Cannabis may hold promise to treat PTSD but evidence lags behind use
September 3, 2019
Science Daily/University College London
As growing numbers of people are using cannabis to treat post-traumatic stress disorder (PTSD), a new UCL study reports that prescriptions are not backed up by adequate evidence.
The systematic review, published in the Journal of Dual Diagnosis, finds that the active components of cannabis, called cannabinoids, may hold promise as a treatment for PTSD, particularly for reducing nightmares and helping people sleep, but more research is needed to determine whether these drugs should be used in routine clinical practice.
"There has been a recent surge of interest in the use of cannabinoids to treat PTSD, particularly from military veterans, many of whom are already self-medicating or obtaining prescriptions in some American states," said the study's lead author, Dr Chandni Hindocha (UCL Clinical Psychopharmacology Unit).
"The lack of evidence supporting cannabis as a PTSD treatment is striking given the vast interest in it, and the large unmet need for better PTSD treatments," she said.
PTSD is a potentially debilitating condition affecting roughly 1% of the UK population, typically consisting of re-experiencing a traumatic event through intrusive memories, flashbacks or nightmares, and often involves hyper-reactivity (a state of constant vigilance) and insomnia.
Psychotherapies (talking therapies) including trauma-focussed cognitive-behavioural therapy have been shown to be effective for PTSD. However, not everyone can access talking therapies and they do not work for everyone, so many people still need to take prescribed medications. Existing drugs approved for PTSD do not work for everyone, and can have side effects, so researchers say there is an urgent need to identify new treatments.
A growing number of people have turned to cannabinoids, which is an approved treatment for PTSD in most states in the USA that permit medical cannabis.
Cannabinoids, the active ingredients of cannabis, which include tetrahydrocannabinol (THC) and cannabidiol (CBD), may be helpful at treating PTSD as they can change how the brain processes memories. The cannabinoids act on the brain's in-built endocannabinoid system which also regulates other brain functions that are affected by PTSD.
The research team conducted a systematic review of all studies where someone with a PTSD diagnosis has been using a cannabinoid to reduce their symptoms, and they assessed the quality of each study.
They found 10 studies that met their criteria, which cover a range of products including smoked cannabis, THC or CBD separately in oil or pill form, and a synthetic cannabinoid called nabilone.
Every study had medium to high risk of bias and all were assessed as low in quality due to limitations such as small sample size, retrospective study design, lack of a control group or placebo, short follow-up periods, and not reporting other medication use or addiction. Only one study was a randomised controlled trial, investigating nabilone, but it was in a small sample over a relatively short period of time.
The researchers say there are still many unanswered questions about the safety and efficacy of cannabis-based medications for PTSD, and potential long-term effects such as addiction or a risk of psychosis.
The existing evidence shows promise, however, as some studies showed that cannabis products appeared to reduce PTSD symptoms such as insomnia and nightmares.
"Based on the evidence, we cannot yet make any clinical recommendations about using cannabinoids to treat PTSD. Current prescribing of cannabinoids for PTSD is not backed up by high quality evidence, but the findings certainly highlight the need for more research, particularly long-term clinical trials," said the study's senior author, Dr Michael Bloomfield (UCL Psychiatry and the Traumatic Stress Clinic, St Pancras Hospital).
"Many of these studies have been conducted in military veterans, but we also need to be looking at other groups, as PTSD can vary depending on the nature of the trauma so different approaches may benefit different groups," he added.
Dr Hindocha added: "Unfortunately, medicinal uses of cannabis have historically been difficult to study due to legal restrictions, so it could take a long time before there is enough evidence to support clinical recommendations. New approaches are needed to make the most of existing evidence in the meantime."
The study was conducted by researchers at UCL and the University of Amsterdam, and was supported by the National Institute for Health Research UCLH Biomedical Research Centre.
https://www.sciencedaily.com/releases/2019/09/190903194249.htm
Cannabis prevents negative behavioral, physiological effects of traumatic events
September 4, 2014
Science Daily/University of Haifa
Administering synthetic marijuana (cannabinoids) soon after a traumatic event can prevent PTSD-like (post-traumatic stress disorder) symptoms in rats, caused by the trauma and by trauma reminders. This is according to a new study conducted by Nachshon Korem and Irit Akirav of the Department of Psychology at the University of Haifa, which was published in the journal Neuropsychopharmacology. "The importance of this study is that it contributes to the understanding of the brain basis of the positive effect cannabis has on PTSD and thus supports the necessity to perform human trials to examine potential ways to prevent the development of PTSD and anxiety disorders in response to a traumatic event," the researchers noted.
According to the Israel Medical Association approximately nine percent of the population suffers from post-traumatic stress disorder, whereas among at-risk populations such as combat soldiers, prisoners, victims of assault, citizens in lines of confrontation, etc., the percentages are even higher. A common phenomenon among those who suffer from trauma is that exposure to a "trauma reminder" -- an event that is not traumatic in essence but that evokes the memory of the experience of the traumatic event -- can further heighten the negative effects of the trauma. For example, for a person who has developed post-traumatic syndromes as a result of "Color Red" sirens (air raid sirens), a trauma reminder can occur following a loud car alarm.
In previous studies performed by Dr. Irit Akirav, she discovered that the use of cannabinoids within a specific time window after the traumatic event has occurred reduces PTSD symptoms in rats. In this current study, conducted by Dr. Irit Akirav together with the doctoral student Nachshon Korem, the researchers aimed to examine whether the use of cannabinoids may also moderate the effects of trauma in cases of exposure to trauma reminders. The researchers chose rats because of their great physiological similarity to humans in the way they respond to stressful and traumatic events.
During the first half of the experiment, the rats underwent the traumatic event of receiving an electric shock and were exposed to trauma reminders on the third and fifth days of the trial. After the event, and within the time window found in earlier studies, some of the rats were injected with a cannabinoid substance. The rats then went through extinction procedures for trauma (a conditional psychological procedure similar to exposure therapy in humans, the purpose of which is to cope with post-trauma symptoms).
From the findings it became clear that the rats that were injected with the cannabinoid substance showed no PTSD symptoms such as impaired extinction learning, increased startle response, changes in sensitivity to pain and impaired plasticity in the brain's reward center (the nucleus accumbens), compared to those not injected with the drug. The researchers added that the rats that were injected with the drug showed better results compared to rats who received sertraline (an antidepressant of the SSRI group) a substance that is used in the treatment of PTSD with limited success in reducing symptoms. In fact, for some of the symptoms, the rats that were injected with the drug showed similar behavior to rats exposed to trauma but that were not exposed to trauma reminders. In other words -- cannabis made the effects of trauma reminders "disappear."
Once they found the moderating effect of cannabis on behavioral aspects, the study aimed to examine the neurobiological basis for the improvement caused by the drug. It was found that rats who were exposed to trauma and to trauma reminders showed an increase in the expression of two receptors in the brain associated with emotional processing: the CB1 receptor, a receptor in the brain that cannabinoids are known to bind to, and receptor GR, the receptor associated with exposure to stress. On the other hand, in rats that received cannabinoids, the increase in the expression of these two receptors was prevented in the hippocampus and prefrontal cortex, areas involved in forming and saving traumatic memories.
"The findings of our study suggest that the connectivity within the brain's fear circuit changes following trauma, and the administration of cannabinoids prevents this change from happening. This study can lead to future trials in humans regarding possible ways to prevent the development of PTSD and anxiety disorders in response to a traumatic event," the researchers concluded.
https://www.sciencedaily.com/releases/2014/09/140904084252.htm