Fibro fog – also known as fibromyalgia fog and brain fog – is a term commonly used for the cognitive difficulties that can occur with fibromyalgia. These include confusion, lapses in memory, word mix-ups and difficulty concentrating. 

The cause of fibromyalgia fog has been the subject of several studies and much speculation. One of the most popular theories about fibro fog has been that these problems are caused by sleep deprivation and/or depression, but one study found that neither poor sleep nor depression seemed related to cognitive performance.  

Brain scan studies have shown that from time to time, people with fibromyalgia do not receive enough oxygen in different parts of their brain. One possible reason is that part of their nervous system is off-kilter, causing changes in the brain’s blood vessels.

Additional research – though not on fibromyalgia specifically – shows that chronic pain itself may affect the brain. A technology called functional MRI found that in people with chronic pain, a front region of the brain mostly associated with emotion is constantly active. The affected areas fail to “shut off” when they should, wearing out neurons and disturbing the balance of the brain as a whole.