title: Cognitive impairments in poly-drug ketamine users.
abstract: BACKGROUND
  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.
authors.affiliation: Department of Psychiatry, Chinese University of Hong Kong, Hong Kong, China.
authors.forename: H J
authors.initials: HJ
authors.lastname: Liang
authors.forename: C G
authors.initials: CG
authors.lastname: Lau
authors.forename: A
authors.initials: A
authors.lastname: Tang
authors.forename: F
authors.initials: F
authors.lastname: Chan
authors.forename: G S
authors.initials: GS
authors.lastname: Ungvari
authors.forename: W K
authors.initials: WK
authors.lastname: Tang
mesh_terms: D001007:Anxiety / Q000523:psychology; D016022:Case-Control Studies; D003072:Cognition Disorders / Q000139:chemically induced*; D003863:Depression / Q000523:psychology; D018691:Excitatory Amino Acid Antagonists / Q000009:adverse effects*; D056344:Executive Function / Q000187:drug effects; D005260:Female; D006801:Humans; D007649:Ketamine / Q000009:adverse effects*; D008297:Male; D008569:Memory Disorders / Q000139:chemically induced*; D008570:Memory, Short-Term / Q000187:drug effects; D011939:Mental Recall / Q000187:drug effects; D021641:Recognition, Psychology / Q000187:drug effects; D019966:Substance-Related Disorders / Q000523:psychology*; D055815:Young Adult
chemical_list: D018691:Excitatory Amino Acid Antagonists; D007649:Ketamine
keywords: Cognitive function; Executive function; Ketamine; Memory; Substance abuse