Preserved Learning during the Symbol–Digit Substitution Test in Patients with Schizophrenia, Age-Matched Controls, and Elderly

Abstract

Objective: Speed of processing, one of the main cognitive deficits in schizophrenia is most frequently measured with a digit–symbol-coding test. Performance on this test is additionally affected by writing speed and the rate at which symbol–digit relationships are learned, two factors that may be impaired in schizophrenia. This study aims to investigate the effects of sensorimotor speed, short-term learning, and long-term learning on task performance in schizophrenia. In addition, the study aims to explore differences in learning effects between patients with schizophrenia and elderly individuals.Methods: Patients with schizophrenia (N = 30) were compared with age-matched healthy controls (N = 30) and healthy elderly volunteers (N = 30) during the Symbol–Digit Substitution Test (SDST). The task was administered on a digitizing tablet, allowing precise measurements of the time taken to write each digit (writing time) and the time to decode symbols into their corresponding digits (matching time). The SDST was administered on three separate days (day 1, day 2, day 7). Symbol–digit repetitions during the task represented short-term learning and repeating the task on different days represented long-term learning.Results: The repetition of the same symbol–digit combinations within one test and the repetition of the test over days resulted in significant decreases in matching time. Interestingly, these short-term and long-term learning effects were about equal among the three groups. Individual participants showed a large variation in the rate of short-term learning. In general, patients with schizophrenia had the longest matching time whereas the elderly had the longest writing time. Writing time remained the same over repeated testing.Conclusion: The rate of learning and sensorimotor speed was found to have a substantial influence on the SDST score. However, a large individual variation in learning rate should be taken into account in the interpretation of task scores for processing speed. Equal learning rates among the three groups suggest that unintentional learning in schizophrenia and in the elderly is preserved. These findings are important for the design of rehabilitation programs for schizophrenia.

Altered cerebellar‐cerebral functional connectivity in benign adult familial myoclonic epilepsy

“…The neuropsychological assessments included the following: (1) severity of myoclonus, Unified Myoclonus Rating Scale (UMRS); (2) severity of tremor, Fahn‐Tolosa‐Marin Tremor Rating Scale (FTRS); and (3) global cognitive function, Chinese version of Mini Mental State Examination (MMSE) . In addition, we used the following assessments to evaluate executive functions and attention: Trail‐Making Test part‐A (TMTA) and part‐B (TMTB), Digit Symbol Test (DST), and Verbal Fluency Test (VFT, Animal Naming) …”

Cognitive Processing Speed across the Lifespan: Beyond the Influence of Motor Speed

“…Neuropsychological testing has traditionally assessed processing speed across the lifespan with paper-and-pencil tests such as the Symbol Search and Coding tasks from the Information Processing Speed Index of the Wechsler Adult Intelligence Scale (WAIS) (Wechsler, 2008) i.e., Cornelis et al (2014), Joy et al (2004), and Kreiner and Ryan (2001). Such tests are reported to measure working memory, psychomotor and visuomotor processing speed, visual discrimination and attention; See Holdnack et al (2013) and Wechsler (2008).…”

Cognitive training improves the disturbed behavioral architecture of schizophrenia-like rats, “Wisket”

“…However, the eating time in the Wisket rats were longer than controls until the last day, which was due, at least partially, to the fact that the first visit into a box delayed. In this respect, it is interesting to note that processing speed is the domain that accounts for most of the differences in the neurocognitive performance between schizophrenia patients and healthy controls [34][35][36].…”