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      Electroencephalographic delta/alpha frequency activity differentiates psychotic disorders: a study of schizophrenia, bipolar disorder and methamphetamine-induced psychotic disorder

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          Abstract

          Electroencephalography (EEG) has been proposed as a neurophysiological biomarker to delineate psychotic disorders. It is known that increased delta and decreased alpha, which are apparent in psychosis, are indicative of inappropriate arousal state, which leads to reduced ability to attend to relevant information. On this premise, we investigated delta/alpha frequency activity, as this ratio of frequency activity may serve as an effective neurophysiological biomarker. The current study investigated differences in delta/alpha frequency activity, in schizophrenia (SCZ), bipolar I disorder with psychotic features and methamphetamine-induced psychosis. One hundred and nine participants, including individuals with SCZ ( n = 28), bipolar I disorder with psychotic features ( n = 28), methamphetamine-induced psychotic disorder (MPD) ( n = 24) and healthy controls (CON, n = 29). Diagnosis was ascertained with the Structured Clinical Interview for Diagnostic and Statistical Manual of Mental Disorders, 4th Edition disorders and current medication was recorded. EEG was undertaken in three testing conditions: resting eyes open, resting eyes closed and during completion of a simple cognitive task (visual continuous performance task). EEG delta/alpha frequency activity was investigated across these conditions. First, delta/alpha frequency activity during resting eyes closed was higher in SCZ and MPD globally, when compared to CON, then lower for bipolar disorder (BPD) than MPD for right hemisphere. Second, delta/alpha frequency activity during resting eyes open was higher in SCZ, BPD and MPD for all electrodes, except left frontal, when compared to CON. Third, delta/alpha frequency activity during the cognitive task was higher in BPD and MPD for all electrodes, except left frontal, when compared to CON. Assessment of EEG delta/alpha frequency activity supports the delineation of underlying neurophysiological mechanisms present in psychotic disorders, which are likely related to dysfunctional thalamo-cortical connectivity. Delta/alpha frequency activity may provide a useful neurophysiological biomarker to delineate psychotic disorders.

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          The positive and negative syndrome scale (PANSS) for schizophrenia.

          L Opler, Jennifer Kay, Paul Opler … (1986)
          The variable results of positive-negative research with schizophrenics underscore the importance of well-characterized, standardized measurement techniques. We report on the development and initial standardization of the Positive and Negative Syndrome Scale (PANSS) for typological and dimensional assessment. Based on two established psychiatric rating systems, the 30-item PANSS was conceived as an operationalized, drug-sensitive instrument that provides balanced representation of positive and negative symptoms and gauges their relationship to one another and to global psychopathology. It thus constitutes four scales measuring positive and negative syndromes, their differential, and general severity of illness. Study of 101 schizophrenics found the four scales to be normally distributed and supported their reliability and stability. Positive and negative scores were inversely correlated once their common association with general psychopathology was extracted, suggesting that they represent mutually exclusive constructs. Review of five studies involving the PANSS provided evidence of its criterion-related validity with antecedent, genealogical, and concurrent measures, its predictive validity, its drug sensitivity, and its utility for both typological and dimensional assessment.
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            High-resolution EEG mapping of cortical activation related to working memory: effects of task difficulty, type of processing, and practice.

            A Gevins, M. E. Smith, L. McEvoy … (1997)
            Changes in cortical activity during working memory tasks were examined with electroencephalograms (EEGs) sampled from 115 channels and spatially sharpened with magnetic resonance imaging (MRI)-based finite element deblurring. Eight subjects performed tasks requiring comparison of each stimulus to a preceding one on verbal or spatial attributes. A frontal midline theta rhythm increased in magnitude with increased memory load. Dipole models localized this signal to the region of the anterior cingulate cortex. A slow (low-frequency), parietocentral, alpha signal decreased with increased working memory load. These signals were insensitive to the type of stimulus attribute being processed. A faster (higher-frequency), occipitoparietal, alpha signal was relatively attenuated in the spatial version of the task, especially over the posterior right hemisphere. Theta and alpha signals increased, and overt performance improved, after practice on the tasks. Increases in theta with both increased task difficulty and with practice suggests that focusing attention required more effort after an extended test session. Decreased alpha in the difficult tasks indicates that this signal is inversely related to the amount of cortical resources allocated to task performance. Practice-related increases in alpha suggest that fewer cortical resources are required after skill development. These results serve: (i) to dissociate the effects of task difficulty and practice; (ii) to differentiate the involvement of posterior cortex in spatial versus verbal tasks; (iii) to localize frontal midline theta to the anteromedial cortex; and (iv) to demonstrate the feasibility of using anatomical MRIs to remove the blurring effect of the skull and scalp from the ongoing EEG. The results are discussed with respect to those obtained in a prior study of transient evoked potentials during working memory.
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              Reliability and validity of a depression rating scale for schizophrenics.

              Donald Addington, Jean Addington, Eleanor Maticka-Tyndale … (1992)
              The Calgary Depression Scale (CDS) is a nine item structured interview scale, in which each item has a four point measure, each point anchored by descriptors. The scale has been specifically developed to assess depression in schizophrenics. This article describes the testing of the reliability and validity of the CDS. The scale is assessed and compared to three established measures, the Hamilton Depression Rating Scale (HDRS) the Beck Depression Inventory (BDI) and a depression measure derived from the Brief Psychiatric Rating Scale (BPRS). Confirmatory factor analysis demonstrated that the CDS is unidimensional, measuring the same construct in both in- and outpatients. The scale has high internal consistency, significant strong correlations with scores on the Hamilton, Beck and BPRS depression measures, and the presence of a major depressive episode. All items of the CDS significantly discriminate between the presence and absence of a major depressive episode. It is concluded that the CDS is a parsimonious reliable scale which is suitable for assessing depression across both the acute and residual stages of schizophrenia.
              Article 0 comments Cited 113 times – based on 0 reviews     Review now
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                Author and article information

                Contributors
                Fleur M Howells: +27(0)21 404 5480 , howellsfleur@gmail.com
                Journal
                Journal ID (nlm-ta): Transl Psychiatry
                Journal ID (iso-abbrev): Transl Psychiatry
                Title: Translational Psychiatry
                Publisher: Nature Publishing Group UK (London )
                ISSN (Electronic): 2158-3188
                Publication date (Electronic): 12 April 2018
                Publication date PMC-release: 12 April 2018
                Publication date Collection: 2018
                Volume: 8
                Electronic Location Identifier: 75
                Affiliations
                [1 ]ISNI 0000 0004 1937 1151, GRID grid.7836.a, Department of Psychiatry and Mental Health, , University of Cape Town, ; Cape Town, South Africa
                [2 ]ISNI 0000 0004 1937 1151, GRID grid.7836.a, Neuroscience Institute, , University of Cape Town, ; Cape Town, South Africa
                [3 ]ISNI 0000 0004 1936 9297, GRID grid.5491.9, Clinical and Experimental Sciences, , University of Southampton, ; Southampton, UK
                [4 ]ISNI 0000 0004 1937 1151, GRID grid.7836.a, MRC Unit on Risk and Resilience in Mental Disorders, Department of Psychiatry and Mental Health, , University of Cape Town, ; Cape Town, South Africa
                Article
                Publisher ID: 105
                DOI: 10.1038/s41398-018-0105-y
                PMC ID: 5895848
                PubMed ID: 29643331
                SO-VID: 614519a6-34ed-45d5-b1a9-39a293b73ce1
                Copyright © © The Author(s) 2018
                License:

                Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/.

                History
                Date received : 5 September 2017
                Date revision received : 29 November 2017
                Date accepted : 13 December 2017
                Categories
                Subject: Review
                Custom metadata
                issue-copyright-statement © The Author(s) 2018

                ScienceOpen disciplines: Clinical Psychology & Psychiatry
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                ScienceOpen disciplines: Clinical Psychology & Psychiatry

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