Expert: Dana Krempels, Ph.D. - 2/10/2011

Question
QUESTION: Before you claim this as "outside of your expertise" I want you to know that I would still love to hear your answer and what you know, even if it is only a little bit, you can email me back privately at  or on this, either or is fine. So my really really really important question is,

What does smoking Marijuana do to people, psychologically and physiologically?

As in, when we smoke marijuana, what happens to us afterwards exactly and why? How does it work, scientifically and in layman's terms? I would love a play by play informed answer. I’m talking about in terms of psychological and physiological. But again, not just WHAT happens, but also  why each thing happens the way it does. 
I’m curious as to what it does to the body and brain exactly?

I use to smoke weed for 2 years, stopped for about 3 and then smoked it once recently and my heart was pounding and racing for about 2 and a half hours while I was high. Either I was paranoid (so it was psychological) or it was just physiological from the marijuana, what do you think? Do I have anything to be worried about? I felt like I was going to "die" but this is only marijuana you know! Not Crack!

I'm 19 and male. Thanks again

ANSWER: Dear Josh,

Tetrahydrocannibanol, the active ingredient in marijuana, has both physiological and psychological effects because our cells have receptors for chemicals that are physically similar enough to accommodate the THC molecules.  And then it's off to the races!

As you suspect, I am not an expert in this area, but I did find an excellent overview of the literature that covers--in a very understandable way--the physical and psychological effects of marijuana on the human body.  You can find it here:

http://www.druglibrary.org/Schaffer/hemp/medical/nelson1.htm

Of perhaps greatest interest to you might be a section from the above regarding the effects of THC on the cardiovascular system:  (Tachycardia is rapid heart rate)

"When cannabis is first smoked one of its most prominent immediate effects is tachycardia which tends to be proportional to the ingested dose (Stimmel, 1979). The rate increase varies from 50-100% of resting pulse with an accompanying decrease in orthostatic blood pressure. It was observed by Aronow and Cassidy that the consumption of one marijuana cigarette containing 19 mg of THC decreased exercise time until angina by 48% as compared to a marijuana placebo which only reduced time to angina by 9%. The authors of this study concluded that cannabis smoking increased myocardial oxygen demand while decreasing myocardial oxygen delivery (Aronow and Cassidy, 1974). Hollister (1988) concludes from these results that, although smoking is not recommended for anyone with angina, the shorter time until angina seen with cannabis combined with its induction of tachycardia makes it particularly deleterious for those suffering from arteriosclerosis of the coronary arteries or congestive heart failure. Nahas (1984) summarises what he believes to be the cardiovascular threat of cannabis ingestion based on the above findings:

"The smoking of marihuana increases the work of the heart by increasing heart rate, and in some cases by increasing blood pressure. This increase in work load poses a threat to patients with hypertension, cerebro-vascular disease, and coronary atherosclerosis."

In short, pot isn't good for you if you have cardiovascular problems.

Cannabis makes this compound to deter herbivores.  But some silly primates ignore that warning and have a little fun with it.  In most cases, the harm is minimal (but you're still giving your body a toxic insult; there's no way around that).  But chronic, long-term use of the drug can have some pretty nasty adverse effects on health, just as smoking tobacco or drinking too much alcohol can.

Hope you find that article informative.  

Dana

---------- FOLLOW-UP ----------

QUESTION: Your answer was great actually. It's just that, the main reason i'm asking and worried about this is because when I did it a few days ago my heart was pounding like crazy, I felt like I was going to die and I was thinking some crazy thoughts, and so I'm just trying to make sure i'll be safe if I continue for the next few weeks?

if you're really not sure then that's ok your first answer was probably good enough. thanks again.

ANSWER: Dear Josh,

If you had a really bad cardiac reaction to the weed, then I certainly would not recommend smoking any for two more weeks...or maybe ever.  Please discuss this with your physician.  It might technically be illegal, but your physician should be able to counsel you without problems, as there is patient/physician confidentiality that must be honored.

Hope this helps.

Dana

---------- FOLLOW-UP ----------

QUESTION: Yes I was thinking the same thing but then as I was doing massive research on the herb, I read that one of the affects is that it DOES increase heart rate, and I asked my long time smoking friend and he says it increases his heart rate every time. and so I think I'll be fine you know? what's your say on this?

Answer
Dear Josh,

Well, it's similar to undertaking any physical challenge:  you should check with your physician first.  I cannot advise you on the safety of your smoking pot without knowing about your general health.  And even a physician would not be able to foresee the future.

Just be safe, okay?

Dana