HW: Various

[Nick Medford]

On Fri, 2 Jul 2004 13:41:57 +0100, M Holmes <fofp at HOLYROOD.ED.AC.UK> wrote:

>Sure.  As I said, about 3% of the population can be regarded as
>pre-schizophrenic

Not sure where you get this figure. Schizophrenia affects approx 0.8% of
the population, though the rates in "at-risk" populations (e.g. the Afro-
Caribbean population of the UK) can be much higher (as much as 10 times
higher in one study).

"Pre-schizophrenic" is a nebulous and difficult concept. Certainly family
history is relevant, but in the absence of any definite evidence on the
genetic factors, one can't really put a figure on that. It is estimated
that the heritability of schizophrenia (i.e. the degree to which it can be
attributed to genetic factors, which is not at all the same thing as the
likelihood of developing it if you have a family history) is around 45%,
but this is of no value in trying to predict whether a particular
individual will develop the disorder. There are also certain constellations
of personality traits (notably "schizotypal personality disorder") that
have been claimed to predispose people to schizophrenia, but the evidence
is inevitably rather circumstantial, and the supposed prevalence of this
personality style varies wildly from study to study.

>and LSD is one of the things that can tip those people
>over the edge.

This, interestingly enough, has never actually been proven, although I
think you are right to presume that it must be true.

Amphetamines, on the other hand, are well-known for producing a psychosis
that is pretty much indistinguishable from schizophrenia.

>
>What's been interesting recently is that there's been a moral panic due to
>some research claims that regular use of strong cannabis can induce
>similar effects. It's appeared in the press as "Cannabis Psychosis"
>stories involving "super skunk" and "marijuana ten times as strong as
>their parents used in the 60's". It doesn't seem to be hard to find
>doctors who'll say that the incidence of admission for this reason is up,
>and it wouldn't be exactly easy to compare the strength of cannabis now
>to 40 years ago.

It's not impossible- cannabis denatures very slowly, and in any case there
is data from the 60s which can be compared with the present day. I know of
two well-conducted studies which have concluded that yes, cannabis has got
stronger overall, and one of them did indeed mention *one* exceptional
sample which was  "ten times as strong as the 60s" - naturally the media
seized on this and reported it as being the present-day norm, which it
almost certainly isn't. But it seems likely that the expansion of interest
in growing techniques, hybridisation, etc, will have produced more potent
strains.

As for the link between cannabis and psychosis- it is established beyond
all reasonable doubt that if you *already* have a serious mental illness,
cannabis use is likely to be very bad news indeed, and significantly
increases your chances of relapse. What's more controversial is whether
cannabis can, in and of itself, *cause* psychosis. A recent paper reviewing
the evidence concluded that it is indeed a risk factor, but..."cannabis use
appears to be neither a sufficient nor a necessary cause for psychosis. It
is a component cause, part of a complex constellation of factors leading to
psychosis". Just like almost everything else that has been identified as a
risk factor, in other words.

Personally I don't find it hard to believe that heavy use of mind-altering
drugs can alter your mind in a lasting way, particularly when certain other
conditions are satisfied. Indeed it seems very unlikely to me that it could
really be otherwise.

Of course, what has (to my knowledge) *never* been studied is the
possibility that moderate use of cannabis may have *beneficial* effects on
some people's mental health, which also strikes me as entirely plausible.

Going back to Syd Barrett, I read (admittedly in a Sunday newspaper rather
than anywhere scientifically reputable) that he has never been given any
formal psychiatric diagnosis, and never been sectioned. I got the
impression that while he surely does have his problems, he is not quite the
acid-fried casualty of popular myth. There again, I also remember Dave
Gilmour saying in an interview that after Syd's burnout, he (Gilmour) only
took acid a couple more times, as "Syd was a walking example of why not
to". So who knows.

cheers

Nick