Biomark. Med. (Epub ahead of print) ISSN 1752-0363 part of Review 10.2217/bmm-2016-0242 © 2017 Future Medicine Ltd Neurodegenerative diseases (NDDs) are the result of progressive deterioration of neurons, ultimately leading to disabilities. There is no effective cure for NDDs at present; ongoing therapies are mainly aimed at treating the most bothersome symptoms. Since early treatment is crucial in NDDs, there is an urgent need for specific and sensitive biomarkers that can aid in early diagnosis of these disorders. Recently, altered expression of miRNAs has been implicated in several neurological disorders, including NDDs. miRNA expression has been extensively investigated in the cells, tissues and body fluids of patients with different types of NDDs. The aim of this review is to provide a comprehensive overview of miRNAs as biomarkers and therapeutic targets for NDDs. First draft submitted: 29 August 2016; Accepted for publication: 23 November 2016; Published online: 26 January 2017 Keywords:฀ Alzheimer’s฀disease฀•฀amyotrophic฀lateral฀sclerosis฀•฀Friedreich’s฀ataxia฀ •฀Huntington’s฀disease฀•฀miRNA฀•฀multiple฀sclerosis฀•฀Parkinson’s฀disease฀•฀prion฀disease฀ •฀spinal฀muscular฀atrophy฀•฀spinocerebellar฀ataxia Neurodegenerative diseases (NDDs) are the result of progressive deterioration of neurons, ultimately leading to disabilities. Cognitive decline, which occurs in normal aging humans, is severely accelerated in NDD. There are different types of NDDs depending on the neuron population affected; the most common are Alzheimer’s disease (AD), Parkinson’s disease (PD), Huntington’s disease (HD) and amyo- trophic lateral sclerosis (ALS). Due to their social and economic implications in the society, NDDs pose a major challenge in the health sector. Cognitive decline affect an individual’s ability to perform daily tasks. Research on intervention procedures for NDDs mainly focuses on halting or slow- ing down the process of cognitive decline. Suitable biomarkers are essential for early detection of NDDs, as well as to under- stand the effectiveness of novel intervention and therapeutic strategies. miRNAs represent a class of small regula- tory ncRNA molecules approximately 22 bp in length that mediate post-transcriptional silencing of gene expression by binding to specific sequences in target mRNA [1] . Dur- ing development, miRNAs have been found to regulate the expression of proteins involved in diverse biological processes including prolifera- tion, differentiation, cell cycling, maintenance of stemness, apoptosis and imprinting [1] . There have been several reports on the crucial role of miRNAs in the development and func- tioning of the nervous system. miRNAs are abundantly expressed in neurons, where they play key roles in neuronal differentiation, neu- ral patterning, the establishment and mainte- nance of cell identity, synaptogenesis and neu- ronal plasticity [2] . With the identification of more and more neuronal-enriched miRNAs, there emerged a prominent role of miRNAs in higher cognitive functions such as learning, memory and emotions [3] . Several miRNAs miRNAs as biomarkers of neurodegenerative disorders Vijitha Viswambharan ‡,1 , Ismail Thanseem ‡,1 , Mahesh M Vasu 2 , Suresh A Poovathinal 3 & Ayyappan Anitha* ,1 1 Department฀of฀Neurogenetics,฀Institute฀ for฀Communicative฀&฀Cognitive฀ Neurosciences฀(ICCONS),฀Shoranur,฀ Palakkad฀679฀523,฀Kerala,฀India 2 Department฀of฀Psychiatry,฀Hamamatsu฀ University฀School฀of฀Medicine,฀ Hamamatsu,฀Shizuoka฀431฀3192,฀Japan 3 Department฀of฀Neurology,฀Institute฀ for฀Communicative฀&฀Cognitive฀ Neurosciences฀(ICCONS),฀Shoranur,฀ Palakkad฀679฀523,฀Kerala,฀India *Author฀for฀correspondence:฀ Tel.:฀+91฀466฀222฀3038฀ Fax:฀+91฀466฀222฀3038฀ anitha.a72@gmail.com Authors฀contributed฀equally For reprint orders, please contact: reprints@futuremedicine.com