INVESTIGATOR: Fadel Zeidan, Ph.D.

STUDY LOCATION: University of California, San Diego

PROJECT TITLE: The effects and brain mechanisms supporting cannabis-induced chronic low back pain relief

FUNDING SOURCE: Center for Medicinal Cannabis Research

PROJECT TYPE: Clinical Study

STATUS: Active 

ABSTRACT:

Chronic pain is a significant health epidemic that impacts 1.5 billion people worldwide with substantial financial burden incurring well over $635 billion in medical treatment and lost work productivity losses a year. Chronic low back pain (cLBP) is complicated and there are no known therapies that immediately attenuate acute and chronic pain. Cannabis is a natural product that has been used to treat pain for thousands of years. In fact, the most common reason individuals use cannabis is to treat pain. Converging preclinical results indicate that the endogenous endocannabinoid pain control system recruits a unique subset of functional mechanisms to facilitate pain relief. Yet, there are no known studies that have examined the immediate effects of inhaled (vaporized) cannabis on subjective pain reports and corresponding brain mechanisms. The primary objective of the proposed pilot study is to determine if medium-dose cannabis can attenuate acutely evoked cLBP as compared to a very low dose cannabis. We also aim to identify the neural mechanisms supporting pain relief by cannabis. The proposed doubled-blind, placebo-controlled project will recruit 52 cLBP patients (26, 5.6% THC and 26, .1% THC) will employ two distinct neuroimaging approaches, perfusion-based arterial spin labeling and blood oxygen level dependent fMRI, alongside an acute low-back pain exacerbation maneuver (the straight leg raise test) and noxious heat (48°C; calf) in cLBP patients to provide a specific and comprehensive delineation of how cannabis impacts pain. Our new pilot study in three cLBP patients found that inhaled cannabis directly lowered back and noxious heat-induced pain. When compared to rest, cannabis also produced significant activation in the prefrontal cortices and weakened processing in the contralateral thalamus and primary somatosensory cortex. The central hypothesis is that low-back pain relief produced by a “medium” dose (5.6% THC) of vaporized cannabis will be associated with lower pain, attenuated nociceptive, and higher reward-related processing when compared to .1% THC. This study is an important step in appreciating if cannabis can be used to directly treat pain and will be an important step in appreciating the neurobiological processes supporting cannabis. We will target larger NIH funds with the pilot data accrued from this study across variable clinical samples and examine way to optimize therapies to better target multimodal aspects of pain.