Hand preference and hand skill in families with schizophrenia

Abstract

Direction and degree of handedness in humans are variable between individuals and thought to be in part inherited. Several studies have shown an increase in non-right handedness among patients with schizophrenia, and some have included unaffected relatives. The present study was designed to determine whether reduced right handedness is more frequent among individuals with schizophrenia as compared with their well relatives and whether it clusters within families having multiple ill members. A total of 259 families comprising 418 individuals diagnosed with schizophrenia or schizoaffective disorder, 54 individuals with other psychoses, 145 family members with depression and other minor diagnoses, and 288 unaffected individuals were included. Hand preference was assessed by the Annett Scale and right relative to left hand skill measured using the Tapley-Bryden test. For all assessments of hand preference and hand skill, females were significantly more lateralised towards the right than males. Those individuals with schizophrenia or schizoaffective disorder had significantly less right hand preference than their unaffected relatives when measured as a quantitative index of items from the Annett Scale (p = .019), but not categorically (right, left or mixed). In contrast, there was no difference in hand skill between diagnostic groups. Hand preference was significantly correlated among male-male affected sibling pairs (p = .01) and similar results were found for hand skill among the total group of affected pairs (p = .001). Although these results only partially support a relationship between handedness and schizophrenia, they nevertheless draw attention to sex differences in hand preference and the familial aspects of hand preference in this disorder. More direct approaches to the genetics of cerebral dominance and psychosis are required.

Is lateral bias anomalous in early-onset schizophrenia? Selected comparisons with normal populations

“…DeLisi et al (2002) reported mixed handedness in 11.4% of 275 adult male and 7.8% of 143 female patients with schizophrenia or schizoaffective disorder. Orr et al (1999) found 16% mixed handedness in a sample of 94 schizophrenic subjects.…”

Verbal creativity and schizotypal personality in relation to prefrontal hemispheric laterality: A behavioral and near-infrared optical imaging study

“…Schizophrenia is associated with reduced functional and structural laterality. There is robust support for mixed handedness in schizophrenia (Cannon et al, 1995;Crow et al, 1996;DeLisi et al, 2002) and in schizotypes (Chapman and Chapman, 1987;Claridge et al, 1998;Kim et al, 1992;Richardson, 1994) rather than pure left-handedness (Shaw et al, 2001). Mixed handedness is associated with decreased cerebral lateralization, schizotypy, and enhanced creativity (Claridge and Broks, 1984).…”

LRRTM1 on chromosome 2p12 is a maternally suppressed gene that is associated paternally with handedness and schizophrenia

“…10,11 Schizophrenia is also associated with a slightly elevated rate of mixed or left-handedness. 12,13 Crow drew attention to the association of abnormal brain asymmetry with schizophrenia-like psychoses, 14 and was drawn to a human-specific rearrangement of the sex chromosomes and a candidate gene there, 15 Protocadherin X-Y. However, this gene has not so far been shown to be linked to asymmetry, language or psychosis.…”