Abstract
BackgroundWe previously demonstrated that the high heterogeneity of response to computerized Auditory Training (AT) in psychosis can be ascribed to individual differences in sensory processing efficiency and neural plasticity. In particular, we showed that Auditory Processing Speed (APS) serves as a behavioral measure of target engagement, with faster speed predicting greater transfer effects to untrained cognitive domains. Here, we investigate whether the ability of APS to function as a proxy for target engagement is unique to AT, or if it applies to other training interventions, such as Executive Functioning Training (EFT). Additionally, we examine whether changes in APS are durable after these two forms of training.MethodsOne hundred and twenty-five participants with Recent Onset Psychosis (ROP) were randomized to AT (n = 66) and EFT (n = 59), respectively. APS was captured at baseline, after treatment, and at 6-month follow-up. Mixed models repeated measures analysis with restricted maximum likelihood was used to examine whether training condition differentiated APS trajectories. Within-group correlational analyses were used to study the relationship between APS and performance improvements in each of the training exercises.ResultsThe two groups were matched for age, gender, education, and baseline APS. Participants showed high inter-individual variability in APS at each time point. The mixed model showed a significant effect of time (F = 5.99, p = .003) but not a significant group-by-time effect (F = .73, p = .48). This was driven by significant APS improvements AT patients after treatment (d = .75) that were maintained after 6 months (d = .63). Conversely, in EFT patients, APS improvements did not reach statistical significance after treatment (p = .33) or after 6 months (p = .24). In AT patients, baseline APS (but not APS change) highly predicted peak performance for each training exercise (all r’s >.42).ConclusionsParticipant-specific speed in processing basic auditory stimuli greatly varies in ROP, and strongly influences the magnitude of response to auditory but not executive functioning training. Importantly, enhanced auditory processing efficiency persists 6 months after AT, suggesting the durability of neuroplasticity processes induced by this form of training. Future studies should aim to identify markers of target engagement and durability for cognitive training interventions that target sensory modalities beyond the auditory domain.
Highlights
Uncoordinated neural activity during early sensory processing is well-documented in individuals with schizophrenia early in the course of illness [1,2,3], and among individuals at risk for developing psychosis [4,5,6]
We showed that Auditory Processing Speed (APS): (i) can be reliably measured in patients with schizophrenia undergoing Auditory Training (AT) via a time-order judgment task using frequency-modulated sound stimuli [21, 26, 27]; (ii) significantly improves after 20 h of AT [21, 28, 29], but does not show additional significant changes at 30 or 40 h of training [21, 30]; and (iii) shows a high degree of interindividual variability at baseline, in the steepness of the initial change, and in the efficiency threshold reached after 20 h—indicating heterogeneity both in terms of baseline psychophysical efficiency and in terms of training-induced engagement of prefrontal-temporal neural systems [21]
We found that the faster the APS that is reached after 20 h of training, the greater the transfer effects to untrained cognitive domains—suggesting a significant association between a patient’s ability to reach a threshold of sensory processing efficiency and their degree of cognitive improvement after AT [21]
Summary
Uncoordinated neural activity during early sensory processing is well-documented in individuals with schizophrenia early in the course of illness [1,2,3], and among individuals at risk for developing psychosis [4,5,6]. Impaired early processing operations are known to contribute to widespread neurocognitive-perceptual impairments, including deficits in attention, speed of processing, learning and memory, problem solving, and executive functioning [7]. Albeit heterogeneous, these impairments are observed across the illness course of schizophrenia [8], are present in antipsychotic-naïve firstepisode individuals and in individuals at risk for psychosis [9, 10], and predict the transition from prodromal to first-episode psychosis [11]. We examine whether changes in APS are durable after these two forms of training
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