An affective basis for the effects of cannabinoids in pain?

Further attention focused upon cannabis-derived products as a possible strategy for pain management, published in a recent edition of JAMA Psychiatry. Researchers conducted a systematic review addressing the relationship between cannabinoid drug administration and experimental pain outcomes in healthy adults. In all, 18 placebo-controlled studies (with 442 participants) were identified. Cannabinoids produced small increases in pain threshold, small to medium increases in pain tolerance and a small to medium reduction in the unpleasantness of ongoing experimental pain, but was not reliably associated with a decrease in experimental pain intensity or mechanical hyperalgesia. The analysis concluded that cannabinoid drugs may prevent the onset of pain by producing small increases in pain thresholds but may not reduce the intensity of experimental pain already being experienced; but may make experimental pain feel less unpleasant and more tolerable, suggesting an influence on affective processes, this suggesting that pain-related negative affect may partially explain the widely held belief that cannabis relieves pain.