Investigating how dopamine affects chronic pain

The Role of Dopamine in the Central Neural Signature of Chronic Pain

This study is testing how changes in dopamine levels might affect chronic pain in patients by using different treatments and brain scans to see what happens.

Quick facts

• Phase: Phase 2
• Study type: Interventional
• Enrollment: 10 (estimated)
• Ages: 18 Years and up
• Sex: All
• Sponsor: University of Rochester (Academic / other)
• Locations: 1 site (Rochester, New York)
• Trial ID: NCT05285683 on ClinicalTrials.gov

What this trial studies

This study aims to explore the role of dopamine in chronic pain by examining how dopaminergic transmission is altered in the limbic brain of chronic pain patients. Participants will undergo four visits, including baseline and randomized treatment sessions with methylphenidate, carbidopa-levodopa, and placebo. Each visit will involve brain imaging and assessments of pain, mood, and anxiety. The study seeks to understand the relationship between dopamine modulation and chronic pain experiences.

Who should consider this trial

Good fit: Ideal candidates are adults aged 18 and older who have been experiencing chronic pain for more than one year and rate their pain at 40 or above on a scale of 100.

Not a fit: Patients with significant other medical diseases or a history of traumatic brain injury may not benefit from this study.

Why it matters

Potential benefit: If successful, this study could lead to new treatment strategies for managing chronic pain by targeting dopamine pathways.

How similar studies have performed: While the role of dopamine in chronic pain is an emerging area of research, similar studies have shown promise in understanding the neurobiological underpinnings of pain.

Eligibility criteria

Inclusion Criteria:

The following inclusion criteria must be met for all subjects to be considered eligible to participate:

1. 18 years old or older
2. Equal numbers of men and women, as well as racial and ethnic makeup representative of surrounding area
3. Able to speak, read, and understand English
4. In generally stable health
5. Sign informed consent document

The following inclusion criteria must be met for chronic pain patients to be considered eligible to participate:

1. Patients must report chronic pain for more than 1 year.
2. The reported pain should be rated at ≥ 40/100

Exclusion Criteria:

General exclusion criteria for all subjects include:

1. Significant other medical disease, such as unstable diabetes mellitus, congestive heart failure, coronary or peripheral vascular disease, chronic obstructive lung disease, or malignancy
2. History of traumatic brain injury (TBI)
3. Current misuse/dependence on substance(s), including alcohol, at the time of study enrollment
4. Major psychiatric disorder during the past 6 months
5. Significantly abnormal laboratory values, which include, but are not limited to, the following:

   1. White blood cell (WBC) \< 1.5 or \>15.0 x 10\^3/μL
   2. Hemoglobin (Hgb) \< 8 gm/dL
   3. Hematocrit (Hct) \< 24% or \> 50%
   4. Platelets (Plts) \<50 or \> 1000 x10\^3
   5. Creatine \> 2 mg/dL
   6. Glucose \> 125 mg/dL
   7. Aspartate aminotransferase (AST) \> 250 U/L
   8. Alanine Transaminase (ALT) \> 250 U/L
   9. Bilirubin \> 3 mg/dL
6. Intra-axial implants (e.g. - spinal cord stimulators or pumps)
7. Inability to adequately perform the finger-span visual tracking task (training for rotating pain perception, see Brain Imaging Details).
8. All MRI exclusionary criteria: any metallic implants, brain or skull abnormalities, tattoos on large body parts, pregnancy, and claustrophobia.
9. In the judgement of the investigator, unable or unwilling to follow the protocol and instructions.
10. Gambling addiction self-reported during screening process (ensure computer-based games do not cause psychological or emotional problems)
11. Chronic pain patients with past history of allergic reactions to methylphenidate or levodopa/carbidopa.

For healthy control subjects, current complaint(s) of pain, or a history of pain lasting \>4 weeks in the last year, will be excluded from participating.

In addition, exclusion criteria for chronic pain subjects also includes:

1. Pain that is associated with any systemic signs or symptoms (e.g. - fever, chills)
2. Evidence of rheumatoid arthritis, ankylosing spondylitis, acute vertebral fractures, fibromyalgia, history of tumor(s) in the back.
3. Involvement in litigation regarding their pain, or having a disability claim, or receiving workman's compensation, or seeking either because of their pain.
4. Treated with methadone for opioid use disorder (i.e. - not just for pain)

Where this trial is running

Rochester, New York

• University of Rochester Medical Center — Rochester, New York, United States (Recruiting)

Study contacts

• Study coordinator: Pain Lab

Conditions Chronic Pain; dopamine; loss of motivation; chronic back pain