Unsatisfied with the subjective system of rating pain on a 1-10 scale, researchers at Columbia University are using a new technology that provides a more precise measure to quantify the therapeutic effects of cannabinoids.

The new technology, known as quantitative sensory testing (QST), has only been used in a few clinical settings such as measuring neuropathic pain, but it is being used by Dr Caroline Arout to develop new approaches for pain medications such as cannabis.

QST measures nerve responses by using calibrated equipment to precisely apply different types of stimulation, including vibration and heat, cold, or pressure pain.

Currently Arout is using QST for two projects that are both aimed at developing a model of cannabis-induced changes in pain perception over time. The research is using the technology to apply heat stimulation to measure effects of the two main cannabinoids, CBD and THC (Delta-9). 

Assistant professor of clinical neurobiology Dr Caroline Arout (Photo: Vinson Sanders)

One study is using cannabis with high CBD levels to examine its effects on the pain induced by the technology itself while the other has a similar design and is investigating how repeated administration of high-THC cannabis effects pain over time. Both are using the QST neurosensory analyser. 

Arout said: “We don’t know how the effectiveness of cannabis for pain management changes over time with regular use.”

In the research, participants receive several pulses of heat and, as the intensity of each pulse changes, they control a lever to indicate pain perception on a scale of 0-100.

While that numbering system is still subjective, it uses an exact stimulus over a specific period so the researchers can quantify how participants are perceiving the pain. 

In the projects — which are still seeking participants — the QST equipment assesses temporal summation, an experimental correlate of central sensitisation. When nerve cells become sensitised that may be a marker of increased pain (hyperalgesia). 

Arout said QST may have applications in patients with opioid use disorder. As people look to replace opioids with less addictive analgesic medicines such as cannabis, she said research is still needed to understand the best way to manage treatment.

Through QST, the studies aim to gauge if withdrawal from cannabinoids creates increased pain sensitivity, as happens with opioids.

She added: “If people are starting to transition into using cannabis for pain, we need to find those characteristics before we walk down that problematic road.”

Data from QST could have potential for predicting both drug outcomes and patients at a higher risk of developing opioid use disorder due to higher pain sensitivity. 

The study is being conducted through the New York State Psychiatric Institute (NYSPI) Cannabis Research Laboratory.

Hannah Adler

Hannah is a communications professional and early-career researcher in the disciplines of health communication and health sociology. She is a PhD student at Griffith University currently writing a...