Is there a way to determine the risk of psychosis in individuals? Detecting predictive markers is a significant challenge in the field of psychiatry. Researchers have discovered that imbalances in the connectivity between specific brain regions could serve as a potential predictive marker for psychosis.
The 22q11.2DS gene microdeletion is the most common genetic deletion, affecting 1 in 2000 individuals. This genetic anomaly, characterized by a missing DNA sequence on chromosome 22, can lead to various health issues, including heart defects, immune dysfunction, and psychotic disorders in 35% of carriers during adolescence or adulthood.
At the University of Geneva (UNIGE), a team led by Professor Stéphan Eliez from the Department of Psychiatry and the Synapsy Centre for Neuroscience and Mental Health Research has been studying a group of 300 individuals, aged 5 to 34, with the 22q11.2DS microdeletion for two decades. Nearly 40% of this cohort has developed schizophrenia, making it a unique case study globally and has resulted in several research publications.
Abnormal Brain Development from Childhood
In a recent study, researchers at UNIGE examined the development of connectivity between brain regions in individuals with the 22q11.2DS anomaly from childhood to adulthood. Silas Forrer, a PhD student in Professor Eliez’s team and the primary author of the study, explains that cognitive processes are influenced by interactions, or “couplings,” between different brain regions. The study aimed to determine if less efficient coupling in these individuals indicated a higher risk of psychosis.
Brain synchronization, crucial for optimal brain function, evolves during adolescence and adulthood. Using magnetic resonance imaging, scientists monitored the maturation of brain connectivity over twelve years in the cohort and a control group. The results showed persistent developmental discrepancies in individuals with the microdeletion since childhood, exhibiting regions of both hyper- and hypo-coupling throughout the brain.
These discrepancies are most pronounced in adolescence in three key brain regions of individuals with the 22q11.2DS anomaly who developed schizophrenia: the frontal cortex, involved in voluntary motor coordination and language; the cingulate cortex, responsible for decision-making; and the temporal cortex, associated with somato-sensory activities. There was observed hypo-coupling in the first two regions and hyper-coupling in the third.
Progress Towards Identifying Predictive Markers
The strong link between developmental discrepancies and the 22q11.2DS microdeletion marks a significant advancement in identifying predictive markers for psychosis. Professor Eliez, leading the study, suggests that the next step involves determining how these patterns of brain connectivity can serve as unique “fingerprints” to assess an individual’s risk of psychosis or protection against it.
This research, supported by the Swiss National Science Foundation, represents a methodological innovation by combining observations of brain structure and function to analyze the developmental trajectory of a population concerning psychiatric conditions.
