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Biomedical subjects

István Szendi

Publications and source records attributed to István Szendi.

6 recordsLinked to original sources
PubMed2006

Abnormal neurological signs, visual contrast sensitivity, and the deficit syndrome of schizophrenia.

This study was designed to investigate the relationship between abnormal neurological signs, visual contrast sensitivity, and the deficit syndrome of schizophrenia. Visual contrast sensitivity for counterphase-modulated low spatial frequency gratings was measured in 32 non-deficit and 12 deficit schizophrenia patients and 20 healthy controls subjects. Abnormal neurological signs were evaluated with the Neurological Evaluation Scale (NES). Compared with the controls, patients with schizophrenia displayed impaired visual contrast sensitivity, which was associated with sensory integration deficits, as measured with the NES. The deficit syndrome was predicted by negative symptoms and sensory integration deficits. These results suggest that early-stage perceptual dysfunctions, which may reflect the abnormality of precortical magnocellular visual pathways, are related to a specific group of abnormal neurological signs.

Adult↗
PubMed2006

Correlations between clinical symptoms, working memory functions and structural brain abnormalities in men with schizophrenia.

Thirteen male patients with schizophrenia and thirteen male normal control subjects were compared by magnetic resonance imaging (MRI) on volumes of the straight gyrus (SG), anterior cingulate gyrus, middle frontal gyrus, hippocampus, third ventricle, cavum septi pellucidi, total brain volume and intracranial volume. In addition, neuropsychological tasks were used to measure working memory and executive functions. Healthy volunteers and schizophrenic patients showed no significant differences in mean values for volumes of regions of interests. In the case of the SG, we found a significant difference in laterality: the tendency toward left dominance in healthy volunteers changed to significant right dominance in patients. The schizophrenic patients showed lower performance in working memory tasks, and strongly significant group differences were observed in measures of neurological signs assessed by the Neurological Evaluation Scale (NES). Negative symptoms correlated with the level of spatial working memory and executive functions. Negative symptoms also correlated with the volume of the right hippocampus, while the rate of anhedonia negatively correlated with the relative volume of the left SG.

Adult↗
PubMed2005

Habit learning and the genetics of the dopamine D3 receptor: evidence from patients with schizophrenia and healthy controls.

In this study, the authors investigated the relationship between the Ser9Gly (SG) polymorphism of the dopamine D3 receptor (DRD3) and striatal habit learning in healthy controls and patients with schizophrenia. Participants were given the weather prediction task, during which probabilistic cue-response associations were learned for tarot cards and weather outcomes (rain or sunshine). In both healthy controls and patients with schizophrenia, participants with Ser9Ser (SS) genotype did not learn during the early phase of the task (1-50 trials), whereas participants with SG genotype did so. During the late phase of the task (51-100 trials), both participants with SS and SG genotype exhibited significant learning. Learning rate was normal in patients with schizophrenia. These results suggest that the DRD3 variant containing glycine is associated with more efficient striatal habit learning in healthy controls and patients with schizophrenia.

Adult↗
PubMed2004

Role of dopamine D3 receptor (DRD3) and dopamine transporter (DAT) polymorphism in cognitive dysfunctions and therapeutic response to atypical antipsychotics in patients with schizophrenia.

Molecular components of the dopaminergic system may play an important role in the pathophysiology of schizophrenia. In this study, we investigated the relationship of the Ser9Gly (S/G) polymorphism of the dopamine D3 receptor (DRD3) and the variable number of tandem repeats (VNTR) polymorphism of the dopamine transporter (DAT) with therapeutic response to atypical antipsychotics (clozapine, olanzapine, quetiapine, risperidone) and cognitive functions. No associations were found between the DRD3 and DAT polymorphisms and schizophrenia. The S/S genotype and the S allele were more frequent in the non-responder patients (n = 28) than in the group of responders (n = 47) (cut-off: >20-point improvement in Global Assessment of Functioning (GAF) scale). The patients with S/S genotype completed fewer categories and had more perseverative errors in the Wisconsin Card Sorting Test (WCST) compared with the S/G patients. The S/S and S/G patients did not differ in positive and negative symptoms, GAF scores, WCST failure to maintain set, and verbal learning. No differences in symptoms or WCST measures were observed in the patients with different DAT genotypes. These results suggest that the S/S genotype of the DRD3 is associated with worse therapeutic response and more severe executive dysfunctions in patients with schizophrenia.

Adult↗
PubMed2002

[Correlation between the effectiveness of atypical antipsychotics and dopamine D3 receptor polymorphism in schizophrenia].

OBJECT: Numerous relevant variants of dopamine receptors have been identified in schizophrenia. The Ser9Gly gene polymorphism of dopamine D3 receptor is known as a susceptibility factor for the disease. In addition, it has a role in the modification of therapeutic effect of antipsychotics. In this naturalistic study the authors investigated the relationship between this polymorphism and the therapeutic response to atypical antipsychotics. METHOD: 75 patients with schizophrenia according to DSM-IV and 45 healthy controls were recruited. The patients were divided to responder and nonresponder subgroups, cut-off: > 20 point improvement in Global Assessment of Functioning. By polymerase chain reaction the genotype of dopamine D3 receptor of every participant was determined. RESULTS: The Ser9Ser genotype of dopamine D3 receptor was more frequent in the nonresponder subgroup (64%, p = 0.0018). The Ser9 allele was overrepresented among nonresponder patients (82%, p = 0.0172). CONCLUSION: Based on our results, the worse therapeutic response to atypical antipsychotics is associated with Ser9 variant of dopamine D3 receptor.

Adult↗