Quantifying the psychological effects of ketamine: from euphoria to the k-Hole.

52 ketamine users were "opportunistically" recruited to take part in a survey of the psychological effects of the drug, in Manchester, United Kingdom in 2008. Twenty-seven ketamine-naïve respondents were also recruited for comparison in respect of "other" recreational drug use and level of schizotypy. Ketamine users attributed a wide range of appetitive, aversive, after-effect, and dissociative experiences to the drug. They also reported using a much wider range of other recreational drugs than ketamine non-users. Former users reported significantly fewer positive or dissociative experiences than current users.