Researchers from Fudan University, King's College London, Paris-Saclay University and several other research institutions have conducted a large-scale study aimed at identifying common biological mechanisms underlying a range of psychiatric and neurodevelopmental disorders. The findings were published in the journal Nature Mental Health.

The researchers focused on conditions such as schizophrenia, bipolar disorder, attention-deficit/hyperactivity disorder (ADHD), autism spectrum disorder (ASD), major depressive disorder, and insomnia, which are traditionally viewed as distinct diagnoses. However, it remains unclear whether these disorders share common genetic and molecular pathways.

To investigate this question, the team analyzed data from the IMAGEN project, a large European study that collected biological data from 1,274 healthy adolescents. None of the participants had diagnosed psychiatric or neurological disorders, allowing researchers to examine biological markers before the onset of disease.

The scientists examined genetic variants associated with changes in DNA methylation and gene expression levels. DNA methylation is a mechanism that regulates gene activity by adding chemical “tags” that influence how actively a gene is expressed.

Using genomic analyses and Mendelian randomization techniques, the researchers identified 73 potentially causal DNA methylation sites (CpG sites) and 62 genes linked to the six conditions under investigation. While some of these markers appeared to be specific to individual disorders, others showed overlapping effects across multiple conditions.

Particular attention was drawn to three genes—MAD1L1, MRPL2, and HLA-DRB1. According to the analysis, these genes are involved in biological pathways associated with several disorders simultaneously. For example, DNA methylation changes affecting MRPL2 were found to be potentially linked to both schizophrenia and insomnia.

The authors also noted that many of the identified genes are enriched in pathways associated not only with psychiatric disorders but also with autoimmune diseases. This finding suggests that the immune system and mental health may share elements of a common genetic architecture.

The researchers emphasize that the results do not fully explain the development of these disorders. However, they highlight potential biological “crossroads” that may play an important role in future diagnostic approaches and the development of new therapies.