Metabolic changes that spurred the evolution of our cerebral abilities may have possibly pushed the brain to its limits. The latest research adds weight to the theory that schizophrenia is a costly byproduct of human brain evolution.

Philipp Khaitovich from the Max-Planck-Institute for Evolutionary Anthropology led researchers from Cambridge, Leipzig and Shanghai to investigate brains from healthy and schizophrenic humans and compared them with chimpanzee and rhesus macaque brains.

They looked for differences in gene expression and metabolite concentrations and as Khaitovich explained "identified molecular mechanisms involved in the evolution of human cognitive abilities by combining biological data from two research directions: evolutionary and medical."

The study's authors used new technical approaches to test the theory that neurological diseases are the byproducts of increase in metabolic capacity and brain size during human evolution.

They identified the molecular changes that took place over the course of human evolution and considered those molecular changes observed in schizophrenia, a psychiatric disorder.

They found that expression levels of many genes and metabolites that are altered in schizophrenia, especially those related to energy metabolism, also changed rapidly during evolution.

According to Khaitovich, "Our new research suggests that schizophrenia is a byproduct of the increased metabolic demands brought about during human brain evolution."

The findings have been published on Monday in BioMed Central's open access journal Genome Biology.