(CN) – A new look at research into cannabis as a treatment for chronic pain and post-traumatic stress disorder offers no definitive conclusions for or against the much-touted treatment, the U.S. Department of Veterans Affairs said Monday.
“The scientific evidence is too limited to make firm conclusions about the effectiveness and safety of cannabis and cannabinoid products in treating chronic pain or post-traumatic stress disorder,” the agency said in a statement.
VA researchers looked at 27 chronic pain trials, finding “low-strength” evidence that cannabis helps with neuropathic pain, but not enough evidence to draw conclusions about its effectiveness for other types of pain. They concluded, however, that cannabis could increase users’ risk of car accidents, psychotic symptoms and short-term cognitive impairment.
“There was insufficient evidence to determine the risks for other types of harms associated with heavy or long-term cannabis use or in older populations,” the agency said.
The researchers drew similar conclusions about the use of plant-based cannabis for PTSD, which is listed as the primary reason for cannabis treatment by more than one-third of patients where PTSD is a qualifying condition.
“Evidence was insufficient to draw firm conclusions about the efficacy of cannabis in this patient population, but one of the largest observational studies of veterans with PTSD found small but significant worsening of symptoms in patients who continued or started cannabis use compared with patients who had never used or stopped using cannabis during the study,” the agency said.
Research into cannabis as a medical treatment is notoriously hard to find. Because only one medical cannabis clinical trial has been approved by the Food and Drug Administration and Drug Enforcement Administration – a study of smoked cannabis as a treatment for PTSD in veterans currently underway at the Scottsdale Research Institute in Phoenix, Arizona – no federally approved research is available.
Dr. Sue Sisley, the lead researcher on that clinical trial which is funded by a $2 million grant from the Colorado Department of Public Health, did not immediately respond to a request for comment.
An editorial that accompanied the Veterans Affairs review urges physicians to keep abreast of current research and educate patients accordingly.
“Regardless of the research gaps, states are unlikely to remove medical indications from legislation. Practicing physicians must learn what they can about cannabis, educate their patients, and make recommendations based on the science,” the editorial said.
Cannabis is legal for medical use in 28 states and the District of Columbia. The Veterans Affairs researchers published the reviews in the Annals of Internal Medicine.