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Objective: To systematically investigate previously examined biomarkers in blood, urine, cerebrospinal fluid, tear fluid, and saliva of patients with cluster headache. Background: Cluster headache is a condition with extensive clinical challenges in terms of diagnosis and treatment. Identification of a biomarker with diagnostic implications or as a potential treatment target is highly warranted. Methods: We conducted a systematic review including peer reviewed full text of studies that measured biochemical compounds in either blood, urine, cerebrospinal fluid, tear fluid, or saliva of patients with cluster headache diagnosed after the implementation of the International Classification of Headache Disorders (1988) written in English, Danish, Swedish, or Norwegian. Inclusion required a minimum of five participants. The search was conducted in PubMed and EMBASE, in September 2022, and extracted data were screened by two authors. Preferred Reporting Items for Systematic Reviews and Meta‐Analyses guidelines for reporting systematic reviews were followed. The Newcastle–Ottawa Scale was used to assess the risk of bias in case–controlled studies. Results: We included 40 studies involving 832 patients with cluster headache and 872 controls, evaluating 80 potential biomarkers. The risk of bias for case–controlled studies was a median of 6 (range: 3–8) and 20 studies out of 40 (50%) were of fair or good quality. Most studies were identified within three groups: hypothalamic‐regulated hormones, inflammatory markers, and neuropeptides. Among the hypothalamic hormones, cortisol was the most frequently investigated (N = 7) and was elevated in cluster headache in most of the studies. The most frequently examined inflammatory marker was interleukin 1 (N = 3), but findings were divergent. Calcitonin gene–related peptide was the most investigated neuropeptide (N = 9) and all studies found increased levels during attacks. Conclusion: Biomarker findings have been inconsistent and widely non‐specific for cluster headache, which explains why none of the previous studies succeeded in identifying a unique biomarker for cluster headache, but instead contributed to substantiating the underlying pathophysiologic mechanisms. Several of the examined biomarkers could hold promise as markers for disease activity but are unfit for a clear distinction from both controls and other headaches. [ABSTRACT FROM AUTHOR]

Objective: To evaluate the feasibility and prophylactic effect of psilocybin as well as its effects on hypothalamic functional connectivity (FC) in patients with chronic cluster headache (CCH). Background: CCH is an excruciating and difficult‐to‐treat disorder with incompletely understood pathophysiology, although hypothalamic dysfunction has been implicated. Psilocybin may have beneficial prophylactic effects, but clinical evidence is limited. Methods: In this small open‐label clinical trial, 10 patients with CCH were included and maintained headache diaries for 10 weeks. Patients received three doses of peroral psilocybin (0.14 mg/kg) on the first day of weeks five, six, and seven. The first 4 weeks served as baseline and the last 4 weeks as follow‐up. Hypothalamic FC was determined using functional magnetic resonance imaging the day before the first psilocybin dose and 1 week after the last dose. Results: The treatment was well tolerated. Attack frequency was reduced by mean (standard deviation) 31% (31) from baseline to follow‐up (pFWER = 0.008). One patient experienced 21 weeks of complete remission. Changes in hypothalamic–diencephalic FC correlated negatively with a percent change in attack frequency (pFWER = 0.03, R = −0.81), implicating this neural pathway in treatment response. Conclusion: Our results indicate that psilocybin may have prophylactic potential and implicates the hypothalamus in possible treatment response. Further clinical studies are warranted. [ABSTRACT FROM AUTHOR]

Objective: Caffeine, a non‐selective adenosine receptor (AR) antagonist, is the most consumed psychostimulant in the world. Caffeine has been suggested to regulate cerebrospinal fluid secretion and is known both to alleviate and to trigger headache; however, its effect on the regulation of intracranial pressure (ICP) is not known. Therefore, we aimed to investigate the effects of caffeine on ICP and nociceptive responses. Methods: Female Sprague–Dawley rats were implanted with a novel telemetric device for continuous ICP recordings, which allowed for continuous recordings in freely moving rats. A single dose of caffeine (30 or 120 mg/kg intraperitoneally) was given. In a second group (non‐implanted), the acute effects of 30 mg/kg caffeine on periorbital threshold using Von Frey testing and spontaneous behavior were utilized using an automated behavioral registration platform (Laboratory, Animal, Behavior, Observation, Registration and Analysis System) in a randomized cross‐over study. Quantitative polymerase chain reaction and immunofluorescence were used to localize ARs in the choroid plexus. Results: A single dose of 30 mg/kg caffeine lowered the ICP by 35% at 165 min after administration (saline: 0.16 ± 0.9 vs caffeine: −1.18 ± 0.9 ΔmmHg, p = 0.0098) and lasted up to 12 h. Administration of 120 mg/kg caffeine showed a faster onset of decrease in ICP within 15 min by 50% (p = 0.0018) and lasted up to 12 h. The periorbital pain thresholds were higher after 1 h (saline: 224.6 ± 15.1 vs caffeine: 289.5 ± 8.7 g, p = 0.005) and lasted up to 5 h. Caffeine‐treated rats had increased locomotor activity, speed, and changed grooming behavior. Expression of AR1 was found in the choroid plexus. Conclusions: This study demonstrates that caffeine has a lowering effect on ICP as an acute treatment. Interestingly, caffeine acutely caused an increased response in cephalic thresholds supporting hypoalgesic effects. Future studies investigating the beneficial effects of caffeine for elevated ICP are warranted. [ABSTRACT FROM AUTHOR]

Objective To examine whether detoxifying patients with medication-overuse headache can reduce long-term medication costs. Background Direct costs of medications in medication-overuse headache have been reported to be very high but have never been calculated on the basis of exact register data. Long-term economic savings obtained by detoxification have never been investigated. Methods We conducted a registry-based observational retrospective follow-up study on 336 medication-overuse headache patients treated and discharged from the Danish Headache Center over a 2-year period. By means of the Danish Register of Medicinal Product Statistics, we collected information on the costs and use of prescription-only medication 1 year before admission and 1 year after discharge from Danish Headache Center. Results The average medication costs per patient per year decreased with 24%, from US$971 before treatment to US$737 after ( P = .001), and the average medication use decreased with 14.4% ( P = .02). Savings were most pronounced for patients overusing triptans. In this group, the average medication costs per patient per year decreased with 43% ( P < .001), while the average triptan use decreased with 38% ( P < .001). Conclusions The study demonstrates that detoxification of medication-overuse headache at a tertiary headache center has a long-lasting effect on the medication costs and use, in particular among patients overusing triptans. The results may not be generalizable to all countries and may be sensitive to the costs of triptans. [ABSTRACT FROM AUTHOR]