STUDIES WEED OUT THE GOOD NEWS AND BAD

Smoking marijuana will not cause long-term harm to your brain but it could
have an impact on your time perception, two US research papers released
yesterday reported.

University of California researchers said that though marijuana causes
short-term harm to memory and learning - part of the brain's selective
memory functions - it does not cause permanent brain damage.

"If there is an effect, it is very small," said Igor Gray, a professor of
psychiatry who led the study of well-educated young people to assess the
long-term impact of the drug on adults' neurocognitive abilities.

California approved a law in 1996 that allows doctors to prescribe cannabis
for some patients. A number of US studies are examining the effects of
cannabis and its use as a medicinal drug.

Meanwhile, University of Georgia scientists have shown, for the first time,
that marijuana really does alter time perception, and most likely makes
people more dangerous at the wheel of a vehicle and slower to respond in
conversations - assuming that the behaviour of stoned rats offers clues
about humans.

The scientists trained rats to tell the difference between short and long
bursts of sound. If the sound was short, rats that pressed the right lever
got a pellet of food. The animals had to press the other lever if the sound
was long.

Once the rodents were stoned, however, they could no longer concentrate
enough to press the feeder levers.