Attentional and executive dysfunctions in schizophrenia and depression: evidence from dichotic listening performance.
BACKGROUND
We compared performance on a dichotic listening (DL) task between schizophrenic, depressed, and healthy control subjects. A variant of the traditional DL paradigm was used in which the subjects were required to focus attention either on the left (forced-left condition) or right (forced-right condition) ear stimulus.


METHODS
The subjects were 51 patients with a DSM-IV diagnosis of schizophrenia, 49 patients with recurrent unipolar major depression, and 49 healthy control subjects. They were tested with a consonant-vowel syllables dichotic listening task under three attentional instructions.


RESULTS
There was a significant overall right ear advantage during the nonforced condition, which increased dramatically during the forced-right condition and was eliminated during the forced-left condition. The depressed patients showed no signs of impairments compared with the healthy control group. Thus, they showed a right ear advantage during the nonforced and forced-right conditions, which was shifted to a left ear advantage during the forced left condition. The schizophrenic patients, however, were impaired on the forced-left condition compared with the healthy control and depressed subjects.


CONCLUSIONS
The results are discussed in terms of separating attentional and inhibitory executive impairments in schizophrenia and depression, taking into consideration illness duration and information-processing demands.
Hugdahl
Kenneth
K
Department of Biological and Medical Psychology, University of Bergen, Bergen, Norway.
Rund
Bjørn Rishovd
BR
Lund
Anders
A
Asbjørnsen
Arve
A
Egeland
Jens
J
Landrø
Nils Inge
NI
Roness
Atle
A
Stordal
Kirsten I
KI
Sundet
Kjetil
K
D001288:Attention; D016000:Cluster Analysis; D003072:Cognition Disorders / Q000503:physiopathology; D003866:Depressive Disorder / Q000503:physiopathology*; D004007:Dichotic Listening Tests; D004423:Ear / Q000503:physiopathology; D005260:Female; D006309:Hearing / Q000502:physiology; D006801:Humans; D008297:Male; D012559:Schizophrenia / Q000503:physiopathology*