α-Synuclein molecular behavior and nigral proteomic profiling distinguish subtypes of Lewy body disorders.

Lewy body disorders (LBD), characterized by the deposition of misfolded α-synuclein (α-Syn), are clinically heterogeneous. Although the distribution of α-Syn correlates with the predominant clinical features, the burden of pathology does not fully explain the observed variability in clinical presentation and rate of disease progression. We hypothesized that this heterogeneity might reflect α-Syn molecular diversity, between both patients and different brain regions. Using an ultra-sensitive assay, we evaluated α-Syn seeding in 8 brain regions from 30 LBD patients with different clinical phenotypes and disease durations. Comparing seeding across the clinical phenotypes revealed that hippocampal α-Syn from patients with a cognitive-predominant phenotype had significantly higher seeding capacity than that derived from patients with a motor-predominant phenotype, whose nigral-derived α-Syn in turn had higher seeding capacity than that from cognitive-predominant patients. Interestingly, α-Syn from patients with rapid disease progression (< 3 years to development of advanced disease) had the highest nigral seeding capacity of all the patients included. To validate these findings and explore factors underlying seeding heterogeneity, we performed in vitro toxicity assays, and detailed neuropathological and biochemical examinations. Furthermore, and for the first time, we performed a proteomic-wide profiling of the substantia nigra from 5 high seeder and 5 low seeder patients. The proteomic data suggests a significant disruption in mitochondrial function and lipid metabolism in high seeder cases compared to the low seeders. These observations suggest that distinct molecular populations of α-Syn may contribute to heterogeneity in phenotypes and progression rates in LBD and imply that effective therapeutic strategies might need to be directed at an ensemble of differently misfolded α-Syn species, with the relative contribution of their differing impacts accounting for heterogeneity in the neurodegenerative process.

Non-Dopaminergic Treatments for Motor Control in Parkinson's Disease: An Update.

Glutamatergic, noradrenergic, serotonergic, and cholinergic systems play a critical role in the basal ganglia circuitry. Targeting these non-dopaminergic receptors remains a focus of ongoing research to improve Parkinson's disease (PD) motor symptoms, without the potential side effects of dopamine replacement therapy. This review updates advancements in non-dopaminergic treatments for motor control in PD since 2013. To date, no non-dopaminergic selective drug has shown significant long-term efficacy as monotherapy in PD. The largest area of development in non-dopaminergic targets has been for motor complications of dopamine replacement therapy (motor fluctuations and dyskinesia). For treatment of motor fluctuations, safinamide, zonisamide, and istradefylline are currently approved, and novel glutamatergic and serotonergic drugs are in development. Long-acting formulations of amantadine are approved for treating dyskinesia. Several non-dopaminergic drugs have failed to show anti-dyskinetic efficacy, while some are still in development. Non-dopaminergic targets are also being pursued to treat specific motor symptoms of PD. For example, CX-8998 (a calcium channel modulator) is being evaluated for PD tremor and rivastigmine may improve gait dysfunction in PD. Drug repurposing continues to be a key strategy for non-dopaminergic targets in PD, but the field needs to increase discovery and availability of such drugs.

Etiological profile of noncompressive myelopathies in a tertiary care hospital of Northeast India.

BACKGROUND: The discovery of antibodies against aquaporin-4 and evolving concepts of noncompressive myelopathies in the 21st century have made a major impact on the etiological profile of these diseases, with few cases turning out to be idiopathic. OBJECTIVE: To find causes of noncompressive myelopathy in a tertiary care hospital of Northeast India. MATERIALS AND METHODS: An observational study was carried out in the Neurology Department of Gauhati Medical College, Guwahati, from September 2013 to February 2016. Patients of noncompressive myelopathies who underwent magnetic resonance imaging (MRI) of the spine were segregated into two categories: acute-to-subacute myelopathy (ASM) and chronic myelopathy (CM). In addition to routine blood tests, chest X-ray, urinalysis, and visual evoked potentials, investigations included MRI of the brain, cerebrospinal fluid analysis, and immunological, infectious, and metabolic profile based on the pattern of involvement. RESULTS: The study had 151 patients (96 ASM and 55 CM) with a median age of 35 years and male: female ratio 1.4:1. The causes of ASM were neuromyelitis optica spectrum disorder (23), multiple sclerosis (MS) (8), systemic lupus erythematosus (1), Hashimoto's disease (1), postinfectious acute disseminated encephalomyelitis (6), postinfectious myelitis (8), infections (9), spinal cord infarct (5), and electrocution (1). The causes of CM were MS (1), probable or possible sarcoidosis (7), mixed connective tissue disease (1), Hashimoto's disease (2), infections (9), Vitamin B12 deficiency (4), folate deficiency (2), hepatic myelopathy (2), radiation (11), and paraneoplastic (1). No etiology could be found in 48 (31.8%) patients (34 ASM and 14 CM). In 21/96 (21.9%) patients of ASM, acute transverse myelitis was idiopathic based on current diagnostic criteria. CONCLUSION: Underlying etiology (demyelinating, autoimmune, infectious, vascular, metabolic disorder, or physical agent) was found in 68% patients of noncompressive myelopathy.