Cannabis shrinks brain volume: study

Sydney Morning Herald, 4 June 2008
Heavy marijuana use over many years appears to shrink parts of the brain that control emotion and memory, an Australian study shows. Brain scans on 15 men who smoked at least five joints a day for more than a decade show for the first time that they have structural brain abnormalities not seen in non-smokers. The researchers from the University of Melbourne say their findings should settle the historic controversy over the long-term effects of cannabis use with solid proof of the damage it causes. more...

There is some further valuable information here to use when talking with young people about the dangers of marijuana use.