Post Traumatic Stress Disorder,
or PTSD, is a prevalent, chronic,
and disabling psychiatric condition that
may develop following exposure to a traumatic event.
If left untreated, the condition may persist for years.
PTSD patients often re-experience their traumatic event and display avoidance behavior,
emotional numbness, concentration problems, anger,
irritability, hypervigilance, and suffer from insomnia.
Treatment consists of psychotherapy and pharmacological intervention,
but outcomes are often disappointing.
It's interesting to point out that several lines
of evidence point to possible involvement of
the endocannabinoid system and
particularly the CB1 receptors in the development and maintenance of PTSD.
A recent review on PTSD and marijuana found no less than 46 articles
directly addressing the question of efficacy of medical marijuana on PTSD symptoms.
Lack of randomized controlled trials was also noted.
Since most of these reports are observational in nature,
they suggest a decrease in symptoms such as anxiety and insomnia,
and affirm improved coping with marijuana use.
On the flip side,
increase incidence of cannabis use disorders among
adults with PTSD was noted in a number of these reports.
We'll talk more about cannabis use disorder in our next model.
While cannabis may help PTSD patients,
it has been shown that
even temporary discontinuation can lead to withdrawal and aggravate PTSD symptoms.
This also generates cannabis addiction.
Despite these observations, medical cannabis has been
approved for the treatment of PTSD in certain countries.
Physicians are advised to use their own clinical judgment when weighting
their potential risks and benefits of
such a treatment for the patients on a case by case basis.
Depression and chronic pain are tightly linked and
likely share some of the same neurobiological mechanisms.
Indeed, as we have mentioned earlier in this course,
antidepressants can reduce certain types of pain.
Given the large interest in cannabis for pain intervention,
we naturally wonder if it can affect depression as well.
Studies have shown a bi-directional effect of marijuana on depression.
On the one hand,
studies on patients with chronic pain
demonstrated positive effect of medical cannabis on mood.
Cannabis had the same effect on PTSD and other conditions as well.
That said, given the coexistence of these conditions with depression,
it is difficult to say if medical cannabis improves mood by relieving
other symptoms or if it has a direct independent effect on depression.
On the other hand,
cannabis use, and especially early onset use,
that is used in youth under the age 17,
has shown an association with later onset of depression.
A 2010 epidemiologic study gathered data from some 85,000 subjects from
17 countries participating in
a population-based WHO World Mental Health Survey Initiative.
After controlling for confounding factors,
such as tobacco use and other mental health problems,
the study showed a 1.5 increase in the risk for
developing depression among marijuana users compared to non-users.
This is considered a modest effect,
but it was statistically significant and showed no gender differences.
These results are further supported by another study published in 2015 where
an association was found between early onset of
cannabis use and the early onset of Bipolar Affective Disorder,
also known as Manic Depressive Disorder, and suicide attempts.
Bipolar Disorder, by the way,
is associated with poor health outcome and is responsible for
the highest rate of suicide among all mental disorders.
We can conclude by saying that research points to
a clear link between early cannabis use and later mental health problems,
possibly in those with genetic vulnerability,
and that there is a particular issue in the use of cannabis by children and adolescents.
Elon EisenbergProfessor of Neurology and Pain Medicine
