[Senile Dementia of the Neurofibrillary Tangle Type (SD-NFT)].

A subset of older individuals with dementia have neurofibrillary tangles (NFTs) in the medial temporal lobe and show absence of amyloid β-protein (Aβ) deposition in the brain. In 1996, the author's group reported senile dementia of the NFT type (SD-NFT) as a disease entity characterized by these pathological features as well as late-onset dementia in older subjects. In 2014, it was proposed that this pathological condition, irrespective of the presence of cognitive impairment, should be referred to as primary age-related tauopathy (PART). SD-NFT is a dementing disease caused by severe PART pathology. This article reviews features of SD-NFT, relationships among PART, cognitive impairment, and Alzheimer's disease (AD) pathogenesis; and PART/SD-NFT as a background of SNAP [suspected non-AD pathophysiology] in the differential diagnosis of AD.