors, and brain iron deficiency. We propose an additional mechanism, which may well have therapeutic implications: caffeine withdrawal-related headache.

Children and adolescents with ADHD consume significantly more caffeinated beverages than their peers without ADHD (Dosh et al., Reference Dosh, Helmbrecht, Anestis, Guenthner, Kelly and Martin2010; Jang & Kim, Reference Jang and Kim2012; Walker, Abraham, & Tercyak, Reference Walker, Abraham and Tercyak2010). It has been previously suggested that as subjects with ADHD start therapy with a simulant such as methylphenidate, the most commonly used drug in this indication (Storebø et al., Reference Storebø, Pedersen, Ramstad, Kielsholm, Nielsen, Krogh and Gluud2018), they decrease their caffeine consumption (Musafia & Rosenberg, Reference Musafia and Rosenberg2013). Consequently, headaches encountered when methylphenidate therapy is commenced may not be a direct side effect of this drug but rather a symptom of caffeine withdrawal.

Pan et al. (Reference Pan, Jonsson, Şahpazoğlu Çakmak, Häge, Hohmann, Nobel Norrman and Bölte2021) point to the paucity of data on the relationship between the time of exposure to an ADHD medication and the risk of headache. We suggest that future trials not only correlate these two paraments but also examine whether the risk of headache is related to a change in the consumption of caffeinated beverages. Additionally, in order to avoid the development of headaches, patients should likely be advised not to reduce their daily intake of caffeinated beverages too rapidly, although the rate this should be done at remains at present unknown.