Young males, ethnic minorities and people living in socioeconomically disadvantaged areas are more likely to experience first-episode psychosis, defined as the first manifestation of one or more severe mental disorders including schizophrenia, bipolar affective disorder, and depression with psychotic symptoms such as hallucinations, delusions and cognitive disorganization.
This is the main finding of a study conducted by an international consortium that estimated the incidence of first-episode psychosis in five European countries - England, France, Italy, the Netherlands and Spain - as well as Brazil. The results were published in JAMA Psychiatry.
In recent years, research has shown that the incidence of first-episode psychosis varies among regions and populations. In European countries, these disorders have been found to be more frequent in large cities than smaller towns or rural areas and also to be relatively frequent among ethnic minorities such as black immigrants from the Caribbean and Africa.
The researchers in the consortium set out to confirm or refute these observations by means of an investigation conducted in 17 urban and rural areas in the six participating countries between 2010 and 2015.
In Brazil, with the support from the São Paulo Research Foundation - FAPESP, the study conducted a survey which covered 26 municipalities in the Ribeirão Preto administrative area in São Paulo State. Studies were coordinated by Paulo Rossi Menezes, a professor in the Preventive Medicine Department of the University of São Paulo's Medical School (FM-USP), and Cristina Marta Del Ben, a professor in the Neuroscience & Behavioral Science Department of the same university's Ribeirão Preto Medical School (FMRP-USP).
They began by identifying 2,774 individuals who contacted mental health services in the areas concerned with suspected first-episode psychosis. Of these, 1,578 were male, and 1,196 were female. Their median age was 30.
Analysis of the data showed an eightfold variation in the incidence of first-episode psychosis across the areas surveyed. In Santiago, Spain, it was 6 new cases per 100,000 inhabitants per year, compared with 46 in Paris, France. In Ribeirão Preto, Brazil, it was 21.
"The study confirmed that the incidence of first-episode psychosis varies considerably between major cities and rural areas. It also showed that environmental factors probably play a crucial role in this significant variation," Menezes said.
"Until the end of the twentieth century, the etiology of psychotic disorders was believed to be mainly genetic, but the results of this study show that environmental factors are extremely important."
The study also showed that the incidence of first-episode psychosis was higher among men aged 18 to 24 than among women in the same age group. Menezes said this finding confirms fairly consistent data in the literature.
He noted that the incidence of first-episode psychosis among young adult males is higher than among young adult females according to previous research, which also shows that as men approach 35, it tends to converge with the incidence among women. In women aged 45-54, it is slightly higher than among men in the same age group.
"We don't know exactly why there are these differences in incidence between sexes and age groups, but they may be linked to the process of cerebral maturation: the brain matures between the ages of 20 and 25, and during this period, men seem to be more vulnerable to mental disorders than women," Menezes said.
The researchers also found that the incidence of first-episode psychosis is high among ethnic minorities and in areas with less owner-occupied housing.
"This suggests that socioeconomic conditions and the environment in which people live play important roles in the etiology of psychotic disorders. We need a better understanding of the mechanisms involved in order to explain variations in incidence between population groups," Menezes said.
The researchers plan to analyze data on the patients' life histories and socioeconomic conditions, comparing them with controls from the general population (people who have no history of psychosis) in order to identify risk factors for the development of first-episode psychosis.
Traumatic childhood experiences or smoking pot when a teenager or young adult, for example, are factors that increase the risk of mental disorders, according to Menezes. "If we can identify the risk factors for the development of these mental disorders in more vulnerable groups, we'll be able to intervene to reduce their incidence," he said.
Psychosis accounts for a significant proportion of the global disease burden, given the incapacity it causes. Furthermore, the evolution of psychotic disorders varies considerably, with some cases leading to a high degree of incapacity. "A large proportion of patients require specialized care in psychiatric and mental health centers," Menezes said.
About São Paulo Research Foundation (FAPESP)
The São Paulo Research Foundation (FAPESP) is a public institution with the mission of supporting scientific research in all fields of knowledge by awarding scholarships, fellowships and grants to investigators linked with higher education and research institutions in the State of São Paulo, Brazil. FAPESP is aware that the very best research can only be done by working with the best researchers internationally. Therefore, it has established partnerships with funding agencies, higher education, private companies, and research organizations in other countries known for the quality of their research and has been encouraging scientists funded by its grants to further develop their international collaboration. For more information: http://www.fapesp.br/en.