Gene deletion linked to brain discrepancies may predict psychosis risk, study finds

DISCREPANCIES between brain regions linked to a common gene deletion, affecting one in every 2,000 individuals, could help assess the risk for developing psychosis, according to a new study.

For 20 years, a team of researchers at the University of Geneva, Switzerland, followed 300 patients aged 5-34 years who were affected by a specific gene deletion, the 22q11.2DS microdeletion.

This common genetic deletion results in the absence of a small DNA sequence on chromosome 22 and is known to lead to heart defects and immune system malfunctions in carriers.

About a third of individuals with this gene deletion can also develop psychotic disorders during their teenage years or adulthood, which results in a loss of contact with reality and symptoms that disrupt thoughts and perceptions. Almost 40 percent of the study cohort developed schizophrenia, the researchers reported.

In the study, published in the journal Biological Psychiatry: Cognitive Neuroscience and Neuroimaging recently, the researchers looked at how the interactions or "coupling" between brain regions developed from childhood to adulthood. These interactions form the basis of our cognitive (thinking) processes, they explained.      

The authors wanted to find out if a less efficient coupling in the people having the gene deletion meant an increased risk of developing psychosis.    

Using magnetic resonance imaging, the team observed for 12 years brain development in the individuals in their study cohort.    

They found a “persistent” discrepancy in the interactions between three brain regions, the frontal cortex, responsible for coordinated movement and language; the cingulate cortex, which helps process pain and emotions; and the temporal cortex, which processes auditory and visual information, along with memory.        

The discrepancy is especially marked in teenage, the researchers said.          

“We found that patients with the (gene deletion) had a persistent developmental discrepancy since childhood, with regions of hyper- and hypo-coupling throughout the brain,” said first author Silas Forrer, a PhD student in the Department of Psychiatry, University of Geneva.      

While hyper-coupling refers to a more-than-optimal coherent interactions between brain regions during development, hypo-coupling refers to a less-than-optimal coherence.      

The strong link found between the gene deletion and discrepancies developed during brain's development is a “significant step towards identifying predictive markers for the disease (psychosis),” the researchers said.        

“The next step will be to determine how these couplings can constitute an individual 'fingerprint' of the brain, making it possible to clearly know whether that individual is more at risk than another of developing psychosis, or conversely, is protected from it,” explained lead author Stephan Eliez, a professor in the Department of Psychiatry, University of Geneva. (PTI)