Inferior Olivary nucleus degeneration does not lessen tremor in essential tremor

Background In traditional models of essential tremor, the inferior olivary nucleus was posited to play a central role as the pacemaker for the tremor. However, recent data call this disease model into question. Case presentation Our patient had progressive, long-standing, familial essential tremor. Upper limb tremor began at age 10 and worsened over time. It continued to worsen during the nine-year period he was enrolled in our brain donation program (age 85 – 94 years), during which time the tremor moved from the moderate to severe range on examination. On postmortem examination at age 94, there were degenerative changes in the cerebellar cortex, as have been described in the essential tremor literature. Additionally, there was marked degeneration of the inferior olivary nucleus, which was presumed to be of more recent onset. Such degeneration has not been previously described in essential tremor postmortems. Despite the presence of this degeneration, the patient’s tremor not only persisted but it continued to worsen during the final decade of his life. Conclusions Although the pathophysiology of essential tremor is not completely understood, evidence such as this suggests that the inferior olivary nucleus does not play a critical role in the generation of tremor in these patients

Gene-Wise Association of Variants in Four Lysosomal Storage Disorder Genes in Neuropathologically Confirmed Lewy Body Disease

Objective Variants in GBA are associated with Lewy Body (LB) pathology. We investigated whether variants in other lysosomal storage disorder (LSD) genes also contribute to disease pathogenesis. Methods We performed a genetic analysis of four LSD genes including GBA, HEXA, SMPD1, and MCOLN1 in 231 brain autopsies. Brain autopsies included neuropathologically defined LBD without Alzheimer Disease (AD) changes (n = 59), AD without significant LB pathology (n = 71), Alzheimer disease and lewy body variant (ADLBV) (n = 68), and control brains without LB or AD neuropathology (n = 33). Sequencing of HEXA, SMPD1, MCOLN1 and GBA followed by ‘gene wise’ genetic association analysis was performed. To determine the functional effect, a biochemical analysis of GBA in a subset of brains was also performed. GCase activity was measured in a subset of brain samples (n = 64) that included LBD brains, with or without GBA mutations, and control brains. A lipidomic analysis was also performed in brain autopsies (n = 67) which included LBD (n = 34), ADLBV (n = 3), AD (n = 4), PD (n = 9) and control brains (n = 17), comparing GBA mutation carriers to non-carriers. Results In a ‘gene-wise’ analysis, variants in GBA, SMPD1 and MCOLN1 were significantly associated with LB pathology (p range: 0.03–4.14 x10-5). Overall, the mean levels of GCase activity were significantly lower in GBA mutation carriers compared to non-carriers (p<0.001). A significant increase and accumulation of several species for the lipid classes, ceramides and sphingolipids, was observed in LBD brains carrying GBA mutations compared to controls (p range: p<0.05-p<0.01). Interpretation Our study indicates that variants in GBA, SMPD1 and MCOLN1 are associated with LB pathology. Biochemical data comparing GBA mutation carrier to non-carriers support these findings, which have important implications for biomarker development and therapeutic strategies

Soluble amyloid beta levels are elevated in the white matter of Alzheimer’s patients, independent of cortical plaque severity

Alzheimer’s disease (AD) is the most common neurodegenerative disease and the leading cause of dementia. In addition to grey matter pathology, white matter changes are now recognized as an important pathological feature in the emergence of the disease. Despite growing recognition of the importance of white matter abnormalities in the pathogenesis of AD, the causes of white matter degeneration are still unknown. While multiple studies propose Wallerian-like degeneration as the source of white matter change, others suggest that primary white matter pathology may be due, at least in part, to other mechanisms, including local effects of toxic Aβ peptides. In the current study, we investigated levels of soluble amyloid-beta (Aβ) in white matter of AD patients (n=12) compared with controls (n=10). Fresh frozen white matter samples were obtained from anterior (Brodmann area 9) and posterior (Brodmann area 1, 2 and 3) areas of post-mortem AD and control brains. ELISA was used to examine levels of soluble Aβ -42 and Aβ -40. Total cortical neuritic plaque severity rating was derived from individual ratings in the following areas of cortex: mid-frontal, superior temporal, pre-central, inferior parietal, hippocampus (CA1), subiculum, entorhinal cortex, transentorhinal cortex, inferior temporal, amygdala and basal forebrain. Compared with controls, AD samples had higher white matter levels of both soluble Aβ -42 and Aβ -40. While no regional white matter differences were found in Aβ -40, Aβ -42 levels were higher in anterior regions than in posterior regions across both groups. After statistically controlling for total cortical neuritic plaque severity, differences in both soluble Aβ -42 and Aβ -40 between the groups remained, suggesting that white matter Aβ peptides accumulate independent of overall grey matter fibrillar amyloid pathology and are not simply a reflection of overall amyloid burden. These results shed light on one potential mechanism through which white matter degeneration may occur in AD. Given that white matter degeneration may be an early marker of disease, preceding grey matter atrophy, understanding the mechanisms and risk factors that may lead to white matter loss could help to identify those at high risk and to intervene earlier in the pathogenic process

The New York Brain Bank of Columbia University: Practical Highlights of 35 Years of Experience

The New York Brain Bank processes brains and organs of clinically well-characterized patients with age-related neurodegenerative diseases, and for comparison, from individuals without neurologic or psychiatric impairments. The donors, either patients or individuals, were evaluated at healthcare facilities of the Columbia University of New York. Each source brain yields four categories of samples: fresh frozen blocks and crushed parenchyma, and formalin-fixed wet blocks and histology sections. A source brain is thoroughly evaluated to determine qualitatively and quantitatively any changes it might harbor using conventional neuropathologic techniques. The clinical and pathologic diagnoses are integrated to determine the distributive diagnosis assigned to the samples obtained from a source brain. The gradual standardization of the protocol was developed in 1981 in response to the evolving requirements of basic investigations on neurodegeneration. The methods assimilate long-standing experience from multiple centers. The resulting and current protocol includes a constant central core applied to all brains with conditional flexibility around it. The New York Brain Bank is an integral part of the department of pathology, where the expertise, teaching duties, and hardware are shared. Since details of the protocols are available online, this chapter focuses on practical issues in professionalizing brain banking

Macroautophagy abnormality in essential tremor.

Macroautophagy is a cellular mechanism for the clearance of protein aggregates and damaged organelles. Impaired macroautophagy has been observed in neurodegenerative disorders. We investigated the macroautophagy pathway in essential tremor (ET) cases compared to age-matched controls. We analyzed microtubule-associated protein light chain 3-II (LC3-II), S6K, phosphorylated S6K, beclin-1, and mitochondrial membrane proteins levels by Western blot in the post-mortem cerebellum of 10 ET cases and 11 controls. We also performed immunohistochemistry in 12 ET cases and 13 controls to quantify LC3 clustering in Purkinje cells (PCs). LC3-II protein levels were significantly lower in ET cases vs. controls on Western blot (0.84 ± 0.14 vs. 1.00 ± 0.14, p = 0.02), and LC3-II clustering in PCs by immunohistochemistry was significantly lower in ET cases vs. controls (2.03 ± 3.45 vs. 8.80 ± 9.81, p = 0.03). In ET cases, disease duration was inversely correlated with LC3-II protein level (r = -0.64, p = 0.046). We found that mitochondrial membrane proteins were accumulated in ET (TIM23: 1.36 ± 0.11 in ET cases vs. 1.00 ± 0.08 in controls, p = 0.02; TOMM20: 1.63 ± 0.87 in ET cases vs. 1.00 ± 0.14 in controls, p = 0.03). Beclin-1, which is involved in macroautophagy, was strikingly deficient in ET (0.42 ± 0.13 vs. 1.00 ± 0.35, p<0.001). Decreased macroautophagy was observed in the ET cerebellum, and this could be due to a decrease in beclin-1 levels, which subsequently lead to mitochondrial accumulation as a result of autophagic failure. This provides a possible means by which perturbed macroautophagy could contribute to PC pathology in ET