Magnetic resonance imaging of the thalamus and adhesio interthalamica in twins with schizophrenia.

Context: Abnormalities of the thalamus are thought to be central to the pathophysiology of schizophrenia. These abnormalities include altered structure and shape of the thalamus itself and possibly changes to the adhesio interthalamica (or massa intermedia), the gray matter bridge connecting the 2 thalamic lobes. However, it is not clear to what extent these abnormalities are determined by the genetic liability for schizophrenia.

Neurological abnormalities in schizophrenic twins.

Background: Neurological abnormalities (NAs) are well recognized in schizophrenia, though their genetic and environmental determinants, and pathophysiological significance, are poorly understood.

Methods: Sixty-three twin pairs, varying in their zygosity and concordance for schizophrenia, and 73 unaffected control twin pairs were examined for total, primary and integrative NAs using the Neurological Evaluation Scale.

Results: NAs were increased in probands with schizophrenia compared to nonschizophrenic co-twins and to healthy control twins but there were no significant differences between patients from the concordant and discordant pairs.

A controlled study of brain structure in monozygotic twins concordant and discordant for schizophrenia.

Background: We examined monozygotic twins concordant and discordant for schizophrenia to clarify the role of genetic and environmental factors in determining brain abnormalities.

Methods: Magnetic resonance imaging brain scans were obtained from 14 monozygotic twin pairs concordant and 10 monozygotic pairs discordant for schizophrenia, as well as 17 pairs of monozygotic control twins. Twenty-two discordant sibling-pairs and 56 pairs of unrelated control subjects were included to assess the extent of genetic control over these structures.

Further evidence that congenital dermatoglyphic abnormalities are associated with psychosis: a twin study.

The presence of abnormal palmar flexion creases (APFC) and dermatoglyphic ridge dissociation (RD) may constitute enduring evidence of a prenatal insult that occurred before the third trimester of intrauterine life. We examined these dermatoglyphic abnormalities in a twin study of psychotic disorders. RD and APFC were analyzed in a monozygotic (MZ) twin sample from the Maudsley Hospital in London (11 normal control pairs, 16 pairs concordant for psychosis, 9 pairs discordant for psychosis, 1 concordant triplet, and 1 triplet with one affected member).

Heritability estimates for psychotic disorders: the Maudsley twin psychosis series.

Background: Previous twin studies have supported a genetic contribution to the major categories of psychotic disorders, but few of these have employed operational diagnostic criteria, and no such study has been based on a sample that included the full range of functional psychotic disorders.

Methods: A total of 224 twin probands (106 monozygotic, 118 dizygotic) with a same-sex co-twin and a lifetime history of psychosis was ascertained from the service-based Maudsley Twin Register in London, England. Research Diagnostic Criteria psychotic diagnoses were made on a lifetime-ever basis.