Cognitive impairments in poly-drug ketamine users

• Published in: Addictive behaviors Vol. 38; no. 11; pp. 2661 - 2666
• Main Authors: Liang, H.J, Lau, C.G, Tang, A, Chan, F, Ungvari, G.S, Tang, W.K
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.11.2013; Elsevier Science Ltd
• Subjects: Anesthesia; Anxiety; Anxiety - psychology; Case-Control Studies; Cognition Disorders - chemically induced; Cognitive function; Depression - psychology; Drug use; Excitatory Amino Acid Antagonists - adverse effects; Executive function; Executive Function - drug effects; Female; Humans; Ketamine; Ketamine - adverse effects; Male; Memory; Memory Disorders - chemically induced; Memory, Short-Term - drug effects; Mental depression; Mental Recall - drug effects; Psychiatry; Recall; Recognition (Psychology) - drug effects; Substance abuse; Substance-Related Disorders - psychology; Young Adult; Executive function; Substance abuse; Ketamine; Cognitive function; Memory
• ISSN: 0306-4603; 1873-6327
• DOI: 10.1016/j.addbeh.2013.06.017

Abstract Rationale Cognitive impairment has been found to be reversible in people with substance abuse, particularly those using ketamine. Ketamine users are often poly-substance users. This study compared the cognitive functions of current and former ketamine users who were also abusing other psychoactive substances with those of non-users of illicit drugs as controls. Methods One hundred ketamine poly-drug users and 100 controls were recruited. Drug users were divided into current (n = 32) and ex-users (n = 64) according to the duration of abstinence from ketamine (> 30 days). The Beck Depression Inventory (BDI), the Hospital Anxiety Depression Scale (HADSA) and the Severity of Dependence Scale (SDS) were used to evaluate depression and anxiety symptoms and the severity of drug use, respectively. The cognitive test battery comprised verbal memory (Wechsler Memory Scale III: Logic Memory and Word List), visual memory (Rey–Osterrieth Complex Figure, ROCF), executive function (Stroop, Wisconsin Card Sorting Test, and Modified Verbal Fluency Test), working memory (Digit Span Backward), and general intelligence (Information, Arithmetic and Digit-Symbol Coding) tests. Results Current users had higher BDI and HADSA scores than ex-users (p < 0.001 for BDI and p = 0.022 for HADSA) and controls (p < 0.001 for BDI and p = 0.002 for HADSA). Ex-users had higher BDI (p = 0.006) but equal HADSA scores (p = 1.000) compared to controls. Both current and ex-users had lower scores on Logical Memory delayed recall (p = 0.038 for current users and p = 0.032 for ex-users) and ROCF delayed recall (p = 0.033 for current users and p = 0.014 for ex-users) than controls. Current users also performed worse on ROCF recognition than controls (p = 0.002). No difference was found between the cognitive functions of current and ex-users. Conclusions Ketamine poly-drug users displayed predominantly verbal and visual memory impairments, which persisted in ex-users. The interactive effect of ketamine and poly-drug use on memory needs further investigation.