Weekly Cannabis Science News


Stay up to date with our CBD and medicinal cannabis timeline

By Dr Julie Moltke

October 9

Illegal Cannabis Use Causes Mental Health Problems in Norwegian Young Adults 

A recent study found that cannabis use in young adults was associated with later prescription of antipsychotics, antidepressants and anxiolytics (anti-anxiety)(17). The study was a retrospective, longitudinal study, using data from 2,602 individuals from the "Young In Norway Study".  After adjusting for relevant factors like additional drug use and mental illness, the researcher found that cannabis use was associated with the prescription of antipsychotic and antidepressant drugs as well as medications to treat anxiety.

The above finding might be related to the percentage high THC in illegal cannabis, as researchers have found a link between the amount of THC and the risk of psychosis(18). This might be one of the most persuasive arguments for cannabis legalisation. With a regulated recreative market, the authorities will be able to control the percentage of THC found in the available strains and hopefully prevent the rise in cannabis-related psychosis.

September 25

Study Explores The Effect of CBD on Embryos 

A new study(16) investigates the effects of both synthetic and plant-derived cannabidiol (CBD) on the survival of chick embryos. The different compounds were injected directly into the egg yolk in varying concentrations. After nine days, the growth of the chick embryo was assessed by the Hamburger Hamilton scale to see the effect of the injected cannabinoids. 

The study showed that exposure to both synthetic and plant-derived cannabinoids during the early developmental stages was associated with decreased vitality and viability of chick embryos.

Even though we cannot directly extrapolate data across species, from chicken to human embryo, these data argue against the use of CBD and recreational cannabis during pregnancy. As CBD becomes more of a mainstream health supplement, it is essential to remember that we still lack the evidence of the effects of CBD during pregnancy. At Dosage, we recommend stopping using CBD supplements during pregnancy unless informed otherwise by your doctor. If in doubt, always consult your physician. 

August 28

CBD reduces activity in areas of the brain associated with psychosis

Earlier this month, an interesting randomised controlled trial(15) was published. Several studies have indicated that cannabidiol (CBD) might have an antipsychotic effect, but the exact neurocognitive mechanisms behind these observations are still unknown.

The study investigated 33 people with a clinical high risk for psychosis (CHR), who had never been treated with antipsychotic treatment and compared them with 19 healthy controls. The participants were randomised to 600 mg oral CBD or placebo. During a brain fMRI scan, the participants were submitted to a neutral and a motivational salience condition (reward behavior). Among CHR participants who had received placebo, there was an abnormal activity in a region of the brain called the Insula (associated with psychotic symptoms) when compared to CHR participants who had received CBD and to normal controls.

The authors suggest that CBD’s antipsychotic effect is due to the normalising of motivational salience and moderating of motor response.

August 21

Can cannabis use lower insulin levels in obese with type 2 diabetes?

A new American retrospective study(14) looked at 129,509 adult patients between the age of 18-59, all with type 2 diabetes. The association between fasting insulin levels and marijuana use was estimated for all participants based on their weight category.  

The results showed that in obese with type 2 diabetes, using marijuana as little as four times per month was associated with 52% lower fasting insulin levels. Obese participant who had stopped smoking less than twelve months before, but had smoked cannabis more than eight times per month before quitting, had a reduction in fasting insulin of 47% compared to non-marijuana users. In non-obese, there was not the same association between cannabis use and reduction in fasting insulin levels.  

Fasting insulin is measured to see how the body processes insulin and whether you are becoming insulin resistant. High fasting insulin can be a sign of beginning type 2 diabetes.

August 14

Cannabis might interact with our skeleton

 A new review(13) published earlier this month looks at the role of the endocannabinoids system in bone metabolism.

Endocannabinoid receptors are generally most abundant in the brain, though it is widely acknowledged that we also find CB1 and CB2 receptors in other parts of the body, including bone tissue.

The review is analysing the existing literature, consisting mainly of in vitro (in the laboratory) and animal studies, which shows that the endocannabinoid system is involved in bone metabolism. The effects of endocannabinoids and cannabinoids on bone metabolism is still unclear. Further studies should be conducted to understand this connection as the use of medicinal and recreational use is increasing worldwide. Such studies will also be able to evaluate the role of endocannabinoids as a potential target to help treat disorders associated with bone loss.

August 7

Researchers find that CBD can reduce aggressive behaviour induced by social isolation

A new study published by a team of Brazilian researchers shows that cannabidiol (CBD) can effectively reduce the aggressiveness associated with social isolation in mice (12). The researchers tested several different doses of CBD and all seemed to reduce the number of attacks on other mice by the isolated individual.
The decrease in violent and aggressive behaviour seems to work by activation of 5-HT1A receptors, also known as serotonin receptors, and CB1 receptors, responsible for binding the endocannabinoids and cannabinoids.

These findings are encouraging as both clinical and pre-clinical research has shown that cannabidiol has anxiolytic (anxiety decreasing), antidepressant, and antipsychotic effects.

The results indicate that CBD may be of use in a clinical setting to treat the aggressive behaviour that is often associated with a variety of psychiatric disorders.

July 31

A new study shows that CBD can kill gastric cancer cells 

A team of Chinese researchers has studied cannabidiol (CBD), the second most abundant cannabinoid in the cannabis plant, and the effects on human gastric cancer cells(11).

The study showed that CBD could make human cancer cells stop proliferating and multiplying and thereby arresting tumour growth. The study also showed that CBD could make the cancer cells go into a state of programmed cell death called apoptosis, which in easy words means to "commit cell suicide". Cancer cells are generally characterised by having lost the ability to "commit suicide" leading to abnormal growth.  

These findings are promising and suggest that CBD can help treat gastric cancer, both by stopping tumour growth and inducing cancer cell death.


July 24

A new study explores how cannabis improves gut health

A new research study(6) shows how the acute and long-term administration of tetrahydrocannabinol (THC) can alter important gut metabolite profiles in mice.

The study was conducted to investigate further how the therapeutic effects of THC in the gut works on a cellular level.

The gut protective effects of THC have been documented for several intestinal inflammation processes such as diarrhoea, inflammatory bowel disease (IBD) and abdominal pain(7-8) and can be useful in preventing and improving the accompanying symptoms.

The study shows that lipid (fat) metabolism is being affected by administration of THC, most noticeably the breakdown of glycerophospholipids and the building of fatty acid. The authors note that the above-mentioned metabolic pathway is involved in many health disorders that THC seems to protect against, like Parkinson’s disease(9) and multiple sclerosis(10).

This study gets us a little closer to understanding the real benefits of cannabis. The more we know about the way cannabis works on the pathways in the body, the more efficient we will be at helping patients worldwide.

July 18

Patients enrolled in the Minnesota medicinal cannabis program reported that cannabis helps their PTSD.

A report (5) released Thursday, July 18, by the Minnesota Department of Health shows that 71% of patients with PTSD report a meaningful improvement of symptoms, three months after their first cannabis purchase.

The Minnesota Department of Health surveyed 751 patients who were enrolled in the state’s medicinal cannabis program with PTSD as the qualifying condition.

However, the drop-out rate after three months was 49%, which makes the results somehow questionable.

Minnesota was the 33 state to legalise medicinal cannabis in 2014, and they added PTSD to the list of qualifying conditions in 2016. Patients with PTSD started receiving medical cannabis from August 2017, and as of May 2019, there were 2,873 people with PTSD in Minnesota’s medical cannabis program.

July 10

Researchers have found that CBD has antibiotic properties.

In a new scientific study, a team of Australian scientists have found that Cannabidiol (CBD), the most well-known of the 144 cannabinoids from the cannabis plant, might one day be used as an antibiotic drug. The study was carried out on a specific type of gram-positive bacteria called staphylococcus aureus that is dreaded for its ability to become multi-resistant to antibiotics (MRSA). CBD killed all strains of the bacteria produced in the laboratory, including the most resistant ones that are often difficult to kill with standard antibiotics. This seems promising considering that drug-resistant bacterias are posing a significant threat all over the world. CBD was also shown to combat skin infections in mice.

The findings were presented at the annual conference of the American Society for Microbiology San Francisco, even before being published in a peer-reviewed study. Study leader Mark Blaskovich said that this is only the very early research stages and more studies need to be carried out to make any conclusions. Asked about if you can substitute antibiotics for CBD he answered: "Don't! Most of what we have shown has been done in test tubes—it needs a lot more work to show it would be useful to treat infections in humans."

The results are expected to be published in a peer-reviewed study later this year.

July 2

Cannabis potency has more than doubled in 10 years in Europe.

The European Monitoring Centre for Drugs and Drug Addiction (EMCDDA) has released a report about the development in the European cannabis market. The report outlines the existing and emerging products on the illicit and the legal market in Europe (3). Approximately 1% of the adult European population between 15-64 years uses cannabis daily, and it is estimated that around 17,5 million Europeans between 15-34 years of age have used cannabis in the last year (4). In the report, you can read that the THC levels in both herbal cannabis (flower) and cannabis resin (hash) have increased over the last decade.

Herbal cannabis had an average potency of 5% THC in 2006, and in 2016 it had doubled to 10%. The numbers are similar for cannabis resin with an increase from 8% THC in 2016 to 17% in 2016. This is alarming as adverse mental health effects are associated with higher levels of THC. The report is also stressing the fact that with the emerging European medical cannabis market, and the booming of CBD as a food-supplement the dynamics of the European market are becoming more complex and that we need more assessment tools to monitor the development of the market.

June 17

A new study shows that CBD can help reduce anxiety in psychiatric patients.

A psychiatric clinic has revealed a relatively big retrospective case report where CBD was added as adjunct to the usual treatment to improve anxiety and sleep in 72 patients. Results showed decreased anxiety scores in 80% of the patients after the first month of the study and it remained decreased during the rest of the study period. 67% of patients had decreased anxiety scores after one month even though they fluctuated over time (2).

This study looks promising for CBD as an additional treatment to help psychiatric patients reduce anxiety and improve sleep. We are still lacking clinical trials investigating how CBD works on healthy individuals who are not taking any other medications, but who suffer from insomnia.

June 11

A New study suggests that CBD has no negative long-term effect on learning and memory

A new animal study of long term cannabidiol treatment in mice shows no adverse effect on motor performance, spatial learning and long-term memory. This suggests that there are no measurable side effects of long-term treatment with CBD in mice. We still need to see these findings replicated in human clinical trials, but it does support the common understanding that CBD might be a safe treatment for a variety of conditions in the future (1).



(1) Schleicher, E. M., Ott, F. W., Müller, M., Silcher, B., Sichler, M. E., Löw, M. J. Bouter, Y. (2019). Prolonged Cannabidiol Treatment Lacks on Detrimental Effects on Memory, Motor Performance and Anxiety in C57BL/6J Mice. Frontiers in Behavioral Neuroscience, 13, 94. https://doi.org/10.3389/fnbeh.2019.00094

2) Shannon, S., Lewis, N., Lee, H., & Hughes, S. (2019). Cannabidiol in Anxiety and Sleep: A Large Case Series. The Permanente Journal, 23, 18–041. https://doi.org/10.7812/TPP/18-041

(3) Developments in the European cannabis market, EMCDDA Papers — www.emcdda.europa.eu/publications/emcdda-papers/developments-in-the-european-cannabis-market

(4) European Drug Report 2019 — www.emcdda.europa.eu/edr2019

(5) Post-Traumatic Stress Disorder Patients in the Minnesota Medical Cannabis Program: Experiences of Enrollees During the First Five Months https://www.health.state.mn.us/people/cannabis/docs/about/ptsdreport.pdf

(6) Oza M, Becker W, Gummadidala PM, Dias T, Omebeyinje MH, Chen L, et al. Acute and short-term administrations of delta-9-tetrahydrocannabinol modulate major gut metabolomic regulatory pathways in C57BL/6 mice. Sci Rep [Internet]. 2019 Dec 19 [cited 2019 Jul 24];9(1):10520. Available from: http://www.nature.com/articles/s41598-019-46478-0

(7) Ravikoff Allegretti J, Courtwright A, Lucci M, Korzenik JR, Levine J. Marijuana Use Patterns Among Patients with Inflammatory Bowel Disease. Inflamm Bowel Dis [Internet]. 2013 Dec 1 [cited 2019 Jul 24];19(13):2809–14. Available from: https://academic.oup.com/ibdjournal/article/19/13/2809-2814/4604851

(8) Lal S, Prasad N, Ryan M, Tangri S, Silverberg MS, Gordon A, et al. Cannabis use amongst patients with inflammatory bowel disease. Eur J Gastroenterol Hepatol [Internet]. 2011 Oct 1 [cited 2019 Jul 24];23(10):891–6. Available from: http://www.ncbi.nlm.nih.gov/pubmed/21795981

(9) Nakano N, Matsuda S, Ichimura M, Minami A, Ogino M, Murai T, et al. PI3K/AKT signaling mediated by G protein-coupled receptors is involved in neurodegenerative Parkinson’s disease (Review). Int J Mol Med [Internet]. 2017 Feb 1 [cited 2019 Jul 24];39(2):253–60. Available from: https://www.spandidos-publications.com/10.3892/ijmm.2016.2833

(10) Sättler MB, Merkler D, Maier K, Stadelmann C, Ehrenreich H, Bähr M, et al. Neuroprotective effects and intracellular signaling pathways of erythropoietin in a rat model of multiple sclerosis. Cell Death Differ [Internet]. 2004 Dec 1 [cited 2019 Jul 24];11(S2):S181–92. Available from: http://www.nature.com/articles/4401504

11.        Zhang X, Qin Y, Pan Z, Li M, Liu X, Chen X, et al. Cannabidiol Induces Cell Cycle Arrest and Cell Apoptosis in Human Gastric Cancer SGC-7901 Cells. Biomolecules [Internet]. 2019 Jul 25 [cited 2019 Jul 31];9(8):302. Available from: https://www.mdpi.com/2218-273X/9/8/302

12.  Hartmann A, Lisboa SF, Sonego AB, Coutinho D, Gomes FV, Guimarães FS. Cannabidiol attenuates aggressive behavior induced by social isolation in mice: Involvement of 5-HT1A and CB1 receptors. Prog Neuro-Psychopharmacology Biol Psychiatry [Internet]. 2019 Aug 30 [cited 2019 Aug 7];94:109637. Available from: http://www.ncbi.nlm.nih.gov/pubmed/31054943

13.       Ehrenkranz J, Levine MA. Bones and Joints: The Effects of Cannabinoids on the Skeleton. J Clin Endocrinol Metab [Internet]. 2019 Aug 8 [cited 2019 Aug 14]; Available from: http://www.ncbi.nlm.nih.gov/pubmed/31393556

14.        Ngueta G, Ndjaboue R. Lifetime marijuana use in relation to insulin resistance in lean, overweight, and obese US adults. J Diabetes [Internet]. 2019 Jul 1 [cited 2019 Aug 21];1753-0407.12958. Available from: http://www.ncbi.nlm.nih.gov/pubmed/31152633

15) Wilson R, Bossong MG, Appiah-Kusi E, Petros N, Brammer M, Perez J, et al. Cannabidiol attenuates insular dysfunction during motivational salience processing in subjects at clinical high risk for psychosis. Transl Psychiatry [Internet]. 2019 Dec 22 [cited 2019 Aug 28];9(1):203. Available from: http://www.ncbi.nlm.nih.gov/pubmed/31439831

(16)  Gustafsson SB, Jacobsson SOP. Effects of cannabinoids on the development of chick embryos in ovo. Sci Rep [Internet]. 2019 Dec 17 [cited 2019 Sep 25];9(1):13486. Available from: http://www.ncbi.nlm.nih.gov/pubmed/31530885

(17) Rognli EB, Bramness JG, von Soest T. Cannabis use in early adulthood is prospectively associated with prescriptions of antipsychotics, mood stabilizers and antidepressants. Acta Psychiatr Scand [Internet]. 2019 Sep 27 [cited 2019 Oct 9];acps.13104. Available from: http://www.ncbi.nlm.nih.gov/pubmed/31560790

(18) Ortiz-Medina MB, Perea M, Torales J, Ventriglio A, Vitrani G, Aguilar L, et al. Cannabis consumption and psychosis or schizophrenia development. Int J Soc Psychiatry [Internet]. 2018 Nov 16 [cited 2019 Oct 9];64(7):690–704. Available from: http://www.ncbi.nlm.nih.gov/pubmed/30442059