title: Clinical correlates of parametric digit-symbol substitution test in schizophrenia.
abstract: Processing speed deficit, ascertained by digit-symbol substitution test (DSST), is considered as a fundamental impairment in schizophrenia. Clinical correlates of processing speed abnormalities, especially using the parametric version of DSST is yet to be evaluated comprehensively. In this study, we examined schizophrenia patients (N=66) and demographically matched healthy controls (N=72) using computer-administered parametric DSST (pDSST) with fixed (pDSSTF) as well as random (pDSSTR) conditions and analysed the relationship between pDSST performance and clinical symptoms. Psychopathology was assessed using Scale for Assessment of Positive Symptoms (SAPS)/Negative Symptoms (SANS) with good inter-rater reliability. In comparison with healthy controls, patients demonstrated significantly lesser number of correct responses (CN) in pDSSTF (t=8.0; p<0.001) and pDSSTR (t=7.8; p<0.001) as well as significantly prolonged reaction time in pDSSTF (t=7.1; p<0.001) and pDSSTR (t=7.0; p<0.001). The difference in CN between pDSSTF and pDSSTR [ΔCN] was significantly lesser in patients than healthy controls (t=2.61; p=0.01). The pDSST reaction time had significant positive correlation with negative syndrome scores as well as bizarre behaviour score. Significantly greater processing speed deficits in pDSST suggest potential relational memory/visual scanning abnormalities in schizophrenia. Furthermore, pDSST deficits demonstrated a significant association with the psychopathology, especially with the various negative symptoms and bizarre behaviour.
authors.affiliation: Department of Psychiatry, National Institute of Mental Health & Neurosciences (NIMHANS), Bangalore, India; Translational Psychiatry Laboratory, Cognitive Neurobiology Division, Neurobiology Research Centre, National Institute of Mental Health & Neurosciences, Bangalore, India.
authors.forename: Anekal C
authors.initials: AC
authors.lastname: Amaresha
authors.affiliation: Department of Psychiatry, National Institute of Mental Health & Neurosciences (NIMHANS), Bangalore, India; Translational Psychiatry Laboratory, Cognitive Neurobiology Division, Neurobiology Research Centre, National Institute of Mental Health & Neurosciences, Bangalore, India.
authors.forename: Vijay
authors.initials: V
authors.lastname: Danivas
authors.affiliation: Department of Psychiatry, National Institute of Mental Health & Neurosciences (NIMHANS), Bangalore, India; Translational Psychiatry Laboratory, Cognitive Neurobiology Division, Neurobiology Research Centre, National Institute of Mental Health & Neurosciences, Bangalore, India.
authors.forename: Venkataram
authors.initials: V
authors.lastname: Shivakumar
authors.affiliation: Department of Psychiatry, National Institute of Mental Health & Neurosciences (NIMHANS), Bangalore, India; Translational Psychiatry Laboratory, Cognitive Neurobiology Division, Neurobiology Research Centre, National Institute of Mental Health & Neurosciences, Bangalore, India.
authors.forename: Sri Mahavir
authors.initials: SM
authors.lastname: Agarwal
authors.affiliation: Department of Psychiatry, National Institute of Mental Health & Neurosciences (NIMHANS), Bangalore, India; Translational Psychiatry Laboratory, Cognitive Neurobiology Division, Neurobiology Research Centre, National Institute of Mental Health & Neurosciences, Bangalore, India.
authors.forename: Sunil V
authors.initials: SV
authors.lastname: Kalmady
authors.affiliation: Department of Psychiatry, National Institute of Mental Health & Neurosciences (NIMHANS), Bangalore, India; Translational Psychiatry Laboratory, Cognitive Neurobiology Division, Neurobiology Research Centre, National Institute of Mental Health & Neurosciences, Bangalore, India.
authors.forename: Janardhanan C
authors.initials: JC
authors.lastname: Narayanaswamy
authors.affiliation: Department of Psychiatry, National Institute of Mental Health & Neurosciences (NIMHANS), Bangalore, India; Translational Psychiatry Laboratory, Cognitive Neurobiology Division, Neurobiology Research Centre, National Institute of Mental Health & Neurosciences, Bangalore, India. Electronic address: venkat.nimhans@yahoo.com.
authors.forename: Ganesan
authors.initials: G
authors.lastname: Venkatasubramanian
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D000328:Adult; D002135:Calcium-Binding Proteins; D003072:Cognition Disorders / Q000150:complications* / Q000523:psychology; D016326:Extracellular Matrix Proteins; D005260:Female; D006801:Humans; D008297:Male; D008565:Membrane Proteins; D009483:Neuropsychological Tests; D011930:Reaction Time / Q000502:physiology*; D015203:Reproducibility of Results; D012559:Schizophrenia / Q000150:complications*; D012565:Schizophrenic Psychology
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D002135:Calcium-Binding Proteins; D016326:Extracellular Matrix Proteins; D008565:Membrane Proteins; C469999:SCUBE2 protein, human
keywords: Cognitive deficits; Negative symptoms; Processing speed; Schizophrenia