WCST performance and schizotypal features in the first-degree relatives of patients with schizophrenia.

Since the findings concerning the Wisconsin Card Sorting Test (WCST) performance of healthy first-degree relatives of patients with schizophrenia are equivocal, it still remains unclear whether the WCST may serve as a neuropsychological indicator of vulnerability to schizophrenia. The aim of this study was to evaluate whether the first-degree relatives' schizotypal features could account for these discrepancies. The subjects were 24 schizophrenic probands, 49 of their first-degree relatives and 41 normal controls. The computerized version of the WCST was used and schizotypy features were assessed using four of Chapman's scales. The patient group performed worse on the WCST and had higher scores of schizotypy than the control group. The relatives group did not significantly differ from the control, neither on the WCST performance nor on the scores of schizotypy. However, the subgroup of relatives and the subgroup of patients with high scores on the negative dimension of schizotypy showed a worse performance on the WCST than the subgroups with low scores. There were no differences on the WCST performance between the subgroups with high vs. low scores on the positive dimension of schizotypy. Thus, discrepancies across studies could be explained by a confounding factor represented by the negative dimension of schizotypy.

Executive/attentional performance and measures of schizotypy in patients with schizophrenia and in their nonpsychotic first-degree relatives.

Previous studies of executive/attentional functions have found impairments in nonpsychotic first-degree relatives of patients with schizophrenia. The aims of this study were: (1) to replicate these findings by three laboratory measures of attention/information processing - a continuous performance test (DS-CPT), a forced-choice span of apprehension task (SPAN), and a digit symbol substitution test (DSST), and by a series of neuropsychological tests sensitive to prefrontal cortical damage - Trail Making A and B, verbal fluency (VFT), Stroop Color and Word Test (Stroop), and Wisconsin Card Sorting Test (WCST); (2) to investigate whether such executive/attentional deficits are associated with schizotypal traits assessed using the social anhedonia, physical anhedonia, perceptual aberration and magical ideation scales (Chapman, L.J., Chapman, J.P., Raulin, M.L. 1976. Scales for physical and social anhedonia. J. Abnorm. Psychol. 85, 374-382; Chapman, L.J., Chapman, J.P., Raulin, M.L., 1978. Body-image aberration in schizophrenia. J. Abnorm. Psychol. 87, 399-407; Eckblad, M., Chapman, L.J., 1983. Magical ideation as an indicator of schizotypy. J. Consult. Clin. Psychol. 51, 215-225). In both patient and relative groups, performance was significantly poorer on the DSST, VFT and Trail B, and the reaction time on the SPAN was significantly longer. These neuropsychological impairments were present as much in siblings as in parents of schizophrenic patients; age did not appear to cancel differences between the relative and control groups. In the relative group, the four scores of schizotypy were at an intermediate level between those of patient and control groups, and the social anhedonia and perceptual aberration scores tended to be significantly different between the relative and the control groups. Only two significant correlations were found between the neuropsychological performance and the measures of schizotypy.

The histidines of the iron-uptake regulation protein, Fur.

There are 12 histidine residues/molecule in the iron-uptake regulation protein (Fur). Here we examine their pH dependence using proton nuclear magnetic resonance spectroscopy. The histidines have widely spread acid dissociation constants but we can not offer a simple explantation for their complicated behaviour.