Observations were made over @ hours for pre - and post-working memory ( WM ) , glycaemic and insulin responses and biomarkers of Alzheimer 's disease ( AD ) ( @ , @ , @ and @ hours ) : amyloid precursor protein ( APP ) , - secretase subunits presenilin-@ ( PS@ ) , presenilin-@ ( PS@ ) , and glycogen synthase kinase ( GSK-@ ) .