Zajicek, FRCP, PhD (Peninsula
Medical School, Plymouth, UK)
and colleagues expect to report
results this year from a study
exploring whether a cannabis
derivative taken orally can slow
disease progression in 500 people
with primary-progressive and
secondary-progressive MS (the
“CUPID” trial).
Cannabis versus
the immune system
Multiple sclerosis involves
immune system attacks and
inflammation in the brain and
spinal cord. Dr. Pryce’s team,
this time joined by Katarzyna
Maresz, PhD, and Bonnie Dittel,
PhD (Blood Research Institute,
Milwaukee, Wis.) looked at the
possibility that CB1 and CB2
may have immune-regulating
capabilities as well.
MIke MyOGA
The team induced EAE in
mice using immune T cells that
lacked CB2 molecules, and found
that the disease was significantly
more severe in these models.
These results indicate that CB2
controls the extent of inflammation in the CNS during EAE
specifically through its activity
on these immune cells.
In other experiments, the
team administered the cannabis
derivative tetrahydrocannabinol
(THC) to mice lacking CB1.
When CB1 was deficient on
nerve cells, THC did not sup-
press EAE. When CB1 was defi-
cient on T cells, however, THC
did suppress EAE. These results
indicate that CB2 works through
T cells and CB1 works through
nerve cells. Nature Medicine
2007; 13( 4):492– 7
The highs and lows
Unfortunately, it has proven difficult to do carefully controlled
clinical trials because marijuana
is psychoactive and makes people
feel “high.” People taking the
active drug usually become aware
of it—thus “unblinding” the
study and possibly biasing results.
Study participants have often
reported uncomfortable side
effects and smoked marijuana
poses health risks known to be
similar to tobacco. The fact that
marijuana is an illegal drug in
many states and by federal statute
further complicates the issue.
The Society’s National Clinical Advisory Board continues
to examine the use of cannabis
in MS, and finds that there are
currently insufficient data to
recommend marijuana or its
derivatives as a treatment for
MS symptoms. The Society is
also currently funding a carefully
controlled trial of cannabis to
treat MS spasticity. It is recommended that people wait for
evidence from clinical trials and
the possible development of less
dangerous ways to take cannabis products before using them
medicinally.
