Q&A with medpot pioneer Lester Grinspoon

Renowned Harvard professor of psychiatry talks about his research into prohibition, how Carl Sagan turned him on to the wonders of weed and why, at age 42, he started using it himself. "It was just too interesting an experience to let go."


Lester Grinspoon, associate professor emeritus of psychiatry at the Harvard Medical School, began researching the medicinal legitimacy of marihuana 45 years ago and discovered that an immense chain of lies served as a basis for sending millions of people to jail in the US. Since then, he has become an ardent promoter of pot’s spiritual and medicinal benefits. 

Q. How did you became interested in marihuana?

Well it started in 1966. During my anti-Vietnam activism I met Carl Sagan and he and I became very good friends. I was convinced that cannabis was a very harmful drug. Going to his house one day I discovered that he smoked cannabis and so did many of his friends. Now these were not unsophisticated people but I tried to tell Carl how harmful marihuana was but he responded in a joyful manner that it wasn’t harmful at all. With this experience came the idea of writing a paper which would summarize the medical scientific basis for the marihuana prohibition. At that time marihuana prohibition was leading to the arrest of some 300,000 mainly young people a year in the United States, most of those for simple possession. For me, it became important that this prohibition was justified. Eventually, I wrote my book Marihuana Reconsidered. When I was doing the research I did not only find out that marihuana was not harmful but I started to understand what the attraction was for people who use it, and I decided, at the age of 42, that I was going to use it as well. It was just too interesting an experience to let go.

Q. You said you came to understand through your research why people use marihuana. What are the reasons?

Most people are familiar with recreational use. But marihuana has an ancient history as a medicine as well. We know that Shen Nung, a Chinese emperor, who lived about 5,000 years ago used marihuana as a medicine. In the modern western medicine we had to wait until the mid-19th century for the introduction of marihuana as medicine through an Englishman named William O’Shaughnessy. He worked in Calcutta and observed the indigenous people using marihuana. He started studies on animals to be sure it was safe and published his first paper when he returned to England in 1849. I came across about 100 critical papers about marihuana as a medicine in my review of the literature. Everybody that has used marihuana knows that an ordinary meal can taste like a culinary treat and that it can enhance sexual experiences. But these are enhancements that are on the surface. Once one becomes more experienced with cannabis, he or she can use it for creative or spiritual purposes.

Q. What were the reactions of your peers and other scholars to your first book?

Well yes there was a lot of reaction. I remember the most significant of all: I was put up for early professorship by my chief at Harvard Medical School who told me after meeting with the promotions committee that they loved my work on schizophrenia but hated Marihuana Reconsidered because it was much too controversial.

Q. Even with all the data that you used to support your work?

Oh yes. I just couldn’t believe it. I said to him, “Controversial, what do they think scholarship is all about?” The affair resulted in the committee turning down my application for a professorship. I had to wait until 1995 to become professor at Harvard. In the beginning I was heartbroken but because I did not become a professor I could skip a lot of department meetings and other things, so I had a lot of time for my own research. Because of the free time I started to become active against the cannabis prohibition that was and still is very destructive in American society.

Q. What can you tell me about marihuana as an addictive substance and any medicinal benefits?

There are still people that say that about 10 per cent of users become addicted. I don’t see it as an addictive substance. Sure you see some people using it all the time, especially many young people, but they do it because they did not figure out yet what to do with their lives. I used it for more than four decades, almost everyday, when there were times I could not use it I missed it but I felt nothing more. Some people are very concerned when they discover that their college kid is using marihuana. They will get upset and take him to the psychiatrist. This doctor as no other choice than diagnosing the youngster as marihuana-addicted because without putting a label on the “patient” the doctor will not be reimbursed. Another thing is that you can smoke marihuana safely, there is no pulmonary bronchial effect, even if you smoke it straight without using a vaporizer.

Q. Can cannabis cause psychoses or schizophrenia?

Absolutely not! Schizophrenia is a disorder which one is born. Usually, it’s in the adolescence that it starts showing. People who are not used to cannabis can become anxious or paranoid which is of course uncomfortable. That’s why people have to learn how to smoke it. I have never seen this, but I can imagine that the naïf use of marihuana can act as an precipitating event. The prevalence of schizophrenia is 1 per cent around the world, across all different cultures. Given the amount of people who started smoking marihuana, including adolescents no scientist picked up even the tiniest increase in the prevalence of schizophrenia. So the people who write this can not prove it.

Q. What do we know about marihuana in relation to cancer?

I am glad that you bring that one up. I hear a lot of people talking as if cannabis can cure cancer, and that worries me. People who are not sophisticated about this will not go to a doctor and they will miss chemo treatment, radiation or surgery and just rely on cannabis. You can not say that cannabis cures cancer. However, there are some properties of cannabis which in my view make it very important that those patients use marihuana alongside the modern western oncological treatment. In the case of chemotherapy, for instance, cannabis can combat the side effects of distressful nausea. Cannabis can help as well to diminish the size of tumours which can be important when the tumour causes an obstruction, it stimulates appetite and in vitro it stops cancer cells from spreading, kills cancer cells and leaves healthy cells untouched and interferes with the blood flow in the tumour. So there are a number of effects which shows that marihuana pushes back cancer. This makes it important to use marihuana but along with the modern medicine.

Q. In Belgium, the minister of health Maggie De Block, who is a doctor as well, says you can’t use marihuana as a medicine. According to her, the only thing that is useful is sativex and only for MS patients.

Sativex is marihuana! To state that there is no evidence is nonsense. There are mountains of anecdotal evidence, you cannot deny them. We are used to medicines coming from pharmaceutical enterprises. But this is a plant, and you cannot patent a plant and have the exclusive license to sell it. That’s why the pharmaceutical enterprises are not interested in doing very expensive tests with marihuana, because at the end of a positive test anyone could bring a medication on the market.

Q. Are you saying that marihuana is a great medicine for people but for pharmaceutical enterprises it is worthless?

Absolutely. Some people say I should not tell people to use marihuana for this or for that reason. But that is silly, because it might help and surely will not hurt you. If it does help you, you are very fortunate because it has no side effects – and it will always be cheap.

Patrick Dewals is pursuing a masters in political science at Free University of Brussels.

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