Study Identifies Distinct Immune Signatures to Early Depression and Psychosis

Diagnosis of depression and psychosis still relies largely on clinical symptoms, despite growing evidence that biological markers can reveal underlying disease mechanisms. In the early stages, both conditions are associated with changes in inflammatory blood markers and gray matter structure, creating an opportunity for earlier and more precise stratification. Distinguishing between them in young adults is particularly important to enable timely intervention and prevent severe progression. New findings now show that distinct brain-blood signatures can differentiate early-stage depression from psychosis.

Researchers at the University of Cologne, together with collaborators at the Max Planck Institute of Psychiatry and University of Oxford, have published an international study in JAMA Psychiatry describing multivariate brain-blood signatures in early-stage depression and psychosis. The investigation highlights fundamentally different inflammatory profiles and neuroanatomical patterns between the conditions even at their earliest stages. According to the authors, these biological differences support more precise early intervention.

Image: Early detection of distinct brain-blood signatures in depression and psychosis can enable quicker and more effective intervention (photo courtesy of Adobe Stock)

The approach combined analysis of inflammatory signatures in blood with MRI of gray matter across brain regions central to emotional processing, including the limbic system. Cytokine levels were assessed to capture immune dysregulation, while MRI quantified gray matter volume to define brain signatures associated with each disorder. Together, these multimodal data were used to differentiate disease-specific patterns in young adults.

Study procedures were conducted between 2013 and 2018 across sites in Germany, Italy, Switzerland, Finland, and the United Kingdom, drawing on 678 selected participants from the PRONIA (Personalized Prognostic Tools for Early Psychosis Management) project, which ran from 2014 to 2019. Participants included individuals with a recent history of depression or psychosis and those at high clinical risk of psychosis, most with minimal prior medication exposure; healthy control subjects were also enrolled. The study design focused on early-stage illness to identify signatures before extensive treatment effects or chronic progression.

Results showed complex but internally consistent cytokine differences in both conditions, with no overlap between depression and psychosis signatures in either inflammatory markers or brain structure. Evidence of impaired cognitive abilities emerged only within the psychosis signature, whereas the depression signature did not show cognitive deficits. The findings indicate clear, non-intersecting profiles across all collected data and analyses, supporting more targeted early therapeutic strategies.

The authors note that early detection of these distinct signatures can enable prompt intervention and may help reduce the risk of severe disease progression. Further work is planned, including a diffusion tensor imaging study to examine neuroinflammation in greater detail and to assess the stability of the observed signatures over time. 

"These signatures open up new approaches for both biologically- and psychosocially-based early interventions in depression and psychosis. This paves the way for customized therapies, depending on whether the young person is in a depression or psychosis development curve," said lead author Dr. David Popovic from the Max Planck Institute of Psychiatry in Munich.

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Max Planck Institute of Psychiatry in Munich