Arguably the best ME/CFS blood test we have at present is the one used by Myhill et al in their studies on mitochondrial energy metabolism (namely the "ATP Profiles" test from Acumen Lab). That not only correctly categorized almost every patient and healthy control under the right label (their studies looked at around 200 patients), but also, the measured degree of energy metabolism blockage in the "ATP Profiles" test correlated quite well with the severity of ME/CFS (as measured on the Bell scale). Unfortunately that test and those studies have not been independently replicated (but an independent replication study is being conducted). And also it's only this one small specialist lab in the UK which provides the test. I know one case of an ME/CFS patient whose family thought her illness was "all in the mind", but once she had this test at Acumen Lab which showed poorly functioning mitochondria, the family finally understood that it was a real illness. Interesting, I did not notice that. (Neurasthenia is the name of an illness similar to ME/CFS that was routinely diagnosed from around 1870 to 1950. In the early period of its life, neurasthenia was considered a neurological disease, and treated by neurologists. But later on, it appears that the psychologists/psychiatrists may have moved in, taking over control of the disease (now where have I come across that before)? Although most of the details of this are lost in history. A history of neurasthenia is provided in this paper.) But anyway, the two earlier papers on the buspirone challenge test were by Prof Peter Behan and Dr John Richardson, both from the classic ME camp.