Serum changes of apolipoproteins in Medication Overuse Headache (MOH)

Background Medication Overuse Headache (MOH) is a prevalent and disabling disorder resulting from the overuse of analgesic drugs, triptans or other acute headache medications. Previous proteomic studies have identified some altered proteins, including different forms of apolipoproteins, which are probably associated with the chronic painful symptom and its consequences. The aim of the study was to explore the relationship between cutaneous pain thresholds, Zung Self- Rating Depression Scale (ZUNG-D) scores, Leeds Dependence Questionnaire (LDQ) scores and serum levels of apolipoprotein A1 (APOA1) and apolipoprotein E (APOE) in patients with MOH. Methods 69 patients with MOH and 42 healthy volunteers as control group were enrolled in the study between September 2016 and January 2018. To investigate skin sensitivity, Von Frey-like filaments were applied sequentially to the skin territories innervated by the divisions of the trigeminal nerve, to determine cutaneous pain thresholds. APOA1 and APOE, previously identified as potential biomarkers candidates for the pathophysiology of chronic pain, were quantified in the serum by Enzyme-linked Immunosorbent Assay (ELISA). Results Cutaneous pain thresholds were lower among patients with MOH than healthy controls. Serum APOE was significantly lower in patients with MOH, compared to healthy volunteers (p < 0.01), but no differences were found concerning serum APOA1 (Fig. 1). In patients with MOH, serum APOE was positively related to Body Mass Index, albumin and uric acid, whereas serum APOA1 was positively related to creatinine. Serum APOA1 and APOE did not have any relationship with cutaneous pain thresholds, ZUNG-D scores, LDQ scores and other clinical or laboratory parameters. Conclusions Serum APOE is significantly altered in patients with MOH compared to controls, but it is apparently not correlable with any aspect of the disease. APOE may play a role in the pathophysiology of MOH and the consequences associated with medication overuse; further studies are needed to deepen this finding. Ethics approval This study was performed following the Helsinki Declaration principles and approved by the local Ethical Committee (prot. 2073).