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Study Summary: Medical Cannabis for Depression in the U.K.

Updated: Jan 5

A January 2023 study entitled "Assessment of Clinical Outcomes of Medicinal Cannabis Therapy for Depression: Analysis From the UK Medical Cannabis Registry" that was published in the journal Expert Review of Neurotherapeutics explored the ability of cannabis-derived cannabinoids to "reduce depressive symptoms" while noting a current "paucity of clinical evidence."

"This study aims to analyze the health-related quality of life changes and safety outcomes in patients prescribed cannabis-based medicinal products (CBMPs) for depression," reported the study's authors.


Understanding Depression

According to the Mayo Clinic, depressiontechnically known as major depressive disorder—is a mood condition that causes a "persistent feeling of sadness and loss of interest." Also called clinical depression, major depressive disorder affects how patients "feel, think, and behave and can lead to a variety of emotional and physical problems."


"Depression may cause noticeable problems in day-to-day activities, such as work, school, social activities, or relationships with others."

The famous clinic reports that those with depression suffer symptoms that are severe enough to cause "noticeable problems in day-to-day activities such as work, school, social activities, or relationships with others," but that the cause of these symptoms may elude them.


Depression Defined

According to the U.S. National Institute of Mental Health (NIMH) (citing the 5th edition of the Diagnostic and Statistical Manual of Mental Disorders [DSM-5]), major depressive disorder involves a minimum period of two weeks during which a person "experiences a depressed mood or loss of interest or pleasure in daily activities and suffers a majority of specified symptoms such as problems with sleep, eating, energy, concentration, or self-worth."


According to the Mayo Clinic, symptoms of depression include the following:

  • Feelings of sadness, tearfulness, emptiness, or hopelessness

  • Angry outbursts, irritability, or frustration—even over small matters

  • Loss of interest or pleasure in most or all normal activities, such as sex, hobbies, or sports

  • Sleep disturbances, including insomnia or sleeping too much

  • Tiredness and lack of energy, so even small tasks take extra effort

  • Reduced appetite and weight loss or increased cravings for food and weight gain

  • Anxiety, agitation, or restlessness

  • Feelings of worthlessness or guilt, fixating on past failures or self-blame

  • Trouble thinking, concentrating, making decisions, and remembering things

  • Frequent or recurrent thoughts of death, suicidal thoughts, suicide attempts, or suicide


Depression Statistics

According to the NIMH, major depressive disorder "is one of the most common mental disorders in the United States." The organization estimates that 21 million adults in the U.S. had "at least one major depressive episode" during 2020, a number that represents more than eight percent of the adult population.


The NIMH observed that major depressive episodes are higher "among adult females (11 percent of the population) compared to males (six percent)" and that young people aged 18-25 suffer depression more than other age groups (at a rate of 17 percent).

According to the U.S. Centers for Disease Control and Prevention (CDC), nearly five percent of those 18 and over suffer "regular feelings of depression." It reports that nearly 11 percent of physician office visits include depression on the medical record. It also notes that more than 11 percent of hospital emergency room visits indicate depression on the official medical record.

Depression is also noted as the leading cause of suicide, with the CDC reporting 46,000 suicides occurring in the United States each year (14 per 100,000 people).


The Study

The study defined depression as "a mental health condition that has been shown to be associated with impaired health-related quality of life (HRQoL)." It reported that there is a need to address HRQoL in those suffering depression "via a holistic mental health approach, including appropriate pharmacological treatments alongside psychological and social measures."


"The study noted problems with conventional antidepressant drugs, including low response rates, no efficacy in those with mild to moderate cases, and a slew of negative effects."

The researchers noted a number of problems with conventional antidepressant pharmaceutical drugs, including low response rates (roughly 50 percent as revealed by one study) and the fact that the efficacy of such commonly prescribed drugs may be limited to those with severe depression, not those with mild to moderate cases of the disorder. Another concern with such pharmaceutical approaches to the treatment of depression is a slew of potential negative side effects.

The study involved 129 patients, all of whom featured a primary diagnosis of major depressive disorder and a mean age of 36. Males constituted 74 percent of study participants, with 26 percent females. Participants consumed cannabiswhat the study dubbed "cannabis-based medicinal products," or CBMPsin a variety of forms, including "sublingual, oral, or vaporized routes of administration."


"Significant percentages of the participants suffered secondary diagnoses, including anxiety (33 percent) and insomnia (six percent)."

"Vaporized dry flower preparations alone were prescribed to 61 patients (47 percent), oral or sublingual oils alone were prescribed to 21 patients (16 percent), and 33 patients (26 percent) were prescribed both," reported the research. Significant percentages of the participants featured secondary diagnoses, including anxiety (33 percent) and insomnia (six percent).


Results

The study found that treatment with CBMPs "was associated with statistically significant improvements in depression," including decreases in anxiety and improvement in sleep. Study participants were surveyed after one, three, and six months of treatment with CBMPs, with improvements noted in depression, anxiety, and sleep after each survey.

"Theories about the antidepressant effects of CBMPs are centered around the actions of the endocannabinoid system [ECS] and its interaction with other systems," reported the study's authors. They noted that activation of CB1 receptors in the prefrontal cortex and hippocampus regions of the braina critical part of the ECShave "been linked to antidepressant effects."


A number of adverse events were noted over the six-month period of CBMP consumption. Overall, 14 percent of the study subjects reported adverse events, the most common of which were fatigue and insomnia.


The research report concluded that "treatment with CBMPs was associated with improvements in depression after one, three, and six months of treatment."

Conclusions

The research report concluded that "treatment with CBMPs was associated with improvements in depression after one, three, and six months of treatment" in patients who suffered major depressive disorder in the United Kingdom. It found that cannabis use among those suffering severe depression was associated with "improvements in anxiety, sleep quality, and overall HRQoL."


Summarized the scientists: "This suggests that CBMPs could have antidepressant effects, although the limitations of the study design mean that a causal relationship cannot be proven."


View the original study.


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