Recreational Drugs

Research into the effects of recreational drugs on cognition is hampered by several factors, most especially the fact that use of a drug is usually confounded with the taking of other recreational drugs, including nicotine and alcohol, and other lifestyle factors that may in themselves be associated with impaired memory. Moreover, while you can try your hardest to match your drug users with controls that are like the users in all aspects except that of substance abuse, without neurocognitive data on their brains and cognitive performance before they began taking drugs, you cannot be sure that any damage or impairment seen is a consequence, and not a precursor.

In the light of these problems, it is not surprising that the evidence for the effects of recreational drugs on cognition is inconsistent.

See separate pages for



Cocaine & amphetamines

Older news items (pre-2010) brought over from the old website

Heavy use of ketamine impairs memory

A large-scale, year-long study following 150 people of whom 30 were heavy users of the illegal drug ketamine (K, Special K) , 30 were 'recreational' (once or twice a month), 30 were former users, 30 were users of other illicit drugs, and 30 did not use any illicit drugs, has found that heavy ketamine users were impaired in verbal memory, working memory, and visual memory. Although there was no sign of impairment in the recreational users and former users, all ketamine users showed evidence of unusual beliefs or mild 'delusions', the degree of which depended on amount of the drug used. Ketamine use is increasing faster than any other drug in the UK.

[1484] Morgan CJA, Muetzelfeldt L, Curran VH. Consequences of chronic ketamine self-administration upon neurocognitive function and psychological wellbeing: a 1-year longitudinal study. Addiction [Internet]. 2009 ;9999(9999). Available from:

Computer-assisted cognitive rehabilitation improves substance-abuse treatment response

"Brain exercises" originally developed for the rehabilitation of head-injury patients have been found to improve the cognitive functioning of individuals in substance-abuse treatment and their commitment to the treatment program. Those who participated in the computer-assisted cognitive rehabilitation exercises stayed in treatment significantly longer than others and twice as many of them "graduated" from treatment. The exercises are designed to improve cognitive functioning with tasks that focus on impaired skills (such as memory and attention) through repetition. Impaired memory and attention have been linked to poorer retention and results in treatment.

Grohman, K. & Fals-Stewart, W. 2003. Computer-Assisted Cognitive Rehabilitation with Substance-Abusing Patients: Effects on Treatment Response. The Journal of Cognitive Rehabilitation, 21 (4)