Brain-derived neurotrophic factor (BDNF) is considered a biomarker of brain plasticity. Since different alterations in brain plasticity have been found in chronic pain patients, the investigators want to study whether there are differences at the molecular level in this population compared to an asymptomatic population in order to be able to accurately measure the impact of different physiotherapy interventions in an objective way.
A case-control study will be conducted to analyze the differences in BDNF levels between patients with chronic pain and asymptomatic people.