I came across this on the BBC world service "The science hour"
Dr George Stothart has led the team at Bath University in the development of a 2 Minute test for Alzheimers
"Fastball, a new EEG method for the passive and objective measurement of recognition memory, that requires no behavioural memory response or comprehension of the task ."
https://academic.oup.com/brain/advance-article/doi/10.1093/brain/awab154/6372384