Background: previous research has been inconclusive about the nature of hem
ispheric asymmetry in emotional processing. Method: 13 patients with DSM-IV
bipolar disorder received repeated QEEGs over 2 years in different mood st
ates. Z-score measures of asymmetry were assessed. Results: asymmetry in fr
ontotemporal slow-wave activity appeared to be in opposite directions in de
pression compared to mania/hypomania, Conclusions: mood change in bipolar d
isorder is associated with change in QEEG asymmetry. Limitations: study of
larger numbers of more homogenous patients under similar conditions is need
ed. Clinical relevance: study of mood state-dependent asymmetry changes in
bipolar disorder may lead to better understanding of hemispheric processing
of emotion. (C) 1999 Elsevier Science B.V. All rights reserved.