What this Trial Is About

Researchers are investigating how dopamine affects the brain's response to chronic pain, focusing on key brain areas like the amygdala, hippocampus, thalamus, and nucleus accumbens. This Phase 2 study aims to understand changes in dopamine activity in the limbic system of people with chronic pain, which may influence motivation and pain experience. The study uses brain imaging to measure brain activity and volume changes related to dopamine modulation. Participants with chronic pain will attend four visits involving brain scans. The first visit serves as a baseline without any medication. During the next three visits, participants will receive one of three treatments in randomized order: carbidopa-levodopa, methylphenidate, or a placebo. After taking each oral medication or placebo, participants will wait three hours before completing brain scans and motivation tests. The study is double-blind, so neither patients nor researchers know which treatment is given at each visit. Throughout the study, participants will complete questionnaires about pain, mood, anxiety, trauma, and motivation. Their pain levels will be assessed before and after drug administration using scales like the Visual Analogue Scale (VAS). Brain imaging will measure changes in activity and volume of specific brain areas from baseline to three hours post-treatment. The study also monitors safety and side effects. Total participation includes these four visits with brain scans and assessments.

The Role of Brain Dopamine in Chronic Pain