I went to a gastro doctor a year ago and had a blood test for celiac, I don't know if it was a 'comprehensive panel' as I wasn't given the info..but they told me I don't have celiac disease. Maybe I don't, but I definitely notice a reaction to eating gluten and have been avoiding it.
I notice some alleviation of the symptoms when I eat more fruit/vegetables and basic food. But it's not just gluten that causes brain fog..it seems like food with sugar and gluten-free flour can cause similar symptoms. The reaction to gluten-free flour products (like spaghetti, or bread; the worst would be a pastry with flour + sugar) is similar but not as strong as with wheat flour foods.