title: Differentiation between deviant trajectory planning, action planning, and reduced psychomotor speed in schizophrenia.
abstract: BACKGROUND
  Abnormal psychomotor behaviour in schizophrenia might be based on separate deficits. Here we studied the relationship between trajectory planning, action planning, psychomotor speed, and indices of cognitive functioning in a large group of stabilised patients with schizophrenia.
  
  
  METHODS
  Sixty-one patients and 30 controls were tested. Trajectory planning was assessed in a graphic task in which sequences of single lines, gradually changing in direction, had to be drawn. Shifts to a comfortable drawing direction reflect anticipatory trajectory planning. Action planning was evaluated in a task in which figures varying in complexity and familiarity had to be copied. Psychomotor speed was measured by use of a simple line copying task. Measures of information processing speed, attention, working memory, and problem solving were derived from neuropsychological tests.
  
  
  RESULTS
  Patients much more often opted for the unusual bottom-to-top direction to draw the vertical lines in the drawing task. They changed the line orientation less often than the controls did. In the patient group, these trajectory planning indices did not correlate with measures of action planning, psychomotor speed, or neuropsychological test scores.
  
  
  CONCLUSIONS
  Deviant trajectory planning strongly characterises schizophrenia, and is independent from action planning deficits and reduced psychomotor speed.
authors.affiliation: Collaborative Antwerp Psychiatric Research Institute (CAPRI), Antwerp, Belgium. sofie.houthoofd@ua.ac.be
authors.forename: Sofie
authors.initials: S
authors.lastname: Houthoofd
authors.forename: Manuel
authors.initials: M
authors.lastname: Morrens
authors.forename: Wouter
authors.initials: W
authors.lastname: Hulstijn
authors.forename: Bernard
authors.initials: B
authors.lastname: Sabbe
mesh_terms: D000328:Adult; D059031:Anticipation, Psychological / Q000502:physiology; D001696:Biomechanical Phenomena; D003071:Cognition / Q000502:physiology; D039721:Diagnostic and Statistical Manual of Mental Disorders; D005260:Female; D006801:Humans; D008297:Male; D009483:Neuropsychological Tests; D009949:Orientation; D011597:Psychomotor Performance / Q000502:physiology*; D012565:Schizophrenic Psychology