I recommend this paper
I find this paper from researchers at the Imaging Institute at the University of Texas both interesting and puzzling.
Like their more recent paper (Huang et al., 2013), they report that methylene blue (MB) aka methylthioninium chloride, enhances hemodynamics and metabolism in the rat brain.
Yet, in human septic shock patients, Gachot et al. (Gachot et al., 1995) reported that MB induces systemic and pulmonary vasoconstriction in patients with septic shock, without significant decrease in cardiac index.
Their concern was that the worsening of arterial oxygenation following MB injection may limit its use in patients with the adult respiratory distress syndrome.
Barber et al. (Barber et al., 1995) observed that MB has the potential to adversely affect vascular reactivity in patients.
Similarly, MB in a variety of animal model studies has been shown to be vasoconstrictive. Given that the hemodynamics in AD patients' brains are already impaired, could MB further exacerbate this condition?
To put this in context, Wischik et al. (Wischik et al., 1996)...