Schizophrenia, like many mental disorders, is a tricky thing to diagnose. But new research suggests that one way to sniff it out may be through closely examining the patient’s nose – really!

At the moment, the most common way that doctors diagnose schizophrenia is with a psychological evaluation. Through interviews and observation, a psychiatrist assesses whether a patient has been showing symptoms such as hearing voices for at least six months, and that there’s no alternative explanation for their behavior, such as another mental illness or reaction to a drug. But a less subjective method would remove doubt – and possibly allow for earlier detection of schizophrenia, which tends to blossom in adulthood.

Now, a team of researchers from Tel Aviv University and the Johns Hopkins University School of Medicine has a possible way to spot a molecular signature associated with schizophrenia. Previously, it was assumed that the biological traces of schizophrenia were only found in nerve cells in the brain that can't be examined while the patient is still alive.

But the researchers say the traces of schizophrenia can be found in a different set of nerve cells – the ones in the nose. Olfactory, or smelling, tissue is one of the few easily accessible sources of neurons that doesn’t require you to be dead for it to be harvested. A simple biopsy could be all that’s needed to examine olfactory neurons to see if they bear the telltale sign.

In a paper forthcoming in the journal Neurobiology of Disease, the team found that olfactory tissue from schizophrenic patients had more of a certain microRNA – a small piece of genetic material that regulates gene expression – called miR-382.

"We were able to narrow down the microRNA to a differentially expressed set, and from there down to a specific microRNA which is elevated in individuals with the disease compared to healthy individuals," Shomron said in a statement on Monday.

Further investigation showed that miR-382 is directly involved with two genes called FGFR1 and SPRY4, both of which are involved in a signaling pathway that, when interfered with, is thought to result in abnormal brain development characteristic of schizophrenia.

Translating the procedure into a diagnostic test could be a way to deliver a quick and accurate diagnosis, the researchers say. A patient’s nasal tissue could be collected in a quick outpatient procedure, and microRNA profiles could be generated in a few hours.

There are still some missing pieces to the puzzle though. It’s not yet clear if the microRNA flag crops up before schizophrenia develops, or whether it’s a byproduct of the condition. Answering this question will be key to determining if it’s possible to sniff out schizophrenia years in advance.

SOURCE: Mor et al. “MicroRNA-382 expression is elevated in the olfactory neuroepithelium of schizophrenia patients.” Neurobiology of Disease 55: 1-10, July 2013.

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