Epidemiology of schizophrenia--an update with a focus on developing countries

The relationship between human development and prevalence of deficit schizophrenia: Results from a systematic review and meta-analysis

This study examined the relationship between the prevalence of deficit schizophrenia (DS) and a country's Human Development Index (HDI). A systematic review and meta-analysis of the literature published in the last decade were conducted to acquire data on the worldwide prevalence of deficit syndrome in schizophrenia cohorts and examine the correlation between DS prevalence and the HDI of the countries in the review. Twenty-six studies meeting our eligibility criteria provided prevalence data on DS in 14 countries with both low-to-middle and high-incomes, ranging from 14.34%-to 61.57%. The pooled prevalence of DS was 32.19% (95% CI = 26.17 to 38.52). Statistical analysis yielded a correlation coefficient (r) of -0.518 (95% CI = -0.754 to -0.164; p = 0.007), indicating a moderate inverse correlation between DS prevalence and HDI. This relationship remained significant in partial correlation analysis after controlling for potential sources of bias in the DS estimates (r = -0.489, p = 0.013). Our results show that schizophrenia cohorts from low-to-middle-income countries are more prone to primary and enduring negative symptoms, and contribute to the emerging evidence questioning the axiom that schizophrenia in the developing world has a better course than in high-income countries.

Schizophrenia: the new etiological synthesis

Schizophrenia has been an evolutionary paradox: it has high heritability, but it is associated with decreased reproductive success. The causal genetic variants underlying schizophrenia are thought to be under weak negative selection. To unravel this paradox, many evolutionary explanations have been suggested for schizophrenia. We critically discuss the constellation of evolutionary hypotheses for schizophrenia, highlighting the lack of empirical support for most existing evolutionary hypotheses-with the exception of the relatively well supported evolutionary mismatch hypothesis. It posits that evolutionarily novel features of contemporary environments, such as chronic stress, low-grade systemic inflammation, and gut dysbiosis, increase susceptibility to schizophrenia. Environmental factors such as microbial infections (e.g., Toxoplasma gondii) can better predict the onset of schizophrenia than polygenic risk scores. However, researchers have not been able to explain why only a small minority of infected people develop schizophrenia. The new etiological synthesis of schizophrenia indicates that an interaction between host genotype, microbe infection, and chronic stress causes schizophrenia, with neuroinflammation and gut dysbiosis mediating this etiological pathway. Instead of just alleviating symptoms with drugs, the parasite x genotype x stress model emphasizes that schizophrenia treatment should focus on detecting and treating possible underlying microbial infection(s), neuroinflammation, gut dysbiosis, and chronic stress.

Economic strain, parental education and psychotic experiences among college students in the United States: Findings from the Healthy Minds Study 2020

AIM

Socioeconomic status (SES) is linked to psychosis, and much can be learned by examining how various indicators of SES-specifically economic strain and intergenerational transfer of resources-are related to sub-threshold psychotic experiences among college students.

METHODS

Using data from the Healthy Minds Survey (September 2020-December 2020), we used multivariable logistic regression models to examine the associations between five SES indicators and 12-month psychotic experiences, adjusting for age, gender and race/ethnicity. We also examined the count of predictors and psychotic experiences.

RESULTS

Each indicator of economic strain was associated with greater odds of psychotic experiences. In particular, increasing levels of financial stress (current, childhood and pandemic-related) were associated with greater odds of psychotic experiences in a dose-response fashion. Food insecurity was associated with double the odds of psychotic experiences. In terms of intergenerational transfer of resources, having either one or no parents who attended college was associated with significantly greater odds of having psychotic experiences, when compared with having both parents who attended college. Examining all predictors in the same model, only childhood and current financial stress and food insecurity were significantly associated with psychotic experiences. The count of predictors was significantly associated with greater odds of having psychotic experiences in a dose-dependent fashion.

CONCLUSIONS

Among college students, economic strain and intergenerational transfer of resources were associated with recent psychotic experiences, highlighting the importance of economic interventions targeting young adults to influence risk for psychosis.

Cognitive dysfunction and psychosis: expanding the phenotype of SPG7

Spastic paraplegia type 7 (SPG7) is one of the most common forms of autosomal recessive hereditary spastic paraplegia, which can lead to a hybrid spastic-ataxic phenotype. Recently, novel complicated forms of SPG7, including cognitive and social impairment phenotypes, have been reported. We present a SPG7 case with two pathogenic variants in compound heterozygosity in the SPG7 gene, featuring a cerebellar cognitive affective syndrome with psychosis not yet described in the literature.

A Novel Genotyping Method for Detection of the Muscarinic Receptor M1 Gene rs2067477 Polymorphism and Its Genotype/Allele Frequencies in a Turkish Population

Objectives

Gene variation in the cholinergic muscarinic receptor 1 (CHRM1) has potential to become a candidate biomarker in the development of several disorders as well as drug response. In this study, a novel polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) assay was developed to determine the C to A single nucleotide polymorphism at position 267 in the CHRM1 gene.

Materials and Methods

A new reverse primer and a mismatched forward primer were designed to obtain 125 bp PCR products. The PCR products were then digested with the Hae III restriction enzyme to detect the rs2067477 polymorphism that comprises a C to A base change. The novel assay developed was tested in 51 Turkish schizophrenia patients.

Results

The genotyping assay was successfully performed in patients with schizophrenia in order to confirm the accuracy and validity of this method. The frequency of CC, CA, and AA genotypes was 72.5%, 25.5%, and 2%, respectively. On the basis of these findings, the allele frequency of C was 0.85 and the allele frequency of A was 0.15.

Conclusion

This genotyping assay is practical for screening the CHRM1 C267A polymorphism in pharmacogenetic studies. The present polymorphism may be used as a candidate biomarker to determine genetic susceptibility to related diseases and may contribute to the implementation of individualized drug therapy for M1-related diseases.

The Potential Role of Traditional Medicine in the Management of Schizophrenia

PURPOSE OF REVIEW

This article presents an overview of recent literature examining the place of traditional methods of mental healthcare in the management of schizophrenia.

RECENT FINDINGS

Patients with schizophrenia make up a large proportion of people seeking traditional methods of mental healthcare, and a majority of such users perceive traditional medicine treatment as helpful. Adherence rates to traditional treatment methods among users may be well over 80%. Nevertheless, evidence is currently too weak to inform recommendation of traditional methods as standalone treatments for schizophrenia. Collaboration between traditional medicine practitioners and biomedical mental healthcare providers is feasible and may lead to safer treatments and better outcomes for patients with schizophrenia. Many patients with schizophrenia preferentially use traditional methods of mental healthcare. A collaborative working relationship that includes training and clinical support for traditional medicine providers by biomedical providers is feasible and may help narrow the global treatment gap for schizophrenia.

Association Between REELIN Gene Polymorphisms (rs7341475 and rs262355) and Risk of Schizophrenia: an Updated Meta-analysis

Schizophrenia (SCZ) is a destructive neuropsychiatric illness affecting millions of people worldwide. The correlation between RELN gene polymorphisms and SCZ was investigated by previous researches, though the results remained conflicting. Based on the available studies, we conducted this meta-analysis to provide a more comprehensive outcome on whether the RELN gene polymorphisms (rs7341475 and rs262355) are associated with SCZ. A total of 15 studies with 25,403 subjects (9047 cases and 16,356 controls) retrieved from PubMed, ScienceDirect, EMBASE, Wiley, BMC, Cochrane, Springer, MDPI, SAGE, and Google Scholar up to June 2020 were included. Meta-analysis was performed using Review Manager 5.3. The heterogeneity was checked using I² statistics and Q-test, whereas publication bias was also measured. The rs7341475 polymorphism showed a significantly lower risk for SCZ for the allele (A vs. G: OR = 0.93, 95%CI = 0.87-0.99), codominant 1 (AG vs. GG: OR = 0.92, 95%CI = 0.85-0.99), dominant model (AA+AG vs. GG: OR = 0.92, 95%CI = 0.86-0.98), and over dominant model (AG vs. AA+GG: OR = 0.92, 95%Cl = 0.86-0.99). The allele, codominant model 1, and dominant models remained statistically significant after the correction of the Bonferroni (p < 0.025). Subgroup analysis confirmed the association of allele and dominant models in the Caucasian after Bonferroni correction. For rs262355 polymorphism, a significantly increased risk of SCZ was found only in Caucasians for codominant 2, dominant, and allele models, but significance exists only for the allele model after Bonferroni correction. Publication bias was found in the case of codominant 2 and recessive models for rs7341475 in the overall population, but this publication was not found after performing the Bonferroni correction or after performing the subgroup analysis. No such publication was found for rs262355. The results suggest that RELN rs7341475 is associated with a lower risk of SCZ in the overall population and Caucasian population, but rs262355 is associated with an increased risk of SCZ only in the Caucasian population.

Glutathione S-transferase gene polymorphisms (GSTT1 and GSTM1) and risk of schizophrenia: A case-control study in Chinese Han population

Schizophrenia (SCZ) is a chronic disability disorder related to oxidative stress. Glutathione S-transferase (GST) is a group enzyme that protects cells and tissues from oxidative stress damage. Among GSTs, GSTT1 and GSTM1 have well defined genetic polymorphisms. The purpose of our research was to explore the correlation between GSTT1 and GSTM1 polymorphism and SCZ risk in Chinese Han population.A total of 650 subjects (386 SCZ patients and 264 healthy individuals) were included in this case-control designed study. The GSTT1 and GSTM1 polymorphisms were analyzed by multiplex polymerase chain reaction (PCR). We explored the relationship between these 2 polymorphisms and the risk of SCZ.We found that the GSTT1 null genotype had a protective effect on the development of SCZ [odds ratio (OR) = 0.601, 95% confidence interval (95% CI) = 0.412-0.986, P = .031]. We also found that the combination of null genotypes of the GSTT1 and GSTM1 genes was made at a lower risk of SCZ (OR = 0.452, 95% CI = 0.238-0.845, P = .028). However, we found no correction between Positive and Negative Syndrome Scale score (PANSS) and GSTM1, GSST1 genotypes in SCZ patients.Our finding revealed that GSTT1 null polymorphisms may be related to the reduced risk of SCZ in Chinese Han population, and this risk was further reduced with the combination of GSTT1 null polymorphisms and GSTM1 null polymorphisms.

An ethnic-group comparison of caregiver beliefs about early psychotic illness in a UK sample: Implications for evidence-based caregiver interventions

This study aimed to investigate potential ethnic differences in cognitive responses to caregiving in psychosis that might be relevant to the delivery of caregiver interventions for difficulties related to psychosis. We compared cross-sectional outcomes across early-stage caregivers who self-identified as white British (n = 37) and those who self-identified as black African or Caribbean (n = 41) using United Kingdom (UK) census ethnicity criteria. Self-report questionnaires were used to examine caregiver beliefs about psychosis, including the perceived causes, consequences, timeline, the degree of control that patients have over their difficulties, as well as their appraisals of caregiving. Caregivers from black African or Caribbean backgrounds reported a significantly shorter expected duration of illness than white British caregivers. They were also more likely to cite psychosocial causes (e.g., relationship issues), and less likely to cite biological and genetic causes, as their principal explanations for problems. However, overall differences in perceived causes of illness between ethnicities were not significant, despite the power in this sample to detect medium-sized effects. Factors associated with ethnicity may contribute to individual differences in explanatory models of illness and in experiences of caregiving. A degree of sensitivity to the range of views that people might hold about psychosis may help to engage caregivers from diverse ethnic backgrounds.

The 10-year functional outcome of schizophrenia in Butajira, Ethiopia

BACKGROUND

Long-term functional schizophrenia outcomes are not well characterized in low-income environments because of the rarity of prospective studies.

OBJECTIVES

To assess and describe long-term schizophrenia's functional outcomes and potential outcome predictors.

METHODS

Following a baseline assessment, 316 people with schizophrenia were studied for 10 years, on average. Of the total, 79 were incident cases: cases with onset of the illness occurring two years or less from entry into the study. SF-36 scores of physical and social functioning were used to assess functional outcomes. Linear mixed models were employed to evaluate the association of functioning with potential predictors.

RESULTS

Social and physical functioning scores regarding the cohort were lower than the population's norm for most of the follow-up period. Incident cases had better function than prevalent cases. Fifteen percent of incident and 30% of prevalent cases had reduced social functioning for at least six years. Declining symptom severity during the follow-up period was significantly associated with improvement in social functioning. When baseline functioning was controlled for, the long-term trend in functionality was not associated with demographic or illness characteristics (age and speed of onset, duration of illness and neuroleptic use at entry, substance use, and medication adherence).

CONCLUSION

Long-term physical and social functioning of the population with schizophrenia were significantly lower than the population norm. A significant proportion of the cohort had lower functioning for the long-term. Functioning was not associated with demographic or illness characteristics of the study population.

SNP Variation of RELN Gene and Schizophrenia in a Chinese Population: A Hospital-Based Case-Control Study

Aims: We aimed to explore whether RELN contributes to the vulnerability and severity of clinical symptoms of schizophrenia (SZ) in a Chinese population. Methods: The following were conducted in an adult Han Chinese population from southern China: case-control association analyses of 30 representative single nucleotide polymorphisms (SNPs) that were screened according to specific programs based on bioinformatics tools and former research and quantitative trait locus analyses with SNPs and psychiatric symptoms evaluated with the positive and negative symptoms scale. Results: A 4-SNP haplotype consisting of rs362814, rs39339, rs540058, and rs661575 was found to be significantly associated with SZ even after Bonferroni correction (χ² = 29.024, p = 6.42E-04, p _Bonf = 0.017), and the T-C-T-C haplotype was a protective factor for SZ (OR = 0.050, 95% CI = 0.004-0.705). Moreover, the 4-SNP haplotype showed a significant association with G16 (active social avoidance) after false discovery rate correction (χ² = 28.620, p = 1.697E-04, p _FDR = 0.025). In addition, P7 (hostility) was related to the haplotype comprising rs2229864, rs2535764, and rs262355 (χ² = 31.424, p = 2.103E-05, p _adjustment = 0.019) in quantitative trait loci analyses. Conclusion: Overall, this study showed several positive associations between RELN and SZ, as well as psychiatric symptoms, which not only supports the proposition that RELN is a susceptibility gene for SZ but also provides information on a genotype-phenotype correlation for SZ in a Chinese population.

Pregnenolone as an adjunct to risperidone for treatment of women with schizophrenia: A randomized double-blind placebo-controlled clinical trial

There have been few studies of pregnenolone therapy in schizophrenia and those that exist have been subject to several critical limitations, thus yielding inconsistent results. We attempted to assess the therapeutic effect of pregnenolone in a patient sample as homogeneous as possible. In this randomized double-blind clinical trial, 82 female inpatients with chronic schizophrenia, who had discontinued their antipsychotic medications for at least one week in case of any oral antipsychotic medication or a month for any depot antipsychotic medication, received risperidone plus either pregnenolone (50 mg/day) or placebo for 8 weeks. Inclusion criteria were acute illness with a baseline Positive and Negative Syndrome Scale (PANSS) negative subscale score of ≥20. Exclusion criteria were the presence of severe depression or other concomitant psychiatric disorders. Primary outcome was defined as the difference in the PANSS total score change from baseline to week 8 in the pregnenolone group compared to the placebo group. No significant difference was found in the PANSS total score changes between the two arms (mean difference (CI 95%) = -9.41 (-20.24 to 1.41); p = 0.087). Significant differences were initially found for PANSS negative change scores (mean difference (CI 95%) = -2.61 (-5.03 to -0.19); p = 0.035) and general psychopathology change scores (mean difference (CI 95%) = -5.93 (-11.37 to -0.48); p = 0.033). However, these findings did not survive Bonferroni correction for multiple testing. While this trial may suggest a potential effect of pregnenolone on schizophrenia symptoms, further studies are warranted.

Simvastatin adjunct therapy for negative symptoms of schizophrenia: a randomized double-blind placebo-controlled trial

We investigated the effects of simvastatin adjunctive therapy on the negative symptoms of schizophrenia. In this double-blind trial, inpatients with chronic schizophrenia were clinically stabilized on a constant dose of risperidone for at least 4 weeks before the study and were then randomized to receive risperidone (4-6 mg/day) plus either simvastatin (40 mg/day) (n=33) or placebo (n=33) for 8 weeks. The Positive and Negative Syndrome Scale was used to measure the negative, positive, and general symptoms of schizophrenia at baseline and every 2 weeks. The Hamilton Depression Rating Scale and the Extrapyramidal Symptom Rating Scale were used to measure depression and extrapyramidal symptoms at baseline and week 8. Difference in change in negative symptoms score from the baseline to week 8 was considered the single primary outcome. At baseline, negative symptoms scores were higher than positive symptoms scores in both simvastatin and placebo groups. There was no baseline difference between the two groups in terms of any of the measured variables. Compared with the placebo group, the simvastatin group showed a significantly higher reduction in negative symptoms scores from baseline to week 8 [mean difference: 95% confidence interval=-1.42 (-2.32 to -0.52), P=0.003]. Similar findings were observed for total scores [mean difference: 95% confidence interval=-1.85 (-2.87 to -0.83), P=0.001]. The results were not significant for positive symptoms or general psychopathology scores. We found a favorable effect of simvastatin on negative symptoms of patients with schizophrenia; however, future studies are warranted to confirm these results.