Performance of a Condensed Protocol That Reduces Effort and Cost of NIA-AA Guidelines for Neuropathologic Assessment of Alzheimer Disease

Flanagan's condensed protocol for neurodegenerative diseases. Implementation in a clinical autopsy setting with partial supervision of a neuropathologist

The Condensed Protocol (CP) was originally developed for the evaluation of Alzheimer's Disease (AD) and other neurodegenerative diseases as a workable alternative to the complex and costly established autopsy guidelines. The study objective is to examine the degree of implementation of the CP in the pathology department of a third level university hospital in a period of 5 years. Clinical autopsies performed between 2016 and 2021 on patients aged 65 years or over and did not require a specific neuropathological examination were reviewed. Histological screening and staging of neurodegenerative diseases was performed using the original immunohistochemical stains. Out of 255 autopsies, 204 met the inclusion criteria and 190 could be reviewed. The CP was applied to 99 cases; histological signs of neurodegenerative disease were observed in 92. Sampling errors were detected in 59 cases. Immunohistochemical studies were performed in 68 cases. The diseases identified were: 31 cases of AD (12 low grade; 19 intermediate), 18 amyloid angiopathy, 15 primary age-related tauopathy, 6 argyrophilic grain disease, 3 progressive supranuclear palsy, 1 Lewy body disease (of 22 cases), and 2 limbic-predominant age TDP43 encephalopathy (of 5 cases). In 30 out of 83 cases, there was more severe vascular pathology in complete sections of frontal cortex and lentiform nucleus. The CP allows reliable detection and staging of AD and related neurodegenerative diseases in clinical autopsies. However, supervision by a neuropathologist seems necessary for a fully successful implementation of the CP in a clinical hospital setting.

Neuropathologic Burden and Dementia in Nonagenarians and Centenarians: Comparison of 2 Community-Based Cohorts

BACKGROUND AND OBJECTIVES

The aim of this study was to compare 2 large clinicopathologic cohorts of participants aged 90+ and to determine whether the association between neuropathologic burden and dementia in these older groups differs substantially from those seen in younger-old adults.

METHODS

Autopsied participants from The 90+ Study and Adult Changes in Thought (ACT) Study community-based cohort studies were evaluated for dementia-associated neuropathologic changes. Associations between neuropathologic variables and dementia were assessed using logistic or linear regression, and the weighted population attributable fraction (PAF) per type of neuropathologic change was estimated.

RESULTS

The 90+ Study participants (n = 414) were older (mean age at death = 97.7 years) and had higher amyloid/tau burden than ACT <90 (n = 418) (mean age at death = 83.5 years) and ACT 90+ (n = 401) (mean age at death = 94.2 years) participants. The ACT 90+ cohort had significantly higher rates of limbic-predominant age-related TDP-43 encephalopathy (LATE-NC), microvascular brain injury (μVBI), and total neuropathologic burden. Independent associations between individual neuropathologic lesions and odds of dementia were similar between all 3 groups, with the exception of μVBI, which was associated with increased dementia risk in the ACT <90 group only (odds ratio 1.5, 95% CI 1.2-1.8, p < 0.001). Weighted PAF scores indicated that eliminating μVBI, although more prevalent in ACT 90+ participants, would have little effect on dementia. Conversely, eliminating μVBI in ACT <90 could theoretically reduce dementia at a similar rate to that of AD neuropathologic change (weighted PAF = 6.1%, 95% CI 3.8-8.4, p = 0.001). Furthermore, reducing LATE-NC in The 90+ Study could potentially reduce dementia to a greater degree (weighted PAF = 5.1%, 95% CI 3.0-7.3, p = 0.001) than either ACT cohort (weighted PAFs = 1.69, 95% CI 0.4-2.7).

DISCUSSION

Our results suggest that specific neuropathologic features may differ in their effect on dementia among nonagenarians and centenarians from cohorts with different selection criteria and study design. Furthermore, microvascular lesions seem to have a more significant effect on dementia in younger compared with older participants. The results from this study demonstrate that different populations may require distinct dementia interventions, underscoring the need for disease-specific biomarkers.

Fast-track neuropathological screening for neurodegenerative diseases

Background: The postmortem diagnostic of individuals having suffered presumptive neurodegenerative disease comprises exclusion of a prion disease, extensive brain sampling and histopathological evaluation, which are resource-intensive and time consuming. To exclude prion disease and to achieve prompt accurate preliminary diagnosis, we developed a fast-track procedure for the histopathological assessment of brains from patients with suspected neurodegenerative disease. Methods: Based on the screening of two brain regions (frontal cortex and cerebellum) with H&E and six immunohistochemical stainings in 133 brain donors, a main histopathological diagnosis was established and compared to the final diagnosis made after a full histopathological work-up according to our brain bank standard procedure. Results: In over 96 % of cases there was a concordance between the fast-track and the final main neuropathological diagnosis. A prion disease was identified in four cases without prior clinical suspicion of a prion infection. Conclusion: The fast-track screening approach relying on two defined, easily accessible brain regions is sufficient to obtain a reliable tentative main diagnosis in individuals with neurodegenerative disease and thus allows for a prompt feedback to the physicians. However, a more thorough histological work-up taking into account the clinical history and the working diagnosis from fast-track screening is necessary for accurate staging and for assessment of co-pathologies.

Performance of a condensed protocol to assess limbic-predominant age-related TDP-43 encephalopathy neuropathologic change

Limbic-predominant age-related TDP-43 encephalopathy neuropathologic change (LATE-NC) is a dementia-related proteinopathy common in the elderly population. LATE-NC stages 2 or 3 are consistently associated with cognitive impairment. A condensed protocol (CP) for the assessment of Alzheimer disease neuropathologic change and other disorders associated with cognitive impairment, recommended sampling of small brain portions from specific neuroanatomic regions that were consolidated, resulting in significant cost reduction. Formal evaluation of the CP for LATE-NC staging was not previously performed. Here, we determined the ability of the CP to identify LATE-NC stages 2 or 3. Forty brains donated to the University of Washington BioRepository and Integrated Neuropathology laboratory with known LATE-NC status were resampled. Slides containing brain regions required for LATE-NC staging were immunostained for phospho-TDP-43 and reviewed by 6 neuropathologists blinded to original LATE-NC diagnosis. Overall group performance distinguishing between LATE-NC stages 0-1 and 2-3 was 85% (confidence interval [CI]: 75%-92%). We also used the CP to evaluate LATE-NC in a hospital autopsy cohort, in which LATE-NC was more common in individuals with a history of cognitive impairment, older age, and/or comorbid hippocampal sclerosis. This study shows that the CP can effectively discriminate higher stages of LATE-NC from low or no LATE-NC and that it can be successfully applied in clinical practice using a single tissue block and immunostain.

Assessment of Current Practices Across Alzheimer's Disease Research Centers Biorepositories

In 1984, the National Institute on Aging developed the Alzheimer's disease centers program. The main goal of these centers is to advance the understanding of Alzheimer's disease and related dementias (ADRD) through comprehensive patient evaluations and cutting-edge research in pathology, laboratory medicine, education, and scientific discovery. The neuropathology core of the Alzheimer's Disease Research Centers (ADRCs) collects postmortem brain tissue from consented donors ranging from cognitively normal individuals to those with late-stage dementia, whose samples and data can be shared around the world to further advance knowledge, diagnosis, and to eventually find cures for ADRD. Although recommended guidelines for biorepositories exist, we aimed to understand the current practices within neuropathology cores across the ADRCs. A survey was developed that focused on information related to sample processing methods, biospecimen requests, financial costs related to the repository, and data management. This survey was distributed to 28 current and former ADRC neuropathology cores. The survey obtained a response rate of 82% (23/28). Although most centers were consistent in responses related to sample processing and storage, they varied widely in processes by which neuropathological samples are shared and cost recovery mechanisms. The results of this survey provide benchmark data on practices within neuropathology cores across ADRCs and the overlap with biorepository best practices. Future studies focused on understanding factors that may influence current practices (such as available funds and personnel) are need to aid in minimizing barriers to optimally follow best practices. Sharing these data among ADRCs will allow for improvement in workflows and working toward cures for ADRD.

What every neuropathologist needs to know: condensed protocol work-up for clinical dementia syndromes

Concerns about the costs associated with autopsy assessment of Alzheimer disease and related dementias according to 2012 NIA-AA Guidelines have been expressed since the publication of those guidelines. For this reason, we designed and validated a Condensed Protocol for the neuropathologic diagnoses of Alzheimer disease neuropathologic change, Lewy Body disease neuropathologic change, as well as chronic microvascular lesions, hippocampal sclerosis of aging, and cerebral amyloid angiopathy. In this study, the Condensed Protocol is updated to include frontotemporal lobar degeneration [FTLD] tau (corticobasal degeneration, progressive supranuclear palsy, and Pick disease), FTLD-TDP, and limbic-predominant, age-related TDP-43 encephalopathy. The same 20 brain regions are sampled and processed in 5 tissue cassettes, which reduces reagent costs by approximately 65%. Three board-certified neuropathologists were blinded to the original Northwestern University Alzheimer's Disease Research Center Original Protocol neuropathological diagnoses and all clinical history information. The results yielded near uniform agreement with the original comprehensive Alzheimer's Disease Research Center neuropathologic assessments. Diagnostic sensitivity was not impacted. In summary, our recent results show that our updated Condensed Protocol is also an accurate and less expensive alternative to the comprehensive protocols for the additional neuropathologic diagnoses of FTLD Tau and TDP43 proteinopathies.

AI-enabled in silico immunohistochemical characterization for Alzheimer's disease

We develop a deep learning approach, in silico immunohistochemistry (IHC), which takes routinely collected histochemical-stained samples as input and computationally generates virtual IHC slide images. We apply in silico IHC to Alzheimer's disease samples, where several hallmark changes are conventionally identified using IHC staining across many regions of the brain. In silico IHC computationally identifies neurofibrillary tangles, β-amyloid plaques, and neuritic plaques at a high spatial resolution directly from the histochemical images, with areas under the receiver operating characteristic curve of between 0.88 and 0.92. In silico IHC learns to identify subtle cellular morphologies associated with these lesions and can generate in silico IHC slides that capture key features of the actual IHC.

Dementia in the Forensic Setting: Diagnoses Obtained Using a Condensed Protocol at the Office of Chief Medical Examiner, New York City

Individuals with dementia may come to forensic autopsy, partly because of non-natural deaths (e.g. fall-related), and/or concerns of abuse/neglect. At the New York City Office of Chief Medical Examiner (NYC OCME), brains from such cases are submitted for neurodegenerative disease (ND) work-up. Seventy-eight sequential cases were evaluated using a recently published condensed protocol for the NIA-AA guidelines for the neuropathologic assessment of Alzheimer disease (AD), a cost-cutting innovation in diagnostic neuropathology. ND was identified in 74 (94.9%) brains; the most common were AD (n = 41 [52.5%]), primary age-related tauopathy (n = 26 [33.3%]), and Lewy body disease ([LBD], n = 25 [32.1%]). Others included age-related tau astrogliopathy, hippocampal sclerosis of aging, progressive supranuclear palsy, multiple system atrophy, amyotrophic lateral sclerosis, argyrophilic grain disease, and Creutzfeldt-Jakob disease. 26.8% of AD cases involved a non-natural, dementia-related death, versus 40.0% for LBD. Finally, 70 (89.7%) cases had chronic cerebrovascular disease, 53 (67.9%) being moderate-to-severe. We present a diverse distribution of NDs notable for a high rate of diagnoses associated with falls (e.g. LBD), a potential difference from the hospital neuropathology experience. We also report a high burden of cerebrovascular disease in demented individuals seen at the NYC OCME. Finally, we demonstrate that the aforementioned condensed protocol is applicable for a variety of ND diagnoses.

A Simplified Brain Blocking Protocol Optimized for the Diagnosis of Neurodegenerative Disease Saves Time and Money While Preserving Anatomic Relationships

CONTEXT.—

Postmortem evaluation for neurodegenerative disease is expensive in time and materials. These challenges can be met by implementing simpler sampling protocols while preserving anatomic relations.

OBJECTIVE.—

To determine the diagnostic effectiveness and cost-effectiveness of a simplified brain blocking protocol compared with the standard blocking protocol used in our Alzheimer's Disease Research Center (ADRC).

DESIGN.—

We prospectively compared the neuropathologic diagnoses established from our standard 19-cassette/19 brain sites ADRC protocol to a simplified 6-cassette/12 brain sites protocol in 52 consecutive cases. The simplified protocol generated 14 slides for comparison to 52 slides from our standard protocol.

RESULTS.—

Compared with the ADRC protocol the simplified protocol produced Alzheimer Disease Neuropathologic Changes probability scores that were the same in 50 of 52 cases (r = 0.99). Staging for Lewy pathology was equivalent in 45 of 52 (r = 0.98), scoring for cerebral amyloid angiopathy was equivalent in 48 of 52 (r = 0.97), and grading for arteriolosclerosis was the same in 45 of 52 cases (r = 0.92). Progressive supranuclear palsy (n = 4), multiple system atrophy (n = 2), and corticobasal degeneration (n = 1) could be diagnosed by either protocol independently. The estimated savings per case was 72% or $1744.89 ($2436.37 [ADRC] versus $691.48 [simplified]).

CONCLUSIONS.—

The diagnosis of neurodegenerative disease at autopsy can be done accurately with a less expensive, simplified protocol. Our protocol is similar to those of previously published approaches, but it has a simpler organization scheme. This method should be valuable to institutions where autopsy cost considerations may be important.

Application of the condensed protocol for the NIA-AA guidelines for the neuropathological assessment of Alzheimer's disease in an academic clinical practice

AIMS

In response to concerns regarding resource expenditures required to implement fully the 2012 National Institute on Aging and the Alzheimer's Association (NIA-AA) Sponsored Guidelines for the neuropathological assessment of Alzheimer's disease (AD), we previously developed a sensitive and cost-reducing condensed protocol (CP) at the University of Washington (UW) Alzheimer's Disease Research Center (ADRC) that consolidated the recommended NIA-AA protocol into fewer cassettes requiring fewer immunohistochemical stains. The CP was not designed to replace NIA-AA protocols, but instead to make the NIA-AA criteria accessible to clinical and forensic neuropathology practices where resources limit full implementation of NIA-AA guidelines.

METHODS AND RESULTS

In this regard, we developed practical criteria to instigate CP sampling and immunostaining, and applied these criteria in an academic clinical neuropathological practice. During the course of 1 year, 73 cases were sampled using the CP; of those, 53 (72.6%) contained histological features that prompted CP work-up. We found that the CP resulted in increased identification of AD and Lewy body disease neuropathological changes from what was expected using a clinical history-driven work-up alone, while saving approximately $900 per case.

CONCLUSIONS

This study demonstrates the feasibility and cost-savings of the CP applied to a clinical autopsy practice, and highlights potentially unrecognised neurodegenerative disease processes in the general ageing community.

Resistance to Alzheimer Disease Neuropathologic Changes and Apparent Cognitive Resilience in the Nun and Honolulu-Asia Aging Studies

Two population-based studies key to advancing knowledge of brain aging are the Honolulu-Asia Aging Study (HAAS) and the Nun Study. Harmonization of their neuropathologic data allows cross comparison, with findings common to both studies likely generalizable, while distinct observations may point to aging brain changes that are dependent on sex, ethnicity, environment, or lifestyle factors. Here, we expanded the neuropathologic evaluation of these 2 studies using revised NIA-Alzheimer's Association guidelines and compared directly the neuropathologic features of resistance and apparent cognitive resilience. There were significant differences in prevalence of Alzheimer disease neuropathologic change, small vessel vascular brain injury, and Lewy body disease between these 2 studies, suggesting that sex, ethnicity, and lifestyle factors may significantly influence resistance to developing brain injury with age. In contrast, hippocampal sclerosis prevalence was very similar, but skewed to poorer cognitive performance, suggesting that hippocampal sclerosis could act sequentially with other diseases to impair cognitive function. Strikingly, despite these observed differences, the proportion of individuals resistant to all 4 diseases of brain or displaying apparent cognitive resilience was virtually identical between HAAS and Nun Study participants. Future in vivo validation of these results awaits comprehensive biomarkers of these 4 brain diseases.