Think Cannabis is Harmless? So Did I. But I Know Better Now

Opinion: In 2017, 567 people were treated at Vancouver-area

hospitals for cannabis overdoses or related mental issues.

I was one of them.

The emergency entrance at St. Paul's Hospital in Vancouver is seen in a file photo from June 24, 2009.

Ian Lindsay/Postmedia

By Jennifer Foden, National Post

Last year, shortly before cannabis was legalized, StarMetro Vancouver reported that in 2017, 567 people were admitted to emergency rooms at St. Paul’s, Vancouver General, Surrey Memorial and Kelowna General hospitals for cannabis overdoses or related mental and behavioural issues.

I was one of them.

This isn’t easy to write about. I’m well aware that this will be part of my story forever, for anyone to look up online. Still, people need to know the risks.

In mid-2017, on a typical Saturday night, two friends and I were cooking dinner. A friend offered me half a medical marijuana gummy. She took the other half. About 45 minutes later, I started to feel strange. It’s hard to explain how. I had had bad experiences with weed before. This felt similar; like I knew something very bad was about to happen.

People need to know the risks

I decided to go home. I, still, to this day, don’t know what actually happened that night and what didn’t. I was totally disconnected from reality. I was hallucinating, dreaming while awake. Welcome to a weed overdose, friends — a drug-induced psychosis.

I remember walking down the street, not being able to swallow. Falling down. Laying face-first on Robson Street in downtown Vancouver yelling at people driving and walking by that I was dying. I remember the paramedics kicking me out of the ambulance. I remember dead people being wheeled past me in the emergency room at St. Paul’s. But I’m not entirely sure if any of these things happened.

I didn’t know my name or who I was or where I was or what it even means to be human and have a body and a brain. I didn’t understand time or space, life or death. It was very metaphysical.

Recreational marijuana became legal in Canada on Oct. 17, 2018. Trevor Hagan/Bloomberg

My friend, who ate the other half of the gummy, showed up to hold my hand in the hospital. She was high, but fine. She wasn’t having an adverse reaction like I was.

I started feeling strange after that “bad trip.” Unlike before, my brain was filled with thoughts of suicide, death and existential questions. I attempted to push the thoughts out of my mind, assuming it was the after-effect of that little green drug.

Six weeks after that drug trip, I had nervous breakdown. I was sitting at my desk when suddenly, something felt different, something felt off. I felt uncomfortable in my body. My heart started racing. I began to think a lot about existence. I felt disconnected. Like my mind and my body had separated. Like I was living in an altered reality. I thought I was losing my mind, or perhaps I was dying. The worst part? I wanted to die.

The worst part? I wanted to die

   

I wound up in the emergency room and then a mental health facility. Further psychiatric assessment would tell me I was suffering from panic and residual drug-induced psychotic disorders. Later, I’d have symptoms of post-traumatic stress disorder.

It’s been almost a year and a half since the drug trip. I continue to suffer from panic attacks. And, every single day, I still feel disconnected, like my mind and my body have separated, like I’m living in an altered reality. Some days are worse than others.

For some reason, I feel compelled to clarify that up until this point — for over 30 years — I was mentally stable. I have the privilege of white skin, a middle-class upbringing, great friends, a university degree and a post-grad education, too. I’ve held staff editor jobs. I’ve freelanced successfully. There were no red flags for my mental health.

There were no red flags for my mental health

   

A recent report claimed that a bad drug trip can be a sign of mental illness — not as a cause, but as a trigger. I’ve spent a lot of the past year and a half feeling guilty. Like I caused my mental illness by eating that weed gummy. But how could I have known? I have smoked and eaten weed before, sometimes with adverse effects. But the end result has never been multiple mental illnesses: panic, post-traumatic stress and residual drug-induced psychotic disorders. Maybe it was the perfect storm: I ate the right amount of the right strain at a time when I was stressed, and therefore vulnerable to a breakdown.

This is not a pity party. I don’t want you to feel bad for me. I’m telling this story because I think it’s important for people to realize that although cannabis has a reputation as being safe and benign, that’s not always the case. As my psychiatrist likes to remind me: people’s minds and bodies are different, and have varying reactions to drugs, to alcohol, to stress.

I’m still going through the process of healing. For people who haven’t been through something similar: be careful. It’s been reported that the current endorsed guidelines to prevent mental illness risk from marijuana consumption is to use less, use lower levels of THC or abstain. But, talk to your friends. Share this story. So, I guess this article is a PSA: don’t be number 568.

— Originally from Toronto, Jennifer Foden is a freelance writer and editor living in Vancouver.

Jennifer appears to be in her 30s as she recovers from her nightmarish experience. I'm not convinced that you need a predilection toward mental illness to be triggered by cannabis. I am aware, especially of teenagers who have protracted severe schizophrenia and paranoia from using pot, and like Jennifer, had no indicators of mental illness whatsoever.

I hope Coastal and Fraser Health keep detailed records on people who end up in ERs because of cannabis related issues. We have much to learn about this insidious experiment that our Very Liberal government has hastily inflicted upon Canadian society.

Cannabis, Even Medical Cannabis Could Be Much Worse Than Thalidomide - Medical Journal

Medical cannabis on the NHS

This article from a prestigious medical journal is written for medical professionals with terms that most of us

will not understand. I have highlighted a several points so you don't have to read every word.

BMJ - British Medical Journal
doi: https://doi.org/10.1136/bmj.k335

Known Cannabis Teratogenicity (Birth Defects) Needs to be Carefully Considered

It is no accident that in almost the same week both Australia and UK have decided that cannabis is to be recommended for a host of medical disorders mostly in advance of gold standard clinical trials. This is a direct product of the organized transnational global drug liberalization movement orchestrated from New York 1.

I wish to most respectfully disagree with the points made by BMJ editor Dr. Godlee. Diarrhoea and colic occur in cannabis withdrawal; Crohn’s disease has a prominent immune aspect, and cannabinoids are likely acting partly as immune modulators. Statements from patients are uninterpretable without understanding the treatments tried, their withdrawal symptomatology and their personal preferences.

Most importantly, as Dr Godlee states, cannabis is a mixture of 104 cannabinoids. The tide cannot be both out and in at the same time. Medicines in western nations are universally pure substances. This comprises a fundamental difficulty.

Medical research has confirmed that the body’s endocannabinoid system is a finely regulated and highly complex system which is involved in the detailed regulation of essentially all body systems including the brain and cardiovascular systems and stem cell niches.

Studies have shown that the rate of use of cannabis by expecting mothers closely parallels that in the wider community. In fact given the long half-life of cannabis in tissues even were a maternal habitual smoker to stop when she discovered her pregnancy, her infant would continue to be exposed to her on-board cannabinoid load for several months afterwards during critical periods of organogenesis. And other studies show that the father’s cannabis use is even more damaging than the mothers’ 2.

Studies show that the father’s cannabis use

is even more damaging than the mothers’

Whilst much research has focussed on the effects of endocannabinoids in the adult brain relatively little research has looked at the impact of these same effects in the developing brain of the foetus and neonate. Whilst the brain stem is almost devoid of type 1 cannabinoid receptors (CB1Rs) they are in high concentration in many parts of the midbrain, limbic system, subcortical regions and cerebral and cerebellar cortices 3. Foetal CB1Rs have been shown to play key roles in virtually all aspects of brain development including neural stem cell function, determining the ratio of glial v neuronal differentiation, brain inflammation, axonal growth cone guidance, stem cell niche function and signalling, blood flow signalling, white matter and CNS tract formation, glial cell differentiation, myelination, dendrite formation, neural migration into the developing cortex, synapse formation and integration of newly formed neurons into the neural network. They are also found in high density on endoplasmic reticulum and mitochondria from which latter they indirectly control major issues including cognition, DNA maintenance and repair systems both by supplying energy and by metabolite shuttle and RNA signalling 4 5.

Hence it is not surprising that gestational cannabis has been linked with a clear continuum of defects, including in protracted longitudinal studies from Pittsburgh, Ottawa and Netherlands impaired cortical and executive functioning; reduced spatial judgement; the need to recruit more brain to perform similar computational tasks 6; microcephaly 7; lifelong smaller heads and smaller brains 6; anencephaly (in two CDC studies 8), and increased foetal death. This progression clearly reflects a spectrum of congenital neurological impairment which is quite consistent with the known distribution of CB1Rs mainly across the foetal and adult forebrain and midbrain and its derivatives 3.

Consistent with a recent explosion of autism

It is also consistent with a recent explosion of autism in Colorado, California, New Jersey and many other sites in USA and internationally in recent years 9. Moreover cannabis induced synpatopathy closely mimics that seen in autism 10 11, as do similar white matter disconnection endophenotypes 3 12.

A similar scenario plays out in the cardiovasculature. The American Heart Association and American Academy of Pediatrics issued a joint statement as long ago as 2007 noting that foetal cannabis exposure was linked with increased rates of ventricular septal defect and Ebstein's anomaly (complex tricuspid valvopathy) 13. This is consistent with recent Colorado experience where ventricular septal defect has risen from 43.9 to 59.4 / 10,000 live births, or 35.3% 2000-2013. Both of these structures are derivatives of the endocardial cushions which are rich in CB1Rs. Concerningly Colorado has also seen a 262% rise in atrial septal defects over the same period. Exposure to other drugs does not explain this change as they were falling across this period. It has also been reported that the father’s use of cannabis is the strongest environmental factor implicated in cardiovascular defects, here involving transposition of the great arteries 2, which is a derivative of the conoventricular ridges immediately distal and continuous with embryonic endocardial cushions, and also rich in CB1Rs.

Similar findings play out in gastroschisis (a birth defect of the abdominal (belly) wall. The baby's intestines are found outside of the baby's body, exiting through a hole beside the belly button). There is an impressive concordance amongst the larger studies of the relationship of gastroschisis and congenital cannabis exposure where senior Canadian authors concluded that cannabis caused a three-fold rise in gastroschisis 14, consistent with a high density of CB1Rs on the umbilical vessels 15.

A 3-fold increase in babies born

with their intestines outside of their bellies.

And cannabis has also been implicated as an indirect chromosomal clastogen and indirect genotoxin through its effect to disrupt the mitotic spindle by microtubule inhibition 16, and likely DNA maintenance and repair 17 by its effect on nuclear actin filaments 18.

Moreover cannabidiol has been shown to alter the epigenome, to be genotoxic, and to bind to CB1Rs at high doses, so the simplistic case that “Cannabidiol is good” – fails.

The simplistic case that “Cannabidiol is good” – fails

These considerations imply that if clinical trials continue to show efficacy for additional indications for cannabinoids, their genotoxic and teratogenic potential, from both mother and father, will need to be carefully balanced with their clinical utility. They also imply that these issues will need to be more widely canvassed and discussed in order to introduce more balance into the heavily biased present global media coverage of the highly misleading misnomer “medical cannabis”.

Only once before has a known teratogen been marketed globally: 

thalidomide

Only once before has a known teratogen been marketed globally: the thalidomide disaster is the proximate reason for modern pharmaceutical laws. With its widespread uptake, rising concentrations, asymptotic genotoxic dose-response curves and actions through the paternal line cannabis could be much worse.

References

1. Open Society Foundations. Open Society Foundations New York: Open Society Foundations; 2018 [cited 2018 4th August 2018]. Available from: https://www.opensocietyfoundations.org/ accessed 4th August 2018 2018.

2. Wilson PD, Loffredo CA, Correa-Villasenor A, et al. Attributable fraction for cardiac malformations. Am J Epidemiol 1998;148(5):414-23.

3. Yang Q, Huang P, Li C, et al. Mapping alterations of gray matter volume and white matter integrity in children with autism spectrum disorder: evidence from fMRI findings. Neuroreport 2018 doi: 10.1097/WNR.0000000000001094

4. Hebert-Chatelain E, Desprez T, Serrat R, et al. A cannabinoid link between mitochondria and memory. Nature 2016;539(7630):555-59. doi: 10.1038/nature20127

5. Yates D. Learning and memory: The cannabinoid connection. Nat Rev Neurosci 2016;18(1):4. doi: 10.1038/nrn.2016.171

6. Brents L. Correlates and consequences of Prenatal Cannabis Exposure (PCE): Identifying and Characterizing Vulnerable Maternal Populations and Determining Outcomes in Exposed Offspring In: Preedy V.R., ed. Handbook of Cannabis and Related Pathologies: Biology, Pharmacology, Diagnosis and Treatment. London: Academic Press 2017:160-70.

7. Forrester MB, Merz RD. Risk of selected birth defects with prenatal illicit drug use, Hawaii, 1986-2002. Journal of toxicology and environmental health 2007;70(1):7-18.

8. Van Gelder MMHJ, Donders ART, Devine O, et al. Using bayesian models to assess the effects of under-reporting of cannabis use on the association with birth defects, national birth defects prevention study, 1997-2005. Paediatric and perinatal epidemiology 2014;28(5):424-33. doi: 10.1111/ppe.12140

9. Christensen DL, Baio J, Van Naarden Braun K, et al. Prevalence and Characteristics of Autism Spectrum Disorder Among Children Aged 8 Years--Autism and Developmental Disabilities Monitoring Network, 11 Sites, United States, 2012. MMWR Surveill Summ 2016;65(3):1-23. doi: 10.15585/mmwr.ss6503a1

10. Anderson GR, Aoto J, Tabuchi K, et al. beta-Neurexins Control Neural Circuits by Regulating Synaptic Endocannabinoid Signaling. Cell 2015;162(3):593-606. doi: 10.1016/j.cell.2015.06.056

11. Won H, Mah W, Kim E. Autism spectrum disorder causes, mechanisms, and treatments: focus on neuronal synapses. Front Mol Neurosci 2013;6:19. doi: 10.3389/fnmol.2013.00019

12. Zalesky A, Solowij N, Yucel M, et al. Effect of long-term cannabis use on axonal fibre connectivity. Brain 2012;135(Pt 7):2245-55. doi: aws136 [pii]

10.1093/brain/aws136 [published Online First: 2012/06/07]

13. Jenkins KJ, Correa A, Feinstein JA, et al. Noninherited risk factors and congenital cardiovascular defects: current knowledge: a scientific statement from the American Heart Association Council on Cardiovascular Disease in the Young: endorsed by the American Academy of Pediatrics. Circulation 2007;115(23):2995-3014. doi: 10.1161/CIRCULATIONAHA.106.183216

14. Moore A., Roulean J., Skarsgard E. Congenital Anomalies in Canada, 2013. A Perinatal Health Surveillance Report. Chapter 7. Gastroschisis.

. In: Public Health Agency of Canada HC, ed. Ottawa: Health Canada, 2013:57-63.

15. Pacher P, Steffens S, Hasko G, et al. Cardiovascular effects of marijuana and synthetic cannabinoids: the good, the bad, and the ugly. Nat Rev Cardiol 2018;15(3):151-66. doi: 10.1038/nrcardio.2017.130

16. Reece AS, Hulse GK. Chromothripsis and epigenomics complete causality criteria for cannabis- and addiction-connected carcinogenicity, congenital toxicity and heritable genotoxicity. Mutat Res 2016;789:15-25. doi: 10.1016/j.mrfmmm.2016.05.002

17. Caridi CP, D'Agostino C, Ryu T, et al. Nuclear F-actin and myosins drive relocalization of heterochromatic breaks. Nature 2018;559(7712):54-60. doi: 10.1038/s41586-018-0242-8

18. Wang J, Yuan W, Li MD. Genes and pathways co-associated with the exposure to multiple drugs of abuse, including alcohol, amphetamine/methamphetamine, cocaine, marijuana, morphine, and/or nicotine: a review of proteomics analyses. Molecular neurobiology 2011;44(3):269-86. doi: 10.1007/s12035-011-8202-4

Dutch PM Warns Canadians Against Sparking Up

Mark Rutte is not my favourite person. His government is far-left, though not as far as Trudeau's. He, like other far-left governments in parts of the EU are putting their own women and children at risk by hiding the disastrous atrocities committed by migrants, in the name of political correctness. He also supported Islamic brigades in Syria that supported ISIS. So, no, I don't like Mark Rutte, but what he has to say about cannabis makes sense and comes from a country with 40 years of experience.

Dutch PM Mark Rutte and some cannabis at a dispensary in Ottawa, Canada

© (L) Reuters / Aris Oikonomou ; (R) Reuters / Chris Wattie

Canadians had barely enjoyed legal marijuana for even a fortnight when they received high-level advice against using it, from the unlikeliest of people: the prime minister of the Netherlands.

Mark Rutte’s warnings came on his Thursday visit to Canada, just over a week after its much-anticipated cannabis legalization. He and Canadian PM Justin Trudeau were talking pot use in front of a young audience in Ottawa.

The best policy on drugs for yourself is 'no first use.'

It sounds conservative, but I would urge you:

Don't try at all.

That, coming from the prime minister of a country where buying and using marijuana in designated spaces has been legal for over 40 years. Many of Amsterdam's five million annual tourists specifically flock to its "coffee shops" to spark up or eat pot edibles without fearing the long arm of the law.

One of the problems with today's cannabis is that it's

"so much stronger than when we were young,"

Naturally, young Canadians were interested in Rutte's experience – but didn't get the endorsement they perhaps expected. One of the problems with today's cannabis is that it's "so much stronger than when we were young," Rutte said. He then mentioned his friends' children who were having mental health problems from its use.

He then mentioned his friends' children

who were having mental health problems from its use.

“At least make sure that you don't move from this stuff to other drugs,” Rutte added, perhaps acknowledging that his advice may fall on deaf ears.

Canada is only the second country after Uruguay, and the first of the G20 countries, to fully legalize the growing, selling, and consumption of cannabis, with Trudeau saying the laws removed the “contact that people had with criminals.”

Despite his misgivings about cannabis use, Rutte said the Netherlands too were looking at potential reforms to their own laws, saying coffee shops now have no way of getting the product legally. He added a pilot project was now underway in 10 Dutch cities to fix that.

Like I said!

Saskatchewan Dad Charged After Son Suffers Seizures from Eating Marijuana Cookies

Edible marijuana products on display at medical marijuana dispensary in Denver

Children who consume food containing marijuana are at serious risk, according to a Regina consultant on drug and alcohol addictions.

Rand Teed, from Regina, says the effects of marijuana on children can be damaging.

"It's very harmful to kids, no matter how you do it," Teed said.

"An overdose causes anxiety, panic attacks. It can cause hallucinations," he added. "[For] a little kid, if that kind of stuff starts to happen to them, they're going to have no idea what's going to go on. So that becomes very frightening."

Rand Teed, a Regina-based consultant on drug and alcohol addictions, warns
that  eating marijuana-laced cookies can easily lead to an overdose for a child

Teed's observation follows a report from Swift Current RCMP that a toddler suffered seizures and spent two days in intensive care in January after eating cookies made with marijuana.

RCMP said the 20-month-old boy survived and the father is facing charges.

Teed noted that cookies made with marijuana taste like regular cookies.

"So you can eat yourself into an overdose situation before you even realize that there's anything happening," Teed said..

The effects of the marijuana can harm brain development, he said.

"Kids that ... use it accidentally are risking changing how their brain is going to develop," he said. "It can cause comas and seizures."

Teed said marijuana could be compared to alcohol when it comes to keeping it away from children.

"You wouldn't leave a glass of alcohol where a toddler get it and drink it because we know that it is toxic," he said. "And marijuana is equally toxic, but in a different way."

RCMP did not provide details on how the Swift Current youngster came to ingest the marijuana cookies beyond stating the toddler "was given access to the cookies."

Last fall, an elementary student brought marijuana cookies to school and shared them with classmates.

RCMP in Dawson Creek, British Columbia, are investigating an incident in which a child brought cookies suspected of containing drugs to a local elementary school, and then shared them with classmates.

Officials with the Peace River South School District confirm the incident happened at École Frank Ross at the end of October, but are saying little else, refusing to confirm how many students ate the cookies in question, or whether any of them became ill as a result.

Police, however, admitted that several children were made sick and had to be taken home.

'Skunk-Like Cannabis' Increases Risk of Psychosis by 3 to 5 Times

Former skunk user Liaquat Zaman: "It brought me to a very dark place in my life"

Smoking potent cannabis was linked to 24% of new psychosis cases analysed in a study by King's College London.

The research suggests the risk of psychosis is three times higher for users of potent "skunk-like" cannabis than for non-users.

The study of 780 people was carried out by KCL's Institute of Psychiatry, Psychology and Neuroscience.

A Home Office spokesman said the report underlines the reasons why cannabis is illegal.

Scientists found the risk of psychosis was five times higher for those who use it every day compared with non-users.

They also concluded the use of hash, a milder form of the drug, was not associated with increased risk of psychosis.

Psychosis refers to delusions or hallucinations that can be present in certain psychiatric conditions such as schizophrenia and bipolar disorder.

Risk increased 'threefold'
"Compared with those who had never tried cannabis, users of high potency skunk-like cannabis had a threefold increase in risk of psychosis,' said Dr Marta Di Forti, lead author on the research.

She added: "The results show that psychosis risk in cannabis users depends on both the frequency of use and cannabis potency."

Dr Di Forti told BBC Radio 4's Today programme that the availability of skunk-like cannabis was becoming more widespread.

'I was a wreck'
Cath from Berkshire, who asked to remain anonymous, believes smoking skunk caused her to experience mental health problems.

"I dabbled with a friends' group in my early 20s, and went from someone who had never experienced any mental health issues whatsoever, to an absolute wreck.

"I was terrified of leaving the house, and I became petrified of death, of the mysteries of the universe, and of being alone. You name it, I was terrified of it.

"It took about six years to feel normal again and now, almost 20 years later, I have absolutely no doubt that my issues were triggered by casually and naively smoking this so called 'soft' drug.

"For years I have shuddered as campaigners have sought to declassify or promote the product as I understand first-hand the hidden yet, until now, unspoken dangers of this awful drug."

"In London, it's very difficult to find anything else," Dr Di Forti said.

"There were lots of reports from police across the UK saying we have become a great producer of skunk. And not only do we use it locally but we export, so this is a Made in England product."

Someone suffering from psychosis would often be "extremely paranoid and become very suspicious" about the people around them, she added.

She has called for "a clear public message" to cannabis users, comparable to medical advice on alcohol and tobacco.

GPs should be encouraged to ask how often and what type of cannabis patients use, she added,

A Home Office spokesman said the findings backed up the government's approach: "Drugs such as cannabis are illegal because scientific and medical evidence demonstrates they are harmful.

"This report serves to emphasise how they can destroy lives and communities."

'Without risk'
Skunk contains more THC - the main psychoactive ingredient - than other types of cannabis.

Unlike skunk, hashish - cannabis resin - contains substantial quantities of another chemical called cannabidiol or CBD and research suggests this can act as an antidote to the THC, counteracting psychotic side effects.

Sir Robin Murray, professor of psychiatric research at King's, commented: "This paper suggests that we could prevent almost one quarter of cases of psychosis if no-one smoked high potency cannabis.

"This could save young patients a lot of suffering and the NHS a lot of money."

The research was carried out over several years, comparing 410 patients aged 18-65 who reported a first episode of psychosis at a south London psychiatric hospital with 370 healthy participants within the same age range from the same area of London.

It will be published later this week in the Lancet Psychiatry.

Rosanna O'Connor, director of alcohol, drugs and tobacco at Public Health England, responded: "No drug use is without risk as this report demonstrates.

"Anyone having problems with drug use should seek help from their local specialist drug services. It is important to remember that treatment for all types of drug problems, including cannabis, are readily available and very effective".

Cannabis user Robert, from Hertfordshire experienced a "temporary psychosis" after taking home-grown cannabis in his 20s.

"It was utterly terrifying, and the worst night of my life," he told the BBC News website.

"As someone affected by this issue it is hard watching mainstream media, particularly comedy films, portraying cannabis as a harmless life-enhancing substance with limited ill-effects - it's simply not true."

Another person who contacted the BBC website felt that legalising cannabis would allow varieties to be regulated.

Phil, from Cambridgeshire, said: "Speaking as a 'toker' for past 25 years, super skunk is the term they should be using.

"The cause of all this is the illegality. If things were more open and informed, people could buy 'saner' variety seeds."

Yes, people 'could' buy 'saner' seeds, but would they? I doubt it very much. If there was a demand for less potent marijuana, it would dominate the market, but it doesn't. Users want the maximum impact from the drug.

Skunk, has been reclassified as a hard-drug in Holland where pot is legal.

See, Playing Russian Roulette with Your Sanity, for more info and several more links.

‘Significant Link’ Between Cannabis Use and Onset of Mania Symptoms

YES, VIRGINIA, SMOKING POT CAN DRIVE YOU CRAZY

Researchers from the University of Warwick have found evidence to suggest a significant relationship between cannabis use and the onset and exacerbation of mania symptoms.

In a paper published in the Journal of Affective Disorders, mental health researchers from Warwick Medical School carried out a review of scientific literature examining the effect of cannabis use. The literature sampled 2,391 individuals who had experienced mania symptoms.

Mania symptoms are part of bipolar disorder and can include feelings of persistent elation, heightened energy and hyperactivity and a reduced need for sleep. Mania can also make people feel angry and aggressive with extreme symptoms including becoming delusional or hearing voices.

Lead author Dr Steven Marwaha said: “Previously it has been unclear whether cannabis use predates manic episodes. We wanted to answer two questions – does cannabis use lead to increased occurrence of mania symptoms or manic episodes in individuals with pre-existing bipolar disorder? But also, does cannabis use increase the risk of onset of mania symptoms in those without pre-existing bipolar disorder?”

The researchers looked at a number of previous studies and concluded that cannabis use preceded the onset of mania symptoms.

Dr Marwaha said: “The observed tendency for cannabis use to precede or coincide with rather than follow mania symptoms, and the more specific association between cannabis use and new onset manic symptoms, suggests potential causal influences from cannabis use to the development of mania. It is a significant link.”

The University of Warwick is in Coventry in central England

Dr Marwaha also said the review suggested that cannabis use significantly worsened mania symptoms in people who had previously been diagnosed with bipolar disorder.

He added: “There are limited studies addressing the association of cannabis use and manic symptoms, which suggests this is a relatively neglected clinical issue. However our review suggests that cannabis use is a major clinical problem occurring early in the evolving course of bipolar disorder. More research is needed to consider specific pathways from cannabis use to mania and how these may be effected by genetic vulnerability and environmental risk factors.

“Cannabis is the most prevalent drug used by the under-18s and during this critical period of development services should be especially aware of and responsive to the problems that cannabis use can cause for adolescent populations.