MAPT and dementia: Our findings highlighted that plasma p-tau181 was (1) positively associated with CSF t-tau and p-tau in pre-clinical AD, prodromal AD, and dementia stage; (2) longitudinally correlated with change and change rate of global cognition, executive function, memory, language-related, and visuospatial domains and hippocampal volume; (3) significantly predictive of clinical conversion to dementia.