EEG Microstate Differences in Medicated vs. Medication-Naïve First-Episode Psychosis Patients

Abstract

There has been considerable interest in the role of synchronous brain activity abnormalities in the pathophysiology of psychotic disorders and their relevance for treatment; one index of such activity are EEG resting-state microstates. These reflect electric field configurations of the brain that persist over 60–120 ms time periods. A set of quasi-stable microstates classes A, B, C, and D have been repeatedly identified across healthy participants. Changes in microstate parameters coverage, duration and occurrence have been found in medication-naïve as well as medicated patients with psychotic disorders compared to healthy controls. However, to date, only two studies have directly compared antipsychotic medication effects on EEG microstates either pre- vs. post-treatment or between medicated and unmedicated chronic schizophrenia patients. The aim of this study was therefore to directly compare EEG resting-state microstates between medicated and medication-naïve (untreated) first-episode (FEP) psychosis patients (mFEP vs. uFEP). We used 19-channel clinical EEG recordings to compare temporal parameters of four prototypical microstate classes (A–D) within an overall sample of 47 patients (mFEP n = 17; uFEP n = 30). The results demonstrated significant decreases of microstate class A and significant increases of microstate class B in mFEP compared to uFEP. No significant differences between groups were found for microstate classes C and D. Further studies are needed to replicate these results in longitudinal designs that assess antipsychotic medication effects on neural networks at the onset of the disorder and over time during illness progression. As treatment response and compliance in FEP patients are relatively low, such studies could contribute to better understand treatment outcomes and ultimately improve treatment strategies.

Large-scale EEG neural network changes in response to therapeutic TMS

“…Most of our patients continued on multiple psychotropic medications, including antidepressant agents, during their courses of TMS. While it has not been specifically investigated, the use of psychotropic medications may impact microstates associated with specific patterns (53). While representing an important subset of the general depression patient population, the characteristics of our naturalistically treated sample may limit comparisons of the current findings to those previously reported.…”

EEG microstate features for schizophrenia classification

“…Microstate analysis was performed under several psychiatric conditions (e.g., sleep [31], anxiety disorder [32], mood disorder [33], and neurodegenerative disorder [34][35][36]. In particular, the characteristic microstate change has been investigated [8,24,[37][38][39][40][41][42][43][44] and the change in microstates C and D has been well-known [45][46][47] in schizophrenia. These studies have been performed in various areas related to schizophrenia, such as clinical symptoms [38,39,43,48], genetic vulnerability [40], and medication [42] as well as presence of disease [24,36,37,44].…”

“…In particular, the characteristic microstate change has been investigated [ 8 , 24 , 37 – 44 ] and the change in microstates C and D has been well-known [ 45 – 47 ] in schizophrenia. These studies have been performed in various areas related to schizophrenia, such as clinical symptoms [ 38 , 39 , 43 , 48 ], genetic vulnerability [ 40 ], and medication [ 42 ] as well as presence of disease [ 24 , 36 , 37 , 44 ]. Recently, the potential as a state and trait biomarker has been reported that can suggest the progress [ 49 ] and genetic underpinnings [ 41 ] of illness.…”

EEG Microstates and Its Relationship With Clinical Symptoms in Patients With Schizophrenia

“…In addition, a study found that microstate class B could be used to distinguish patients with first-episode psychosis from high-risk individuals with and without later transition to psychosis (36) and proposed that microstate class B might be a state biomarker underlying the progression of psychosis. However, some studies had shown the opposite effect (18,37) in medicated patients, which was attributed to the effect of antipsychotic drugs on microstates. This effect can also be used to explain our findings, since more than half of the subjects with schizophrenia were medication-free.…”