METHYLPHENIDATE IMPROVED CHRONIC PAIN IN AN ADULT PATIENT WITH ATTENTION DEFICIT HYPERACTIVITY DISORDER: A CASE REPORT AND LITERATURE REVIEW

Abstract Background Attention deficit hyperactivity disorder (ADHD) is a common mental disorder that co-occurs with pain disorders.1 In comorbidity of ADHD and chronic pain, many patients may first present to the clinic with only pain complaints. Treatment that merely focuses on eliminating pain may obscure the diagnosis of ADHD. In addition, untreated ADHD can lead to worsened symptoms, including chronic pain.2 Aims We present a well-documented case of an adult patient with chronic pain and a late diagnosis of ADHD that was effectively managed with methylphenidate (MPH). We discuss whether the effectiveness of MPH in treating pain regardless of ADHD comorbidity was likely coincidental or a potentially consistent phenomenon. Method A case report and literature review. Result A 43-year-old Japanese male patient with 15 years of chronic idiopathic pain symptoms did not adequately respond to standard pain management. Pain also persisted after treatments with antidepressants, an epidural block, and modified electroconvulsive therapy. After a thorough assessment, we confirmed a diagnosis of adult ADHD with a predominantly inattentive type. Considering this newly established diagnosis, we prescribed osmotic-release oral system (OROS) methylphenidate. Within 1 month of treatment at a dose of 18 mg/day of OROS-MPH, the patient’ s chronic pain unexpectedly improved dramatically. The dosage of OROS-MPH was titrated monthly, reaching 72 mg/day as a maintenance dose, and ADHD symptoms improved after 4 months of treatment (Figure 1). The patient was followed up regularly for 7 years during OROS-MPH treatment. He was stable overall and functioned well in his daily activities. Discussion & Conclusion Although MPH use as an analgesic for pain treatment remains uncommon and off-label, several studies have investigated its antinociceptive effect.3,4,5 This case report suggests that MPH may be potentially effective in treating chronic pain. Further studies are needed to confirm whether MPH improved chronic pain simultaneously with or separately from the improvement in ADHD. Moreover, elucidating the anatomical sites and molecular pharmacological mechanisms related to the action of MPH in pain modulation and perception is essential, including descending dopaminergic pain pathways and higher cortical areas. Furthering our understanding will reinforce the justification of MPH in treating chronic pain. References 1.Stickley, A, Koyanagi, A, Takahashi, H, and Kamio, Y. ADHD symptoms and pain among adults in England. Psychiatry Res. (2016) 246:326–31. 2.Siddall, PJ, and Cousins, MJ. Persistent pain as a disease entity: Implications for clinical management. Anesth Analg. (2004) 99:510–20. 3.Pud, D, Broitman, E, Hameed, O, Suzan, E, Aviram, J, Haddad, M, et al. Methylphenidate attenuates the response to cold pain but not to aversive auditory stimuli in healthy human: a double-blind randomized controlled study. Pain Rep. (2017) 2:e593. 4.Johansson, B, Wentzel, AP, André ll, P, Odenstedt, J, Mannheimer, C, and Rö nnbä ck, L. Evaluation of dosage, safety and effects of methylphenidate on post-traumatic brain injury symptoms with a focus on mental fatigue and pain. Brain Inj. (2014) 28:304–10. 5.Yamamotová, A, Fricová, J, Rokyta, R, and Š lamberová, R. The effect of combined treatment of opioids with methylphenidate on nociception in rats and pain in human. Physiol Res. (2016) 65:S567–75.