Performance Differences of a Touch-Based Serial Reaction Time Task in Healthy Older Participants and Older Participants With Cognitive Impairment on a Tablet: Experimental Study.

BACKGROUND: Digital neuropsychological tools for diagnosing neurodegenerative diseases in the older population are becoming more relevant and widely adopted because of their diagnostic capabilities. In this context, explicit memory is mainly examined. The assessment of implicit memory occurs to a lesser extent. A common measure for this assessment is the serial reaction time task (SRTT). OBJECTIVE: This study aims to develop and empirically test a digital tablet-based SRTT in older participants with cognitive impairment (CoI) and healthy control (HC) participants. On the basis of the parameters of response accuracy, reaction time, and learning curve, we measure implicit learning and compare the HC and CoI groups. METHODS: A total of 45 individuals (n=27, 60% HCs and n=18, 40% participants with CoI-diagnosed by an interdisciplinary team) completed a tablet-based SRTT. They were presented with 4 blocks of stimuli in sequence and a fifth block that consisted of stimuli appearing in random order. Statistical and machine learning modeling approaches were used to investigate how healthy individuals and individuals with CoI differed in their task performance and implicit learning. RESULTS: Linear mixed-effects models showed that individuals with CoI had significantly higher error rates (b=-3.64, SE 0.86; z=-4.25; P<.001); higher reaction times (F1,41=22.32; P<.001); and lower implicit learning, measured via the response increase between sequence blocks and the random block (ß=-0.34; SE 0.12; t=-2.81; P=.007). Furthermore, machine learning models based on these findings were able to reliably and accurately predict whether an individual was in the HC or CoI group, with an average prediction accuracy of 77.13% (95% CI 74.67%-81.33%). CONCLUSIONS: Our results showed that the HC and CoI groups differed substantially in their performance in the SRTT. This highlights the promising potential of implicit learning paradigms in the detection of CoI. The short testing paradigm based on these results is easy to use in clinical practice.

Quetiapine and flupentixol differentially improve anterior cingulate cortex function in schizophrenia patients: an event-related potential study.

Atypical antipsychotic agents are a frequently and effectively used treatment in schizophrenia and psychotic disorders. Other than conventional antipsychotics, which mainly exert their pharmacological effect in subcortical dopaminergic systems, atypical antipsychotics additionally affect partly serotonergically innervated structures within prefrontal areas, such as the anterior cingulate cortex (ACC). However, only few controlled, randomized studies have so far investigated direct and indirect effects of atypical antipsychotics on the ACC and, up until now, no clinical investigation has exclusively addressed the specific effects of quetiapine on ACC function. The present study assessed ACC function in 18 quetiapine-medicated patients and 13 flupentixol-treated patients suffering from schizophrenia by means of the error-related negativity (ERN), a neurophysiological marker of ACC function, in a pre-post design. Between-group comparisons revealed different effects of quetiapine and flupentixol on ACC function despite similar improvement in psychopathology, cognitive performance and quality of life. Whereas atypical treatment was associated with an increase in amplitudes over time, there were prolonged ERN peak latencies in patients treated with the typical agent. Moreover, treatment effects depended on baseline prefrontal cortex function in both groups. We conclude that both flupentixol and quetiapine improve prefrontal function especially in patients with weak initial ACC function which might be due to their shared affinity for serotonin receptors in frontal brain regions. However, since this affinity is more pronounced for quetiapine, patients treated with quetiapine seemed to profit more evidently concerning their prefrontal cortex function compared to patients of the flupentixol group, who exhibited a compensatory prolongation of processes.