I have a granduncle with schizophrenia and i smoke cannabis socially. Do i have a risk of developing it?

Title says all, i do go on paranoid google searches about this kind of thing occasionally, and i would like to hear some thoughts. I smoke cannabis with friends sometimes, i don’t own anything nor do i believe i am addicted.

My experience was similar, but I had two bad experiences with cannabis in my late teens and later developed schizoaffective disorder in my mid 20’s. I can’t be certain it was cause and effect.

There’s growing evidence that cannabis use in young adulthood correlates to schizophrenia and other mental illnesses in some people. Whether this is because people with nascent metal illnesses use cannabis to self-medicate or escape, or it’s cause and effect is unclear. It’s well established that your brain doesn’t grow to adulthood until your mid-twenties as myelination completes, and it’s long suspected that issues with myelin sheaths are present in people with schizophrenia.

Given that cannabis is orders of magnitudes stronger than when I was in my teens and twenties, I’d steer clear of cannabis until I passed my mid twenties and I’d consider avoiding it after that. I’ve been extremely lucky to have a recovery, but this is only after decades of psychotherapy and psychiatric (prescription drug) treatments largely at my own and parents’ expense. Not only was this treatment expensive, but my education and social development was delayed 10 years or more.

Looking back on it, I don’t see the “merits” of short-term socialization with stoner friends I rarely had contact with after young adulthood, outweighed my life-long mental, social and economic impairments. But at that time, the risks weren’t known. They are better known now, so even when people offer legal cannabis, I decline, citing health and other reasons. It doesn’t appear to hurt me socially as long as I don’t lecture people on their personal choices (outside of this forum and genetic relatives).


I would like to know more. What were your bad experiences with cannabis? Does schizophrenia run in your family? And also, what were any early signs before you developed the disorder?

To answer your questions:

In high school a friend of mine passed out at a party and started vomiting. The host freaked-out and called an ambulance. I was designated to hold his “stash” which had gotten wet in the commotion of the host trying unsuccessfully to flush it down the toilet (cannabis was illegal at the time). Like you, I was probably the least likely suspect. Over the weekend, I dried it out and rigged up a pipe to smoke it. For several days afterwards I had a headache, was unable to concentrate and spaced-out with a sort of ringing in my ears. I stayed home a day or two from school and the symptoms eventually faded, although I would sometimes get odd feelings and space-out.

A couple years later I’d moved to California and had some particularly strong cannabis and I sort of passed out and was out of it for a day or so with similar although less intense symptoms that persisted and faded. About a year after that, the friend who had passed out at the party was admitted to a mental hospital and committed suicide while I was on winter break.

And yes, as with most families if you inquire carefully there are distant relations with mental illnesses— diagnosed and undiagnosed. My more distant relatives do not speak English natively, so given the language barrier, stigma and a related tendency to go undiagnosed, my brother and I were unaware of mental illnesses in these relations until he developed Bipolar Disorder long before I developed Schizoaffective Disorder. To my knowledge no relatives had a schizophrenia diagnosis per se, but talk of “mental weakness” was prevalent on inquiry.


Cannabis, like meth, heroin, cocaine, energy drinks, caffeine, spikes dopamine in your brain. Your brain’s chemistry balance is affected and studies show that dementia and Alzheimer’s results in those with brain chemistry imbalances. Because you have a relative who had/has it, and because you mess with your brain’s chemistry balance by smoking or ingesting cannibis, you will have a greater probability of brain dysfunction/disease/conditions that upset your reasoning cognitively and really screw up your memory. Google international medical studies and read the briefs. Also, go to Hillsdale.edu website and go to Marijuana, Mental Illness, and Violence - Imprimis (hillsdale.edu)(Marijuana, Mental Illness, and Violence - Imprimis), an article in their newsletter from a few years ago well written by a respected journalist.

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I don’t think you should worry about it, IMO. I see this for a Google search of identical twins:

In twin studies looking at schizophrenia, scientists have shown that if one identical twin has schizophrenia, then there is a 30-50% chance that the other twin will have it as well. If a fraternal twin has schizophrenia, then there is a ~15% chance that the other twin will have it too.

If it was strongly heritable, like the breast cancer BRAC genes, then the chance would be higher. Besides, what I found out about inheriting illnesses is that epigenetics can have a strong role to play and I think that is little understood. Epigenetics is where a gene’s expression is induced by an environmental factor, which is totally unpredictable.

So, for any kind of illness I think you just have to be aware of what the symptoms look like and wait and see if they appear. Any screen that can be done is important for cancer and you have to be diligent about getting all of those done.

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Having trouble following your logic: He shouldn’t worry about because it isn’t highly heritable citing unknown environmental factors perhaps triggering the condition. But isn’t cannabis use an environmental factor?

Given cannabis use is elective, and studies show a correlation between cannabis use at a young age and increased likelihood of a schizophrenia, I’d think avoiding cannabis use would be a more prudent approach. I suppose since studies show the correlation is stronger when cannabis use is started at a younger age, so you might consider that the damage is already done so why not?

I think most caregivers agree that cannabis use once schizophrenia emerges is generally detrimental. There are studies that point to benefits to CBD oil for various mental illnesses, but I don’t think that’s the OP’s question.

I’m not saying the risks are high or a direct or immediate “Reefer Madness” style correlation, but considering the higher livelihood of lifelong disability for at risk individuals and burden to parents and society in general, I don’t see much benefit to recreational use in young adults. Not sure what the legal age is for THC cannabis, but I’d support an age of at least 21 and 25 would seem even more prudent. The reality is kids use much younger, I’m sure.

Here’s a link to aggregate studies on cannabis use and schizophrenia:


Wow, that article is a pretty strong indictment against smoking pot. I think I would agree to avoid it.

What I meant about environmental factors and gene expression is that it’s very hard to prove scientifically what environmental factors influence genes. And the genes themselves work in networks and have to go through mutations or be epigenetically influenced to cause disease.

I think we are making great progress in understanding the genetic basis for disease, but things actionable are away off. My brother came down with leukemia about the same age as I am now and passed away within 2 years. I thought about getting a genetic test, but a hematologist oncologist I spoke with just didn’t think I’d learn anything from it.

23andMe, for example, has https://en.wikipedia.org/wiki/23andMe#Accuracy_concerns

"Regular cannabis users are more than five times more likely to develop a serious mental disorder. Cannabis creates a greater mental health risk than any other substance, including class A drugs, scientists have found.

Those who abuse the drug – now more potent than ever in the form of super-strength ‘skunk’ – are 5.2 times as likely to develop schizophrenia as someone who had never smoked it."