I participated in Dr Natelson's spinal tap study a year ago and part of the study involved a short neuropsych test. You first read a list of words that increased in difficulty and the researcher determined how many you knew based on your pronunciation, which I assumed was a very rough IQ test. Then you copied a drawing and they removed the drawing and asked you to redraw it-- this would be tough to do on-line. The next test was maybe 5 minutes long-- you watched numbers go across a screen and had to press a button when you saw a repeat from one or two numbers ago. This one fried my brain and I had to lie down after a few minutes (and obviously this would be incredibly easy when my brain was working right.) You also had to repeat some numbers backward that were read to you, which seems like an easy online test. I don't know the results or grading for that test, but I feel like if we can find a version of the two numbers tests online it would be a good brain fog test-- I think they compare your results on those tests with your IQ to determine how disabled you are. You would only need to do the IQ test once for a baseline. I will look around a little to see if I can find an online version, but I fear there may not be a free one.