title: Shared impairment in associative learning in schizophrenia and bipolar disorder.
abstract: BACKGROUND
  Schizophrenia (SCZ) and bipolar disorder (BD) share some cognitive commonalities. However, the role of associative learning, which is a cornerstone of human cognition mainly relying on hippocampus, has been under-investigated. We assessed behavioral performance during associative learning in a group of SCZ, BD and healthy controls (HC).
  
  
  METHODS
  Nineteen patients with SCZ (36 ± 8.1 years; 13 males, 6 females; all Caucasians), 14 patients with BD (41 ± 9.6 years; 5 males, 9 females; all Caucasians) and 45 HC (27.7 ± 6.9 years; 18 males, 27 females; all Caucasians) were studied. Learning was assessed using an established object-location paired-associative learning paradigm. Subjects learned associations between nine equi-familiar common objects and locations in a nine-location grid. Performance data were analyzed in a repeated measures analysis of variance with time (repeated) and group as factors.
  
  
  RESULTS
  Learning curves (performance = (1-e(-k x time)) fitted to average performance data in the three groups revealed lower learning rates in SCZ and BD (k = 0.17 and k = 0.34) than HC (k = 0.78). Significant effects of group (F = 11.05, p < 0.001) and time (F = 122.06, p < 0.001) on learning performance were observed.
  
  
  CONCLUSIONS
  Our study showed that associative learning is impaired in both SCZ and BD, being potentially not affected by medication. Future studies should investigate the neural substrates of learning deficits in SCZ and BD, particularly focusing on hippocampus function and glutamatergic transmission.
authors.affiliation: DISM, Inter-University Centre for Behavioural Neurosciences, University of Udine, Udine, Italy. paolo.brambilla@uniud.it
authors.forename: Paolo
authors.initials: P
authors.lastname: Brambilla
authors.forename: Stefania
authors.initials: S
authors.lastname: Cerruti
authors.forename: Marcella
authors.initials: M
authors.lastname: Bellani
authors.forename: Cinzia
authors.initials: C
authors.lastname: Perlini
authors.forename: Adele
authors.initials: A
authors.lastname: Ferro
authors.forename: Veronica
authors.initials: V
authors.lastname: Marinelli
authors.forename: Daniele
authors.initials: D
authors.lastname: Giusto
authors.forename: Luisa
authors.initials: L
authors.lastname: Tomelleri
authors.forename: Gianluca
authors.initials: G
authors.lastname: Rambaldelli
authors.forename: Michele
authors.initials: M
authors.lastname: Tansella
authors.forename: Vaibhav A
authors.initials: VA
authors.lastname: Diwadkar
mesh_terms: D000328:Adult; D000375:Aging / Q000523:psychology; D001245:Association Learning / Q000502:physiology*; D001714:Bipolar Disorder / Q000523:psychology*; D003627:Data Interpretation, Statistical; D039721:Diagnostic and Statistical Manual of Mental Disorders; D005260:Female; D006624:Hippocampus / Q000502:physiology; D006801:Humans; D007360:Intelligence; D008297:Male; D011939:Mental Recall / Q000502:physiology; D009473:Neuronal Plasticity / Q000187:drug effects; D011597:Psychomotor Performance / Q000502:physiology; D012565:Schizophrenic Psychology; D012691:Serial Learning / Q000502:physiology