Huge numbers of news sources are reporting on recent neuroscience studies that have linked the effect of cannabis on the brain to the development of psychosis.
The excitement is because the 2nd International Cannabis and Mental Health Conference is currently under way in London where scientists from around the world are presenting the latest research on the effects of cannabis.
Luckily, the conference programme and summaries for all the research presented are available online as a pdf file, so you can get a more accurate idea of what the studies have found.
It is now clear that cannabis increases the risk of psychosis in some people who have a family history of psychosis and / or certain versions of the COMT gene.
However, the main thrust of the news stories is that even a single dose of THC, the main ingredient in cannabis that causes the ‘high’, can trigger psychotic symptoms.
A study by Dr Cyril D’Souza noted that:
Δ-9-THC produced schizophrenia-like positive and negative symptoms, altered perception, increased anxiety, produced euphoria, disrupted immediate and delayed word recall, impaired performance on tests of attention and working memory without impairing orientation.
The difficulty is that just because something seems to cause similar effects to psychosis, it doesn’t necessarily mean it is strongly linked to it.
For example, a dose of alcohol can ‘produce’ similar symptoms to Alzheimer’s disease – loss of memory, disorientation, mood swings, aggression and so on – but that isn’t a good basis to say that the alcohol is doing the same thing in the short-term as the degenerative brain disorder does in the long-term.
More convincing are the results from the cognitive tests: impairment in immediate and delayed recall, attention and working memory without impairing orientation.
This is because the subjective effects of both cannabis and psychosis are, well subjective, but the cognitive effects are measurable with controlled neuropsychological tests.
One particularly interesting study from Dr Cecile Henquet found that when compared to controls, patients experienced a greater increase in psychotic experience after taking THC, but also had a greater improvement in their mood.
This might explain why people with psychosis will often continue smoking cannabis even when they know it causes their mental state to deteriorate.
Another fascinating finding, is that as well as containing the possibly psychosis increasing THC, cannabis also seems to contain an antipsychotic called cannabidiol or CBD.
One study presented by Prof Markus Leweke found that purified CBD had a beneficial effect equal to amisulpride, a widely used pharmaceutical antipsychotic medication.
If you’re interested in finding out more about the cutting-edge of cannabis research the surprisingly readable conference programme is well worth checking out.
Link to conference programme and research summaries.
Mind Hacks 
Authorities in white coats are bandying around “psychosis” and pointing at a drug. Hmm? Do you think this might be the type of thing that would involve brain scans and speeches at the United Nations? The research presentation is being used politically and looks designed as a justification for various prohibitionary legal actions.
There are people who have a panic response from using cannabis, I’ve observed it many times. I have to ask:
Why doesn’t it happen every time?
Could set and setting be an issue here?
Has the subject used other drugs, and had similar reactions? It seems to be the most prevalent factor, so I suspect a conditioned response from a traumatic experience.
I dissagree with the blanket psychosis label. They do seem to be able to make basic rational decisions, and avoid dangerous situations.
Well, since I’m unlike Bill Clinton and inhaled, I can remember marijuana increasing a sense of paranoia in my brain at certain times.
I think the previous commenter makes an interesting point. Even if it is true that marijuana increases psychosis in some people, what should society do about it?
I am a believer that marijuana increases symptoms of pyschosis in certain people depending on genetic predispositions and environmental factors. Some people experience extreme anxiety while it puts to rest other’s anxiety issues. I feel that marijuana brings alive a certain social disorder that is able to be masked by the sober state in some individuals; social anxiety and paranoia being the main offenders of this issue. However, in others, a sober state is a world of anxiety and uncomfort and therefore the marijuana is able to reverse the effects of this. So we see a varied individual reaction in “smoking up.” It is clearly connected to the brains ability to produce certain chemicals which is in turn related to the individual’s abilty to respond to particular social stimuli.
Whomever you are KAT, I one hundred percent agree. I recently quit after smoking for at least 10 years on and off. Everyone I know smokes and the effects on the individual vary. Knowing my friends normal state of mind, personality etc. I completely agree with your comment! I also believe THC has the ability to alter a person psychosis, with an untreated mental illness. Post exposure can make condition worse, and may even cause mental, social and emotional problems of heavy users later in life causing them to continue use. A person who smokes marijuana connects social aspects of their life to the drug causing them to continue use based on the fact that they can’t have fun without it. It can cause severe sinus infections and headaches ( I know because I personally, tested it. Marijuana is harmful and the people say that it never killed anyone just don’t know. It is so often used in combination with alcohol or other drugs that studies can not differentiate. Not only can it kill like cigarettes but you are definitely more likely to have unprotected sex with whomever while using it because it makes you horny. When your judgment is impaired by anything bad things can happen and poor choices can be made.
In a quick response to jeneves comment-
I’ve experienced similar effects from smoking pot on and off for about 12 years. It used to give me such a great high where i was energized, creative and exciting. Now it makes me socially awkward and brings about panic attacks and supreme anxiety. it totally sucks.
BUT, i TOTALLY DISAGREE, jeneves, about your comment on how “you are definitely more likely to have unprotected sex with whomever while using it because it makes you horny”.
Thats crap. And completely false. Maybe it does that to you, but first off, i don’t become this sex-crazed maniac who throws all her values and responsibilities to the wind, and has unprotected sex just because I have THC in my system.
Don’t generalize such a ridiculous statement and make it universal.
Speak for yourself.
Thanks.
marijuana is a drug… it has different effects upon different people just like any other drug. it doesn’t come with warning labels or possible dangerous side effects because the government saw fit to not regulate a drug that should be a person’s personal choice to take or not to take – just like stackers or those energy things people can buy at the convenience store, or alcohol. i see this article as being used a tool to a)incite fear against the use of marijuana and those who choose to consume it and b)further anti-marijuana legislation that takes away the process of free thought and action that every person should be guaranteed to when it doesn’t infringe upon the rights of others.
I’m 24 years old and had previously used marijuana, almost daily, for 9 years. It became so much a part of my life that there were very few things that I enjoyed, or could do sober; at least that was my perception. Last May I was under tremendous pressure with work while concurrently managing issues in my personal life. For whatever reason, one day I was smoking with friends and began to panic (heavy breathing, weakness, etc.) Since then I have been unable to enjoy Marijuana. In fact, the thought alone makes my heart race with anxiety. I keep telling myself I’ll wait a few months and try it again, maybe the symptoms will go away. Though each time I end up in a panic attack, wishing I hadn’t smoked. This is particulary difficult because I see so many of my friends still enjoying Marijuana on a daily basis. I want desperately to be able to enjoy those things as I once did, but fear that those days are long gone. Anyhow, I suppose I just need to vent/see if anyone had similar experiences.
I totally agree with you. i have smoked weed for 7 years and in the last two years I have been a daily heavy smoker. whenever i tried to quit i felt dull and lifeless, couldnt have fun or enjoy life. I made up my mind to totally quit and for three months it was hell (September-november), i got so depressed and anxious, moody and all that crap but I have made up my mind never to smoke again cuz weed takes u to a new world where you care less about tomorrow cuz the high is an illusion that everything will be just fine…oh one last thing…I remember i couldnt enjoy sex without smoking weed…I thank God am clean now.
MY name is Dion I use to be a heavy weed smoker and I can say that weed has the worst effect on your mind. It is not a social drug and it is very hard to quit I have lost my best friends because of weed and this girl I love so much just for the simple fact that weed disturbed my mind state and my moods. I got so addicted to weed that now that I am quiting I can not control my anger and it is so damn hard because I am mean to my friends and was so mean to my girl friend to the point where after a year of being togather she got a restraining order because she became scared of me I Just hope kids do not start smoking weed and if you have go get help before it gets worst. I use to tell myself that I can quit if I want to but its not true weed is highly addictive and it messes with your head extreamly pretty soon you are not goin to know who you are and how to hang out with out smoking weed please dont start or stop please.!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Did you ever stop to think maybe you have a anger issue and the weed was mellowing you out. It does for me when I am stressed.
I don’t really know what to say but i think Ganja only affects you based on your mindset about it.Its a blessing and a curse.it will only work on your mind from which ever way you build and center your perceptions about it on.For Heaven’s sake this herb was created by Jah.And everything created by jah is beautiful and blessed only if you see it so and bless it.prince Enizee,port harcourt,Nigeria 08062803270
I like weed it make me free good but i am afaird if it causes madness.
I had wish my head accepted mrijuana! The 1st day i smoked it was some time arround sept 2009 with my friend i enjoyed it. I smoke for 2nd time it make reason beyond imagination, i like it. But not until the 3rd time i almost mess my self up it make to panic, fear, even to see my self as a mad man. But i know it doesn’t make some1 go mad. That my 3rd attempt i smoked it more than too much.
hi all, i got into pot smoking for social reasons and i became a heavy smoker for 10 or so years. i smoked bongs every evening until i literally was so stoned i had to go to bed. the best times were when i had one or two puffs of a joint after drinking, that produced a great feeling. but in that time i also had several extremely unpleasant incidents where i freaked out, quietly on the inside though and i just had to ride it out til the feeling passed. towards the end i had a couple of times where i lost control of my body and not sure what direction to walk in, i sat down on the ground – my body rocking and my brain fried. basically marjuana doesnt agree with me. now i am left wondering what permanent damage it has caused me. i stuggle with relationships and find it difficult to work with people. how much of that is due to my drug taking history is impossible to tell.
I dnt smoke,i hv nevaa taken pot,but ive seen d effects on male n female alike…..pls dnt use it
Getting high on marijuana can provoke drastically dissimilar effects in different users. It’s similar to hallucinogens insofar that each experience may be positive or negative and can be altered significantly by set and setting. The effects will usually mirror and exaggerate your mental state at the time.
Many professionals have noticed that cannabis use may serve as a trigger for many mental and emotional disorders, especially in those already diagnosed with such a disorder. However, a direct cause has not been demonstrated yet and cannabis use should only be considered an antecedent to something as serious as a psychotic break.
There is data that suggests no significant increase in psychotic related mental illness, i.e.: schizophrenia, corresponding to the widespread adoption of cannabis and other drugs into the popular culture. If smoking marijuana increases the risk of developing a major psychiatric disorder than we should expect to see an increase in diagnoses during the past 50 years. Instead, the rate of diagnoses has remained fairly steady.
If you are experiencing mental health issues that are affecting your daily life, please seek professional treatment and support through a mental health provider. Many anxiety and anger related problems are now highly treatable with the right therapy.
I need someone to enlighten me.. Can marijuana causes madness? I smoked it once and I didn’t like the way I felt that day so I stopped. Months after I started feeling some strange things inside my head. Can this strange feelings be as a result of the marijuana I took months ago? I really need medical advise..
No, Marijuana cannot cause madness. Your beliefs about what’s going on with you are massively more powerful than any drug in causing reactions in your body. Of course, marijuana does have a chemical effect and the topic is complex but most people with difficulties have no idea that their reaction to marijuana is in fact normal in the context of themselves. i.e. you are reacting normally because you are unique. Forget fear and worry and above all, avoid labelling yourself (or allowing yourself to be labelled) with any tags such as “phychotic”, “schizophrenic” and those other nonsense labels. From what you’ve said, you seem to be feeling the effects of your own thoughts and beliefs rather than any chemical effects of the weed you smoked. You’re perfectly ok, fine and normal.