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

男女間の不平等と脳の性差 --男女間の不平等は脳構造の性差と関連する--. 京都大学プレスリリース. 2023-05-10.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

Prevalence of depressive disorder in the adult population of Latin America: a systematic review and meta-analysis.

BACKGROUND: Depressive disorder is one of the leading causes of disability worldwide; however its prevalence and association with inequality and crime is poorly characterised in Latin America. This study aimed to: i. systematically review population-based studies of prevalence of ICD/DSM depressive disorder in Latin America, ii. report pooled regional, country, and sex-specific prevalence estimates, and iii. test its association with four country-level development indicators: human development (HDI), income (Gini) and gender inequality (GII), and intentional homicide rate (IHR). METHODS: We conducted a systematic review and meta-analysis of population-based studies reporting primary data on the prevalence of ICD/DSM depressive disorder in Latin America from 1990 to 2023, irrespective of language. We searched PubMed, PsycINFO, Cochrane Library, SciELO (regional database), LILAC (regional database), and available grey literature. Study quality was assessed using JBI's critical appraisal tools. We generated pooled estimates using random-effects meta-analysis; heterogeneity was assessed using the I2 statistic. Meta-regression analyses were used to test associations of depression prevalence with indicators of inequality and human development. The study was registered with PROSPERO (CRD42019143054). FINDINGS: Using data from 40 studies in Latin America, lifetime, 12-month, and current prevalence of ICD/DSM depressive disorder were calculated at 12.58% (95% CI 11.00%-14.16%); 5.30% (4.55-6.06%), and 3.12% (2.22-4.03), respectively. Heterogeneity was high across lifetime, 12-month, and current prevalence, sex, and countries. 12-month and current prevalence was associated with higher Gini and GII, 12-month prevalence with lower HDI, and current prevalence with higher IHR. INTERPRETATION: We found a high prevalence of ICD/DSM depressive disorders in Latin America, and a statistically significant association with inequality and development indicators. The high heterogeneity found across prevalence periods and the major gaps in country representation underscore the need to escalate efforts to improve mental health access and research capabilities in Latin America. Systematic, comparable prevalence estimates would inform more effective decision-making in the region. FUNDING: Pfizer Independent Medical Education Grant

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

Summary 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- A nd middle-income countries, where potentially less brain vulnerability (less grey matter loss) is sufficient to become unwell in adverse (poor) environments.Fil: Crossley, Nicolas A.. Pontificia Universidad Católica de Chile; ChileFil: Zugman, Andre. Universidade Federal de Sao Paulo; BrasilFil: Reyes Madrigal, Francisco. Instituto Nacional de Neurología y Neurocirugía; MéxicoFil: Czepielewski, Leticia S.. Universidade Federal do Rio Grande do Sul; BrasilFil: Castro, Mariana Nair. Universidad de Buenos Aires. Facultad de Medicina. Departamento de Salud Mental; Argentina. Fundación para la Lucha contra las Enfermedades Neurológicas de la Infancia. Instituto de Neurociencias - Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Neurociencias; ArgentinaFil: Diaz Zuluaga, Ana M.. Universidad de Antioquia; ColombiaFil: Pineda Zapata, Julian A.. No especifíca;Fil: Reckziegel, Ramiro. Universidade Federal do Rio Grande do Sul; BrasilFil: Gadelha, Ary. Universidade Federal de Sao Paulo; BrasilFil: Jackowski, Andrea. Universidade Federal de Sao Paulo; BrasilFil: Noto, Cristiano. Universidade Federal de Sao Paulo; BrasilFil: Alliende, Luz M.. Pontificia Universidad Católica de Chile; ChileFil: Iruretagoyena, Barbara. Pontificia Universidad Católica de Chile; ChileFil: Ossandon, Tomas. Pontificia Universidad Católica de Chile; ChileFil: Ramirez Mahaluf, Juan P.. Pontificia Universidad Católica de Chile; ChileFil: Castañeda, Carmen P.. Instituto Psiquiátrico Dr. José Horwitz Barak; ChileFil: Gonzalez Valderrama, Alfonso. Universidad Finis Terrae; ChileFil: Nachar, Ruben. Instituto Psiquiátrico Dr. José Horwitz Barak; ChileFil: León Ortiz, Pablo. Instituto Nacional de Neurología y Neurocirugía; MéxicoFil: Undurraga, Juan. Universidad del Desarrollo; ChileFil: López Jaramillo, Carlos. Universidad de Antioquia; ColombiaFil: Guinjoan, Salvador Martín. Universidad de Buenos Aires. Facultad de Medicina. Departamento de Salud Mental; Argentina. Fundación para la Lucha contra las Enfermedades Neurológicas de la Infancia. Instituto de Neurociencias - Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Neurociencias; ArgentinaFil: Gama, Clarissa S.. Universidade Federal do Rio Grande do Sul; BrasilFil: De La Fuente Sandoval, Camilo. Instituto Nacional de Neurología y Neurocirugía; MéxicoFil: Bressan, Rodrigo A.. Universidade Federal de Sao Paulo; Brasi