Speaking at a seminar entitled 'Addiction and a Changing Society' in Dublin yesterday, McVerry said heroin users know that drug is the road to death but there is no such awareness about cocaine, which is perceived as a 'good time' recreational substance for the middle classes.

"The reality is that cocaine and crack cocaine are drugs that give the user enormous highs and dreadful lows and those who experience the lows can become so disturbed that their aggression levels soar, " he said.