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Nongenetic Pathologic Developments of Brain-Wave Patterns

Within-Pair EEG Concordance in Healthy Twins

The within-pair EEG concordance of monozygotic (mz) twins is found to be typically as high as r = 0.81 across channels and frequency bands, thus being comparable to that between repeated assessments on the same individual with r = 0.83. Yet our previous investigation into mz twins discordant and concordant for schizophrenia yielded a significantly reduced within-pair EEG concordance for both, the pairs discordant for schizophrenia and the pairs concordant for schizophrenia.

Twins with Schizophrenia

For the within-pair correlation of the global EEG parameter "total power 0-32 Hz", for example, we found a value of r = 0.772 for the healthy twins which is typical of normal mz twins, a reduced value of r = 0.513 for the twins discordant for schizophrenia, and an extremely low correlation of r = 0.210 for the twins concordant for schizophrenia. This marked reduction of within-pair concordance was with 0.488/0.189 [2-5 Hz], 0.484/0.388 [5-8 Hz], 0.642/0.507 [8-12 Hz] and 0.147/0.544 [12-16 Hz] equally true for all power-related EEG parameters in the pairs concordant for schizophrenia.

Affected versus Unaffected Co-Twins

The pairs discordant for schizophrenia displayed a reduction of within-pair concordance for the EEG parameters "centroid" and "symmetry" which measure the power-frequency distribution of frequency bands: 0.258/0.123 [2-5 Hz], 0.294/0.317 [5-8 Hz] and 0.411/0.560 [8-12 Hz]. ANOVAs supported the above results. Specifically, the total EEG power [0-32 Hz] was virtually identical in the healthy co-twins (p > 0.8402), but different between affected and unaffected subjects (p < 0.0001). The severity of illness, as derived from EEG-differences between affected and unaffected subjects, was closely related to the severity of illness as provided by psychopathology syndrome scores.

EEG Anomalies

Consequently, EEG anomalies associated with schizophrenia and manifested differently in the mz co-twins concordant for schizophrenia are likely the effect of nongenetic, pathologic processes that evolved independently in the co-twins’ genetically identical brains once the illness began to progress.

References

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myriel

Fig. 25: Myriel is a longterm schizophrenic patient whose powerful language, as expressed through her prose and poems, enthrall and fascinate the reader instantaneously. A similar fascination emanates from her paintings and drawings. Thus, her individual suffering, reflected through the power of artistic expression, becomes a depiction of the schizophrenic disorders of the self in general.
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