Brain Response to Single Dose of Pregabalin in Fibromyalgia
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior.
HCPA

      Fibromyalgia syndrome represents a "spectrum disorder" characterized by widespread chronic
      pain, fatigue, sleep disturbances, mood and cognitive alterations. The most accepted models
      explaining the causes of the disease have focused on the reduced pain inhibitory systems
      activity, that allow low intensity stimuli to be processed easier, and that finally amplify
      pain stimuli. One of the interventions approved for Fibromyalgia is Pregabalin, which
      demonstrated to be effective reducing pain. Different studies in animals have shown that it
      works reducing the liberation of neuronal messengers, which slow the conduction of pain
      signals. Although studies in humans have confirmed Pregabalin clinical benefits, there are
      still few studies aiming to explain how it actually works in patients with fibromyalgia,
      though.

      A better understanding of the mechanisms by which Pregabalin reduces pain in patients with
      fibromyalgia would allow designing new interventions to enhance its clinical effects. Thus,
      the investigators propose to study in real-time the electrical, vascular and hormonal
      response of the brain of patients with fibromyalgia who receive a single dose of Pregabalin.
      The vascular response will be assessed using functional near infrared spectroscopy (fNIRS)
      neuroimaging techniques. The electrical response will be assessed using Transcranial Magnetic
      Stimulation (TMS). The hormonal response will be assessed in blood, measuring neurotrophins
      (Brain Derived Neurotrophic Factor) and inflammatory mediators (Tumor Necrosis Factor). These
      responses will be studied in consideration of the patients' characteristics that will be
      assessed using validated scales.

      Taken into account the above considerations, a crossover, double-blinded randomized clinical
      trial is proposed. In the investigators' study, patients and healthy volunteers will be asked
      to visit the investigators' laboratory in three opportunities: one for a baseline assessment,
      and the other two to test the effects of either Pregabalin 150 mg PO or Placebo. All
      participants will eventually receive both, Pregabalin and Placebo. In each visit a brain
      hemodynamic, electrical, hormonal and clinical evaluation will be performed.
    
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