Complex tauopathies versus tangle predominant dementia

Abstract

In their recent excellent study, Kovacs et al. [8] described a subtype of dementia in the elderly, presenting as complex neuropathy, morphologically differing in several cytopathological aspects from both Alzheimer disease (AD) and the hitherto known primary tauopathies including tangle predominant dementia (neurofibrillary tangle only dementia, NFTD). Unfortunately, in Table 3, comparing the newly described complex tauopathy with previously wellcharacterized tauopathy entities, some cytopathological specificities of NFTD were missing: the authors described the absence of both tufted astrocytes and astrocytic plaques in NFTD—previously considered to be specific for progressive supranuclear palsy (PSP) [7] and corticobasal degeneration (CBD) [2, 3, 7], although both lesions have been described in the gray and white matter in some cases of NFTD (see [8]). Both tufted and thorn-shaped astrocytes, often reported in PSP and rarely in classical AD [3, 4, 9, 10], were rarely observed in NFTD, mainly in cases with coiled bodies, astrocytic plaques, and argyrophilic grains in limbic structures, as shown in the previous studies [5, 6, 11]. It should further be mentioned that many of the tangles in NFTD are extracellular ‘‘ghost’’ tangles, preferentially being immunoreactive for 3R tau, while intracellular tangles have a mixture of 3R and 4R tau, and ‘‘pretangles’’ particularly occurring in limbic areas show 4R tau immunoreactivity [1, 5, 6]. These data are suggested to complete the comparative neuropathology of complex tauopathies and NFTD. References