What Happens to Your Brain When You Lie Down for 90 Days?

Lying down for a long time can mess with how blood flows in your brain. This is what scientists found out when they studied 36 healthy adults who spent 90 days in a head-down bed rest position. They used a special kind of MRI called pseudo-continuous arterial spin labeling (pCASL) to track changes in blood flow. After 90 days, the overall blood flow in the brain stayed the same. But there were some interesting changes in specific areas. The part of the brain that gets blood from the vertebrobasilar artery saw an increase in blood flow. On the other hand, some other areas like the left fusiform gyrus had more blood flow, while areas like the right superior frontal gyrus, middle cingulate gyrus, and Heschl's gyrus had less.The study also found that changes in blood flow were linked to changes in blood pressure. For example, the blood flow in the vertebrobasilar territory was lower when diastolic blood pressure and mean arterial pressure were higher. Additionally, the heart rate before the bed rest started played a role in how much the blood flow changed in this area. Age also seemed to play a role. In younger adults, the right superior frontal gyrus showed changes in blood flow that were related to age. This suggests that the brain's blood flow can be affected by both short-term changes, like lying down for a long time, and long-term factors, like age. This study gives us a better understanding of how the brain adapts to changes in gravity. It also has implications for both space travel and conditions on Earth that affect blood flow in the brain.