Quantitative electroencephalography as a biomarker for proneness toward developing psychosis

Abstract

The fully dimensional approach to the relationship between schizotypal personality traits and schizophrenia describes schizotypy as a continuum throughout the general population ranging from low schizotypy (LoS) and psychological health to high schizotypy (HiS) and psychosisproneness. However, no biological markers have yet been discovered that reliably quantify an individual's degree of schizotypy and/or psychosis. This study aimed to evaluate quantitative electroencephalographic (qEEG) measures of power spectra as potential biomarkers of the proneness towards the development of psychosis in schizotypal individuals. The resting-state oscillatory brain dynamics under eyes-closed condition from 16 LoS and 16 HiS individuals were analysed for qEEG measures of background rhythm frequency, relative power in δ, θ, low-α, high-α, low-β, high-β and low-γ frequency bands, and the high-temporal crosscorrelation of power spectra between low-and high-frequency bands observed by averaging signals from whole-head EEG electrodes. HiS individuals at rest locked the thalamocortical loop in the low-α band at a lower-frequency oscillation and displayed an abnormally high level of neural synchronisation. In addition, the high-α band was found to be positively correlated with both the high-β and low-γ bands unlike LoS individuals, indicating widespread thalamocortical resonance in HiS individuals. The increase of regional alpha oscillations in HiS individuals suggests abnormal high-level attention, whereas the pattern of correlation between frequency bands resembles the thalamocortical dysrhythma phenomenon which underlies the symptomatology of a variety of neuropsychiatric disorders including schizophrenia. These qEEG biomarkers may aid clinicians in identifying HiS individuals with a high-risk of developing psychosis.

Gamma band oscillations in the early phase of psychosis: A systematic review

“…In the resting state, Fuggetta, Bennett et al (2014) reported decreased spontaneous power in subjects with high schizotypy (though this was not statistically significant), while Tcheslavski (2008) reported increased power and Tcheslavski and Beex (2010) reported increased phase synchrony.…”

“…Eight studies examined gamma in relation to schizotypy, comprising a total of 223 participants (Table 5). Five studies (Vernon, Haenschel et al 2005, Tcheslavski 2008, Tcheslavski and Beex 2010, Fuggetta, Bennett et al 2014 divided healthy volunteers into two groups based on their scores on a schizotypy scale, 2 (Skosnik, Krishnan et al 2006, Kornmayer, Leicht et al 2015 correlated measures of gamma with schizotypy scores of healthy volunteers and one (Brenner, Sporns et al 2003) compared people with schizotypal personality disorder to healthy controls. The Schizotypy Personality Questionnaire (Raine 1991) was used to measure schizotypy in 7 studies (Vernon, Haenschel et al 2005, Skosnik, Krishnan et al 2006, Tcheslavski 2008, Tcheslavski and Beex 2010, Kornmayer, Leicht et al 2015, while Fuggetta, Bennett et al…”

Topographic deficits in alpha-range resting EEG activity and steady state visual evoked responses in schizophrenia

“…Previous studies have suggested that both the spectral power in the alpha band and the slowing of the alpha frequency peak are clinically and functionally relevant parameters in schizophrenia (Jin et al, 2000;Gaspar et al, 2011;Abeles and Gomez-Ramirez, 2014;Fuggetta et al, 2014). Thus, correlational analyses focusing on alpha power and Fig.…”

“…Post-hoc tests showed significantly lower power in SZ relative to HC within this frequency band. Given the possibility of a slowing in spontaneous EC alpha peak frequency reported in prior studies (Jin, et al, 2000;Fuggetta, et al, 2014), the average frequency of individual peaks was evaluated ( Supplementary Fig. 2).…”

Source-Space Cross-Frequency Amplitude-Amplitude Coupling in Tinnitus

“…Electrophysiologically, the prediction can be investigated by analysing cross-frequency amplitude-amplitude coupling (AAC) [ 11 ], that is, correlations between signal amplitudes at two different frequencies f 1 and f 2 in the time-frequency spectrum. Empirical support for an increase in AAC has indeed been found in a number of studies and across various neurological conditions, both in comparison of patients to healthy controls (e.g., various conditions related to TCD [ 11 , 22 ], schizotypy [ 23 ]) and in pre-post intervention studies (e.g., various conditions related to TCD treated by central lateral thalamotomy [ 24 ]; phantom limb pain treated by deep brain stimulation [ 25 ]). However, in a study of obsessive-compulsive disorder, significant coupling between the delta (1–3 Hz) and beta (13–30 Hz) bands as well as between theta and beta was found only for the controls but not the patients [ 26 ].…”