Last year, doctors in Japan started using a relatively new technique — near-infrared spectroscopy (NIRS) — to distinguish between schizophrenia, depression, bipolar disorder and normal mental-health states (see page 148). It is not difficult to see why this was a popular move. Doctors like it because it is easy to use. Patients like its objective nature, and that it provides them with physiological evidence of a disorder. And officials at the health ministry are happy because it represents a public success of their drive to innovate.Click here to read on about the difficulties of introducing any new diagnostic technique and validating it, both in terms of how to define appropriate application of a technique as well as who should foot the bill during the experimental phase of a technique. Still, the idea of using MRI or ultrasound techniques much like infrared is extremely promising given the lack of ionizing radiation involved. Patient safety groups may still raise various concerns, but certainly the main risk of oncogenesis is mitigated.
In Japan, NIRS diagnosis is one of dozens of advanced medical techniques offered to patients — at their own expense — despite not having gone through the clinical trials needed for approval by national health insurance. But is it ready for the clinic? Most scientists contacted by Nature do not think so. The patient groups of the supporting studies were small. The tests have not been reproduced in various clinical settings as one might hope. There is no international consensus on how best to measure NIRS parameters, much less a clear consensus on how to apply them to mental health. And if it is not ready, the same advantage that has patients lining up for it — the authority of an objective, physiological measure, the air of the incontrovertible — will become an obstacle. A misdiagnosis that carries the authority of an 'objective' measurement will probably be even more difficult to overturn.
Regardless of the outcome of this particular technique, the field of "radiopsychiatry" or whatever you would like to call it is almost certain to boom over the next decade, especially as techniques become validated and scaled up for use in clinics around the world, leading to a boom not only in radiology but as well as in psychiatry. Ultimately, patients with mental health disorders will benefit the most as they get more objective and accurate data about the nature of their ailments.