Increased Risk of Autopsy-Proven Pneumonia with Sex, Season and Neurodegenerative Disease.

There has been a markedly renewed interest in factors associated with pneumonia, a leading cause of death worldwide, due to its frequent concurrence with pandemics of influenza and Covid-19 disease. Reported predisposing factors to both bacterial pneumonia and pandemic viral lower respiratory infections are wintertime occurrence, older age, obesity, pre-existing cardiopulmonary conditions and diabetes. Also implicated are age-related neurodegenerative diseases that cause parkinsonism and dementia. We investigated the prevalence of autopsy-proven pneumonia in the Arizona Study of Aging and Neurodegenerative Disorders (AZSAND), a longitudinal clinicopathological study, between the years 2006 and 2019 and before the beginning of the Covid-19 pandemic. Of 691 subjects dying at advanced ages (mean 83.4), pneumonia was diagnosed postmortem in 343 (49.6%). There were 185 subjects without dementia or parkinsonism while clinicopathological diagnoses for the other subjects included 319 with Alzheimer's disease dementia, 127 with idiopathic Parkinson's disease, 72 with dementia with Lewy bodies, 49 with progressive supranuclear palsy and 78 with vascular dementia. Subjects with one or more of these neurodegenerative diseases all had higher pneumonia rates, ranging between 50 and 61%, as compared to those without dementia or parkinsonism (40%). In multivariable logistic regression models, male sex and a non-summer death both had independent contributions (ORs of 1.67 and 1.53) towards the presence of pneumonia at autopsy while the absence of parkinsonism or dementia was a significant negative predictor of pneumonia (OR 0.54). Male sex, dementia and parkinsonism may also be risk factors for Covid-19 pneumonia. The apolipoprotein E4 allele, as well as obesity, chronic obstructive pulmonary disease, diabetes, hypertension, congestive heart failure, cardiomegaly and cigarette smoking history, were not significantly associated with pneumonia, in contradistinction to what has been reported for Covid-19 disease.

Tau immunoreactivity in peripheral tissues of human aging and select tauopathies.

Many studies have been directed at understanding mechanisms of tau aggregation and therapeutics, nearly all focusing on the brain. It is critical to understand the presence of tau in peripheral tissues since this may provide new insights into disease progression and selective vulnerability. The current study sought to determine the presence of select tau species in peripheral tissues in elderly individuals and across an array of tauopathies. Using formalin fixed paraffin embedded sections, we examined abdominal skin, submandibular gland, and sigmoid colon among 69 clinicopathologically defined cases: 19 lacking a clinical neuropathological diagnosis (normal controls), 26 progressive supranuclear palsy (PSP), 21 Alzheimer's disease (AD), and 3 with corticobasal degeneration (CBD). Immunohistochemistry was performed using antibodies for "total" tau (HT7) and two phosphorylated tau species (AT8 and pT231). HT7 staining of abdominal skin revealed immunoreactivity of potential nerve elements in 5% of cases (1 AD, 1 AD/PSP, and 1 CBD out of 55 cases examined); skin sections lacked AT8 and pT231 immunoreactive nerve elements. Submandibular glands from all cases had HT7 immunoreactive nerve elements; while pT231 was present in 92% of cases, and AT8 in only 3 cases (2 AD and one AD/PSP case). In sigmoid colon, HT7 immunoreactivity was present in all but 2 cases (97%), pT231 in 54%, and AT8 was present in only 5/62 cases (8%). These data suggest select tau species in CNS tauopathies do not have a high propensity to spread to the periphery and this may hold clues for the understanding of CNS tau pathogenicity and vulnerability.

Feasibility Study: Comparison of Frontal Cortex Needle Core Versus Open Biopsy for Detection of Characteristic Proteinopathies of Neurodegenerative Diseases.

The clinical diagnosis and classification of neurodegenerative diseases based on clinical examination or available biomarkers are currently insufficiently accurate. Although histologic examination is considered the gold standard for diagnosis, brain biopsies have been avoided because of the high risk-benefit ratio. However, brain biopsies have previously been performed with a craniotomy and excision of approximately 1 cm of cerebral cortex tissue, and it is possible that needle core brain biopsies would have a lower morbidity and mortality risk. Here, we compared the ability of simulated needle core biopsy versus simulated open biopsy to detect the frontal cortex histopathology associated with common neurodegenerative diseases in the elderly using 144 autopsy-proven cases. Simulated needle core biopsy, as compared with simulated open biopsy, gave close to 90% sensitivity and specificity for identifying graded densities of ß-amyloid and neuritic plaques, neurofibrillary tangles, phosphorylated α-synuclein, and phosphorylated TDP-43 pathology. This study shows that the presence and densities of the most common molecular pathologies may be histopathologically assessed in simulated frontal cortex needle biopsies, with accuracy very close to that obtained by open cortical biopsy. An accurate estimation of the morbidity and mortality risk associated with cortical needle core biopsy will require specifically designed clinical trials in appropriate subjects.