Re: Losing brain cells

Hi There!
Sorry it took so long to get back to you!
Wow!  That's kind of a controversial question, but I really think you've 
hit on a very important issue in drug abuse.  I haven't found much 
information on any actual "counts of dead cells", but let me give you a 
little information dealing with the central nervous system (also called the 
CNS….You know, the brain, spine, and that kind of stuff) and how each of 
these drugs affect it (yes, we consider alcohol a drug, too!).

Lets look at what's probably more interesting to most people first…..one of 
the most popular illicit recreational drugs in our culture, marijuana.

It's likely that there is no other drug in contemporary culture that has 
generated as much controversy as this stuff.  The scientific literature 
dealing with this drug is rather specialized, hard to follow most of the 
time and, often rather contradictory.  It's really no wonder that there are 
so many strong, biased opinions, fueled with tentative information and much 
confusion (for a good laugh and an example of this, check out the film 
Reefer Madness).  Marijuana has been accused of having harmful effects 
ranging from serious mental disorders to producing bad genes.   Here are 
some facts:

Marijuana is known to bring about full-blown psychoses in people with 
"psychotic tendencies".   It will also make schizophrenic and paranoid 
symptoms more intense, if the person already has them (Choptra & Smith, 
1974).  However, if a normal person takes abnormally high doses of this 
drug, a person can be overwhelmed by intense feelings of paranoia and maybe 
even experience something called an "adverse psychotic reaction".  This may 
include intense anxiety, hallucinations, and a general "freak out".  This 
usually happens more often with something like LSD, and the user can 
generally be "talked down".  Sometimes, however, a trip to the emergency 
room is needed and a tranquilizer may be given (Dinwiddle & Farber, 1995).

As far as physical effects on the brain, the effective chemical in 
marijuana, (delta -9-tetrahydrocannibinol, called delta-9-THC for short) 
has been shown to permanently affect the brains of rats.  When given at 
relatively high doses for 6 months (Fehr et al., 1976), the rats had a very 
hard time learning how to run a maze.  This persisted two months after not 
having any drugs!  This kind of treatment has been shown to make changes in 
the brain, especially in the hippocampus (that part of the brain that is 
responsible for laying down new memories; Seallet, 1991).  Alcohol also has 
an effect in the hippocampus, though.  We'll see that shortly. 

That stuff sounds pretty scary, but keep in mind that permanent changes in 
a rat due to THC requires about three months of heavy use.  For a rat, 
that's about eight to ten percent of his life!  For a human, that's about 
seven to ten years (Sealet, 1991).  For example, Slikker et al. (1992) 
exposed monkeys to a human dose of marijuana smoke (though a gas mask, if 
you can believe it!) every day for one year.  There were some effects on 
behavior and hormone release, but this could be due to stress.  Seven 
months later, there were no differences in behavior, brain cell amount, 
brain cell size, or the size of the .  This is probably because eight to 
ten percent of those monkey's life span was about three years!  This is not 
to say "go ahead and smoke up, guys!"  The point is that it's never too 
late to stop before something permanent happens.

OK, let's look at the legal stuff:

If folks think that marijuana is bad…..take a good hard look at alcohol!  
Both are believed to be damaging, but alcohol does a great deal more 
destruction than most people realize.  Chronic alcohol use has been linked 
to a variety of problems, including serious liver damage resulting in 
alcoholic hepatitis and cirrhosis, which in turn compromises the immune 
system (Wands, 1979).  Cancer, believe it or not, is also linked to alcohol 
use, although some think it has more to do with the fact that many people 
like to smoke when they drink (Kissen & Kaley, 1974).  It almost seems like 
they want to get all of their vices out at once!  Heavy alcohol use has 
also been connected with heart disease, reproductive problems (including 
Fetal Alcohol Syndrome) and a host of other disorders!

But, we want to talk about the brain.  Many heavy drinkers show a cluster 
of symptoms that include the inability to remember past events, learn new 
material, disorientation, and confusion.   We call this mess the 
Wernicke-Korsakoff's syndrome.   It's caused by what we believe is a 
vitamin B1 deficiency, which is common among many alcoholics (Victor, 
Adams, & Collins, 1971) and is thought to cause damage in certain parts of 
the brain.  Many of the physical problems that alcoholics suffer, however, 
seem to stem from vitamin deficiencies.  This is probably caused by the 
fact that alcohol damages the digestive tract and interferes with the 
absorption of many nutrients.  

But wait, there's more!  When pregnant rats were given alcohol, it impaired 
the formation of the brain cells (called neurons) in the hippocampus (that 
place in the brain for new memories again!) of their offspring (West, 
Hodges, & Black, 1981).  Even when given to adult mice, the part of the 
neuron called the dendrites (they're kind of these branch-like things that 
help it communicate with other neurons) kind of shrivel up in the 
hippocampus (Riley & Walker, 1978)!  

Alcohol use has also been connected with epilepsy, alcoholic dementia 
(another memory-affecting disorder that's a little different from 
Wernecke-Korsakoff's syndrome) and the cerebellar syndrome (Marsden, 1977). 
 The cerebellum is the major part of the brain that is responsible for fine 
motor control.  Since alcohol first affects the brain there, its really no 
wonder that some of the drunk driving tests are things that test fine motor 
movement and balance (like "touch your fingers to your nose" and "walk that 
straight line").  Similarly, cerebellar syndrome symptoms include problems 
with movement and balance. 

So, as a long-winded answer to your short, to-the-point question, both are 
bad for the brain, but most the clinical evidence and a good deal of 
experimental data as well seems to indicate that alcohol does more damage 
to the brain (and the rest of the body) than does marijuana.

I hope this answers your question and settles your debate, guys!  Feel free 
to come back if your curiosity strikes anew!

Dr. Tom Virden
Behavioral Neuroscience
Department of Psychology
Arizona State University


References


Choptra, IC & Smith, JW 1974 Psychotic reaction following cannabis use in 
East Indians.  Archives of General Psychology 30:24-27.

Dinwiddle, SH & Farber, NB 1995 Pharmacological therapies of cannabis, 
hallucinogens, phencyclidine and volatile solvent addiction.  In NS Miller 
& MS Gold (eds) Pharmacological therapies of alcohol and drug addiction NY: 
Marcel Dekker.

Fehr, KA, Kalant, H, Leblanc, AE, & Knox, GC 1976 Permanent learning 
impariment after chronic heavy exposure to cannabis or ethanol in the rat. 
 In GG Nahas (ed) Marijuana:  Chemistry, biochemistry and cellular effects 
NY: Springer-Verlag.

Kissen, B & Kaley, MM 1974 Alcohol and cancer. In B Kissen & H Begletier 
(eds) The biology of alcoholism vol 3 NY: Wiley.

Marsden, CD 1977 Neurological disorders induced by alcohol In G Edwards & M 
Grant (eds) Alcoholism:  New knowledge and new responses London: Croom Helm

Riley, JN & Walker, DW 1978 Morphological alterations in hippocampus after 
long-term alcohol consumption in mice Science 201:646-648.

Seallet, AC (1991) Neurotoxicity of cannabis and THC:  A review of chronic 
exposure studies in animals.  Pharmacology, Biochemistry, and Behavior 
40:671-676.

Slikker, W, Paule, MG, Ali, SF, Scarlett, AC, & Bailey, JR (1992) 
Behavioral, neurochemical, and neurophysiological of chronic marijuana 
smoke on the nonhuman primate.  In L Murphy & A Bartke (eds) 
Marijuana/cannibinoids neurology and neurophysiology Boca Raton, FL: CRC 
Press.

Victor, M, Adams, RD, & Collins, GH 1971 The Wernecke-Korsakoff syndrome 
Philadelphia: Davis.

Wands, JR 1979 Ethanol and the immune response in E Mijchrowitz & FP Noble 
(eds) Biochemistry and pharmacology of ethanol vol 1 NY: Plenum.

West, JR, Hodges, CA & Black, AC 1981 Prenatal exposure to ethanol alters 
the organization of hippocampal mossy fibers in rats Science 211:957-959.