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

Abstract

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- and middle-income countries, where potentially less brain vulnerability (less grey matter loss) is sufficient to become unwell in adverse (poor) environments.

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

“…A study of the Philadelphia Neurodevelopmental Cohort (USA) (Gur et al, 2019) found that lower SES was related to both reduced performances in different cognitive domains and lower volume across brain regions, including white and gray matter, that was related to an accelerated neurodevelopment. In patients from Latin America (Crossley et al, 2021), we recently showed that income was related to total gray matter volume in unaffected individuals but not in psychosis patients. This potentially indicated that less brain vulnerability in patients (e.g.…”

“…This potentially indicated that less brain vulnerability in patients (e.g. less gray matter loss) would be sufficient to become unwell in adverse environments, and that considering the upbringing of patients is critical to understanding schizophrenia's anatomy (Crossley et al, 2021). Although this may seem contradictory to the present report, we believe that these two Latin American findings indicate that environmental variables might be key to explaining disease outcomes.…”

Diversity matters: opportunities in the study of the genetics of psychotic disorders in low- and middle-income countries in Latin America

“…To illustrate this point, a recent study included structural MRI images from 334 patients with schizophrenia and 262 controls and was able to examine the modulating effect of poverty and violence on the brain in the harsh Latin American environment. 86 Currently, projects are analyzing previously acquired genetic data to examine the validity of PRS for Latin American populations.…”

Consent, decisional capacity and guardianship in mental health research

“…MRI, neuropsychological assessments). To date, we have conducted studies on metabolic syndrome and healthy lifestyle 7 , neuroimaging 8 , treatment resistance 9 , social determinants of mental health 10 , epidemiology 11 , and public policies 6 , among other topics. This case report describes the potential benefits and associated challenges of conducting research in the context of a clinical practice in Latin America that works with vulnerable populations who have difficulties with decisional capacity.…”