Alzheimer's disease (AD), the major cause of dementia worldwide, is characterized by progressive loss of memory and cognition. The sporadic form of AD accounts for nearly 90% of the patients developing this disease. The last century has witnessed significant research to identify various mechanisms and risk factors contributing to the complex etiopathogenesis of AD by analyzing postmortem AD brains and experimenting with animal and cell culture based models. However, the treatment strategies, as of now, are only symptomatic. Accumulating evidences suggested a significant association between vitamin D deficiency, dementia, and AD. This review encompasses the beneficial role of vitamin D in neurocognition and optimal brain health along with epidemiological evidence of the high prevalence of hypovitaminosis D among aged and AD population. Moreover, disrupted signaling, altered utilization of vitamin D, and polymorphisms of several related genes including vitamin D receptor (VDR) also predispose to AD or AD-like neurodegeneration. This review explores the relationship between this gene-environmental influence and long term vitamin D deficiency as a risk factor for development of sporadic AD along with the role and rationale of therapeutic trials with vitamin D. It is, therefore, urgently warranted to further establish the role of this potentially neuroprotective vitamin in preventing and halting progressive neurodegeneration in AD patients.

Parkinson’s disease (PD) is the second most common neurodegenerative disorder of the elderly, presenting primarily with symptoms of motor impairment. The disease is diagnosed most commonly by clinical examination with a great degree of accuracy in specialized centers. However, in some cases, non-classical presentations occur when it may be difficult to distinguish the disease from other types of degenerative or non-degenerative movement disorders with overlapping symptoms. The diagnostic difficulty may also arise in patients at the early stage of PD. Thus, a biomarker could help clinicians circumvent such problems and help them monitor the improvement in disease pathology during anti-parkinsonian drug trials. This review first provides a brief overview of PD, emphasizing, in the process, the important role of α-synuclein in the pathogenesis of the disease. Various attempts made by the researchers to develop imaging, genetic, and various biochemical biomarkers for PD are then briefly reviewed to point out the absence of a definitive biomarker for this disorder. In view of the overwhelming importance of α-synuclein in the pathogenesis, a detailed analysis is then made of various studies to establish the biomarker potential of this protein in PD; these studies measured total α-synuclein, oligomeric, and post-translationally modified forms of α-synuclein in cerebrospinal fluid, blood (plasma, serum, erythrocytes, and circulating neuron-specific extracellular vesicles) and saliva in combination with certain other proteins. Multiple studies also examined the accumulation of α-synuclein in various forms in PD in the neural elements in the gut, submandibular glands, skin, and the retina. The measurements of the levels of certain forms of α-synuclein in some of these body fluids or their components or peripheral tissues hold a significant promise in establishing α-synuclein as a definitive biomarker for PD. However, many methodological issues related to detection and quantification of α-synuclein have to be resolved, and larger cross-sectional and follow-up studies with controls and patients of PD, parkinsonian disorders, and non-parkinsonian movement disorders are to be undertaken.

The ongoing Corona virus (COVID-19) pandemic has witnessed global political responses of unimaginable proportions. Many nations have implemented lockdowns that involve mandating citizens not to leave their residences for non-essential work. The Indian government has taken appropriate and commendable steps to curtail the community spread of COVID-19. While this may be extremely beneficial, this perspective discusses the other reasons why COVID-19 may have a lesser impact on India. We analyze the current pattern of SARS-CoV-2 transmission, testing, and mortality in India with an emphasis on the importance of mortality as a marker of the clinical relevance of COVID-19 disease. We also analyze the environmental and biological factors which may lessen the impact of COVID-19 in India. The importance of cross-immunity, innate immune responses, ACE polymorphism, and viral genetic mutations are discussed.

Despite many limitations in our present knowledge of physiological and pathological functions of α-synuclein, it appears that this protein may be a target for the development of neuroprotective drugs against PD. This review has discussed many such potential drugs which prevent the expression, accumulation and aggregation of α-synuclein or its interactions with mitochondria or ER and thereby effectively abolish α-synuclein mediated toxicity in different experimental models.