title: Symptomatology and neuropsychological functioning in cannabis using subjects at ultra-high risk for developing psychosis and healthy controls.
abstract: OBJECTIVE
  The relationship between cannabis use and psychosis has been studied intensively. Few data, however, are available on the relationship between cannabis use, ultra-high risk for developing psychosis and neurocognition. The aim of the present cross-sectional study was therefore to investigate the relationship between cannabis use, ultra-high-risk (UHR) symptoms and cognitive functioning in UHR patients and healthy controls.
  
  
  METHODS
  A total of 63 ultra-high-risk patients (34 cannabis users) and 58 control subjects (28 cannabis users) were assessed with clinical measures and a neuropsychological test battery. Patients were eligible for the study if they were between the ages of 12 and 35 years and if they fell into one or more of the following inclusion groups: familial risk and reduced functioning, attenuated psychotic symptoms, brief limited intermittent psychotic symptoms and basic symptoms. Control subjects were eligible for the study if they were between the ages 12 and 35, had no present or past psychiatric illness, no family history of psychiatric illness, no drug use in the non-cannabis-using group, and use of at least four joints per week in the cannabis-using control group.
  
  
  RESULTS
  In the UHR and the control group, cannabis users experienced more basic symptoms and UHR symptoms than the non-cannabis users. Moreover, cannabis users in the control group performed at the level of the UHR subjects on a test of verbal memory and verbal fluency. Frequency of cannabis use correlated with severity of several UHR symptoms.
  
  
  CONCLUSIONS
  Cannabis-using UHR patients have more basic symptoms than non-using patients. In addition, healthy cannabis users have more subclinical UHR and basic symptoms and more neuropsychological dysfunctions than non-cannabis users. More frequent cannabis use was related to increased severity of certain UHR symptoms.
authors.affiliation: Department of Psychiatry, Academic Medical Center, Meibergdreef 5, 1105 AZ Amsterdam, The Netherlands.
authors.forename: Nikie
authors.initials: N
authors.lastname: Korver
authors.forename: Dorien H
authors.initials: DH
authors.lastname: Nieman
authors.forename: Hiske E
authors.initials: HE
authors.lastname: Becker
authors.forename: J Reinaud
authors.initials: JR
authors.lastname: van de Fliert
authors.forename: Peter H
authors.initials: PH
authors.lastname: Dingemans
authors.forename: Lieuwe
authors.initials: L
authors.lastname: de Haan
authors.forename: Mark
authors.initials: M
authors.lastname: Spiering
authors.forename: Nicole
authors.initials: N
authors.lastname: Schmitz
authors.forename: Don H
authors.initials: DH
authors.lastname: Linszen
mesh_terms: D000293:Adolescent; D000328:Adult; D001288:Attention; D003071:Cognition; D015897:Comorbidity; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008297:Male; D002189:Marijuana Abuse / Q000453:epidemiology / Q000523:psychology*; D009483:Neuropsychological Tests; D011379:Prognosis; D011569:Psychiatric Status Rating Scales; D011597:Psychomotor Performance; D011618:Psychotic Disorders / Q000175:diagnosis / Q000453:epidemiology / Q000523:psychology*; D012307:Risk Factors; D012565:Schizophrenic Psychology; D012720:Severity of Illness Index; D055815:Young Adult