Low blood flow in your foot is a clue to trouble in your brain. A surprisingly simple, noninvasive, inexpensive test called the ankle-brachial index (ABI) can reveal the cognitive state of your brain and your likelihood of stroke and dementia. The primary use of this test is to detect peripheral artery disease in the lower limbs but studies have shown that it is also amazingly accurate in picking up on cognitive impairment in older people and the possibility of stroke and Alzheimer’s. What to do? Ask your doctor about having an ankle-brachial index test to alert you to memory problems ahead. Then, depending on the results, follow your doctor’s advice on what you need to do.