Increased prevalence of toxoplasma gondii seropositivity in patients with treatment-resistant schizophrenia

Introduction

Previous studies suggested that patients with schizophrenia had an increased prevalence of antibodies against toxoplasma gondii (TG) and that those seropositive patients had higher symptom severity. However, there is no data on the relationship between treatment-resistant schizophrenia (TRS) and TG seroprevalence.

Objectives

To determine the association between TRS and TG seropositivity, and to further investigate the relationship between TG seropositivity and different clinical features of schizophrenia.

Methods

In this cross-sectional study, we included 210 male inpatients with schizophrenia. TG seropositivity was determined by ELFA assay. Treatment-resistance was defined as a failure of at least 2 adequate anti-psychotic trials. Data were analyzed using χ2 test or Mann–Whitney test.

Results

The rate of TG seropositivity in the entire sample was 52.3%, whereas 47.6% of patients met the definition for treatment-resistance. Seropositive patients had twice the rate of treatment–resistance compared to seronegative patients (63.6% vs. 30.0%, P < 0.0001). Moreover, in the seropositive group, the patients were older (47.6 ± 12.2 vs. 39.81 ± 12.01 years, P < 0.0001), had higher number of previous hospitalizations (13.9 ± 11.7 vs. 9.6 ± 8.5, P = 0.0073), and increased Calgary depression scale for schizophrenia (CDSS) total score (7.8 ± 4.5 vs. 6.3 ± 3.8, P = 0.012). There were no differences between the groups in the age of disease onset, smoking, positive and negative syndrome scale (PANSS) total, positive and negative scores, and the life-time history of suicide attempts.

Conclusions

Our results support the hypothesis that TG seropositivity might contribute to treatment-resistance in schizophrenia, at least in male patients.

Disclosure of interest

The authors have not supplied their declaration of competing interest.

A protective effect of the BDNF Met/Met genotype in obesity in healthy Caucasian subjects but not in patients with coronary heart disease

OBJECTIVE

Brain-derived neurotrophic factor (BDNF) is a neurotrophic factor with an important role in the regulation of body weight, body mass index (BMI) and obesity. Increased BMI that leads to obesity is a substantial risk factor for coronary heart disease (CHD). The functional BDNF Val66Met polymorphism (rs6265) has been associated with CHD, obesity and BMI. The aim of the study was to determine the association between BDNF rs6265 polymorphism and CHD and/or BMI in patients with CHD and healthy control subjects.

PATIENTS AND METHODS

The study included 704 Caucasian subjects: 206 subjects with CHD and 498 healthy control subjects. The BDNF rs6265 genotype frequency was similar in male and female subjects, and there were no differences in the frequency of the BDNF rs6265 genotypes in 206 patients with CHD and in 498 healthy subjects. When study participants were subdivided according to the BMI categories into normal weight, overweight and obese subjects, significantly different BDNF rs6265 genotype frequency was found within healthy subjects, but not within patients with CHD. Healthy subjects, but not patients with CHD, subdivided into carriers of the Met/Met, Met/Val and Val/Val genotype, had different BMI scores.

RESULTS

The BDNF rs6265 genotype frequency was similar in male and female subjects, and there were no differences in the frequency of the BDNF rs6265 genotypes in 206 patients with CHD and in 498 healthy subjects. When study participants were subdivided according to the BMI categories into normal weight, overweight and obese subjects, significantly different BDNF rs6265 genotype frequency was found within healthy subjects, but not within patients with CHD. Healthy subjects, but not patients with CHD, subdivided into carriers of the Met/Met, Met/Val and Val/Val genotype, had different BMI scores. BDNF rs6265 polymorphism was not associated with a diagnosis of CHD or with BMI categories among patients with CHD. In contrast, healthy Caucasians, carriers of the BDNF Met/Met genotype, had more frequently normal weight compared to carriers of other BDNF genotypesBDNF rs6265 polymorphism was not associated with a diagnosis of CHD or with BMI categories among patients with CHD. In contrast, healthy Caucasians, carriers of the BDNF Met/Met genotype, had more frequently normal weight compared to carriers of other BDNF genotypes.

CONCLUSIONS

BDNF rs6265 polymorphism is associated with BMI categories, and the BDNF Met/Met genotype has a protective role in obesity in healthy subjects, while this effect was not present in patients with CHD.

Zimelidine decreases seizure susceptibility in stressed mice

To further evaluate whether selective serotonin reuptake inhibitors (SSRIs) have pro- or anticonvulsant properties and whether these properties will be modified by stress, we studied the effect of zimelidine on the convulsions produced by picrotoxin, a GABA(A) receptor antagonist, in unstressed and swim stressed mice. Zimelidine potentiated the ability of swim stress to enhance the threshold doses of intravenously administered picrotoxin producing convulsant signs and death, without having an effect in unstressed mice. The anticonvulsant effect of zimelidine was counteracted with mianserin, the antagonist of 5-HT(2A/2C), and diminished with WAY-100635, a selective antagonist of 5-HT(1A) receptors. In stressed mice, WAY-100635 prevented the anticonvulsant effect of 8-OH-DPAT, a 5-HT(1A) receptor agonist. SB-269970 and ketanserin, the antagonists of 5-HT(7) and 5-HT(2A) receptors, respectively, failed to reduce the effect of zimelidine. The results suggest the involvement of 5-HT(2C) and 5-HT(1A) receptors in the anticonvulsant effects of zimelidine and possibly other SSRIs in stress.