title: Delusional disorder and schizophrenia: a comparison of the neurocognitive and clinical characteristics in first-episode patients.
abstract: BACKGROUND
  Delusional disorder (DD) is thought to be distinct from schizophrenia (SZ). However, few systematic investigations have been conducted on DD because of the difficulty in ascertaining a representative sample size. Existing knowledge has been mostly generated from inpatient cohorts, which may be biased towards a more severe sample.
  
  
  METHODS
  We compared the demographic, clinical and cognitive differences between 71 patients with first-episode DD and 71 age-matched patients with first-episode SZ. Participants were consecutively recruited from a population-based territory-wide study of early psychosis in Hong Kong targeting first-episode psychosis. Basic demographic information, premorbid functioning, duration of untreated psychosis, pathways to care, symptomatology, social, occupational, and cognitive functioning were comprehensively assessed using standardized measurements.
  
  
  RESULTS
  Patients with DD had less premorbid schizoid and schizotypal traits compared to patients with SZ. More patients with DD were married compared to patients with SZ. However, at first episode, there were no significant differences between the two groups in regards to the duration of untreated psychosis, pathways to care, symptom severity, neurocognitive performance, treatment, and functioning.
  
  
  CONCLUSIONS
  Our findings challenge previous thinking that patients with DD had better functioning than patients with SZ. This study not only provides an updated perspective into conceptualizing the clinical differences between DD and SZ, but also expands the descriptive account of the two disorders to include the neurocognitive dimension.
authors.affiliation: Department of Psychiatry,University of Hong Kong,Hong Kong SAR,China.
authors.forename: C L M
authors.initials: CL
authors.lastname: Hui
authors.affiliation: Department of Psychiatry,University of Hong Kong,Hong Kong SAR,China.
authors.forename: E H M
authors.initials: EH
authors.lastname: Lee
authors.affiliation: Department of Psychiatry,University of Hong Kong,Hong Kong SAR,China.
authors.forename: W C
authors.initials: WC
authors.lastname: Chang
authors.affiliation: Department of Psychiatry,University of Hong Kong,Hong Kong SAR,China.
authors.forename: S K W
authors.initials: SK
authors.lastname: Chan
authors.affiliation: Department of Psychiatry,University of Hong Kong,Hong Kong SAR,China.
authors.forename: J
authors.initials: J
authors.lastname: Lin
authors.affiliation: Department of Psychiatry,University of Hong Kong,Hong Kong SAR,China.
authors.forename: J Q
authors.initials: JQ
authors.lastname: Xu
authors.affiliation: Department of Psychiatry,University of Hong Kong,Hong Kong SAR,China.
authors.forename: E Y H
authors.initials: EY
authors.lastname: Chen
mesh_terms: D000328:Adult; D003071:Cognition; D003430:Cross-Sectional Studies; D003702:Delusions; D005260:Female; D000066505:Help-Seeking Behavior; D006801:Humans; D007578:Jealousy; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests; D011569:Psychiatric Status Rating Scales; D012559:Schizophrenia / Q000175:diagnosis* / Q000503:physiopathology; D012563:Schizophrenia, Paranoid / Q000175:diagnosis* / Q000503:physiopathology
keywords: Delusional disorder; first episode; neurocognition; schizophrenia