TY - JOUR
T1 - Dedifferentiation and substitute strategy
T2 - Deconstructing the processing-speed impairment in schizophrenia
AU - Knowles, Emma E.M.
AU - Weiser, Mark
AU - David, Anthony S.
AU - Dickinson, Dwight
AU - Glahn, David
AU - Gold, James
AU - Davidson, Michael
AU - Reichenberg, Abraham
PY - 2012/12
Y1 - 2012/12
N2 - Background: Recent research has identified impairment in processing speed, measured by the digit-symbol substitution task, as central to the cognitive deficit in schizophrenia. However, the underlying cognitive correlates of this impairment remain unknown. Methods: A sample of cases (N = 125) meeting DSM-IV criteria for schizophrenia and a sample of community controls (N = 272) from the same geographical area completed a set of putative measures of processing-speed ability to which we implemented confirmatory factor and structural regression modelling in order to elucidate the latent structure of processing speed. Next, we tested the degree to which the structural and relational portions of the model were equal across groups. Results: Processing-speed ability was best defined, in both controls and cases (χ2=38.5926, p=0.053), as a multidimensional cognitive ability consisting of three latent factors comprising: psychomotor speed, sequencing and shifting, and verbal fluency. However, cases exhibited dedifferentiation (i.e., markedly stronger inter-correlations between factors; χ2=59.9429, p<.01) and a reliance on an alternative ensemble of cognitive operations to controls when completing the digit-symbol substitution task. Conclusion: Dedifferentiation of processing-speed ability in schizophrenia and subsequent overreliance on alternative (and possibly less than optimal) cognitive operations underlies the marked deficit observed on the digit-symbol substitution task.
AB - Background: Recent research has identified impairment in processing speed, measured by the digit-symbol substitution task, as central to the cognitive deficit in schizophrenia. However, the underlying cognitive correlates of this impairment remain unknown. Methods: A sample of cases (N = 125) meeting DSM-IV criteria for schizophrenia and a sample of community controls (N = 272) from the same geographical area completed a set of putative measures of processing-speed ability to which we implemented confirmatory factor and structural regression modelling in order to elucidate the latent structure of processing speed. Next, we tested the degree to which the structural and relational portions of the model were equal across groups. Results: Processing-speed ability was best defined, in both controls and cases (χ2=38.5926, p=0.053), as a multidimensional cognitive ability consisting of three latent factors comprising: psychomotor speed, sequencing and shifting, and verbal fluency. However, cases exhibited dedifferentiation (i.e., markedly stronger inter-correlations between factors; χ2=59.9429, p<.01) and a reliance on an alternative ensemble of cognitive operations to controls when completing the digit-symbol substitution task. Conclusion: Dedifferentiation of processing-speed ability in schizophrenia and subsequent overreliance on alternative (and possibly less than optimal) cognitive operations underlies the marked deficit observed on the digit-symbol substitution task.
KW - Cognition
KW - Confirmatory factor modelling
KW - Dedifferentiation
KW - Processing speed
KW - Schizophrenia
UR - http://www.scopus.com/inward/record.url?scp=84869875010&partnerID=8YFLogxK
U2 - 10.1016/j.schres.2012.08.020
DO - 10.1016/j.schres.2012.08.020
M3 - Article
C2 - 23084540
AN - SCOPUS:84869875010
SN - 0920-9964
VL - 142
SP - 129
EP - 136
JO - Schizophrenia Research
JF - Schizophrenia Research
IS - 1-3
ER -