Schizophrenia: The new etiological synthesis.

Area of Science:

• Evolutionary biology
• Neuroscience
• Psychiatry

Background:

• Schizophrenia presents an evolutionary paradox due to high heritability and reduced reproductive success.
• Existing evolutionary hypotheses lack empirical support, except for the evolutionary mismatch hypothesis.
• Environmental factors, including microbial infections, are increasingly recognized in schizophrenia etiology.

Purpose of the Study:

• To critically evaluate evolutionary hypotheses for schizophrenia.
• To propose a new etiological synthesis integrating genetic, infectious, and environmental factors.
• To suggest novel treatment strategies for schizophrenia.

Main Methods:

• Critical review of existing evolutionary hypotheses for schizophrenia.
• Synthesis of evidence supporting the evolutionary mismatch hypothesis.
• Integration of host genotype, microbial infection, and chronic stress models.

Main Results:

• Most evolutionary hypotheses for schizophrenia lack empirical validation.
• The evolutionary mismatch hypothesis, implicating modern environmental factors, is relatively well-supported.
• A new etiological model suggests schizophrenia arises from an interaction between host genotype, microbial infection, and chronic stress, mediated by neuroinflammation and gut dysbiosis.

Conclusions:

• Schizophrenia etiology is complex, involving gene-environment-microbe interactions.
• Neuroinflammation and gut dysbiosis are key mediators in schizophrenia development.
• Schizophrenia treatment should target underlying infections, inflammation, gut health, and stress, beyond symptom management.