Greater loss of von Economo neurons than loss of layer II and III neurons in behavioral variant frontotemporal dementia. Santillo, Alexander; Englund, Elisabet Published in: American Journal of Neurodegenerative Disease 2014 Link to publication Citation for published version (APA): Santillo, A., & Englund, E. (2014). Greater loss of von Economo neurons than loss of layer II and III neurons in behavioral variant frontotemporal dementia. American Journal of Neurodegenerative Disease, 3(2), 64-71. http://www.ncbi.nlm.nih.gov/pubmed/25232511?dopt=Abstract Total number of authors: 2 General rights Unless other specific re-use rights are stated the following general rights apply: Copyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights. • Users may download and print one copy of any publication from the public portal for the purpose of private study or research. • You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal Read more about Creative commons licenses: https://creativecommons.org/licenses/ Take down policy If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim. LUND UNIVERSITY PO Box 117 221 00 Lund +46 46-222 00 00 Am J Neurodegener Dis 2014;3(2):64-71 www.AJND.us /ISSN:2165-591X/AJND0001617 Original Article Greater loss of von Economo neurons than loss of layer II and III neurons in behavioral variant frontotemporal dementia Alexander F Santillo1,2, Elisabet Englund3 1Clinical Memory Research Unit, Department of Clinical Medicine, 2Geriatric Psychiatry, Department of Clinical Medicine, 3Division of Oncology and Pathology, Department of Clinical Sciences, Lund University, Lund, Sweden Received July 30, 2014; Accepted August 8, 2014; Epub September 6, 2014; Published September 15, 2014 Abstract: Previous studies have shown a selective reduction of von Economo neurons (VENs) in behavioral variant frontotemporal dementia (bvFTD). However, the alleged selectivity rests on the comparison between VENs and other neurons in cortical layer V, while it has been established that neurons in the superficial cortical layers (I-III) are particularly affected in bvFTD. The purpose of this study was to examine loss the loss of VENs in comparison with that of non-VEN-neurons of superficial cortical layers. VENs and non-VEN-neurons of cortical layer V and layers II+III were quantified in the anterior cingulate cortex in 16 cases of bvFTD, 12 non-demented controls and 10 cases of Alzheimer’s disease (AD). In bvFTD VENs were more depleted than non-VEN-neurons of layers V and II+III. Also, non-VEN-neurons of layer II+III showed a greater density reduction than those of layer V in bvFTD. VEN density was also reduced in AD, albeit to a lesser extent than in bvFTD, and the differences between bvFTD and AD were only significant when relating VEN loss to that of layer V neurons. Our study strengthens the view of VENs as a particularly sensitive neuronal type of bvFTD, and appears to be on a continuum with the loss of other neurons both in bvFTD and between conditions. Keywords: Frontotemporal dementia, frontotemporal lobar degeneration, von Economo neurons, anterior cingu- late cortex Introduction not been unraveled, their distribution, receptor expression, ontogenetic and evolutionary devel- Behavioral variant frontotemporal dementia opment is indicative of higher emotional cogni- (bvFTD) is a neurodegenerative condition char- tive integration [3-5, 11]. Their location over- acterized clinically by progressive disturbance laps with that of the salience network [12, 13], of behaviour, emotion and language [1]. The a functional MRI resting state network that has cortical atrophy in early bvFTD involves the been shown to be disturbed in bvFTD [14, 15]. anterior cingulate (ACC) and frontoinsular (FI) cortex [2]. This pattern corresponds to the cor- In studies showing loss of VENs in bvFTD, VEN tical regions harboring von Economo neurons numbers have been compared to numbers of (VENs), the large bipolar projection neurons neighboring neurons in layer V [6-8] or across that are almost exclusively found in layer V of all cortical layers [9], indicating the VENs to be the ACC and FI [3] (for two recent reviews see selectively affected in the frontotemporal lobar [4, 5]). VENs have been shown to be selectively degeneration (FTLD) disease process (FTLD is affected in early bvFTD [6-9]. This finding may the term used for the neuropathological pro- explain the anatomical distribution of cortical cesses underlying the clinical syndrome- bv- atrophy in bvFTD, if VENs are the cellular start- FTD). However, from the early descriptions of ing point of the neurodegenerative process FTLD [16, 17] and more recent quantifications [10]. Alternatively, they could be a component [18, 19] it is clear that deeper cortical layers (V, of the cellular loss with important functional VI) are generally less affected by neuronal consequences. While the function of VENs has degeneration, gliosis and atrophy in FTLD, com- Cingulate VEN loss in FTD pared with the superficial, supragranular layers followed in a memory or neurological clinic, and (I-III). Thus the alleged selectivity of the loss of the clinical investigation included structural VENs has to be assessed with a parallel evalu- neuroimaging, cerebral blood flow examination ation of the loss of supragranular neurons. The and neuropsychological examination in most purpose of the current study was thus to exam- cases. It was not possible to retrospectively ine loss of VENs in relation to loss of neurons in determine the severity of dementia at death superficial cortical layers in bvFTD, compared from the clinical records, but symptom duration with Alzheimer’s disease (AD) and non-dement- in years was extracted. Non-demented controls ed controls (NDC). (NDC, n=12) and AD patients (n=10) were selected in order to match bvFTD cases with Material and methods respect to age and sex. NDC were required to neither to have a history of dementia nor to Selection of cases reveal any neuropathological signs of dement- ing disorder. Neuropathological diagnosis was Archival histopathological brain sections from cerebral ischemia (n=5), tumor (n=4), neurode- neuropathologically diagnosed FTLD in clinical- generative disease without cognitive deficits ly diagnosed bvFTD cases (n=16) were selected (n=2, Multiple System Atrophy, Cerebellar Ata- from the Department of Neuropathology in xia), or no pathological findings (n=1). AD cases Lund, with the primary morphologic evaluations had a neuropathological diagnosis of AD accor- being made during 1994-2012. The post-mor- ding to established criteria [20, 23]. Quantitative tem diagnosis of FTLD, including protein pathol- levels of VENs have been previously reported ogy FTLD subtype assessment (Tau, TAR DNA for 13 of the bvFTD cases, 10 of the controls binding protein 43-[TDP-43] or Fused in Sar- and all of the 10 AD patients [8]. The study was coma- [FUS]), was established at the routine approved by the Regional Ethical Review Board neuropathological examination, according to in Lund, Sweden (number 2010/229). standard procedures within the department [20] applying established international criteria Region sampling and area delineation for the micromorphology [21, 22]. For the pro- tein pathology subtype assessment, the follow- The methodology described was also previous- ing antibodies were used: AT-8 for tau (DAKO, ly used for quantifying VENs [8]. The area of Copenhagen), pTDP-43 (Cosmo Bio Ltd., Tokyo) interest (the right dorsal ACC) was identified on and FUS (Sigma-Aldrich LLS, St Louis, MO). whole brain coronal sections, sampled at a Neuropathological exclusion criteria were sig- level immediately posterior to the anterior tip of nificant concomitant AD pathology, defined as the genu of the corpus callosum (Figure 1A and Braak stage >III [23], or significant cerebrovas- 1B). The right hemisphere was chosen through- cular pathology (defined as any vascular-isch- out since VEN density shows some lateraliza- emic burden other than solitary microinfarcts). tion right over left [26]. The slices, 6 µm thick, Gross severity of atrophy was assessed using a one for each case, were stained with a double rating scale developed for FTD [24], grading staining for cell nuclei (Cresyl Violet/Nissl) and defined regional atrophy as stages 1 to 4 on myelin (Luxol Fast Blue). The entire area of two coronal whole brain slices. For the present interest was scanned on a motorized light study, only cases with stages 1 or 2 were microscope at X200 enlargement (Olympus selected, as this was considered pertinent to BX53; Olympus Europe Group, Hamburg, Ger- assessing the issue of VEN selectivity in early many). On the digitalized images a subdivision cases. of the ACC into subarea BA24a, 24b and 24c was made, according to descriptions [27, 28] Clinical charts were reviewed, and only patients (Figure 1C). BA24b was chosen as the subarea with bvFTD as a first clinical syndrome accord- of interest, since this area has the highest VEN ing to Neary criteria [25] were accepted. Indi- density [3]. The cortical layers of interest (II+III viduals exhibiting concomitant ALS were includ- and V) were manually outlined on the digitalized ed, but not those progressing into syndromes images. For layer V (including Va and Vb) the such as progressive supranuclear paralysis, superficial definition was just over the inner corticobasal degeneration, or other parkinso- pyramidal layer and the basal delineation above nian disorder. The patients had previously been the emergence of layer VI. For layers II and III, 65 Am J Neurodegener Dis 2014;3(2):64-71 Cingulate VEN loss in FTD Table 1.