Predicting therapeutic response to secondary treatment with bupropion:
Dichotic listening tests of functional brain asymmetry

Studies using neuroimaging, electrophysiologic and cognitive measures have raised hopes for developing predictors of
therapeutic response to antidepressants. Pretreatment measures of functional brain asymmetry have been found to be related to
response to the selective serotonin reuptake inhibitor fluoxetine. This report examines the extent to which dichotic listening tests
also predict clinical response to an antidepressant with a different mechanism of action, i.e., bupropion. Dichotic listening data
were obtained for 17 unmedicated depressed patients who were subsequently treated with bupropion. Right-handed outpatients
were tested on dichotic fused-words and complex-tones tests. Seven patients who responded to bupropion and 10 nonresponders
did not differ in gender, age or education. Bupropion responders had significantly larger left-hemisphere advantage for perceiving
words when compared to nonresponders, but there was no difference in their right-hemisphere advantage for tones. All patients
having a left-hemisphere advantage above the normal mean responded to bupropion, whereas only 9% of patients below the normal
mean responded to treatment. These findings should encourage further study of the clinical value of dichotic listening and other
measures of functional brain asymmetry for identifying depressed patients who most benefit from treatment with different classes
of antidepressants.

Dichotic Listening Tests of Functional Brain Asymmetry
Predict Response to Fluoxetine in Depressed Women
and Men

1Department of Psychiatry, Columbia University College of Physicians and Surgeons, New York, NY, USA; 2Department of Biopsychology, New
York State Psychiatric Institute, New York, NY, USA; 3Depression Evaluation Service, New York State Psychiatric Institute, New York, NY, USA
Patients having a depressive disorder vary widely in their therapeutic responsiveness to a selective serotonin reuptake inhibitor (SSRI),
but there are no clinical predictors of treatment outcome. Studies using dichotic listening, electrophysiologic and neuroimaging measures
suggest that pretreatment differences among depressed patients in functional brain asymmetry are related to responsiveness to
antidepressants. Two new studies replicate differences in dichotic listening asymmetry between fluoxetine responders and
nonresponders, and demonstrate the importance of gender in this context. Right-handed outpatients who met DSM-IV criteria for
major depression, dysthymia, or depression not otherwise specified were tested on dichotic fused-words and complex tones tests before
completing 12 weeks of fluoxetine treatment. Perceptual asymmetry (PA) scores were compared for 75 patients (38 women) who
responded to treatment and 39 patients (14 women) who were nonresponders. Normative data were also obtained for 101 healthy
adults (61 women). Patients who responded to fluoxetine differed from nonresponders and healthy adults in favoring left- over righthemisphere
processing of dichotic stimuli, and this difference was dependent on gender and test. Heightened left-hemisphere advantage
for dichotic words in responders was present among women but not men, whereas reduced right-hemisphere advantage for dichotic
tones in responders was present among men but not women. Pretreatment PA was also predictive of change in depression severity
following treatment. Responder vs nonresponder differences for verbal dichotic listening in women and nonverbal dichotic listening in
men are discussed in terms of differences in cognitive function, hemispheric organization, and neurotransmitter function.

"The magnitude of the right ear advantage in the DL task significantly correlated with resting electroencephalographic (EEG) asymmetry. Subjects with larger-left-than-right EEG resting activation also had better recall from the right as compared to the left ear in the DL. "

http://books.google.com/books?id=1G6p80GQn...vCG6A&hl=en

Thanks for this study, Oyster. I do electrophys studies for a living, and might be able to integrate this in with some of the audiologists we have on board.

We'll start a frowny face clinic