I have chronically low ceruloplasmin(?) what could this mean? can it be a cause for my brain fog?

Ceruloplasmin=Copper: Ceruloplasmin is an enzyme produced by the liver that is the main copper-carrying protein. Low ceruloplasmin may point to liver disease (not able to make ceruloplasmin), low copper intake in food (i.e., shellfish), a genetic condition like Wilson's disease (copper overload) or Menkes' disease, or a side effect of iron overload. Or it could be "just you", a lab result w/ no symptom or consequence.

It depends.: What is causing your low ceruloplasmin? Your doctor must have an idea since the test was ordered. There are several possible causes and some of the diseases that cause it can affect well-being and thinking. It's a protein that carries copper, too much copper, instead of too little, is more likely to cause problems in the brain. See http://www.nlm.nih.gov/medlineplus/ency/article/003662.htm