People with high blood pressure are often told to watch the salt. And it's long been thought that hypertension related to excess salt is caused by the salt increasing the volume of the blood. Which in turn puts added pressure on the blood vessel walls. But going back to the 1960s and '70s, some researchers thought that the salt might be having a different effect. Now long-time hypertension researchers Irene and Haralambos Gavras at the Boston University School of Medicine have analyzed the studies in the field and published a review article explaining what they think salt's role really is: it stimulates the sympathetic nervous system to produce adrenalin. And it's the adrenalin that constricts the arteries and causes the high blood pressure, not excess fluid volume. The review is in the Journal of Hypertension. Physicians have accepted a nervous system involvement in hypertension that's bad enough to cause kidney failure. Fluid-decreasing diuretics are a common treatment in those severe cases. This new analysis implies that researchers should look for additional hypertension treatments that focus on the nervous system.