HIGH AS A KITE

A review of: Cannabis and Cognitive Functioning by Nadia Solowij, Cambridge
University Press

It'S official: marijuana does change your brain.

Luckily for the many millions of people worldwide who use the drug, the rot
is so limited that only a very subtle neurological test can detect it. But
the longer you smoke marijuana, the worse it gets.

We know this from a neat series of experiments by Nadia Solowij, a young
Australian researcher, whose work is reported for the first time in her
monograph Cannabis and Cognitive Functioning. She also critically reviews
other studies, and is well aware of the difficulties of delivering hard
facts. How can you do controlled psychological studies when the effects are
so slight?

Another problem is that people who choose to smoke marijuana (usually
illegally) may be psychologically different from those who don't.

Solowij has found a way of separating the dope smokers from the abstemious.
Using a method widely employed in brain research, her subjects listen to
tones through headphones and hit a button when they hear one of particular
location (left or right ear), pitch and length.

Marijuana smokers pass easier tests of how well they focus their attention
with flying colours, but not this one. They make more mistakes, even though
they are not under the drug's influence at the time. Analysis of their brain
waves during the test shows that dope smokers are not as good at filtering
out distracting information.

We don't know how important this impairment might be in real life. But we do
have a few hard facts which, as Solowij concludes, might help people to
"make an informed decision about whether to use the drug and, if they use,
how much, how long and how often". Everyone with a serious interest in the
marijuana debate should have a copy of this book, for its thorough review of
the topic and for its new data.

Alun Anderson is New Scientist's editor

Checked-by: "Rolf Ernst"