title: Time-based but not event-based prospective memory remains impaired one year after the onset of schizophrenia: A prospective study.
abstract: BACKGROUND
  Prospective memory (PM) deficits have been consistently found in people with schizophrenia. Although there is evidence to suggest that PM deficits may be putative markers for schizophrenia, no longitudinal study has investigated the persistence of PM deficits.
  
  
  OBJECTIVE
  We examined whether PM deficits persist after the onset of schizophrenia, and compared the trajectories of time- and event-based PM performance 12 months after illness onset. We also examined whether the association between PM and clinical symptoms changes over time 12 months after illness onset.
  
  
  METHODS
  We recruited 58 individuals with first-episode schizophrenia for a 12-month follow-up study. Comparison participants were 37 healthy individuals who were matched in terms of demographics and intelligence with the patient group. PM functions and clinical symptoms were measured at baseline, the sixth month, and the twelfth month, using a computerized PM task and the Positive and Negative Syndrome Scale.
  
  
  RESULTS
  People with schizophrenia showed a gradual improvement in both time- and event-based PM 12 months after illness onset. However, compared to event-based PM, deficit in time-based PM persisted and was relatively stable. At baseline, PM functions were not associated with clinical symptoms. However, an association between time-based PM and PANSS positive and general symptoms emerged 12 months after the onset of schizophrenia.
  
  
  CONCLUSIONS
  People with first-episode schizophrenia exhibit persistent time-based PM deficit. Our findings support that PM deficit, in particular, time-based deficit, may be a putative neuropsychological marker of schizophrenia.
authors.affiliation: Castle Peak Hospital, Hong Kong Special Administrative Region. Electronic address: cheungfc@ha.org.hk.
authors.forename: Eric F C
authors.initials: EFC
authors.lastname: Cheung
authors.affiliation: Castle Peak Hospital, Hong Kong Special Administrative Region; Neuropsychology and Applied Cognitive Neuroscience Laboratory, Key Laboratory of Mental Health, Institute of Psychology, Chinese Academy of Sciences, Beijing, China; University of Chinese Academy of Sciences, Beijing, China.
authors.forename: Simon S Y
authors.initials: SSY
authors.lastname: Lui
authors.affiliation: Neuropsychology and Applied Cognitive Neuroscience Laboratory, Key Laboratory of Mental Health, Institute of Psychology, Chinese Academy of Sciences, Beijing, China.
authors.forename: Ya
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Neuropsychology and Applied Cognitive Neuroscience Laboratory, Key Laboratory of Mental Health, Institute of Psychology, Chinese Academy of Sciences, Beijing, China.
authors.forename: Tian-Xiao
authors.initials: TX
authors.lastname: Yang
authors.affiliation: Behavioural Basis of Health Research Program, Griffith Health Institute, Griffith University, Gold Coast, Australia.
authors.forename: David H K
authors.initials: DHK
authors.lastname: Shum
authors.affiliation: Neuropsychology and Applied Cognitive Neuroscience Laboratory, Key Laboratory of Mental Health, Institute of Psychology, Chinese Academy of Sciences, Beijing, China.
authors.forename: Raymond C K
authors.initials: RCK
authors.lastname: Chan
mesh_terms: D000293:Adolescent; D000704:Analysis of Variance; D016009:Chi-Square Distribution; D003430:Cross-Sectional Studies; D018450:Disease Progression; D005260:Female; D006801:Humans; D007361:Intelligence Tests; D008297:Male; D008569:Memory Disorders / Q000209:etiology*; D061212:Memory, Episodic; D009483:Neuropsychological Tests; D011446:Prospective Studies; D011569:Psychiatric Status Rating Scales; D012559:Schizophrenia / Q000150:complications*; D012565:Schizophrenic Psychology; D018709:Statistics, Nonparametric; D013997:Time Factors; D055815:Young Adult
keywords: First-episode; Longitudinal stability; Prospective memory; Schizophrenia