Background: In healthy adults, enhanced overnight motor sequencing task (MST) performance (i.e. number of correctly typed sequences) co-occurs with selective improvement of the least efficient (i.e. slowest) within-sequence transitions. Adults with schizophrenia show poorer overnight improvement in MST performance, though why this occurs is unclear. We re-analyzed data from a recently published report (Mylonas et al., 2020) to determine whether adults with schizophrenia demonstrate impairment in selective overnight improvement for slowest within-sequence transitions.
Methods: 25 adult outpatients with schizophrenia and 29 age- and sex-matched healthy controls completed two experimental sessions, spaced one week apart. During each session, participants trained on a motor sequencing task in the evening, then were tested on the same sequence the following morning. The task involved repeatedly typing a string of 5 numbers (e.g. 4-1-3-2-4) using a computer keyboard. During each session, participants were administered Eszopiclone (3 mg) or placebo 30-mins prior to bedtime. Our main outcomes were improvement in slowest and fastest transitions from (1) the beginning to end of training (training improvement) and (2) the end of training to the beginning of test (overnight improvement). We assessed training and overnight improvement using separate repeated-measures ANOVAs. We evaluated ANOVA interactions with post-hoc t-tests.
Results: Schizophrenia patients and healthy controls showed significant improvement for slowest and fastest transitions across training, though the magnitude of this improvement was greatest for slowest transitions. Only slowest transitions significantly improved across overnight sleep. No significant interactions were observed with drug treatment type.
Conclusions: Absent deficits in overnight MST improvement (reported in Mylonas et al., 2020), both schizophrenia patients and healthy controls exhibited selective improvement for slowest within-sequence transitions. Future work is needed to determine whether this mechanism is disrupted in schizophrenia patients who do not demonstrate equivalent levels of overnight MST performance improvement.
Live Zoom Session – April 21st
Ryan Bottary, MA, Dimitrios Mylonas, PhD, Bryan Baxter, PhD, Dara S. Manoach, PhD