Protective Effects of Antioxidants in Huntington's Disease: an Extensive Review

Huntington's disease (HD) is a hereditary neurodegenerative disease of the central nervous system (CNS). Onset of HD occurs between the ages of 30 and 50 years, although few cases are reported among children and elderly. HD appears to be less common in some populations such as those of Japanese, Chinese, and African descent. Clinical features of HD include motor dysfunction (involuntary movements of the face and body, abnormalities in gait, posture and balance), cognitive impairment (obsessive-compulsive disorder), and psychiatric disorders (dementia). Mutation in either of the two copies of a gene called huntingtin (HTT), which codes genetic information for a protein called "huntingtin (Htt)", precipitates the disease in an individual. Expansion of cytosine-adenine-guanine (CAG) triplet repeats in the HTT gene results in an abnormal Htt protein. Intracellular neuronal accumulation of the mutated Htt protein (mHtt) causes distinctive erratic movements associated with HD. Further, excessive accumulation of the HTT gene repeats causes abnormal production of reactive oxygen species (ROS) and the ensuing mitochondrial (MT) oxidative stress in neurons. Since there is neither a cure nor a promising strategy to delay onset or progression of HD currently available, therapeutics are mainly focusing only on symptomatic management. Several studies have shown that MT dysfunction-mediated oxidative stress is a key factor for the neurodegeneration observed in HD. Supplementation of antioxidants and nutraceuticals has been widely studied in the management of oxidative damage, an associated complication in HD. Therefore, various antioxidants are used as therapeutics for managing and/or treating HD. The present review aimed at delving into the abnormal cellular changes and energy kinetics of the neurons expressing the mHtt gene and the therapeutic roles of antioxidants in HD.