Rethinking schizophrenia through the lens of evolution: shedding light on the enigma

Ariel Cariaga-Martinez,Kilian Gutiérrez,Raúl Alelú-Paz

doi:10.3897/rio.4.e28459

Abstract

Schizophrenia refers to a complex psychiatric illness characterized by the heterogenic presence of positive, negative and cognitive symptoms occurring in all human societies. The fact that the disorder lacks a unifying neuropathology, presents a decreased fecundity of the affected individuals and has a cross-culturally stable incidence rate, makes it necessary for an evolutionary explanation that fully accounts for the preservation of “schizophrenic genes” in the global human genepool, explaining the potential sex differences and the heterogeneous cognitive symptomatology of the disorder and is consistent with the neuropsychological, developmental and evolutionary findings regarding the human brain. Here we proposed a new evolutionary framework for schizophrenia that is consistent with findings presented in different dimensions, considering the disorder as a form of brain functioning that allows us to adapt to the environment and, ultimately, maintain the survival of the species. We focus on the epigenetic regulation of thalamic interneurons as a major player involved in the development of the clinical picture characteristic of schizophrenia.

Highlights

Cariaga-Martinez A et al Schizophrenia is considered as a debilitating genetic psychiatric disorder characterized by the presence of a constellation of symptoms that fits into three categories that affects all the cognitive domains described to date
We cannot deny that we are facing a complex issue with several edges, many of them enigmatic (Alelu-Paz et al 2016) which, together, create an unresolved pool of questions such as: Why has natural selection allowed genes to persist in the human genome that increase the likelihood of suffering schizophrenia, despite its reproductive disadvantage? Can we describe a disease entity corresponding to what we call schizophrenia? Is there an exact correlation between genotype and phenotype? What role do environmental factors play in schizophrenia etiology? Is there a link between brain malfunctioning and schizophrenia symptoms?
Previous evolutionary hypotheses have addressed some of these questions trying to explain the constant incidence rates of the disorder independently of the culture or the environment, despite the fact that, as we have indicated before, people suffering from schizophrenia have a reduced fecundity and an increased risk of mortality compared to the general population (Brune 2004)

Summary

Introduction

Schizophrenia is considered as a debilitating genetic psychiatric disorder characterized by the presence of a constellation of symptoms that fits into three categories that affects all the cognitive domains described to date.

Results

Conclusion