Publications · 2017
The Processing-Speed Impairment in Psychosis Is More Than Just Accelerated Aging
Schizophrenia Bulletin , 43(4):814-823 , 2017 · doi:10.1093/schbul/sbw168
Overview
Comparing 51 patients with psychotic illness to 90 IQ-matched controls (all African American) on a digit-symbol coding task analyzed via drift-diffusion modeling, this study tested whether the processing-speed deficit in psychosis is the same phenomenon as age-related slowing. It is not: psychosis lowered information-processing efficiency, while normal aging primarily increased response caution, indicating divergent cognitive mechanisms.
Abstract
Processing speed is impaired in patients with psychosis, and deteriorates as a function of normal aging. These observations, in combination with other lines of research, suggest that psychosis may be a syndrome of accelerated aging. But do patients with psychosis perform poorly on tasks of processing speed for the same reasons as older adults? Fifty-one patients with psychotic illnesses and 90 controls with similar mean IQ (aged 19-69 years, all African American) completed a computerized processing-speed task, reminiscent of the classic digit-symbol coding task. The data were analyzed using the drift-diffusion model (DDM), and Bayesian inference was used to determine whether psychosis and aging had similar or divergent effects on the DDM parameters. Psychosis and aging were both associated with poor performance, but had divergent effects on the DDM parameters. Patients had lower information-processing efficiency ("drift rate") and longer nondecision time than controls, and psychosis per se did not influence response caution. By contrast, the primary effect of aging was to increase response caution, and had inconsistent effects on drift rate and nondecision time across patients and controls. The results reveal that psychosis and aging influenced performance in different ways, suggesting that the processing-speed impairment in psychosis is more than just accelerated aging. This study also demonstrates the potential utility of computational models and Bayesian inference for finely mapping the contributions of cognitive functions on simple neurocognitive tests.
Topics
- psychosis
- schizophrenia
- processing speed
- drift-diffusion model
- Bayesian inference
- cognitive aging
How to cite
Mathias SR, Knowles EM, Barrett J, Leach O, Buccheri S, Beetham T, Blangero J, Poldrack RA, Glahn DC. The Processing-Speed Impairment in Psychosis Is More Than Just Accelerated Aging. Schizophrenia Bulletin, 43(4):814-823; 2017. doi:10.1093/schbul/sbw168
Show BibTeX
@article{mathias2017theprocessing,
title = {{The Processing-Speed Impairment in Psychosis Is More Than Just Accelerated Aging}},
author = {Mathias, S. R. and Knowles, E. M. and Barrett, J. and Leach, O. and Buccheri, S. and Beetham, T. and Blangero, J. and Poldrack, R. A. and Glahn, D. C.},
journal = {Schizophrenia Bulletin},
year = {2017},
volume = {43},
number = {4},
pages = {814--823},
doi = {10.1093/schbul/sbw168},
url = {https://doi.org/10.1093/schbul/sbw168},
abstract = {Processing speed is impaired in patients with psychosis, and deteriorates as a function of normal aging. These observations, in combination with other lines of research, suggest that psychosis may be a syndrome of accelerated aging. But do patients with psychosis perform poorly on tasks of processing speed for the same reasons as older adults? Fifty-one patients with psychotic illnesses and 90 controls with similar mean IQ (aged 19-69 years, all African American) completed a computerized processing-speed task, reminiscent of the classic digit-symbol coding task. The data were analyzed using the drift-diffusion model (DDM), and Bayesian inference was used to determine whether psychosis and aging had similar or divergent effects on the DDM parameters. Psychosis and aging were both associated with poor performance, but had divergent effects on the DDM parameters. Patients had lower information-processing efficiency ("drift rate") and longer nondecision time than controls, and psychosis per se did not influence response caution. By contrast, the primary effect of aging was to increase response caution, and had inconsistent effects on drift rate and nondecision time across patients and controls. The results reveal that psychosis and aging influenced performance in different ways, suggesting that the processing-speed impairment in psychosis is more than just accelerated aging. This study also demonstrates the potential utility of computational models and Bayesian inference for finely mapping the contributions of cognitive functions on simple neurocognitive tests.},
keywords = {psychosis; schizophrenia; processing speed; drift-diffusion model; Bayesian inference; cognitive aging}
}