DRUG use among adults aged over 16 has fallen over the past three years but the use of substances formerly referred to as legal highs has grown.

New figures in the Scottish Crime and Justice Survey show a "statistically significant" overall drop in drug use from 7.6% of those interviewed in 2008-9, compared to 6.6% in 2010-11. The results are taken from a questionnaire completed by 10,999 people.

As well as the annual figures, the proportion of adults taking drugs in the last month of each year dropped from 4.4% to 3.5%.

However, more than one in 10 of those who admitted to taking drugs said they had tried new illicit substances such as mephedrone, which was formerly a "legal high". Almost 5% of men aged 16 to 24 had taken mephedrone in the past year.

The survey also showed that one in four adults in Scotland has taken drugs at some point in their lives.

Cannabis is the most commonly reported drug, followed by amphetamines, ecstasy and cocaine.

Men are more likely to take drugs than women, according to the self-reported findings.

Community Safety Minister Roseanna Cunningham said: "I believe a better general understanding of the risks associated with taking drugs is contributing to the fall.

"Since 2007-08 we have directly invested £5.43 million in our ambitious substance misuse prevention programme.

"Another important factor is the concerted efforts of law enforcement agencies across Scotland to disrupt the supply of drugs into our communities."

The survey was published at the same time as official statistics on drug and alcohol treatment waiting times.

The latest figures show almost 85% of the 11,006 waiting for treatment between October and December 2011 were seen within three weeks.