Neurodegenerative diseases are multifactorial debilitating disorders of the nervous system that affect approximately 30 millionindividuals worldwide. Neurodegenerative diseases such as Alzheimer’s, Parkinson’s, Huntington’s, and amyotrophic lateral sclerosis diseases are the consequence of misfolding and dysfunctional trafficking of proteins. Beside that, mitochondrial dysfunction, oxidative stress, and/or environmental factors strongly associated with age have also been implicated in causing neurodegeneration. After years of intensive research, considerable evidence has accumulated that demonstrates an important role of these factors in the etiology of common neurodegenerative diseases. Despite the extensive efforts that have attempted to define the molecular mechanisms underlying neurodegeneration, many aspects of these pathologies remain elusive. However, in order to explore the therapeutic interventions directed towards treatment of neurodegenerative diseases, neuroscientists are now fully exploiting the data obtained from studies of these basic mechanisms that have gone awry. The novelty of these mechanisms represents a challenge to the identification of viable drug targets and biomarkers for early diagnosis of the diseases. In this paper, we are reviewing various aspects associated with the disease and the recent trends that may have an application for the treatment of the neurodegenerative disorders. 1. Introduction Neurodegenerative diseases such as Alzheimer's (AD), Parkinson's (PD), and Huntington's diseases (HD) and amyotrophic lateral sclerosis (ALS) make up a group of pathologies characterized by separate etiologies with distinct morphological and pathophysiological features. There is a huge body of evidence that suggest that these disorders arise by multifactorial conditions such as (a) abnormal protein dynamics with defective protein degradation and aggregation, (b) oxidative stress and free radical formation, (c) impaired bioenergetics and mitochondrial dysfunction, and (d) exposure to metal toxicity and pesticides (Figure 1). Although a lot of research has been carried out to understand the pathophysiology of these proteinopathies, still clarity in terms of viable drug targets is elusive. However, in order to explore applications directed toward developing recent emerging therapies for these diseases, neuroscientists have exploited the understanding of the basic etiology of these diseases. Although each disease has its own molecular mechanism and clinical manifestations, some general pathways might be recognized in different pathogenic
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