Testing whether lactate can help the aging brain use fuel better

The brain's primary source of fuel is glucose. Unfortunately, the brain's ability to use glucose declines during normal aging. This decline in brain glucose metabolism makes it vulnerable to cognitive impairment and Alzheimer's disease. The brain can use another fuel source - lactate - which becomes available to the brain during exercise. The investigators have discovered that when lactate fuels the brain, brain glucose metabolism also improves. Essentially, from a metabolic angle, the brain appears younger. Recently, the investigators have shown that lactate - even in the absence of exercise - stimulates this beneficial effect on the brain. The investigators propose to compare the effects of lactate in healthy young and older adults to test whether these beneficial lactate-mediated effects persist throughout the lifespan, thereby providing a blueprint to restore youthful brain glucose metabolism.