I am looking for some FACTS associated with long-term marajuana use.

Primarily, I am looking for proven health risks related to smoking
daily for a number of years.

Also, I would like to know if there are any specific vitamins or foods
that can be useful in counteracting the adverse effects.

Any information that is recent and unbiased would be greatly
appreciated.

Factual accounts of persons smoking daily for 20+ years would also be
helpful.

Hello,

There is some evidence from human studies that long-term marijuana use
can have adverse effects, although it seems that the spectrum of these
effects is narrower than previously thought and mainly centres around
cognitive (intellectual) function.

A paper in the Journal of the American Medical Association (JAMA) vol.
287 No. 9, March 6, 2002, pp. 1123-1131) found that long-term cannabis
users performed less well than shorter-term users and controls (people
who didn’t use cannabis) in tests of memory and attention.  The
long-term users averaged 23.9 years of use, compared with 10.2 years
in the shorter-term users. You can find an abstract at the American
Medical Association web site: 
http://jama.ama-assn.org/issues/v287n9/abs/joc11416.html , but access
to the full text requires subscription to the journal.  Note that the
comments associated with the article (links to them are underneath the
abstract) indicate that some other investigators do not agree with
this conclusion.

Another study published in a Canadian medical journal (CMAJ 2002 Apr
2;166(7):887-91 http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11949984&dopt=Abstract)
found that: “Current marijuana use had a negative effect on global IQ
score only in subjects who smoked 5 or more joints per week. A
negative effect was not observed among subjects who had previously
been heavy users but were no longer using the substance. We conclude
that marijuana does not have a long-term negative impact on global
intelligence.”  This study compared IQ scores of individuals aged 9-12
years before they started using cannabis, with their scores at 17-20
years.  Light users, former users and non-users showed a gain in IQ
over the same period.

One reason for the decreased IQ and memory in consistent heavy users
could be the fact that long-term cannabis use has been found to
decrease blood flow to the front areas of the brain (Neurotoxicology
and Teratology 2001 Sep-Oct; vol 23 pp. 437-43  Frontal lobe
dysfunction in long-term cannabis users by  Lundqvist T, Jonsson S,
Warkentin S. of the Division of Medical Neurochemistry, Lund
University Hospital, 221 85, Lund, Sweden  
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11711246&dopt=Abstract

A study published in Public Health and Nutrition, June 2001, vol. 4
pp. 781-786 (Dietary intake and nutritional status of US adult
marijuana users: results from the Third National Health and Nutrition
Examination Survey. By Smit E, Crespo CJ. of the Department of Social
and Preventive Medicine, SUNY School of Medicine, University at
Buffalo, Buffalo, NY 14214, USA.
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11415485&dopt=Abstract
) found that marijuana users have lower levels of carotenoids in the
serum.  The authors concluded this was associated with different
dietary habits: “We found higher cigarette-smoking rates and higher
consumption of sodas and alcohol, specifically beer, among marijuana
users than among non-current marijuana users. Marijuana users also
consumed more sodium, fewer fruits, and more pork, cheese, and salty
snacks.”  Carotenoids are important anti-oxidants which help to
prevent cancer and other diseases.  An increased risk of these
diseases might be due not so much to marijuana use itself as to the
lifestyle led by many who use it.  Better attention to nutrition, in
order to ensure a good intake of fresh fruit and vegetables,
particularly the red, yellow and orange ones, will help to boost
antioxidant status (see below)

A review of various studies came to the conclusion that: “Regular
marijuana use can lead to extensive airway injury and alterations in
the structure and function of alveolar macrophages, potentially
predisposing to pulmonary infection and respiratory cancer.”  Alveolar
macrophages are cells in the lungs that help clear away debris and
bacteria.  (Current Opinions in Pulmonary Medicine, March 2001, vol 7
pp 43-61, Airway effects of marijuana, cocaine, and other inhaled
illicit agents.  by Tashkin DP  of the Division of Pulmonary and
Critical Care Medicine, UCLA School of Medicine, Los Angeles,
California 90095-1690
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11224724&dopt=Abstract
)    Again, to counteract these effects, a diet high in antioxidants
would be helpful.

Obviously, marijuana smoked as joints and mixed with tobacco could
carry all the health risks associated with cigarette smoking.  The use
of marijuana alone might be implicated in cancer.  However, one review
concluded that: “While there is no doubt that marijuana smoke contains
carcinogens, an increase in cancer among users has thus far been
anecdotal. Because of the long latent period between cancer induction
and initiation of cigarette smoking, the full story is yet to be
told.”  (International Journal of Neuropsychopharmacology, July 1998,
vol. 1 pp 71-80, Health aspects of cannabis: revisited. by Hollister
LE. of  Harris County Psychiatric Center, University of Texas-Houston,
Houston, TX http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11281947&dopt=Abstract
) In support of this statement, I only found one recent paper in
Medline describing a case of cancer in one marijuana user.  This in
itself is not absolute proof.

L E Hollister also concluded that: “Many older concerns about adverse
effects on health (chromosomal damage, 'cannabinol psychosis',
endocrine abnormalities, cardiac events, impaired immunity) no longer
seem to elicit much interest. Continuing concerns about the adverse
cognitive effects of chronic use indicate that these can be
demonstrated by proper testing; some studies suggest that they may be
long-lasting. Although cannabis does not produce a specific psychosis,
the possibility exists that it may exacerbate schizophrenia in persons
predisposed to that disorder.”  i.e. the effects tend to be more on
brain function than on other diseases, and it could worsen the status
of people who have a tendency to schizophrenia.

I have not found anything specific about diet in relation to marijuana
use.  However, a diet rich in antioxidants will tend to counteract the
effect of many toxins and thus would probably be helpful against the
toxic effects of marijuana.  This is a diet rich in fresh fruit and
vegetables, with perhaps additional (although not extreme) intake of
vitamins A, C and E.  Red wine is also high in antioxidants :)  and so
is green tea.

Search strategy: “marijuana AND long term” and “marijuana AND cancer” 
 on Medline at http://nlm.nih.gov
Marijuana AND diet,  cannabis AND diet on Google and on Medline
Antioxidant diet: from personal knowledge

Excellent answer!  Thanks so much for the insightful info!

I have a doctorate in psychology and specialize in substance abuse
treatment. This is one of the most succinct, accurate summaries I've
seen on the topic of long-term effects of cannabis use. Excellent job
tehuti-ga!

<blush>  Thank you very much, mdw-ga.

Tehuti:

I agree with mdw.  I'm an epidemiologist at Health Canada and we place
someone with your research skills in high demand.  What field are you
currently employed in?

Do you agree with me when I say that Google should mandate that
Health/Medical answers ONLY be given with reference to PEER-REVIEWED
medical journals?  I think that would yield other great answers like
your own!

Cheers!

Indicted, I have a PhD in biomedical science and am also a qualified
librarian and information specialist. I have worked for more than a
decade as a scientist and information specialist for a non-profit
scientific organizaton, where I do desk research on a variety of
topics, including toxicology.  I also provide tox searches regularly
to a hospital consultant in clinical chemistry and biochemistry who
needs them for his medicolegal work.

As for search sources, it really depends on the question.  The medical
journal literature is, I think, the best place to start to answer a
question on current theories, effects of drugs and toxins,
epidemiology, and matters like that.  It is certainly a lot easier to
find the information there rather than with a general web search! 
However, if someone asked for information on symptoms and treatment of
a specific disease, I would probably point them to a reliable web site
with patient information, unless they were wanting to find out about
very new approaches.  If someone wanted to know how other people cope
with a certain condition, I would hope another researcher with direct
or indirect experience of the condition would answer, and if not, at
second best, I would try to identify some patient support groups. If
someone listed symptoms or drug reactions they were experiencing and
asked what was the matter or what they should do, I would not answer
the question, because I am not a practitioner and do not think I have
the right to act as if I were one.

In all cases, and not just medical queries, I think it is important to
be aware of how reliable or otherwise is the source of the information
you are presenting. When searching the scientific literature, it is
important not to present isolated papers out of context. If there is
disagreement in the scientific or medical community, the researcher
must indicate that consensus is lacking on that issue and not simply
present one side.  Also, it is wise to remember that the peer-review
process is not always necessarily a guarantee of quality.  A study
done some years ago into a set of toxicology papers picked randomly
out of the peer-review literature found that 70% (I think) of them
were presenting data for which the statistical analysis was
questionable or even downright incorrect.

Heloo dopamine-ga,

I wonder if your still out there waiting for responses to your question.

I will write to try and provide input as a long term smoker, 27 years
and still tokin.

I hold a full time job in a responsible position while raising 7 kids
to be decent citizens and human beings. I smoke everyday starting with
my morning coffee, off to work and home at 6 in the evening for my
second joint of the day. And one more before bedtime. (Or 3 or 4 heads
on a bong).

On weekends the routine varies.

I have been smoking since the age of 16 and cannot remember a time
when I didn't smoke. During highschool I naturally didn't smoke
everyday, I was away at boarding school, so it was only on weekends.
The same during the army (input from Israel). I am still married to
the boyfriend I started smoking with. While I don't suffer from any
long term affects, I am also a heavy cigarette smoker and besides
getting out of breath going up 3 stories, I'm OK (knock on wood). One
long term affect may be the fact that I have 7 kids and was stoned
while making all of them, never stopping to think about the future.
Thank god they are all completely normal (one hyperactive) but other
then that they are beautiful, healthy, and all above average
intelligently. Considering all the tests I see younger women having
today, before and during preganancy, I have had "more luck than
brains".

One affect is that I do not get stoned or high, but then I never was
one of those who "lost it" while smoking. I have also smoked a lot of
hash during the years it was more available then grass here in Israel,
but have never tried anything stronger and have no wish to. I am
completely in control at all times.
I just am calm and relaxed and feel good when I smoke. I am probably
addicted, although not physically, as we all know, just in my head. If
there is nothing to be found to smoke for a while the first couple of
days are frustrating and thats it, although this hasn't happened for a
long while and I don't know how I would actually react during a
serious "dry" period.

Are you learning anything? I just happened to find your question
during my own surfing the web and looking for answers (or
verifications) that what I am doing is OK. I may have found a place
here to talk about myself and my smoking, which nobody in my work or
social circles know anything about. My older kids know and accept
although all my smoking at home is done when I am alone. My mother ( a
daily visitor to my household) doesn't know either. My main problem is
red-eyes and I am probably harming myself more with the Stilla then
with the marijuana. My father also smokes and has since I was a child
as far as I know, he lives in the states and I haven't discussed it
with him. I don't see any longterm affects on him either.

My husband on the other hand, who started smoking with me, was
recently diagnossed with mania depression, not from the smoking
because looking back over the years the disease was always there but
more easily overlooked. He stopped smoking cigarettes a few years ago
and was smoking only weed for about a year and he became slightly
crazy and eventually was stopped on the road and found to have some
smoke with him. This was terrible for him, he lost his firearms
license, and consequently his job in security. bringing upon him a
long depression, lasting a very long time. He also stopped smoking at
the time, got himself out of the depression and had a good year. But
when things got too good he became "mania" (or whatever you call the
opposite of depression) and started smoking marijuana again, almost
nonstop, and also drinking a lot of beer. Anyway, to make a long story
short, he has since started treatment for his mania depression and
does not smoke anymore, but one of my worst fears is that he will
start again and our lives will go crazy again. So that, for him,
smoking marijuana is not a good thing, while for me it is fine.

Is this anything like what you were looking for?

tehuti,

Superb information, nice one!

Regards

I am a PhD student in Molecular Biology/Biological Science and very
interested in reading other experiences of long term use of marijuana.
 I have been smoking marijuana for 23 years and I have recently
questioned my ability to live life without it.  I have read about
chemicals that permanently alter the brain chemistry and often
wondered if marijuana has changed mine.  When I smoke MJ I do not feel
the need to consume alcohol at all. I feel relaxed and yet motivated
to keep working, even when I am tired or stressed.  I eat a balanced
diet and exercise everyday.  It doesn't appear to have negatively
affected my memory or ability to think rationally.  For 6 months now I
have stopped using MJ as an experiment to see if I can notice any
changes about myself.  Physically, my body has reponded positively to
a vast reduction of smoke inhallation.  My skin complexion has more of
a healthy glow, my eyes appear brighter and my lungs have become more
efficient.  However, the simple pleasures in life have become dull and
boring.  I cannot feel enthusiastic about mundane tasks like washing
the dishes or weeding the garden.  I think that when I smoked I was
happier somehow, in my everyday life.  I used to take time out to sit
in the sun for a few minutes to listen to the birds and think what a
nice day it was.  I was more at one with myself and the world, whereas
now I feel the simple pleasures in life (although still there) have
lost some of their appeal.  I will endevour to quit MJ and hope that
my brain chemistry will return to some sort of equillibrium, but if it
doesn't and I feel that I am happier as a smoker (with full knowledge
that it will shorten my life)then I will have to choose quality over
quantity.

I am a PhD student in Molecular Biology/Biological Science and very
interested in reading other experiences of long term use of marijuana.
 I have been smoking marijuana for 23 years and I have recently
questioned my ability to live life without it.  I have read about
chemicals that permanently alter the brain chemistry and often
wondered if marijuana has changed mine.  When I smoke MJ I do not feel
the need to consume alcohol at all. I feel relaxed and yet motivated
to keep working, even when I am tired or stressed.  I eat a balanced
diet and exercise everyday.  It doesn't appear to have negatively
affected my memory or ability to think rationally.  For 6 months now I
have stopped using MJ as an experiment to see if I can notice any
changes about myself.  Physically, my body has responded positively to
a vast reduction of smoke inhallation.  My skin complexion has more of
a healthy glow, my eyes appear brighter and my lungs have become more
efficient.  However, the simple pleasures in life have become dull and
boring.  I cannot feel enthusiastic about mundane tasks like washing
the dishes or weeding the garden.  I think that when I smoked I was
happier somehow, in my everyday life.  I used to take time out to sit
in the sun for a few minutes to listen to the birds and think what a
nice day it was.  I was more at one with myself and the world, whereas
now I feel the simple pleasures in life (although still there) have
lost some of their appeal.  I will endevour to quit MJ and hope that
my brain chemistry will return to some sort of equillibrium, but if it
doesn't and I feel that I am happier as a smoker (with full knowledge
that it will shorten my life)then I will have to choose quality over
quantity.