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Biol Psychiatry. 2014 Sep 15;76(6):456-65. doi: 10.1016/j.biopsych.2013.12.008. Epub 2013 Dec 24.

Resting state electroencephalogram oscillatory abnormalities in schizophrenia and psychotic bipolar patients and their relatives from the bipolar and schizophrenia network on intermediate phenotypes study.

Author information

  • 1Olin Neuropsychiatry Research Center, Hartford Hospital (IOL campus), Hartford, Connecticut. Electronic address:
  • 2Olin Neuropsychiatry Research Center, Hartford Hospital (IOL campus), Hartford, Connecticut.
  • 3Department of Electrical and Computer Engineering, University of New Mexico, Albuquerque, New Mexico.
  • 4Department of Psychology, University of Georgia, Athens, Georgia.
  • 5Department of Psychiatry, UT Southwestern Medical School, Dallas, Texas.
  • 6Department of Psychiatry, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts.
  • 7Olin Neuropsychiatry Research Center, Hartford Hospital (IOL campus), Hartford, Connecticut; Department of Psychiatry and Neurobiology, Yale University School of Medicine, New Haven, Connecticut.



Abnormal resting state electroencephalogram (EEG) oscillations are reported in schizophrenia (SZ) and bipolar disorder, illnesses with overlapping symptoms and genetic risk. However, less evidence exists on whether similar EEG spectral abnormalities are present in individuals with both disorders or whether these abnormalities are present in first-degree relatives, possibly representing genetic predisposition for these disorders.


Investigators examined 64-channel resting state EEGs of 225 SZ probands and 201 first-degree relatives (SZR), 234 psychotic bipolar (PBP) probands and 231 first-degree relatives (PBPR), and 200 healthy control subjects. Eight independent resting state EEG spectral components and associated spatial weights were derived using group independent component analysis. Analysis of covariance was conducted on spatial weights to evaluate group differences. Relative risk estimates and familiality were evaluated on abnormal spectral profiles in probands and relatives.


Both SZ and PBP probands exhibited increased delta, theta, and slow and fast alpha activity. Post-hoc pair-wise comparison revealed increased frontocentral slow beta activity in SZ and PBP probands as well as SZR and PBPR. Augmented frontal delta activity was exhibited by SZ probands and SZR, whereas PBP probands and PBPR showed augmented fast alpha activity.


Both SZ and PBP probands demonstrated aberrant low-frequency activity. Slow beta activity was abnormal in SZ and PBP probands as well as SZR and PBPR perhaps indicating a common endophenotype for both disorders. Delta and fast alpha activity were unique endophenotypes for SZ and PBP probands, respectively. The EEG spectral activity exhibited moderate relative risk and heritability estimates, serving as intermediate phenotypes in future genetic studies for examining biological mechanisms underlying the pathogenesis of the two disorders.


Bipolar disorder; EEG; intermediate phenotypes; psychosis; resting state; schizophrenia

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