MAPT and Mental deterioration: Intriguingly, it was recently shown that in AD patients who showed behavioural symptoms of dementia and brains showing Braak stages 3 and 5 pathology, small tau aggregates are present in the synapses to a greater extent compared with patients with the same neuropathological features (same Braak staging) who were resilient to dementia symptoms [66], suggesting that the synaptic localisation of small tau aggregates is a major driver of cognitive decline in AD.