eNO responses may distinguish bipolar disorder from schizophrenia
MedWire News: Different patterns in evoked neural oscillation (eNO) responses to speech distinguish patients with bipolar disorder (BD) from those with schizophrenia and mentally healthy individuals, research shows.
"Psychiatrists have long debated whether BD and schizophrenia are the clinical outcomes of discrete or shared causative processes," explain Shigenobu Kanba (Kyushu University, Higashiku Fukuoka, Japan) and colleagues who add that it is therefore "essential to determine both the homogeneity and heterogeneity between these disorders."
As previous research has demonstrated that schizophrenia patients have "significantly delayed peak latencies of the eNO power and reduced eNO power to speech sounds in the left hemisphere in comparison to normal controls," the team examined whether eNO to speech sounds could be differentiated between BD and schizophrenia patients.
The researchers recruited 11 BD patients, 12 schizophrenia patients, and 15 mentally healthy controls. There were no significant differences in age or handedness between the groups, and none of the participants were dependent on drugs or alcohol.
Using magnetoencephalography, the team recorded the participants' auditory evoked responses (eNO power and phase-locking) in the left hemisphere to the voice of an actor and pure tones.
They found that BD patients showed larger eNO power responses to speech than schizophrenia patients and controls, at 87.69 versus 44.26 and 55.45 fT/cm.
Schizophrenia patients also exhibited delayed eNO responses (103.28 versus 65.76 and 54.01 ms) and phase-locking responses (82.66 versus 70.38 and 55.66 ms) to speech compared with BD patients and controls.
However, there were no significant differences among the groups regarding responses to pure tones, the researchers note.
Kanba and team conclude: "The present study showed that different patterns in eNO to speech sounds are present in BD, schizophrenia, and normal control subjects."
They add: "The eNO to speech sounds in the left hemisphere therefore appears to be a useful index to distinguish BD from schizophrenia."
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By Mark Cowen