Researchers undertook to find out whether psychoactive substance use increased in New York after the tragic events of 11 September 2001. The first phase of the study was carried out in October 2001. A random sample of 988 people was examined. The second phase of the survey was conducted 6 months later, this time on a group of 854 people. The survey was conducted using a telephone survey method - people were asked about their drinking and smoking habits before and after 11 September. The results indicate that the use of psychoactive substances increased in New York after 9/11.

One month after the events, 30 per cent of respondents consumed more alcohol than before and smoked more cigarettes and marijuana. Six months later, this figure had dropped to 27%. Higher rates of psychoactive substance use than before 11 September persisted even after the symptoms of post-traumatic stress disorder had disappeared in respondents