Magnetic resonance imaging brain atrophy assessment in primary age-related tauopathy (PART)

Alzheimer disease (AD) is a neurodegenerative disorder characterized pathologically by the accumulation of amyloid-beta (Aβ) plaques and tau neurofibrillary tangles (NFTs). Recently, primary age-related tauopathy (PART) has been described as a new anatomopathological disorder where NFTs are the main feature in the absence of neuritic plaques. However, since PART has mainly been studied in post-mortem patient brains, not much is known about the clinical or neuroimaging characteristics of PART. Here, we studied the clinical brain imaging characteristics of PART focusing on neuroanatomical vulnerability by applying a previously validated multiregion visual atrophy scale. We analysed 26 cases with confirmed PART with paired clinical magnetic resonance imaging (MRI) acquisitions. In this selected cohort we found that upon correcting for the effect of age, there is increased atrophy in the medial temporal region with increasing Braak staging (r = 0.3937, p = 0.0466). Upon controlling for Braak staging effect, predominantly two regions, anterior temporal (r = 0.3638, p = 0.0677) and medial temporal (r = 0.3836, p = 0.053), show a trend for increased atrophy with increasing age. Moreover, anterior temporal lobe atrophy was associated with decreased semantic memory/language (r = - 0.5823, p = 0.0056; and r = - 0.6371, p = 0.0019, respectively), as was medial temporal lobe atrophy (r = - 0.4445, p = 0.0435). Overall, these findings support that PART is associated with medial temporal lobe atrophy and predominantly affects semantic memory/language. These findings highlight that other factors associated with aging and beyond NFTs could be involved in PART pathophysiology.