The number of people who have a mental illness and are abusing drugs is rising sharply in England and Wales, according to research.
Drug abuse and mental illness rates were higher for men
A study by Keele University researchers
suggested that between 1993 and 1998, the numbers rose from 23,624 to 37,361 - an increase of 62%.
They looked at figures from doctors on the General Practice Research Database.
The link between drugs and depression, psychosis and schizophrenia has been highlighted by anti-drugs campaigners.
Researchers writing in the Journal of Epidemiology and Community Health found the rate of mental illness and substance abuse was up by 62% at 230 general practices between 1993 and 1998.
Men were much more likely to be affected, with their rates up 79%, compared with 44% in women.
Patients aged 16-84 were included in the study, which looked at the abuse of prescription and illegal drugs, but not alcohol and tobacco.
The study looked at about 3 per cent of people in England and Wales.
The average age of someone affected fell from 38 to 34, and the number of cases in the 25-34 age group more than doubled, from 6,874 to 13,240.
Certain types of mental illness saw a bigger growth. Psychosis and drug abuse was up 147%, paranoia 144% and schizophrenia 128%.
Cliff Prior, chief executive of the mental health charity Rethink said: "There is a rapidly growing body of evidence showing that drug use can trigger mental illness in people already at risk.
"However the mental health risks associated with drugs are not widely understood by most young people and more resources need to be put into mental health warnings on the use of drugs.
"A long-term, well-funded, innovative campaign aimed at publicising the real mental health risks associated with drugs including cannabis needs to be in place as soon as possible."