Nadia Davies

Which characteristics of schizophrenia predate psychosis

Neuropsychological and brain structural abnormalities are present in first onset schizophrenia; the balance of evidence is that in the majority of cases these are developmental in origin. A proportion of first degree relatives also show lateral ventricular enlargement, cortical volume decrease and possibly loss of the normal cerebral asymmetry; these findings suggest that certain families transmit a genetic defect in the control of neurodevelopment. On the contrary, decrement in left hippocampal volume appears to be secondary to perinatal hypoxia. High risk, follow-back and cohort studies all demonstrate that preschizophrenics as a group show deviant development; delayed milestones, lower IQ, solitary play, excessive anxiety, and minor neurological problems are all common. It seems likely, but not proven, that these are a manifestation of underlying neurodevelopmental disorder.

5-HT2A receptor and bipolar affective disorder : association studies in affected patients

The aim of this study was to investigate the possible involvement of genetic variation in serotonin receptors in the aetiology of bipolar affective disorder. The 5-HT2A receptor gene was systematically screened for genetic variants by single strand conformation polymorphism (SSCP) methods in subjects with bipolar affective disorder. Four polymorphisms (two structural changes, Thr25Asn and His4 M52Tyr, and two silent polymorphisms, 102-T/C and 516-C/T) which had previously been found in patients with schizophrenia and control subjects were detected. No novel polymorphisms were found in patients with bipolar affective disorder. These polymorphisms were genotyped in a sample of 129 patients and 252 controls of German origin and 176 patients and 182 controls of British origin. No strong associations were found between any of these polymorphisms and bipolar affective disorder. Genetic variation at the 5-HT2A receptor gene does not play a major role in the pathogenesis of the disorder.

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. NAs in the nonpsychotic co-twins from discordant pairs were increased compared to control twins. There were no significant differences in NAs between the nonschizophrenic co-twins from monozygotic (MZ) and dizygotic (DZ) discordant pairs, but the within pair correlations were greater in the MZ compared to DZ pairs. NAs were modified in all groups by pre-morbid schizotypal traits, and in patients by anti-psychotic medication. CONCLUSIONS NAs in schizophrenia are determined in part by genetic risk for the illness but the presence of premorbid schizotypal traits, and anti-psychotic medication confer additional risk for NAs.