Cordance Explained

Cordance, a measure of brain activity, is a quantitative electroencephalographic (QEEG) method, developed in Los Angeles in the 1990s.[1] [2] It combines complementary information from absolute (the amount of power in a frequency band at a given electrode) and relative power (the percentage of power contained in a frequency band relative to the total spectrum) of EEG spectra.[3]

Cordance is a measure of regional brain activity, computed using QEEG measures of brain wave patterns in an algorithm developed at the UCLA Laboratory of Brain, Behavior, and Pharmacology by Drs. Andrew Leuchter and Ian Cook.

The cordance algorithm includes steps of (a) reattribution of EEG power,[4] [5] (b) spatial normalization of absolute and relative power, and (c) combination of the transformed absolute and transformed relative power to yield the cordance values themselves.

In comparison with other QEEG measures, such as absolute power or relative power, cordance appears to have a superior correlation [6] with regional brain perfusion, one of the other standard measures of regional brain activity. Because cordance is derived from EEG signals, assessments of brain function with cordance do not require the use of radioactive tracer molecules, as is the case with some other functional neuroimaging methods (PET or SPECT scanning).

Cordance has been applied to studying brain activity in a variety of neurological and psychiatric disorders. A major area of study has been major depressive disorder, in efforts to develop biomarkers that could help guide treatment.[7] [8] [9] [10] [11] This line of work was begun in the mid 1990s at UCLA and is now the subject of replication studies at other medical centers.[12] [13] [14] [15] [16] [17]

Notes and References

  1. Web site: Leuchter. Andrew and Cook, Ian. Method and Apparatus for determining.... Expired US Patent. US Patent and Trademark Office. 24 March 2013.
  2. Leuchter . A. . Relationship between brain electrical activity and cortical perfusion in normal subjects . 10.1016/S0925-4927(99)00006-2 . Psychiatry Research: Neuroimaging . 90 . 2 . 125–140 . 1999 . 10482384 . 23290168 .
  3. Bares . M. . Brunovsky . M. . Kopecek . M. . Novak . T. . Stopkova . P. . Kozeny . J. . Sos . P. . Krajca . V. . Höschl . C. . 10.1016/j.eurpsy.2008.03.001 . Early reduction in prefrontal theta QEEG cordance value predicts response to venlafaxine treatment in patients with resistant depressive disorder . European Psychiatry . 23 . 5 . 350–355 . 2008 . 18450430.
  4. Web site: Cordance. Cordance Montage Figure 600x600. Wikimedia Commons. 24 March 2013.
  5. Web site: Cordance. Cordance Montage Figure 3000x3000. Wikimedia Commons. 24 March 2013.
  6. Leuchter . A. . Relationship between brain electrical activity and cortical perfusion in normal subjects . 10.1016/S0925-4927(99)00006-2 . Psychiatry Research: Neuroimaging . 90 . 2 . 125–140 . 1999 . 10482384 . 23290168 .
  7. Cook . I. . Leuchter . A. F. . Morgan . M. . Witte . E. . Stubbeman . W. F. . Abrams . M. . Rosenberg . S. . Uijtdehaage . S. H. . Early Changes in Prefrontal Activity Characterize Clinical Responders to Antidepressants . 10.1016/S0893-133X(02)00294-4 . Neuropsychopharmacology . 27 . 1 . 120–131 . 2002 . 12062912. free .
  8. Cook . I. . Leuchter . A. . Morgan . M. . Stubbeman . W. . Siegman . B. . Abrams . M. . 10.1016/j.jpsychires.2004.12.002 . Changes in prefrontal activity characterize clinical response in SSRI nonresponders: A pilot study . Journal of Psychiatric Research . 39 . 5 . 461–466 . 2005 . 15992554.
  9. Hunter . A. M. . Muthén . B. O. . Cook . I. A. . Leuchter . A. F. . Antidepressant response trajectories and quantitative electroencephalography (QEEG) biomarkers in major depressive disorder . 10.1016/j.jpsychires.2009.06.006 . Journal of Psychiatric Research . 44 . 2 . 90–98 . 2010 . 19631948. 2925497 .
  10. Cook . I. A. . Hunter . A. M. . Abrams . M. . Siegman . B. . Leuchter . A. F. . Midline and right frontal brain function as a physiologic biomarker of remission in major depression . 10.1016/j.pscychresns.2009.04.011 . Psychiatry Research: Neuroimaging . 174 . 2 . 152–7 . 2009 . 19853417. 2804067.
  11. Hunter . A. M. . Leuchter . A. F. . Cook . I. A. . Abrams . M. . Brain functional changes (QEEG cordance) and worsening suicidal ideation and mood symptoms during antidepressant treatment . 10.1111/j.1600-0447.2010.01560.x . Acta Psychiatrica Scandinavica . 122 . 6 . 461–469 . 2010 . 20384600. 13220201 .
  12. Horacek . J. . Brunovsky . M. . Novak . T. . Tislerova . B. . Palenicek . T. . Bubenikova-Valesova . V. . Spaniel . F. . Koprivova . J. . Mohr . P. . Balikova . 10.1017/S0033291709991619 . M. . Hoschl . C. . Subanesthetic dose of ketamine decreases prefrontal theta cordance in healthy volunteers: Implications for antidepressant effect . Psychological Medicine . 40 . 9 . 1443–1451 . 2009 . 19995475.
  13. Bares . M. . Brunovsky . M. . Novak . T. . Kopecek . M. . Stopkova . P. . Sos . P. . Krajca . V. . Höschl . C. . 10.1016/j.euroneuro.2010.03.007 . The change of prefrontal QEEG theta cordance as a predictor of response to bupropion treatment in patients who had failed to respond to previous antidepressant treatments . European Neuropsychopharmacology . 20 . 7 . 459–466 . 2010 . 20421161. 30352590 .
  14. Bares . M. . Novak . T. . Brunovsky . M. . Kopecek . M. . Stopkova . P. . Krajca . V. . Höschl . C. . 10.1016/j.jpsychires.2011.09.006 . The change of QEEG prefrontal cordance as a response predictor to antidepressive intervention in bipolar depression. A pilot study . Journal of Psychiatric Research . 46 . 2 . 219–225 . 2012 . 21937059.
  15. Arns . M. . Drinkenburg . W. H. . Fitzgerald . P. B. . Kenemans . J. L. . Neurophysiological predictors of non-response to rTMS in depression . 10.1016/j.brs.2011.12.003 . Brain Stimulation . 5 . 4 . 569–576 . 2012 . 22410477. 10204067 .
  16. Broadway . J. M. . Holtzheimer . P. E. . Hilimire . M. R. . Parks . N. A. . Devylder . J. E. . Mayberg . H. S. . Corballis . P. M. . 10.1038/npp.2012.23 . Frontal Theta Cordance Predicts 6-Month Antidepressant Response to Subcallosal Cingulate Deep Brain Stimulation for Treatment-Resistant Depression: A Pilot Study . Neuropsychopharmacology . 37 . 7 . 1764–1772 . 2012 . 22414813. 3358746 .
  17. Bares. Martin. Novak. Tomas. Vlcek. Premysl. Hejzlar. Martin. Brunovsky. Martin. September 2019. Early change of prefrontal theta cordance and occipital alpha asymmetry in the prediction of responses to antidepressants. International Journal of Psychophysiology. 143. 1–8. 10.1016/j.ijpsycho.2019.06.006. 1872-7697. 31195067.

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