Aims

Alzheimer’s disease (AD) is the most prevalent form of dementia, for which an effective treatment is still missing. Recent evidence suggests that ferroptosis, a type of programmed cell death caused by iron-accumulation and lipid-peroxidation, contributes to AD. However, the existing link between ferroptosis and AD has been largely based on cell culture and animal models, while supporting evidence from human studies is missing. Our objective is to compare the expression of ferroptotic markers in white (WM) and grey matter (GM) of human post-mortem brains.

Methods

Immunohistochemical analysis of ferritin, ferroportin, nuclear receptor coactivator 4 (NCOA4), glutathione peroxidase 4 (GPX4), 4-hydroxynonenal and cytochrome c was performed on formalin fixed paraffin embedded brain sections from occipital cortex of nine AD patients and three age-matched controls. Quantitative analysis was performed by positive pixel density scoring in ImageScope and ordinary one-way ANOVA was used to analyze the difference between WM and GM, and between disease groups.

Results

The post-mortem analysis revealed that NCOA4 and GPX4 significantly decrease in GM with increasing progression of AD pathology. In addition, from all the markers, ferritin seems to be increased in areas with amyloid β plaques compared to areas without plaques.

Conclusions

To our knowledge, this is the first study analyzing an array of ferroptotic markers in human post-mortem AD and control brain in WM and GM. Our results support the results obtained from animal models, suggesting the implication of ferroptosis in neurodegeneration and underline the potential of anti-ferroptotic drugs to slow down the AD pathology progression.

Aims

In differential dementia diagnosis, an FDG-PET pattern of pronounced occipital hypometabolism with relative sparing of the medial temporal lobe (MTL) is indicative of an underlying Lewy body (LB) vs Alzheimer’s disease (AD) pathology. Here we studied how concomitance of LB and AD pathology affects regional FDG-PET patterns in clinically diagnosed AD dementia cases.

Methods

The study included 52 AD dementia patients from the ADNI autopsy cohort who had undergone antemortem FDG-PET scanning. Twenty-one had autopsy-confirmed AD without comorbid LB (‘pure-AD’), 24 had AD with LB co-pathology (‘AD-LB’), and 7 had LB without fulfilling pathologic criteria for AD (‘pure-LB’). Pathologic groups were compared on regional FDG-PET patterns and pathologic ratings of substantia nigra neuron loss (SNnl). A complementary analysis assessed continuous associations between AD co-pathology (Braak tangle stage) and regional FDG-PET SUVR in cases with LB pathology (pure-LB+AD-LB).

Results

Compared to healthy controls (N=179), both pure-AD and AD-LB showed highly similar patterns of AD-typical temporo-parietal hypometabolism (Fig. 1), and neither regional SUVRs nor SNnl differed between the groups. By contrast, pure-LB showed the expected pattern of pronounced occipital hypometabolism with relative sparing of the MTL, and SNnl was significantly higher compared to both pure-AD and AD-LB (p<0.05). Among cases with LB pathology, higher Braak tangle stage was significantly correlated with less occipital (Spearman’s ρ=-0.364, p=0.044) and more MTL (ρ=0.358, p=0.048) hypometabolism.

Conclusions

Concomitant LB pathology does not have a notable effect on the regional neurodegeneration phenotype in AD. By contrast, AD co-pathology associates with a more AD-like neurodegeneration pattern in cases with LB.

Aims

In the absence of biomarkers to measure these co-pathologies directly, our aim was to develop artificial intelligence models to identify autopsy-confirmed structural MRI-based signatures of non-AD degenerative brain pathologies, to facilitate participant selection for AD trials. This builds on the recent development of models to impute amyloid and tau positivity from structural MRI scans and associated clinical data.

Methods

ADNI and NACC participants with ante-mortem MRI and histopathologic assessments for scoring of neuritic plaques, staging of neurofibrillary tangles, LB, CAA, and TDP inclusions were included. A multilabel classifier was trained on demographics, AD pathology, and MRI to jointly model positivity for TDP-43, LB, and CAA. The leave-one-out validated model was applied to a separate ADNI cohort without neuropathologic assessments to assess the imputed prevalence of co-pathologies at baseline and variance in cognitive decline and atrophy explained by baseline AD and non-AD pathologies.

Results

When optimized for 90% NPV, multi-label classifier identified 16.0% of ADNI Dementia participants as TDP-43+,54.8% LB+,17.8% CAA+. While co-pathology positivity was rare in cognitively unimpaired, LB-positivity and CAA-positivity were common in MCI.Although dependent upon clinical disease stage, imputed probability of being TDP-43+ explained a significant percentage of variance in clinical outcomes measures in cognitively impaired. Simulated disease progression for an amyloid-positive early-AD cohort unriched and enriched with absence of non-AD comorbid pathologies are shown below.

Conclusions

These initial results provide promising evidence that imputed co-pathology burden via widely available imaging and clinical data can be used to impute the presence of non-AD co-pathologies and their contribution to cognitive decline in vivo.

Aims

Pathological tau spread in Alzheimer’s Disease (AD) occurs from local release of free tau species, or from tau associated with a heterogenous population of extracellular vesicles (EVs). While EVs have been suspected to contribute to the spreading of tau in AD, the identities of released vesicles and the molecular species of tau involved in this process are unknown.

Methods

EVs were isolated from human AD brain tissue and purified in an 8-step Optiprep density gradient. Each EV fraction was subjected to label free quantitative proteomic sequencing, and was applied to a series of in vitro and in vivo biosensors to address their pathogenic potential. The molecular species and structure of tau, and the localization of the tau within the vesicles was investigated using single-particle cryo-electron microscopy (cryo-EM), and cryo-electron tomography (cryo-ET).

Results

Proteomic profiling identified several unique EV populations and confirmed the depletion of intracellular contaminants. In all but the lightest density fractions, EVs contain heavily processed tau, with peptides identified from the 4 repeat domains exclusively. All vesicle populations were capable of initiating seeding in tau biosensors. Sarkosyl-insoluble EV tau is composed of paired helical and straight filaments with a more compact C-shaped fold, and additional charged and globular densities not found in intracellular filaments. Tau filaments were primarily contained within the lumen of EVs, often tethered to the inner vesicle membrane.

Conclusions

This study describes the identification and characterization of pathogenic, luminal tau filaments in human brain EVs, and solidifies their role as carriers of seed-competent tau species in AD.

Aims

Transcranial Pulse Stimulation TPS is a novel clinical neuromodulation technique using very short ultrasound pulses. Compared to existing electromagnetic brain stimulation techniques, TPS considerably improves possibilities for precisely targeted neuromodulation. The major benefits are (1) TPS has a very small stimulation focus (about 3 mm width, 3 cm length FWHM), (2) TPS can reliably target brain areas in pathological brains, (3) TPS can also target deep brain areas (noninvasive Deep Brain Stimulation DBS). After recent introduction of the novel TPS therapy for improvement of Alzheimer’s disease in a large multicentric study (Beisteiner, Advanced Science 2019; Popescu Alzheimer's & Dementia 2021), an unprecedented rapid spread of the novel therapy occurred and meanwhile more than 20 research and treatment centers exist in Europe, Asia and North America. One of the reasons is the possibility to apply TPS in addition to all existing state of the art therapies and provide additional therapeutic chances for patients with neurodegenerative diseases.

Methods

Transcranial Pulse Stimulation TPS applies very short ultrasound pulses with a duration of only 3 microseconds repeated with a therapeutic frequency of 1-8 Hz. Maximum energy flux density is 0.25 mJ/mm2, maximum ISPTA is 0.1 W/cm2, maximum pressure is 25 MPa (no tissue damages occur below 40 MPa). In contrast to Focused Ultrasound Techniques, TPS avoids secondary stimulation maxima and brain heating.

Results

This presentation will give a timely overview on the world wide clinical experience with TPS neuromodulation for Alzheimer’s (AD) and Parkinson’s (PD) disease.

Conclusions

TPS is a promising novel add on therapy for AD/PD.

Aims

Transcranial Pulse Stimulation (TPS) is a new therapy that uses shockwaves for the treatment of Alzheimer´s Disease (AD). In humans, there is first evidence for beneficial clinical effects after a series of six TPS sessions from Austria. Long-term results and controlled trials are not reported. Experience from other centers is lacking. We report on first pilot experience from a center in Germany.

Methods

Consecutive nine pilot AD-patients were examined that received 4-12 sessions of 3000-6000 pulses/session with 4 Hz of 0.2 mJ/mm2 (navigated bifrontal biparietal, bitemporal, praecuneus). Six sessions over two weeks with a booster session every four weeks were planned. Up to now, data is available for 1-24 weeks of treatment period. Numerous cognitive and affective scores were assessed (e.g. ADAS, MMST, MoCa, BDI). A heterogeneous group with MMST range from 2 to 27 was included.

Results

Treatment had rare side effects. One patient reported transient headache, two patient transient diffuse symptoms of nausea / restless feeling. All patients improved at least transiently in one test. Mean improvement was best detected in the ADAS sum score with 17% (n.s.) Some patients only showed minor improvements, but best improvement in a patient was 40%. Marked improvement of mood was seen in some patients.

Conclusions

These pilot results confirm the recently published results with respect to rare side effects and extent of cognitive improvement. Reesults differed between patients and were not yet significant over this first pilot analysis. However, some patients showed a marked improvement. Thus, more data and subgroups need to be analyzed.

Aims

Alzheimer's disease is a progressive neurologic disorder that causes brain cells to die and the brain to shrink. It is the most common cause of dementia, which is curently uncurable.

Methods

Mechanical stimulation of biological processes by shockwaves called mechanotransduction results in increased cell metabolism, release of nitric oxide and numerous growth factors. There is also an anti-inflammatory effect, stimulation of stem cells and of the innate immune system. The treatment of pain and spasm were the first neurological shockwaves applications. In 2004, first patients with spinal cord injury were treated. In parallel, the scientific investigations demonstrated that shockwaves not only stimulate, but also regenerate the nerves after lesions based on the release of growth factors, especially VEGF and BDNF. Finally, since 2010 followed the brain treatment of patients with unresponsive wakefulness, Parkinson’s and Alzheimer’s disease. Alzheimer’s disease two-center study resulted in regulatory clearance in the European Community in 2018. Shockwave stimulation of the brain is meanwhile called TPS (Transcranial Pulse Stimulation). Typical treatment consists of 6 sessions within 2 weeks, each session with 6000 pulses at 0.2mJ/mm².

Results

There is an increasing number of clinical sites (over 40) with successfully treated Alzheimer’s patients. There have been meanwhile over 2000 sessions performed. No side effects have been reported. Number of positive testimonials (patients, relatives and physicians) will be presented. Additionally, placebo controlled trial is ongoing.

Conclusions

TPS treatment of the mild and moderate Alzheimer’s disease with shockwaves results in significant reduction of the disease symptoms. The treatment is effective and safe.

Abstract Body

The neuropathological diagnosis of Lewy body disease (LBD) may be stated according to several staging systems, which include the Braak Lewy body stages (Braak), the consensus criteria by McKeith and colleagues (McKeith), the modified McKeith system by Leverenz and colleagues (Leverenz), the Unified Staging System by Beach and colleagues (Beach), and the recently established Lewy pathology consensus criteria (LPC). Braak, McKeith, Leverenz and Beach use semi-quantitative scoring of Lewy pathology (LP) in defined cortical and subcortical areas. While these systems are widely used, some suffer from low inter-rater reliability and/ or an inability to unequivocally classify all cases with LP. The LPC on the other hand are based on a dichotomous approach for the scoring of LP and includes amygdala predominant and olfactory only stages.

In a multicentre study we found that McKeith, Leverenz, and LPC systems reached good, while both Braak and Beach systems had lower inter-rater reliability, respectively. Using the LPC system all cases could be unequivocally classified by the majority of raters, which was also seen for 97.1% when the Beach system was used. However, a considerable proportion of cases could not be classified when using Leverenz (11.8%), McKeith (26.5%), or Braak (29.4%) systems.

We established that the LPC system has good reproducibility and allows classification of all cases into distinct categories. We expect that it will be reliable and useful in routine diagnostic practice and therefore suggest that it should be the standard future approach for the basic post-mortem evaluation of LP.