Scientists from Keele University and Cardiff University have discovered new links between the breakdown in brain cell development and the risk of schizophrenia and other psychiatric disorders.
The new research is the first time that genetic disruption of specific cell processes crucial to brain development has been linked to disease risk in psychiatric disorders, such as schizophrenia. It is well-known that genetic risk factors can disrupt brain development in several psychiatric disorders, but little is known about which aspects of this process are affected.
The study was jointly led by Dr Eunju Jenny Shin from Keele University’s School of Life Sciences, and Dr Andrew Pocklington from the Division of Psychological Medicine and Clinical Neurosciences at Cardiff University.
The findings are published today in the journal Nature Communications.
Insight into the root cause of psychiatric disorders
Dr Shin said: “To truly understand the root causes of psychiatric disorders, we focused on studying the development of brain cells. We initially investigated changes in gene expression and characteristics of cells harbouring a rare mutation found in schizophrenia patients. The knowledge gained through this approach may ultimately help guide the development of novel therapies or help explain why some individuals respond to some treatments but not others.”
Dr Pocklington said: “Genetic factors play a significant role in determining a person’s risk of developing psychiatric disorders. Uncovering biological processes impacted by these genetic risk factors is a major step towards understanding the causes of disease.”
The scientists studied the birth and early development of human brain cells, a process is known as neurogenesis, used human pluripotent stem cells, which can develop into a wide variety of human cell types, including brain cells.
They identified several sets of genes that are switched on during neurogenesis – both in vitro and in human foetal brains – with each set appearing to play a distinct functional role. The researchers showed that genetic risk factors contributing to schizophrenia and other psychiatric disorders were highly concentrated in these sets.
Dr Shin said: “In vitro experiments showed that when activation of these sets is disrupted, the shape, movement and electrical activity of developing brain cells are altered, linking changes in these properties to disease. These cellular changes may provide a drug screening platform in the future.”
Targeting cells therapeutically
Disorders linked to disruption of these genes included both early-onset conditions such as developmental delay and autism and conditions with a later onset like bipolar and major depression, for which disruption of early brain development is not generally thought to play a large role.
The researchers raised the question of whether some of these genes – which are first switched on long before birth – remain active later in life and contribute to mature brain function, where they can potentially be targeted therapeutically.
Dr Pocklington said: “Previous studies have shown that genes active in mature brain cells are enriched for common genetic variants contributing to schizophrenia. Much of this enrichment was captured by the early developmental gene sets, which seem to contain a greater burden of common genetic risk factors.
“This suggests that some biological pathways first switched on in the early prenatal brain may remain active in later life, with genetic variation in these pathways contributing to disease by disrupting both development and mature brain function.”
Further work is needed to map out the full range of developmental processes disrupted in different psychiatric disorders and explore their longer-term effects on the brain.
Dr Shin added: “Although much remains to be uncovered, our findings provide valuable insight into the developmental origins of psychiatric disorders such as schizophrenia.”