Schizophrenic patients and their first-degree relatives show an excess of mixed-handedness.
An excess of mixed-handedness in schizophrenia has been reported. However, it is not established whether this excess is manifest in non-schizophrenic psychoses, nor whether the underlying etiology is genetic or environmental. We investigated these issues in a group of patients with schizophrenia (n=94), affective psychosis (n=63), other psychosis (n=26); their respective first-degree relatives (total n=183) and a control group (n=85). A narrow definition of mixed-handedness was used corresponding to groups 5 and 6 as defined by the Annett Handedness Questionnaire. We found an excess of mixed-handedness in the schizophrenic group compared with controls (OR=5.2, 1.4-18.6, p<0.006). There was no difference between the other psychotic groups and controls. There was a trend for an excess of mixed-handedness in the first-degree relatives (n=99) of schizophrenic patients (p=0.055), but not in the relatives of affective or other psychotic patients. There was a striking linear trend in the proportion of mixed-handedness between controls, the relatives and the schizophrenic patients (chi2=7.0, p=0.008). There was no association between mixed-handedness and a history of pregnancy or birth complications in the schizophrenic group. There was some evidence for impaired sociability in the mixed-handed schizophrenic patients. Our results indicate that the excess of mixed-handedness in schizophrenia may have a genetic basis.
Orr
K G
KG
Department of Psychological Medicine, Institute of Psychiatry, Denmark Hill, London, UK. Severian@iinet.net.au
Cannon
M
M
Gilvarry
C M
CM
Jones
P B
PB
Murray
R M
RM
D000328:Adult; D000341:Affective Disorders, Psychotic / Q000453:epidemiology / Q000235:genetics / Q000503:physiopathology; D016022:Case-Control Studies; D002540:Cerebral Cortex / Q000503:physiopathology; D005260:Female; D007839:Functional Laterality / Q000235:genetics*; D020022:Genetic Predisposition to Disease; D006801:Humans; D008297:Male; D009679:Nuclear Family; D011247:Pregnancy; D011248:Pregnancy Complications / Q000453:epidemiology; D011618:Psychotic Disorders / Q000453:epidemiology / Q000235:genetics / Q000503:physiopathology; D012307:Risk Factors; D012559:Schizophrenia / Q000453:epidemiology / Q000235:genetics* / Q000503:physiopathology; D013223:Statistics as Topic