Problems in thinking or concentration. Different from the ADHD symptoms we experience, where we think of too many things and have a hard time keeping our thoughts on just one. Brain fog occurs when you feel as though time has lapsed and you have not been able to think about anything (like your brain is foggy). Brain fog can be caused by traumatic brain injuries (TBI), including Chiari Malformations, but there are other causes common to us: the influence of anesthesia or many of the medications we take to control our pain/spasms; additionally a diet high in sugar/carbohydrates is known to cause brain fog.