PERILS OF CANNABIS

Medical Briefing By Dr Thomas Stuttaford

It is only a matter of days before the Home Secretary will be advised by
his experts to downgrade the status of cannabis from a class B to a class C
drug, reports last weekend suggested.

It seems that the rationale behind this decision is based on policing
rather than medicine. The argument that cannabis is a harmless drug is now
heard less often. However, at the Lib Dems' conference there were a few
supporters of the scientifically unsound belief that, even if not totally
harmless to an individual, it was likely to do less damage than alcohol or
tobacco. It is unfortunately unlikely in most cannabis smokers to be a
question of either/or -- but both. Neither tobacco nor alcohol has the
potential for inducing a psychotic breakdown (to all intents and purposes
schizophrenia) in those who are genetically vulnerable.

Any increased use of cannabis is likely to be reflected by a rise in the
incidence of schizophrenia. It is fortunate that just when there are
proposed changes in the law on cannabis it is possible to see through the
eyes of Professor John Forbes Nash (courtesy of Russell Crowe in A
Beautiful Mind) the blight that schizophrenia can inflict on a promising
career. Whatever the shortcomings in the film (experts thought the
harrowing features of the case were understated), Crowe continues to
harvest awards (he won the coveted Best Film Actor at the Screen Actors
Guild this week).

Doctors are still wondering about the visual hallucinations, which in the
film Nash experienced during schizophrenic episodes. The classic
hallucinations of schizophrenia are auditory -- voices rather than visions
- -- and although visual and olfactory hallucinations occur in schizophrenia,
they are considerably less common than voices. The kindly explanation is
that the licence the scriptwriter took in substituting visual for the
auditory hallucinations in the book was justified as it was the best way to
depict the mental confusion that any sort of hallucination can induce.

In the book Nash did not have visual hallucinations. He was plagued only by
voices. Whether the change was a cinematic device is immaterial as it has
conveyed to those who have seen the film the tangled hell created in a
patient's mind by hallucinations and delusions. To the patients, the voices
in their heads are as real as if they were listening to someone in the room.

Functional Magnetic Resonance Imaging (MRI) studies of a brain's activity
during hallucinations shows that the parts of the brain which normally deal
with hearing light up in the way they would if someone was talking to the
patient. The orders that the inner voices give may be as commanding as any
shouted by a sergeant major, and their advice may be as persuasive as that
of the most silver-tongued QC.

Another symptom of schizophrenia which has received attention recently is
the loss of intellect that is usually associated with each psychotic
breakdown. Experts estimate that an IQ is reduced on average by about ten
points by each relapse. A paper published in a recent issue of
Schizophrenia Research has reported evidence, which confirms clinical
observation, that the new atypical antipsychotics help a patient to retain
their intellect better than the old-fashioned antipsychotics.

In a double-blind, multicentred study patients with schizophrenia were
either treated with haloperidol or with Seroquel, a comparatively new
atypical antipsychotic. Those given Seroquel showed a greater overall
improvement in intellect than those on haloperidol, which was introduced
more than 35 years ago.

When memory, verbal fluency and attention span were tested individually,
they were found to have been better preserved in those patients taking
Seroquel. Retention of these abilities makes it easier for a person with
schizophrenia to fit into the community more readily.

Fortunately Seroquel is no more likely than a placebo to cause involuntary
muscular movements and facial grimacing, and in the long term does not
induce the other side-effect that has previously been the bugbear of all
treatment for schizophrenia -- weight gain.