Cognitive scores as a potential diagnostic tool in schizophrenia: The use of raw and discrepancy scores

Abstract

Objective

Cognitive scores could be a useful tool when discriminating between patients with schizophrenia (SZ) and non‐psychiatric population. However, whether these scores can contribute to the accurate diagnosis of the disease is still unclear. Therefore, this study aimed to identify the best approach as to the inclusion of cognitive impairment as a potential clinical tool in the diagnosis of SZ.

Method

A total of 258 patients with SZ and 202 healthy controls (HC) were assessed by means of the Hopkins Verbal Learning Test‐Revised (HVLT‐R) and the Trail Making Test‐A (TMT‐A). In addition to raw scores, participants' discrepancy scores (DS) in these two cognitive measures were calculated using regression‐based norms controlling for age, years of education and premorbid intelligence quotient. Receiver‐operating characteristic analyses were performed for both scores in order to assess their diagnostic properties.

Results

The areas under the curve (AUC) of the HVLT‐R total and delayed recall, and TMT‐A raw scores were statistically significant and ranged from 0.67 to 0.87. Although significant, AUC of verbal memory DS were lower than those of raw scores (AUC = 0.84; AUC = 0.80). AUC of TMT‐A DS was not significant.

Conclusions

Results suggest that cognitive scores are useful and accurate when discriminating and classifying patients with SZ and HC in the present sample. Raw scores were shown to be more accurate than DS in patients with SZ and to present good diagnostic properties especially regarding verbal memory measures. Obtained indices support the use of cognitive scores as diagnostic criterion in the diagnosis of SZ.

Key words:

• assessment
• cognition
• discrepancy scores
• processing speed
• schizophrenia
• verbal memory

Funding information Basic and Applied Investigation Project of the Basque Government, Grant/Award Number: PI_2014_1_43; Department of education, linguistic politics and culture of the Basque Government, Grant/Award Number: PRE_2015_1_0444; Department of Health of the Basque Government, Grant/Award Number: 2011111102

Funding information Basic and Applied Investigation Project of the Basque Government, Grant/Award Number: PI_2014_1_43; Department of education, linguistic politics and culture of the Basque Government, Grant/Award Number: PRE_2015_1_0444; Department of Health of the Basque Government, Grant/Award Number: 2011111102

ACKNOWLEDGEMENT

The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article. This work was supported by the Department of Health of the Basque Government (2011111102); the Basic and Applied Investigation Project of the Basque Government (PI_2014_1_43); and by the Department of education, linguistic politics and culture of the Basque Government (PRE_2015_1_0444). We would like to thank all the patients and participants that have been involved in this study.

Notes

Funding information Basic and Applied Investigation Project of the Basque Government, Grant/Award Number: PI_2014_1_43; Department of education, linguistic politics and culture of the Basque Government, Grant/Award Number: PRE_2015_1_0444; Department of Health of the Basque Government, Grant/Award Number: 2011111102

Additional information

Funding

Basic and Applied Investigation Project of the Basque Government

Department of education, linguistic politics and culture of the Basque Government

Department of Health of the Basque Government