TY - JOUR
T1 - Memory generalization is selectively altered in the psychosis dimension
AU - Ivleva, Elena I.
AU - Shohamy, Daphna
AU - Mihalakos, Perry
AU - Morris, David W.
AU - Carmody, Thomas
AU - Tamminga, Carol A.
N1 - Funding Information:
This work was supported by National Institute of Mental Health (MH077851-01A1, Bipolar & Schizophrenia Consortium for Parsing Endophenotypes), NARSAD/The Brain and Behavior Research Fund John Kennedy Harrison 2010 Young Investigator Award, and APF/Kempf Fund for Research Development in Psychobiological Psychiatry 2011 Award. The NIMH, NARSAD/The Brain and Behavior Research, and APF/Kempf Fund had no further role in study design; in the collection, analysis and interpretation of data; in the writing of the report; and in the decision to submit the manuscript for publication.
PY - 2012/6
Y1 - 2012/6
N2 - Global deficits in declarative memory are commonly reported in individuals with schizophrenia and psychotic bipolar disorder, and in their biological relatives. However, it remains unclear whether there are specific components within the global declarative memory dysfunction that are unique to schizophrenia and bipolar disorder, or whether these impairments overlap the two psychoses. This study sought to characterize differential components of learning and memory in individuals within the psychosis dimension: probands with schizophrenia (SZP, n = 33), probands with psychotic bipolar I disorder (BDP, n = 20), and biological relatives of SZP (SZR, n = 21), contrasted with healthy controls (HC, n = 26). A computerized cognitive paradigm, the Acquired Equivalence test, with probes for associative learning, memory for learned associations, and memory generalization was administered, along with standardized neuropsychological measures of declarative memory. All study groups were able to learn and remember the associations, although SZP were slower than HC in the initial learning stages. Both SZP (significantly) and BDP (at a trend level) showed altered memory generalization compared to HC (SZP vs. HC, p= .038, d= .8; BDP vs. HC, p= .069, d= .95). SZR showed memory generalization intermediate between SZP and HC, although their performance did not differ significantly from either group. These findings indicate that probands with schizophrenia and bipolar psychoses have similar alteration in the ability to flexibly generalize learned knowledge when probed with novel stimuli, despite overall sufficient associative learning and memory for what they learned. These results suggest that the two disorders present a clinical continuum with overlapping hippocampus-mediated memory generalization dysfunction underlying the psychosis phenotype.
AB - Global deficits in declarative memory are commonly reported in individuals with schizophrenia and psychotic bipolar disorder, and in their biological relatives. However, it remains unclear whether there are specific components within the global declarative memory dysfunction that are unique to schizophrenia and bipolar disorder, or whether these impairments overlap the two psychoses. This study sought to characterize differential components of learning and memory in individuals within the psychosis dimension: probands with schizophrenia (SZP, n = 33), probands with psychotic bipolar I disorder (BDP, n = 20), and biological relatives of SZP (SZR, n = 21), contrasted with healthy controls (HC, n = 26). A computerized cognitive paradigm, the Acquired Equivalence test, with probes for associative learning, memory for learned associations, and memory generalization was administered, along with standardized neuropsychological measures of declarative memory. All study groups were able to learn and remember the associations, although SZP were slower than HC in the initial learning stages. Both SZP (significantly) and BDP (at a trend level) showed altered memory generalization compared to HC (SZP vs. HC, p= .038, d= .8; BDP vs. HC, p= .069, d= .95). SZR showed memory generalization intermediate between SZP and HC, although their performance did not differ significantly from either group. These findings indicate that probands with schizophrenia and bipolar psychoses have similar alteration in the ability to flexibly generalize learned knowledge when probed with novel stimuli, despite overall sufficient associative learning and memory for what they learned. These results suggest that the two disorders present a clinical continuum with overlapping hippocampus-mediated memory generalization dysfunction underlying the psychosis phenotype.
KW - Bipolar disorder
KW - Generalization memory
KW - Hippocampus
KW - Psychosis
KW - Schizophrenia
UR - http://www.scopus.com/inward/record.url?scp=84861526732&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84861526732&partnerID=8YFLogxK
U2 - 10.1016/j.schres.2012.04.004
DO - 10.1016/j.schres.2012.04.004
M3 - Article
C2 - 22551681
AN - SCOPUS:84861526732
SN - 0920-9964
VL - 138
SP - 74
EP - 80
JO - Schizophrenia Research
JF - Schizophrenia Research
IS - 1
ER -