Handedness, language lateralisation and anatomical asymmetry in schizophrenia: meta-analysis.
BACKGROUND
Cerebral lateralisation appears to be decreased in schizophrenia. Results of studies investigating this, however, are equivocal.


OBJECTIVE
To review quantitatively the literature on decreased lateralisation in schizophrenia.


METHODS
Meta-analyses were conducted on 19 studies on handedness, 10 dichotic listening studies and 39 studies investigating anatomical asymmetry in schizophrenia.


RESULTS
The prevalence of mixed- and left-handedness ('non-right-handedness') was significantly higher in patients with schizophrenia as compared to healthy controls, and also as compared to psychiatric controls. The analysis of dichotic listening studies revealed no significant difference in lateralisation in schizophrenia. However, when analysis was restricted to studies using consonant-vowel or fused word tasks, significantly decreased lateralisation in schizophrenia emerged. Asymmetry of the planum temporale and the Sylvian fissure was significantly decreased in schizophrenia, while asymmetry of the temporal horn of the lateral ventricle was not.


CONCLUSIONS
Strong evidence is provided for decreased cerebral lateralisation in schizophrenia.
Department of Psychiatry, University Medical Centre Utrecht, Heidelberglaan 100, 3584 CX Utrecht, The Netherlands. ISommer@azu.nl
I
I
Sommer
N
N
Ramsey
R
R
Kahn
A
A
Aleman
A
A
Bouma
D001921:Brain / Q000473:pathology*; D004007:Dichotic Listening Tests; D007839:Functional Laterality; D006801:Humans; D012559:Schizophrenia / Q000473:pathology*; D012565:Schizophrenic Psychology; D013067:Speech Perception