Beyond the K-hole: a 3-year longitudinal investigation of the cognitive and subjective effects of ketamine in recreational users who have substantially reduced their use of the drug
Morgan CJ, Monaghan L, Curran HV.
Clinical Psychopharmacology Unit,
University College London, London, UK.
Addiction. 2004 Nov;99(11):1450-61.


RATIONALE: Ketamine is a dissociative anaesthetic that is also a drug of abuse. Previous studies have demonstrated persisting episodic and semantic memory impairments in recreational ketamine users 3 days after taking ketamine. However, the degree to which these deficits might be reversible upon reduction or cessation of ketamine use was not known. OBJECTIVE: To follow-up a population of ketamine users tested 3 years previously and examine whether impairments observed 3 days after drug use are enduring or reversible. METHODS: Eighteen ketamine users and 10 polydrug controls from studies conducted between 3 and 4 years earlier were re-tested on the same battery of cognitive tasks and subjective measures. These tapped episodic, semantic and working memory and executive and attentional functioning. Subjective schizotypal, dissociative, mood and bodily symptoms were also examined and a drug use history recorded. RESULTS: The ketamine users had reduced their frequency of use of ketamine by an average of 88.3%. Performance of ketamine users on tasks tapping semantic memory had improved and this improvement was correlated with their reduction in ketamine use. On tasks tapping episodic memory and attentional functioning, ketamine users still showed deficits compared to polydrug controls. Higher levels of schizotypal symptoms and perceptual distortions were exhibited by the ketamine group, although dissociative symptoms were similar to controls. CONCLUSIONS: These findings indicate that semantic memory impairments associated with recreational ketamine are reversible upon marked reduction of use; however, impairments to episodic memory and possibly attentional functioning appear long-lasting. In addition, schizotypal symptoms and perceptual distortions may persist after cessation of ketamine use. Ketamine users, or potential users, should be aware of the enduring effects of this drug on aspects of memory and subjective experience.

The K-hole
Ketamine: structure
Ketamine and cognition
Anaesthesia and anaesthetics
Ketamine as an antidepressant
Ketamine and opiate withdrawal
Ketamine and the nucleus accumbens
Ketamine: medical and non-medical use
The role of ketamine in pain management
Ketamine and the glutaminergic hypothesis of schizophrenia
Biomarker predicts rapid antidepressant response to ketamine
Low-dose ketamine as a fast-onset, long-acting antidepressant
Anxiolytic and antidepressant properties of ketamine in non-human animals

and further reading

Future Opioids
BLTC Research
Utopian Surgery?
The Abolitionist Project
The Hedonistic Imperative
MDMA: Utopian Pharmacology
Dissociative Anaesthetics: Ketamine
The Good Drug Guide
The Responsible Parent's Guide
To Healthy Mood Boosters For All The Family