Laterality effects in schizophrenia and bipolar disorder.
There are numerous reports in the literature of lateralised structural cerebral abnormalities and alterations of the corpus callosum in the major psychoses. In the light of these findings the purpose of this study was to directly compare hemispheric differences and callosal interhemispheric transmission (IT) in schizophrenia and bipolar disorder. To do that we tested schizophrenic (SCZ), bipolar disorder (BD) patients and controls in a simple manual reaction time (RT) task with lateralised visual stimuli (Poffenberger paradigm) which enables one to test both laterality effects and IT time. We found an overall slowing of responses with the right hand in schizophrenics but not in bipolar patients, who, like controls, showed no hand differences. This selective slowing down of the right hand is likely to be related to abnormalities of intrahemispheric cortico-cortical connections in the left hemisphere. In contrast, IT time was similar in SCZ and BD patients and did not differ with respect to controls. Two are the novel findings of the present study: first both SZC and BD share a normal IT of visuomotor information despite the presence of callosal abnormalities. Second, an impairment of intrahemispheric left hemispheric processing is present only in SCZ patients. This represents a potentially important clue to a further understanding of the pathogenetic differences between the two major psychoses.
Inter-University Center for Behavioural Neurosciences, University of Verona, Verona, Italy.
Marcella
M
Bellani
Carlo A
CA
Marzi
Silvia
S
Savazzi
Cinzia
C
Perlini
Stefania
S
Cerruti
Adele
A
Ferro
Veronica
V
Marinelli
Silvia
S
Sponda
Gianluca
G
Rambaldelli
Michele
M
Tansella
Paolo
P
Brambilla
D000368:Aged; D000704:Analysis of Variance; D016880:Anisotropy; D001714:Bipolar Disorder / Q000523:psychology*; D003337:Corpus Callosum / Q000503:physiopathology; D005260:Female; D007839:Functional Laterality / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009434:Neural Pathways / Q000502:physiology; D010775:Photic Stimulation; D010812:Physical Stimulation; D011569:Psychiatric Status Rating Scales; D011597:Psychomotor Performance / Q000502:physiology; D011930:Reaction Time / Q000502:physiology; D012565:Schizophrenic Psychology