Pubdate: July 11, 1998 Source: New Scientist (UK) Contact: http://www.newscientist.com/ Author: Alun Anderson 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"