Common genetic risk links premorbid social and personality deficits to schizophrenia
MedWire News: Children and adolescents who later develop schizophrenia present with abnormalities of social adjustment and personality that are influenced by a common genetic risk, study findings show.
Until now, it has been unclear to what degree premorbid developmental abnormalities in schizophrenia are genetically determined, with familial environmental factors also thought to play a role.
Marco Picchioni, from King's College London in the UK, and colleagues therefore used a combined twin and family study design to assess childhood and adolescent social adjustment and schizotypal personality traits.
The study participants included 98 twin pairs varying in their zygosity and concordance for schizophrenia, 156 sibling clusters (n=335) varying in their concordance for schizophrenia, and 85 mentally healthy control siblings from unaffected families.
After controlling for age and gender, patients with schizophrenia were rated to have had more abnormal childhood and adolescent social development and more abnormal childhood personality than healthy individuals, irrespective of zygosity or concordance for schizophrenia.
Also, among the monozygotic twin pairs discordant for schizophrenia, the co-twins without schizophrenia had more abnormal childhood and adolescent social behavior and childhood personality traits than healthy controls.
In contrast, the schizophrenia-free co-twins in the dizygotic twin pairs discordant for schizophrenia did not significantly differ from controls with regard to childhood social development and personality traits, and only approached significance for adolescent social development.
The researchers then carried out genetic model fitting to determine the degree to which the association between these factors and schizophrenia development are influenced by a common genetic risk.
Significant additive genetic heritability effects were seen for all three variables, and there was further evidence of dominant genetic effects for childhood social development and schizoid/schizotypal personality and shared environmental effects for adolescent social development. The remainder of the variance was explained by unique environmental influences, including measurement error.
The data therefore suggest that "genetically influenced abnormalities in social development and personality are linked to the genetic risk for schizophrenia," conclude Picchioni and team.
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By Lucy Piper