- Substance abuse: People with severe alcohol or drug abuse are not included. Possible abuse is monitored both by interviewing participants and by taking a urine sample at inclusion and at 4, 12 and 52 weeks follow-up (if there is suspicion of substance abuse), testing for the presence of cocaine, amphetamine, cannabis, opiates, metamfetamine (inclusive for extacy), and benzodiazepines. When severe abuse is suspected during the trial, an ad hoc urine sample is taken. Brief periods of large alcohol/cannabis intake are not a cause of exclusion from the trial; however, cognitive and other examinations are not carried out while patients are under the influence of drugs or alcohol.