By BBC News
Drug-related deaths in Scotland have almost doubled in eight years, with 934 recorded in 2017 - up from 545 in 2009.
The Scottish government spent more than £740m on tackling problem drug and alcohol use between 2008 and 2018 but Audit Scotland said "there is still much to do to reduce deaths".
Most drug-related deaths are caused by heroin, according to the findings.
The use of psychoactive substances such as Spice "has largely reduced among the general population" since it was made illegal, Audit Scotland found, although it remains a "problematic" issue in prisons.
More than three-quarters of deaths due to drugs in 2017 were of people aged 35 and over, up from 54% in 2009 to 76%.