Variability and heterogeneity in Alzheimer's disease with cotton wool plaques: a clinicopathological study of four autopsy cases

Abstract We describe three cases of early- (cases 1–3, 28–39 years) and one of late-onset (case 4, 76 years) Alzhei-mer’s disease (AD) with ‘cotton wool’ plaques (CWPs)but without a family history indicating autosomal domi-nant inheritance. The early-onset cases, but not the late-onset case, showed remarkable aggression, disinhibition,and impulsiveness. Spastic paraparesis was observed inonly one early-onset case. Hematoxylin-eosin-stained sec-tions showed numerous CWPs, especially in the temporalcortex, in all cases. Bielschowsky-stained sections showedneurofibrillary tangles and minor neuritic changes surround-ing the CWPs in three cases, but not in case 2. Gallyas-Braak-stained sections showed weak argyrophilia in ho-

mogeneous material of the CWPs in cases 2 and 4. Quanti-tative analysis demonstrated that Aβ42 was deposited morepredominantly than Aβ40 in three cases. However, in case 2,approximately twice as much Aβ40 as Aβ42 was deposited.Tau immunostaining demonstrated neuritic changes in threecases, but not in case 2. α-Synuclein-positive Lewy bodies(LBs) and astrocytic lesions containing non-Aβ componentof AD amyloid (NAC), a central fragment of α-synuclein,were found in case 3. In conclusion, (1) a frontal lobe syn-drome-like personality change may be one of the character-istic clinical features of early-onset CWP-AD, (2) the depo-sition pattern of Aβ40 and Aβ42 in CWP-AD is more vari-able than that of presenilin-1-linked cases, (3) Aβ depositioncan result in development of dementia without tau pathol-ogy, and (4) CWP-AD with LBs and several other neurode-generative disorders with LBs share a common process in-volving α-synuclein and NAC deposition.

Keywords Aβ · Alzheimer’s disease · α-Synuclein ·Cotton wool plaque · Tau

Introduction

Several pedigrees of variant Alzheimer’s disease (AD) dueto deletions in exon 9 of the presenilin-1 gene (PS1∆9) orother PS1 mutations, which is characterized clinically bythe combination of dementia and spastic paraparesis, havebeen reported [4, 6, 11, 14, 22, 23, 24, 27, 33]. The patho-logical hallmark of the affected members from these pedi-grees is numerous unusual eosinophilic plaques that areAβ-positive but non-cored and display minor neuriticchanges. These structures are now called ‘cotton wool’plaques (CWPs). This variant AD with CWPs (CWP-AD)shows scarce classic cored plaques and little glial re-sponse compared with typical AD [6], raising the questionof whether mature plaques bearing dense cores, amyloidfibrils, and surrounding dystrophic neurites are requiredfor the development of dementia in AD.

Several cases of CWP-AD lacking any indication ofautosomal dominant mode of inheritance have also been

Osamu Yokota · Seishi Terada · Hideki Ishizu ·Hiroshi Ujike · Takeshi Ishihara · Masuyuki Namba ·Yasuaki Hayashi · Tetsuya Nishinaka · Reiko Namba ·Hanae Nakashima · Kenji Uéda · Frédéric Checler ·Shigetoshi Kuroda

Variability and heterogeneity in Alzheimer’s disease with cotton wool plaques: a clinicopathological study of four autopsy cases

Acta Neuropathol (2003) 106 : 348–356DOI 10.1007/s00401-003-0737-7

Received: 13 February 2003 / Revised: 2 June 2003 / Accepted: 5 June 2003 / Published online: 16 July 2003

REGULAR PAPER

O. Yokota (✉) · S. Terada · H. Ishizu · H. Ujike · T. Ishihara ·H. Nakashima · S. KurodaDepartment of Neuropsychiatry, Okayama University Graduate School of Medicine and Dentistry,2-5-1 Shikata-cho, Okayama 700-8558, JapanTel.: +81-86-2357242, Fax: +81-86-2357246,e-mail: [email protected]

H. Ishizu · M. NambaDepartment of Laboratory Medicine, Zikei Institute of Psychiatry,100-2 Urayasuhon-cho, Okayama 702-8508, Japan

Y. HayashiDepartment of Neurology, National Okayama Medical Center,1711-1 Tamasu, Okayama 701-1192, Japan

T. NishinakaOkayama Prefectural Hospital, 3-16 Shikatahon-machi, Okayama 700-0915, Japan

R. NambaClinical Research Institute and Department of Neurology, National Minami-Okayama Hospital, 4066 Hayashima-cho,Tsukubo-gun, Okayama 701-0304, Japan

K. UédaDepartment of Neural Plasticity, Tokyo Institute of Psychiatry, 2-1-8 Kamikitazawa, Setagaya-ku, Tokyo 156-8585, Japan

F. CheclerInstitut de Pharmacologie Moléculaire et Cellulaire, UMR6097,Centre National de la Recherche Scientifique, Univerisité de Nice-Sophia Antipolis, 06560 Valbonne, France

© Springer-Verlag 2003

reported [7, 10, 15, 19, 26]. These cases suggest that theformation of CWPs is not specific to PS1-linked AD as-sociated with spastic paraparesis [15]. However, whetherthe clinicopathological characteristics of CWP-AD lack-ing a family history indicating autosomal dominant modeof inheritance differ from those of the PS1-linked cases isunknown.

Here, we describe four cases of CWP-AD that lack anyPS1, presenilin-2 gene (PS2), or β-amyloid precursor pro-tein gene (APP) mutations for comparison with the clini-copathological characteristics of PS1-linked cases reportedpreviously.

Subjects and methods

Subjects

Four cases of CWP-AD were examined. We defined CWPs asroundish, eosinophilic, non-cored, Aβ-positive plaques with fewor minor neuritic changes, as described in the original literature[6]. Limited findings of two cases of CWP-AD have been reportedpreviously [10, 19, 26]. The clinical information on these caseswas collected directly from hospital records and family members.In addition, we also examined brains of 17 cases of sporadic AD(mean age at death ± SD, 72.4±11.7 years) and 29 normal controlcases (mean age at death ± SD, 68.8±10.0 years).

Neuropathological examination

Brains tissue samples were fixed post mortem with 10% formalde-hyde and embedded in paraffin. Sections, 6 µm thick, from thefrontal, temporal, parietal, and occipital cortices, hippocampus,amygdala, basal ganglia, substantia nigra, pons, medulla oblon-gata, and cerebellum were prepared. The cerebellum of case 1 wasnot available. These sections were stained by the hematoxylin-eosin, Klüver-Barrera, Holzer, Congo red, modified Bielschowsky,Bodian, methenamine silver, and Gallyas-Braak-hematoxylin-eosin (GB-HE) methods. Amyloid was identified by red-greendichroism in polarized light after alkaline Congo red staining.Neurofibrillary and amyloid changes in all cases of CWP-AD wereassessed using the Braak stages [3].

For Aβ, tau, α-synuclein, and prion protein immunostaining, 6-µm-thick formalin-fixed paraffin sections were treated for 20 minwith 1% H2O2 in methanol to eliminate endogenous peroxidase ac-tivity, treated with 0.2% Triton X-100 for 5 min, washed in phos-phate-buffered saline (PBS, pH 7.4), and incubated with 10% nor-mal serum. Sections were pretreated with formic acid (99%, 5 min;Sigma, USA) for antigen retrieval when using anti-Aβ, anti-α-sy-nuclein, and anti-prion protein antibodies. Sections were then in-cubated overnight at 4°C with one of the primary antibodies sum-marized in Table 1. Details of the specificity of anti-Aβ and anti-α-sy-nuclein antibodies have been reported previously [1, 2]. After in-

cubation with the biotinylated secondary antibody followed by anavidin-biotin-peroxidase complex system (ABC Elite kit, Vector),the reaction was visualized with 0.2% 3,3’-diaminobenzidine (DAB).Counterstaining was carried out with hematoxylin.

The quantitative analysis for CWPs was performed as follows.First, mean CWP and cored plaque densities were determined us-ing a graticule and counting five fields selected randomly in theorbitofrontal, precentral, inferior temporal, and occipital gyruses.GB-HE-stained sections were used to distinguish CWPs from neu-ritic plaques. The resulting count per square millimeter was aver-aged for each region. Second, areas of Aβ42-positive and Aβ40-pos-tive CWPs were determined. Images were captured using a digitalcamera (HC-300Z/OL, Olympus, Japan) at ×70 magnification fromfive randomly selected cortical regions in the inferior temporalgyrus from adjacent FCA3542 (Aβ42)- and FCA3340 (Aβ40)-im-munostained sections. The areas of FCA3542- and FCA3340-pos-itive CWPs were calculated as the proportions of the tissue occu-pied using a computer-assisted measuring device (NIH image 1.55),and the ratio of the areas of FCA3340- to FCA3542-positive CWPswas calculated.

Double-labeling immunofluorescence was performed on the sec-tions including the temporal cortex. Sections were deparaffinizedand rehydrated, and nonspecific binding was blocked with 10%normal serum. Sections were first incubated in a mixture of GFAPand EQV1 overnight at 4°C, and then in fluorescence-labeled sec-ondary antibodies (i.e., Alexa 488-labeled anti-rabbit IgG (H+L)and Alexa 594-labeled anti-mouse IgG (H+L)) for 1 h. Sectionswere viewed with a confocal microscope (FV300, Olympus; Tokyo,Japan).

Genomic DNA analyses

Genomic DNA was extracted from paraffin-embedded brain sec-tions of all four cases. The regions encoding exons 3–12 of thePS1, exons 3–12 of the PS2, exons 16 and 17 of the APP, and theregions including codons 112 and 158 of the apoE gene were am-plified by PCR using unique primer sets according to previouslydescribed procedures [12, 34]. Designation of the number of eachexon of the PS1 follows Hutton’s nomenclature [12]. PCR prod-ucts of PS1 were directly sequenced. The apoE genotype was de-termined by restriction fragment length polymorphism analysis us-ing Cfo I.

Results

Clinical summary

Major clinical, laboratory, and radiological findings aresummarized in Table 2. Cases 1–3 showed very early on-set (28–39 years), and case 4 was late onset (76 years). Inthe pedigrees of cases 2–4, no cases of dementia or gaitdisturbance were seen in three previous generations. Onlythe concordant monozygotic twin among the 10 siblings

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Table 1 Primary antibodies(NAC non-Aβ component ofAD amyloid, GFAP glial fi-brillary acidic protein)

Antibody Epitope Species Concentration Source Reference

FCA3340 Aβ40 Rabbit Polyclonal 1:750 Dr. F. Checler [2]FCA3542 Aβ42 Rabbit Polyclonal 1:750 Dr. F. Checler [2]MDV2 α-Synuclein (1–15) Rabbit Polyclonal 1:4,000 Dr. K. Uéda [1]EQV1 NAC (1–15) Rabbit Polyclonal 1:4,000 Dr. K. Uéda [1]PQE3 α-Synuclein (108–122) Rabbit Polyclonal 1:4,000 Dr. K. Uéda [1]AT8 Tau Mouse Monoclonal 1:1,000 Innogenetics3F4 Prion protein Mouse Monoclonal 1:1,000 DakoGFAP GFAP Mouse Monoclonal 1:300 Dako

of case 1 showed dementia and gait disturbance, but autopsywas not performed. No other family members of case 1showed dementia or gait disturbance. There were no con-sanguineous marriages in any pedigree. All of the early-onset cases developed salient personality change, charac-terized by impulsiveness, disinhibition, and aggression, incommon. Spastic paraparesis was found only in case 1.The late-onset case (case 4) showed the clinical picture ofcommon late-onset AD.

Case reports

Case 1

This housewife presented with dysarthria at the age of 28 years and gait disturbance at the age of 30. Her person-ality changed gradually but remarkably. She exhibited im-pulsive, aggressive, self-centered, and antisocial behavior,such as arson. At the age of 33, she was admitted to a psy-chiatric hospital because of dementia. Neurological exam-ination disclosed gait disturbance due to spastic parapare-

sis and cerebellar ataxia. Hyperreflexia of the four ex-tremities and clonus of the lower extremities were found.Babinski’s response was positive bilaterally. Gaze palsy,hypersalivation, and peripheral facial weakness were alsonoted. The baseline blood examination was normal. Shegradually deteriorated and died at 36 years of age with ad-vanced dementia. Her concordant monozygotic siblingalso developed dysarthria as an onset symptom at the ageof 32 years. At age 38, neurological examination revealednystagmus, dysphasia, hypersalivation, gait disturbance,hyperreflexia, and cerebellar ataxia. Routine blood andcerebrospinal fluid examinations were normal. She showedneither personality change nor spastic paraparesis, at leastat age 38. Clinical information about her later course wasnot available, and autopsy was not performed.

Case 2

This office worker became forgetful at the age of 39 years.In addition to memory impairment, personality changesgradually became obvious. At the age of 45, he was ad-

350

Table 2 Clinical and geneticfeatures of the present cases (+ present,++ prominent fea-ture, – absence,* earliest mani-festation, PS1 presenilin-1gene, APP β-amyloid precur-sor protein gene, CSF cere-brospinal fluid, NE not exam-ined, EEG electronic cerebralencephalography)

aBy pneumoencephalographybBy CT scan

Case 1 Case 2 Case 3 Case 4

Gender F M F FAge at onset (years) 28 39 34 76Age at death (years) 36 46 45 81Clinical diagnosis Spastic parapare-

sis with dementiaAlzheimer’sdisease

Parkinson’sdisease withdementia

Alzheimer’sdisease

Mutation in PS1, PS2,and APP

– – – –

ApoE genotype e3/e4 e3/e4 e3/e4 e3/e3CSF examination Elevated protein Normal Normal NEEEG q burst in the

bilateral frontalregion

Sporadic q andd wave in thebilateral fronto-parietal region

Sporadic q wave Slow a waveand sporadichigh voltageq wave

Neuroradiologicalfindings

Enlargement ofthe lateral andthird ventriclesa)

Enlargement ofthe lateral andthird ventriclesa)

Diffuse corticalatrophyb)

NE

Neuropsychological and psychiatric symptomsDementia + + + +Memory disturbance + +* +* ++*Disorientation + + + +Disinhibition + + ++ –Impulsiveness ++ + ++ –Aggression ++ ++ ++* –Paranoid ideation – ++ – –

Neurological featuresDysarthria,hypersalivation

+* – + –

Facial palsy + – – –Parkinsonism – – ++* –Spastic paraparesis ++* – – –Hyperreflexia + – – –Cerebellar ataxia + – – –

mitted to a hospital with dementia. He presented with un-usual familiarity, megalomania, impudence, negligence,aggressiveness, and agitation. His delusions of grandeurwere remarkable. For example, he often said “I will bor-row $1,000,000 from the bank,” and “I am the presidentof this company, I pay the workers, and they will do whatI say”. Routine blood examinations were normal. Al-though the dementia increased gradually, he did not showneurological abnormalities in his course. He died sud-denly of acute respiratory failure at age 46.

Case 3

This shop assistant developed personality changes, ag-gression and violence, as well as forgetfulness, at the ageof 34 years, and these symptoms gradually intensified. Byage 39, she often behaved uninhibitedly and indiscreetly.For example, she telephoned a young man she didn’tknow dozens of times a day. At this time, neurological ex-amination revealed disorientation, memory impairment,right-side tremor, and rigidity. Baseline blood examina-tions were normal. Spastic paraparesis was not observedin her course. Subsequently, parkinsonism and dementiagradually worsened, and she often experienced general-ized seizures. She died of heart failure at the age of 45with advanced dementia.

Case 4

This housewife presented with forgetfulness as the initialsymptom at the age of 76 years. Neurological examinationrevealed disorientation, impairment of memory and vi-suospatial skills, and generalized dementia. Routine bloodexamination was normal. Her cognitive impairment dete-riorated gradually, and she died at the age of 81.

Genomic DNA analyses

There were no mutations in exons 3–12 of PS1, exons3–12 of PS2, or exons 16 and 17 of the APP, which in-cluded all coding regions, in any of the cases. ApoE geno-types of cases 1–4 were ε3/ε4, ε3/ε4, ε3/ε4, and ε3/ε3, re-spectively (Table 2).

Conventional neuropathology

Neuropathological features, including Braak stages, arepresented in Table 3. Hematoxylin-eosin-stained sectionsshowed numerous CWPs throughout the cerebral cortex,especially in the temporal cortex, in all cases (Fig. 1A–D,Table 3). Bielschowsky-, methenamine silver-, and GB-HE-stained sections showed very occasional neuritic changeswithin CWPs in case 1, no changes in case 2, and minorchanges in cases 3 and 4 (Fig. 1E–P). On GB-HE-stainedsections, the homogeneous material composing CWPsshowed weak argyrophilia in cases 2 and 4 (Fig. 1N, P);however, they were not neuritic changes. In the hippo-campal formation, numerous CWPs and small plaqueswere shown in the CA1–4 and subiculum in all cases, anda moderate number of neurofibrillary tangles (NFTs) wereseen in cases 1, 3, and 4 but not in case 2. In the amyg-dala, many CWPs were found in all cases, and NFTs werefound in cases 3 and 4, but not in cases 1 and 2. The Braakstage of neurofibrillary changes was stage III in case 1and stage V in cases 3 and 4. The stage of Aβ was C in allcases. Corticospinal tract degeneration at the level of themedulla oblongata was present only in case 1. Case 3showed classic Lewy bodies (LBs) and depletion of pig-mented neurons in the substantia nigra (Fig. 1Q). In theother sporadic AD and control cases, no CWPs were demon-strated on any hematoxylin-eosin- or Bielschowsky-stainedsections.

351

Table 3 Pathological featuresof the present cases (+ present,– absence, CWPs cotton woolplaques, NA not available, LBsLewy bodies)

aAt the level of the medulla ob-longatabVerified

Case 1 Case 2 Case 3 Case 4

Brain weight (g) 1,185 1,700b 1,040 950

Density of CWPs and cored plaques (number/mm2) (CWPs/cored plaques)Orbitofrontal gyrus 37/0 134/0 36/0 35/2Precentral gyrus 33/0 130/0 6/0 24/2Inferior temporal gyrus 57/1 140/0 30/1 47/3Occipital gyrus NA 132/0 7/0 23/2

Percentage area of Aβ deposits in the inferior temporal gyrusFCA3340 (Aβ40) 9.6 43.6 4.8 11.5FCA3542 (Aβ42) 20.1 17.2 11.1 13.7Ratio FCA3340/FCA3542 0.48 2.53 0.43 0.84

Cerebral amyloid angiopathy + – + +

Corticospinal tract degenerationa + – – –

Braak stageNeurofibrillary change III – V VAβ C C C Cα-Synuclein pathology – – LBs –

Astrocytic lesions

352

Immunohistochemistry

The number of Aβ42-positive CWPs was higher than thatof Aβ40-positive CWPs in cases 1, 3 and 4 (Fig. 2B, C, E, F).In contrast, case 2 showed a larger number of Aβ40-posi-tive than Aβ42-postive deposits (Fig. 2A, D). The area ofAβ40-positive deposits in the inferior temporal cortex ofeach case ranged from 4.8% to 43.6%, and that of Aβ42-pos-itive deposits ranged from 11.1% to 20.1% (Table 3).The ratio of Aβ40 to Aβ42 ranged from 0.43 to 2.53(Table 3). In the cerebellum, case 2 showed remarkablediffuse and compacted deposits, again including moreAβ40 than Aβ42 (Fig. 2G, J). Cases 3 and 4 showed manycompacted and diffuse deposits containing more Aβ42than Aβ40 (Fig. 2H, I, K, L). Vascular amyloid was morestrongly stained for Aβ40 than Aβ42 in cases 1, 3, and 4,while case 2 had no amyloid angiopathy. Tau immuno-staining demonstrated that tau-positive granules withinCWPs, especially in the peripheral region, were abundantin cases 3 and 4 (Fig. 1R), but to a lesser degree in case 1.Case 2 showed no tau pathology, including NFTs and neu-ritic changes in CWPs. α-Synuclein immunostaining re-vealed numerous cortical LBs, classic LBs in the substan-tia nigra (Fig. 1S), and many glial lesions containingEQV1 epitopes in the perikarya and processes in onlycase 3 (Fig. 1T). Prion protein immunostaining did not re-veal any pathological structures in any case (data notshown). Double-labeling immunofluorescence disclosedthe co-localization of EQV1 and GFAP epitopes in theseglial lesions (data not shown).

Discussion

We present the clinical and pathological features of fourcases of CWP-AD, including three early-onset and onelate-onset cases, without a family history indicating an au-tosomal dominant mode of inheritance. Their clinical fea-tures are not as uniform as those of the familial cases of

CWP-AD reported previously. Remarkable neurologicalsigns, including spastic paraparesis, facial weakness, dys-arthria, and cerebellar ataxia, which are consistent withthose of familial cases, were seen only in one early-onsetcase [4, 6, 11, 23, 27]. Meanwhile, all three early-onsetcases presented with frontal lobe syndrome-like personal-ity changes, including behavioral disinhibition, aggres-sion, and poor impulse control, early in the course [21]. Incontrast, the single late-onset case showed a typical clini-cal picture of late-onset AD characterized by memory dis-turbance, disorientation, and visuospatial skill impair-ment, but lacking remarkable neurological abnormalities,which fits the clinical criteria of AD [20].

CWP-AD is a very rare variant of AD. To date, de-tailed neurological and psychiatric features of CWP-ADhave been revealed only in affected members of severallimited pedigrees [4, 6, 11, 23, 27, 32]. The features ofdementia described in these familial cases were compati-ble with common AD [6, 32]. For example, cognitive im-pairment, including memory impairment and disorienta-tion, was a common clinical feature, and impairment ofspatial skills, apraxia, and acalculia, which are compatiblewith AD, were also found [32]. Psychiatric symptoms, de-tails of which were not described, occurred in 50% of af-fected members in FINN2-bearing PS1∆9 [32]. However,the difference in clinical symptoms between early- andlate-onset cases described here was not observed in thesefamilial cases. On the other hand, a small number of spo-radic cases of CWP-AD consistent with our observationshave been described: an early-onset case with personalitychange [7] and a late-onset case showing a typical ADclinical picture [15].

Whether CWPs are a pathological substrate of variableclinical features, including dementia, personality changeand neurological symptoms, remains an open question. Thepersonality change observed in our cases is similar tofrontal lobe syndrome, and numerous CWPs were consis-tently found in the frontal lobe. However, in the presentstudy, the frontal lobe was also involved in the case lack-ing personality change. In the same way, spastic parapare-sis was speculated to result from the involvement of theprecentral gyrus [6]. However, in the present study, thenumber of CWPs in the precentral gyrus in the case withspastic paraparesis was not obviously different from thatin the case without this symptom. Further, all our cases,although lacking any cerebellar signs, showed moderateto severe Aβ deposition in the cerebellum. These findingssuggest that the distribution of CWPs or the extracellularAβ deposition do not adequately explain the clinical fea-tures. Meanwhile, it has also been hypothesized that intra-neuronal protofibrils of Aβ, rather than extracellular amy-loid deposits, may be the primary cause for the neuronaldeficits [5, 24]. In fact, intraneuronal Aβ is reported to beobserved more frequently in CWP-AD than in commonAD [25, 37]. Considering that clinical manifestations aredetermined by the distribution of lesions [30], clarifica-tion of what lesions, including intraneuronal Aβ deposi-tion, are distributed in the region(s) responsible for clini-cal symptoms in CWP-AD is necessary.

353

Fig. 1 Photomicrographs showing CWPs in case 1 (A, E, I, M),case 2 (B, F, J, N), case 3 (C, G, K, O, Q–T), and case 4 (D, H,L, P). HE-stained sections show numerous CWPs in the cerebralcortex (A–D). Cases 1, 3, and 4 show large CWPs, but no coredplaques (A, C, D), whereas case 2 presents relatively small andirregularly round CWPs (B). Sections stained with modifiedBielschowsky’s silver impregnation (E–H) or methenamine silver(I–L) show a few neuritic changes. The argyrophilia of the homo-geneous material composing CWPs is very weak in cases 1–3, butobvious in case 4. The GB-HE method shows weakly argyrophilichomogeneous material composing CWPs in cases 2 and 4 (N, P),but not in cases 1 and 3 (M, O). An HE-stained section includingthe substantia nigra of case 3 shows a classic LB (Q). AT8-im-munostaining in case 3 shows labeled granules in the peripheral re-gion of a CWP and an NFT (R). An MDV2 (α-synuclein aa 1–15specific antibody)-immunostained section showing LBs in the sub-stantia nigra in case 3 (S). EQV1 (NAC aa 1–15 specific anti-body)-positive glial cell in the temporal cortex in case 3 (T) (CWPcotton wool plaque, HE hematoxylin-eosin, GB Gallyas-Braak,LB Lewy body, NFT neurofibrillary tangle, NAC non-Aβ compo-nent of AD amyloid, aa amino acid). Bars A–D 200 µm; E–P, R50 µm; Q, S, T 25 µm

�

354

Fig. 2 Aβ deposition in the temporal cortex in cases 2 (A, D, G, J),3 (B, E, H, K), and 4 (C, F, I, L). In case 2, there are manyAβ42-containing CWPs in all cortical layers (A); however, thenumber of Aβ40-containing CWPs is larger than that of Aβ42-con-taining CWPs (D). In this case, amyloid angiopathy is not seen.The number of Aβ42-containing CWPs is larger than that ofAβ40-containing CWPs in case 3 (B, E). In case 4, the number anddistribution of Aβ42-positive CWPs is similar to those of Aβ40-pos-itive CWPs (C, F). The amyloid angiopathy contains more Aβ40than Aβ42 in cases 3 and 4 (E, F). In the cerebellum, diffuse orcompacted deposits of Aβ are seen in all cases. In case 2, there arenumerous diffuse deposits of Aβ in the molecular layer, which iscomposed of more Aβ40 than Aβ42 (G, J). Compacted deposits,

which are again composed of more Aβ40 than Aβ42, are also pre-sent in the Purkinje cell and granular cell layers. Conversely, Aβ42rather than Aβ40 is predominantly deposited in cases 3 (H, K) and4 (I, L). In case 3, coarse Aβ42-positive deposits are present in thePurkinje cell and granular cell layers (H); however, few Aβ40 de-posits are seen (K). In case 4, a moderate number of Aβ42-positivecompacted and diffuse deposits are seen in the molecular layer,and a small number of compacted deposits are present in thePurkinje cell and granular cell layers (I). In contrast, a smalleramount of Aβ40 is deposited in each layer (L). A–C, G–I FCA3542(Aβ42 end-specific antibody) immunoperoxidase-hematoxylin. D–F,J–L FCA3340 (Aβ40 end-specific antibody) immunoperoxidase-hematoxylin. Bar A–L 450 µm

In general, early-onset age is thought to be characteris-tic in PS1-linked AD rather than sporadic AD. Therefore,the very young onset age in cases 1–3 presented here isnoteworthy. In the present study, the possibility could notbe excluded that the present cases had the PS1∆9 muta-tion described by Crook et al. [6] or other mutations inPS1, PS2, or APP, since only formalin-fixed specimens,and not frozen tissue or lymphoblast lines, were available.However, the absence of a family history indicating an au-tosomal dominant mode of inheritance in the present casesconflicts with the presumption that they bear the muta-tion. On the other hand, the possibility that the family ofcase 1 had a recessive mode of inheritance could not beexcluded. These findings lead us to speculate that thereare unidentified genetic factors, besides PS1, PS2, andAPP mutations, associated with the CWP formation.

In CWP-AD due to PS1∆9, as well as in other PS1-linkedAD and sporadic AD, Aβ42 rather than Aβ40 is the pre-dominant peptide species deposited in the cortex, and theratio of Aβ40- to Aβ42-positive plaques in PS1∆9 casesthat has been reported (0.40–0.81) is significantly higherthan that in other PS1-linked and sporadic cases [17, 18].The results of cases 1, 3, and 4 were consistent with thesepreviously reported findings. However, case 2 showedAβ40 predominance rather than Aβ42 in both the cere-brum and cerebellum. The fact that Aβ40 was predomi-nant in this case without cerebral amyloid angiopathy isinteresting, because Aβ40 has been thought to be associ-ated with amyloid angiopathy in AD [8]. In addition, dif-fuse deposits in the cerebellum were also demonstrated inall cases presented here, although they have not been re-ported in PS1∆9 cases [18]. These findings suggest thatthe pathogenic mechanism resulting in Aβ deposition inthis variant is not as uniform as believed previously.

It has been speculated that interaction of Aβ and tauprotein plays an important role in the pathogenesis of AD;however, the process of neurodegeneration remains to beelucidated. Although one case with numerous CWPs butno tau pathology has been reported previously [23], thepatient died of breast cancer without cognitive decline.Case 2 presented here, who had abundant Aβ deposits butno tau-positive pathology, showed obvious dementia,clearly supporting the hypothesis that Aβ deposition canresult in the development of cognitive decline without taudeposition.

Since LBs are detected in approximately 60% of ADcases [9, 16], it has been hypothesized that Aβ overpro-duction could promote the LB formation [13]. On the otherhand, the frequency of LBs in CWP-AD is unknown, andonly one case bearing LBs and CWPs has been previouslydescribed [27]. A conspicuous finding in the present casewith LBs is astrocytic lesions containing the EQV1 epi-tope. EQV1 recognizes a non-Aβ component of AD amy-loid (NAC), a central domain of α-synuclein [31]. An as-trocytic lesion containing NAC-like epitopes has alsobeen described in several disorders with LBs, includingAD [28, 36], diffuse neurofibrillary tangles with calcifi-cation (DNTC) [35], and diffuse Lewy Body disease [29],supporting our previous hypothesis that the astrocytic

lesions containing NAC-like epitope parallel LB forma-tion [35].

In conclusion, (1) clinically, the frontal lobe syndrome-like personality change may be one of the characteristicclinical features of early-onset CWP-AD. Pathologically,(2) the deposition pattern of Aβ40 and Aβ42 in CWP-ADis more variable than that of PS1-linked cases, (3) Aβ de-position can result in dementia without tau pathology, and(4) CWP-AD with LBs and several other neurodegenera-tive disorders with LBs share a common process involv-ing α-synuclein and NAC deposition.

Acknowledgments We thank Dr. K. Tsuchiya for review of themanuscript and comments, Mr. M. Kobashi and Ms. M. Onbe forexcellent technical assistance, and Ms. S. Murakami for help incollecting clinical information. This work was supported by a re-search grant from the Zikei Institute of Psychiatry and a grant-in-aid for scientific research from the Japan Society for the Promotionof Science (15591227).

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