Country-level gender inequality is associated with structural differences in the brains of women and men.

Gender inequality across the world has been associated with a higher risk to mental health problems and lower academic achievement in women compared to men. We also know that the brain is shaped by nurturing and adverse socio-environmental experiences. Therefore, unequal exposure to harsher conditions for women compared to men in gender-unequal countries might be reflected in differences in their brain structure, and this could be the neural mechanism partly explaining women's worse outcomes in gender-unequal countries. We examined this through a random-effects meta-analysis on cortical thickness and surface area differences between adult healthy men and women, including a meta-regression in which country-level gender inequality acted as an explanatory variable for the observed differences. A total of 139 samples from 29 different countries, totaling 7,876 MRI scans, were included. Thickness of the right hemisphere, and particularly the right caudal anterior cingulate, right medial orbitofrontal, and left lateral occipital cortex, presented no differences or even thicker regional cortices in women compared to men in gender-equal countries, reversing to thinner cortices in countries with greater gender inequality. These results point to the potentially hazardous effect of gender inequality on women's brains and provide initial evidence for neuroscience-informed policies for gender equality.

Obstetric complications and cognition in schizophrenia: a systematic review and meta-analysis.

BACKGROUND: Schizophrenia (SZ) is a complex brain disorder linked to cognitive and neurostructural abnormalities that involves genetic and environmental factors with obstetric complications (OCs) at birth conferring a high risk for the disease. Indeed, current research in the general population describes the deleterious effect of OCs on cognitive performance in adulthood. With this rationale, we aim to review the relationship between OCs and cognition in SZ and related psychotic disorders. METHODS: A systematic review and meta-analysis describing cognitive function and OCs in patients with SZ and related disorders were conducted. PubMed, EmBase, SCOPUS, and the Cochrane Library were systematically searched to identify eligible studies up to January 2022. We calculated the effect sizes (Hedges' g) of cognitive domains within each study and quantified the proportion of between-study variability using the I2 statistic. Homogeneity was assessed using the Q-statistic (X2). The study was registered on PROSPERO (CRD42018094238). RESULTS: A total of 4124 studies were retrieved, with 10 studies meeting inclusion criteria for the systematic review and eight for meta-analysis. SZ subjects with OCs showed poor verbal memory [Hedges' g = -0.89 (95% CI -1.41 to -0.37), p < 0.001] and working memory performance [Hedges' g = -1.47 (95% CI -2.89 to -0.06), p = 0.01] in a random-effect model compared to those without OCs. CONCLUSIONS: OCs appear to have a moderate impact on specific cognitive such as working memory and verbal memory. Our findings suggest that OCs are associated with brain development and might underlie the cognitive abnormalities described at onset of psychosis.

Effects of socioeconomic status in cognition of people with schizophrenia: results from a Latin American collaboration network with 1175 subjects.

BACKGROUND: Cognition heavily relies on social determinants and genetic background. Latin America comprises approximately 8% of the global population and faces unique challenges, many derived from specific demographic and socioeconomic variables, such as violence and inequality. While such factors have been described to influence mental health outcomes, no large-scale studies with Latin American population have been carried out. Therefore, we aim to describe the cognitive performance of a representative sample of Latin American individuals with schizophrenia and its relationship to clinical factors. Additionally, we aim to investigate how socioeconomic status (SES) relates to cognitive performance in patients and controls. METHODS: We included 1175 participants from five Latin American countries (Argentina, Brazil, Chile, Colombia, and Mexico): 864 individuals with schizophrenia and 311 unaffected subjects. All participants were part of projects that included cognitive evaluation with MATRICS Consensus Cognitive Battery and clinical assessments. RESULTS: Patients showed worse cognitive performance than controls across all domains. Age and diagnosis were independent predictors, indicating similar trajectories of cognitive aging for both patients and controls. The SES factors of education, parental education, and income were more related to cognition in patients than in controls. Cognition was also influenced by symptomatology. CONCLUSIONS: Patients did not show evidence of accelerated cognitive aging; however, they were most impacted by a lower SES suggestive of deprived environment than controls. These findings highlight the vulnerability of cognitive capacity in individuals with psychosis in face of demographic and socioeconomic factors in low- and middle-income countries.

Structural brain abnormalities in schizophrenia in adverse environments: examining the effect of poverty and violence in six Latin American cities.

BACKGROUND: Social and environmental factors such as poverty or violence modulate the risk and course of schizophrenia. However, how they affect the brain in patients with psychosis remains unclear. AIMS: We studied how environmental factors are related to brain structure in patients with schizophrenia and controls in Latin America, where these factors are large and unequally distributed. METHOD: This is a multicentre study of magnetic resonance imaging in patients with schizophrenia and controls from six Latin American cities. Total and voxel-level grey matter volumes, and their relationship with neighbourhood characteristics such as average income and homicide rates, were analysed with a general linear model. RESULTS: A total of 334 patients with schizophrenia and 262 controls were included. Income was differentially related to total grey matter volume in both groups (P = 0.006). Controls showed a positive correlation between total grey matter volume and income (R = 0.14, P = 0.02). Surprisingly, this relationship was not present in patients with schizophrenia (R = -0.076, P = 0.17). Voxel-level analysis confirmed that this interaction was widespread across the cortex. After adjusting for global brain changes, income was positively related to prefrontal cortex volumes only in controls. Conversely, the hippocampus in patients with schizophrenia, but not in controls, was relatively larger in affluent environments. There was no significant correlation between environmental violence and brain structure. CONCLUSIONS: Our results highlight the interplay between environment, particularly poverty, and individual characteristics in psychosis. This is particularly important for harsh environments such as low- and middle-income countries, where potentially less brain vulnerability (less grey matter loss) is sufficient to become unwell in adverse (poor) environments.

The Relationship between Cytokines and Verbal Memory in Individuals with Schizophrenia and Their Unaffected Siblings.

BACKGROUND: Verbal memory impairment may be considered an endophenotype in schizophrenia (SZ), also affecting the siblings of SZ subjects. Furthermore, the immune-inflammatory system response has an important modulatory effect on brain processes, especially on memory circuits. OBJECTIVE: Investigating the relationship between TNF-α and IL-6 and memory performance in patients with SZ, their unaffected siblings (SB) and healthy controls (HC). METHODS: 35 subjects with SZ, 36 SB, and 47 HC underwent a neurocognitive assessment for verbal memory by means of the revised Hopkins Verbal Learning Test (HVLT-R) in addition to serum cytokines analyses. RESULTS: SZ patients performed worse in HVLT-R than SB and HC, but SB and HC were not different. Regarding the biomarker levels, we found significant results of TNF-α for both groups. However, we did not find differences between groups after multiple-comparisons analysis. There were no significant correlations between episodic verbal memory, TNF-α, and IL-6. CONCLUSION: The results are compatible with the hypothesis that deficits in verbal memory of individuals with SZ could be secondary to inadequate functioning of cognitive processing areas, such as proactive cognitive control.

α-Lipoic Acid as Adjunctive Treatment for Schizophrenia: An Open-Label Trial.

PURPOSE/BACKGROUND: Accumulating evidence suggests an involvement of oxidative stress in the pathophysiology of schizophrenia. This offers a hypothesis-derived therapeutic approach to hinder oxidative damage and its clinical sequelae. α-Lipoic acid (ALA) is a powerful natural antioxidant indicated to treat diabetic neuropathy. METHODS/PROCEDURES: In this pilot investigation, we administered ALA (100 mg/d) for 4 months, as an adjunct to antipsychotic medication, to 10 patients with schizophrenia. FINDINGS/RESULTS: We found robust improvement in measures of psychopathology (63.9% reduction in Brief Psychiatric Rating Scale scores), neurocognitive parameters, extrapyramidal symptoms, and decreased lipid peroxidation. IMPLICATIONS/CONCLUSIONS: If larger, double-blind, placebo-controlled studies confirm these preliminary findings, ALA could prove useful as adjunctive therapy for schizophrenia.

Effects of omega-3 supplementation on interleukin and neurotrophin levels in an animal model of schizophrenia.

New studies suggest that polyunsaturated fatty acids, such as omega-3, may reduce the symptoms of schizophrenia. The present study evaluated the preventive effect of omega-3 on interleukines (IL) and neurotrophin brain-derived neurotrophic factor (BDNF) levels in the brains of young rats subjected to a model of schizophrenia. Treatment was performed over 21 days, starting on the 30th day of rat's life. After 14 days of treatment with omega-3 or vehicle, a concomitant treatment with saline or ketamine (25 mg/kg) was started and maintained until the last day of the experiment. BDNF levels in the rat's prefrontal cortex were decreased at 1 h and 24 h after the last administration of ketamine, whereas the group administered with ketamine and omega-3 showed a decrease in BDNF levels only after 24 h. In contrast, both interventions induced similar responses in levels of IL-1ß and IL6. These findings suggest that the similarity of IL-1ß and IL6 levels in our experimental groups is due to the mechanism of action of ketamine on the immune system. More studies have to be carried out to explain this pathology. In conclusion, according to previous studies and considering the current study, we could suggest a prophylactic role of omega-3 against the outcome of symptoms associated with schizophrenia.

The effect of sunlight exposure on interleukin-6 levels in depressive and non-depressive subjects.

BACKGROUND: The objective of this epidemiological study was to evaluate the effect of length of sunlight exposure on interleukin 6 (IL-6) levels in depressive and non-depressive subjects. METHODS: This was a cross-sectional study with 154 subjects (54 males, mean age: 43.5 ± 12.8 years) who were living in a rural area in south Brazil. Chronobiological and light parameters were assessed using the Munich Chronotype Questionnaire. Sleep quality was evaluated using the Pittsburgh Sleep Quality Index. Depressive symptoms were assessed with the Beck Depression Inventory. Plasma levels of inflammatory cytokines (IL-2, IL-4, IL-6, IL-10, tumor necrosis factor-α, and interferon) were collected during the daytime and measured. RESULTS: IL-6 levels showed a positive correlation with light exposure (r = 0.257; p < 0.001) and a negative correlation with the mid-sleep phase on work-free days (r = -0.177; p = 0.028). Multiple linear regression analysis showed that only the length of light exposure was an independent factor for predicting IL-6 levels (ß = 0.26; p = 0.002). In non-depressed subjects, exposure to a different intensity of light did not affect IL-6 levels (t = -1.6; p = 0.1). However, when the two depressive groups with low and high light exposure were compared, the low light exposure group had lower levels of IL-6 compared with the high light exposure group (t = -2.19 and p = 0.0037). CONCLUSIONS: The amount of time that participants are exposed to sunlight is directly related to their IL-6 levels. Additionally, depressed subjects differ in their IL-6 levels if they are exposed to light for differing amounts of time.

Immunoinflammatory and oxidative alterations in subjects with schizophrenia under clozapine: A meta-analysis.

Clozapine presents immunoregulatory properties not well understood. To address this issue, we performed this systematic review to evaluate the immune alterations induced by clozapine and its relationship with the drug's clinical response and compare it with other antipsychotics. Our systematic review has selected nineteen studies meeting the inclusion criteria, from which eleven were included in the meta-analysis, totalizing 689 subjects distributed over three different comparisons. The results revealed that clozapine treatment activates the compensatory immune-regulatory system (CIRS) (Hedges's g = +1.049; CI +0.62 - +1.47, p < 0.001) but has no effects on the immune-Inflammatory Response System (IRS) (Hedges's g= -0.27; CI -1.76 - +1.22, p = 0.71), M1 macrophage (Hedges's g= -0.32; CI -1.78 - +1.14, p = 0.65) and Th1 (Hedge's g = 0.86; CI -0.93 - +1.814, p = 0.07) profiles. Comparing clozapine-treated patients with other anti-psychotics-treated, plasma levels of interleukin (IL)-6 were greater in the clozapine group (Hedge's g = 0.75; CI 0.35 - 1.15, p<0.001). In addition, higher IL-6 plasma levels after four weeks of clozapine treatment were related to the development of clozapine-induced fever; however, IL-6 levels recovered to baseline in 6-10 weeks due to an unexplained compensatory mechanism. In conclusion, our results show that clozapine treatment causes a time-dependent mixed immune profile characterized by increased IL-6 levels and CIRS activation, which may contribute to this drug mechanism of action and adverse effects. Future studies must be designed to investigate the relationship between clozapine-induced immune alterations and symptom remission, treatment resistance, and adverse effects, given the importance of this drug for treating resistant schizophrenia.