Researchers Develop Diagnostic Test for Chronic Fatigue Syndrome

Alzheimer’s disease is not the only neurologic condition which may one day be diagnosed by blood test. Researchers at Stanford University and the University of California, Irvine, have developed a blood-based assay that may identify people with chronic fatigue syndrome (also known as myalgic encephalomyelitis). Their study was published April 29 in PNAS.

R. Esfandyarpour

Combining techniques in electrical engineering and fluid dynamics, the researchers built a tiny array with thousands of sensors surrounding a fluid channel (see photo). Blood injected into the channel then gets exposed to hyperosmotic stress (a rapid change in external salt concentration), and the sensors measure the resulting electrical activity discharged by the cells. (Salt is composed of positive sodium and negative chlorine ions, and the movement of these ions in and out of cells creates an electrical current.) The idea behind the design is that the neurons of people with chronic fatigue syndrome overreact to stressful signals, leading to increased discomfort and fatigue.

The researchers tested the assay on blood samples from 20 patients with chronic fatigue syndrome and 20 healthy controls. They found that the blood cells from patients with chronic fatigue syndrome had dramatically altered electrical impedance (how well a cell responds to changes in electric current) after osmotic stress, whereas the blood cells from healthy controls had similar impedance before and after stress. Though the exact mechanisms are unclear, the authors said this altered impedance suggests the cell membranes or some membrane pumps are compromised in the blood cells of patients with chronic fatigue syndrome.

In addition to diagnostic use, the researchers said their device could be used in the preclinical testing of medications for chronic fatigue syndrome. Potential drug candidates could be analyzed with the assay to see if they can improve cell membrane resilience. ■