Blood test could help gauge psychosis risk

By Eleanor McDermid, Senior medwireNews Reporter

Researchers have developed a multiplex blood assay that may aid the identification of high-risk individuals who will progress to psychosis.

The assay includes 15 analytes, identified from an initial panel of 185 analytes involved in hormonal responses, inflammation, growth, oxidative stress and metabolism. The team, led by Diana Perkins (University of North Carolina at Chapel Hill, USA), excluded 23 analytes that were not detected in at least 20% of their study participants at baseline and used “greedy algorithms” to narrow the remaining analytes down to identify those that best distinguished between the three groups in the study.

These groups comprised 32 patients at clinical high risk (CHR) of psychosis who developed full-blown symptoms during 2 years of follow-up, 40 who did not and 35 mentally healthy controls of similar age to the patients.

The top 15 analytes distinguished between CHR patients who did and did not develop psychosis with an accuracy of 88% and between those who developed psychosis and controls with an accuracy of 91%. The accuracy using fewer of these analytes was also high, with the top six giving respective accuracies of 83% and 84%.

The top six analytes were malondialdehyde-modified low-density lipoprotein, thyroid-stimulating hormone, interleukin-1 beta, matrix metalloproteinase 7, immunoglobulin E and uromodulin, which the researchers say supports the theory that “activation/dysregulation of the immune system may play a central role in the development of psychosis.”

Perkins et al note that, given a sensitivity of about 60%, the blood assay would have a specificity for psychosis of about 90%. In a cohort with a 30% risk of progressing to psychosis within the next 2 years, this would give a positive predictive value of 72% and a negative predictive value of 84%.

“Persons above this high-risk cut-off could be considered eligible for interventions where the benefits are high but the risks/costs may also be high, eg, antipsychotic medications or relatively intense individual/family therapies”, the team suggests in Schizophrenia Bulletin.

However, the researchers note that more work is needed, “as there are likely many other combinations of analytes with utility in psychosis risk prediction, and a blood assay could be combined with other clinical, imaging, or electrophysiological measures associated with progression to psychosis in clinical high-risk subjects.”

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