Dr. Scott Payne has told this newspaper that figures show more males (between the ages of 15 and 64) have taken the drug in the last year than in the same period in 2006/7.
The Trust reports that 68 per cent of patients seeking help for their addiction are aged under 18 years.
They, along with 62 per cent of clients aged 18-25 years; and 46 per cent of clients aged 26 years and over reported cannabis as their main problem drug. Sixteen per cent of clients aged 18-25 years and 11 per cent of clients aged 26 years and over reported mephedrone/methedrone as their main problem drug.
Statistics from the Northern Ireland Drug Misuse Database show that 301 patients have been treated for their addiction in the Western Trust area during 2010/11.
And a survey carried out by the Public Health Information and Research Branch states that in the last 12 months 55 per cent of people reported their main problem drug as being cannabis.
Smaller proportions of adults had taken other illegal drugs. Respondents reported using ecstasy (two per cent) and mephedrone and cocaine powder (each one per cent).
Less than one per cent of those surveyed had taken poppers (0.8 per cent) and solvents and methadone (each 0.3 per cent).
Less than one per cent had used anabolic steroids (0.4 per cent).
Over one tenth (11 per cent) of respondents had taken anti-depressants and nine per cent had taken sedatives and/or tranquillisers. A smaller proportion of respondents had taken other opiates (three per cent).
Dr. Payne said help is available for anyone with an addiction to drugs: "We would offer assessment in a non-confrontational way and then offer counselling and talking treatment. Addiction is often seen as a physical dependence, but the main problem is a physiological one."
Statistics from the Northern Ireland Drug Misuse Database for the Western Health and Social Care Trust area in 2010/11.
Number of clients: 301.
Number of clients reporting main drug to be:
Other Opiates 22.
Mean age of clients: 27.
Number of clients ever injected: 10.
Number of clients treated before: 78.