Neuroscience: Thought experiment
Japanese hospitals are using near-infrared imaging to help diagnose psychiatric disorders. But critics are not sure the technique is ready for the clinic.
http://www.nature.com/news/2011/110112/pdf/469148a.pdf
In a room full of psychiatrists in downtown Tokyo, I prepare to have my mental health assessed. No probing questions are asked. Instead, I don an odd type of swimming cap, criss-crossed with cables and studded with red and blue knobs. At the flick of a switch, the 17 red knobs send infrared light 2 to 3 centimetres into my brain, where it is absorbed or scattered by neurons. Photoreceptors in the 16 blue knobs retrieve whatever light bounces back to the surface. Buried in the signals, say the researchers operating the system, are clues that can distinguish depression, bipolar disorder, schizophrenia and a normal state of mind.
More than 1,000 people have already been subjects of the technique, called near-infrared spectroscopy (NIRS) and developed by Masato Fukuda, a psychiatrist and neuroscientist at Gunma University Hospital in Maebashi, and the Hitachi Medical Corporation in Tokyo. Most of those were research subjects. But since April 2009, when NIRS was approved by the health ministry as an "advanced medical technology" to assist psychiatric diagnoses, more than 300 people have paid ¥13,000 (US$160) out of their own pocket to access the technique. The University of Tokyo Hospital, one of eight leading Japanese research hospitals now offering NIRS diagnostic neuroimaging, found demand for it to be so high that the hospital stopped taking appointments twice. Gunma University Hospital is fully booked to the end of March. "We've been overwhelmed by requests," says Fukuda.
The appeal of NIRS is its promise of fast, clear-cut diagnoses of psychiatric conditions which, with their messily overlapping symptoms, are frequently diagnosed wrongly or not diagnosed at all. US studies, for example, found that some 70% of bipolar patients were initially misdiagnosed1,2. As for patients, says Fukuda, "They want some kind of hard evidence," especially when they have to explain absences from work.
NIRS could offer an objective measure of mental health reliable and convenient enough for routine use in the clinic. Fukuda says that it can help point to a diagnosis much like a chest X-ray might be used to help diagnose pneumonia or an electrocardiogram to define a heart problem. Aside from Fukuda and a group of doctors in Japan, however, few scientists are persuaded. Critics charge that the studies so far have been too few, too small and too weakly designed to warrant the technique's clinical use. "It's attractive as a research topic, but the data are not convincing enough," says Masahiko Haruno, a neuroscientist at Tamagawa University in Tokyo. John Sweeney, a neuroscientist at the University of Illinois, Chicago, who has spent two decades looking for connections between various brain-monitoring techniques and diseases such as schizophrenia, says that "none has ever been validated to anyone's satisfaction". And NIRS is the least developed of them all, he says, calling it "the thinnest of ice to be treading upon. We are nowhere near ready to tell patients and families that they should have these kinds of tests."
Having entered the research scene some 15 years ago, NIRS is relatively new compared with functional magnetic resonance imaging (fMRI) or electroencephalography (EEG), but in Japan it has raced ahead to the clinic. (The two biggest suppliers of NIRS analytic devices Hitachi and Kyoto-based Shimadzu are both based in Japan and the country accounts for two-thirds of publications using NIRS analysis.) The technique takes advantage of the fact that compared with constituents of other tissues, haemoglobin in blood absorbs more light in the near-infrared spectrum. Blood flow to a particular brain region increases when neurons there are active. So monitoring the changes in haemoglobin concentration gives a site-specific read on blood flow and thus on neuronal activity3. Fukuda's NIRS device focuses on the prefrontal cortex and temporal cortex, regions that are implicated in many of the symptoms seen in psychiatric disorders; the signature pattern of blood flow associated with each disorder is used to help diagnose it. NIRS lacks the precision and depth of fMRI, which can pinpoint changes in blood flow throughout the brain and with much greater spatial resolution. But NIRS is relatively cheap and mobile, and subjects can sit upright without having to endure a spell in the large, loud and sometimes nerve-wracking tube of an fMRI machine. This means that NIRS is easier to use on fidgety subjects such as children, and people with psychotic conditions or anxiety. The advantages have made infrared imaging increasingly popular with brain researchers worldwide. Devices from the largest maker in the United States, NIRx Medical Technologies of Glen Head, New York, are being used to study areas ranging from autism to braincomputer interfaces. Hitachi now offers a stripped-down version that allows the brains of four people interacting in a room to be analysed wirelessly.
read more in PDF file http://www.nature.com/news/2011/110112/pdf/469148a.pd
Japanese hospitals are using near-infrared imaging to help diagnose psychiatric disorders. But critics are not sure the technique is ready for the clinic.
http://www.nature.com/news/2011/110112/pdf/469148a.pdf
In a room full of psychiatrists in downtown Tokyo, I prepare to have my mental health assessed. No probing questions are asked. Instead, I don an odd type of swimming cap, criss-crossed with cables and studded with red and blue knobs. At the flick of a switch, the 17 red knobs send infrared light 2 to 3 centimetres into my brain, where it is absorbed or scattered by neurons. Photoreceptors in the 16 blue knobs retrieve whatever light bounces back to the surface. Buried in the signals, say the researchers operating the system, are clues that can distinguish depression, bipolar disorder, schizophrenia and a normal state of mind.
More than 1,000 people have already been subjects of the technique, called near-infrared spectroscopy (NIRS) and developed by Masato Fukuda, a psychiatrist and neuroscientist at Gunma University Hospital in Maebashi, and the Hitachi Medical Corporation in Tokyo. Most of those were research subjects. But since April 2009, when NIRS was approved by the health ministry as an "advanced medical technology" to assist psychiatric diagnoses, more than 300 people have paid ¥13,000 (US$160) out of their own pocket to access the technique. The University of Tokyo Hospital, one of eight leading Japanese research hospitals now offering NIRS diagnostic neuroimaging, found demand for it to be so high that the hospital stopped taking appointments twice. Gunma University Hospital is fully booked to the end of March. "We've been overwhelmed by requests," says Fukuda.
The appeal of NIRS is its promise of fast, clear-cut diagnoses of psychiatric conditions which, with their messily overlapping symptoms, are frequently diagnosed wrongly or not diagnosed at all. US studies, for example, found that some 70% of bipolar patients were initially misdiagnosed1,2. As for patients, says Fukuda, "They want some kind of hard evidence," especially when they have to explain absences from work.
NIRS could offer an objective measure of mental health reliable and convenient enough for routine use in the clinic. Fukuda says that it can help point to a diagnosis much like a chest X-ray might be used to help diagnose pneumonia or an electrocardiogram to define a heart problem. Aside from Fukuda and a group of doctors in Japan, however, few scientists are persuaded. Critics charge that the studies so far have been too few, too small and too weakly designed to warrant the technique's clinical use. "It's attractive as a research topic, but the data are not convincing enough," says Masahiko Haruno, a neuroscientist at Tamagawa University in Tokyo. John Sweeney, a neuroscientist at the University of Illinois, Chicago, who has spent two decades looking for connections between various brain-monitoring techniques and diseases such as schizophrenia, says that "none has ever been validated to anyone's satisfaction". And NIRS is the least developed of them all, he says, calling it "the thinnest of ice to be treading upon. We are nowhere near ready to tell patients and families that they should have these kinds of tests."
Having entered the research scene some 15 years ago, NIRS is relatively new compared with functional magnetic resonance imaging (fMRI) or electroencephalography (EEG), but in Japan it has raced ahead to the clinic. (The two biggest suppliers of NIRS analytic devices Hitachi and Kyoto-based Shimadzu are both based in Japan and the country accounts for two-thirds of publications using NIRS analysis.) The technique takes advantage of the fact that compared with constituents of other tissues, haemoglobin in blood absorbs more light in the near-infrared spectrum. Blood flow to a particular brain region increases when neurons there are active. So monitoring the changes in haemoglobin concentration gives a site-specific read on blood flow and thus on neuronal activity3. Fukuda's NIRS device focuses on the prefrontal cortex and temporal cortex, regions that are implicated in many of the symptoms seen in psychiatric disorders; the signature pattern of blood flow associated with each disorder is used to help diagnose it. NIRS lacks the precision and depth of fMRI, which can pinpoint changes in blood flow throughout the brain and with much greater spatial resolution. But NIRS is relatively cheap and mobile, and subjects can sit upright without having to endure a spell in the large, loud and sometimes nerve-wracking tube of an fMRI machine. This means that NIRS is easier to use on fidgety subjects such as children, and people with psychotic conditions or anxiety. The advantages have made infrared imaging increasingly popular with brain researchers worldwide. Devices from the largest maker in the United States, NIRx Medical Technologies of Glen Head, New York, are being used to study areas ranging from autism to braincomputer interfaces. Hitachi now offers a stripped-down version that allows the brains of four people interacting in a room to be analysed wirelessly.
read more in PDF file http://www.nature.com/news/2011/110112/pdf/469148a.pd
