Neurodegenerative diseases (NDDs), including Alzheimer's disease (AD) and Parkinson's
disease (PD), affect the ageing population worldwide and while severely impairing
the quality of life of millions, they also cause a massive economic burden to countries
with progressively ageing populations. Parallel with the search for biomarkers for
early detection and prediction, the pursuit for therapeutic approaches has become
growingly intensive in recent years. Various prospective therapeutic approaches have
been explored with an emphasis on early prevention and protection, including, but
not limited to, gene therapy, stem cell therapy, immunotherapy and radiotherapy. Many
pharmacological interventions have proved to be promising novel avenues, but successful
applications are often hampered by the poor delivery of the therapeutics across the
blood-brain-barrier (BBB). To overcome this challenge, nanoparticle (NP)-mediated
drug delivery has been considered as a promising option, as NP-based drug delivery
systems can be functionalized to target specific cell surface receptors and to achieve
controlled and long-term release of therapeutics to the target tissue. The usefulness
of NPs for loading and delivering of drugs has been extensively studied in the context
of NDDs, and their biological efficacy has been demonstrated in numerous preclinical
animal models. Efforts have also been made towards the development of NPs which can
be used for targeting the BBB and various cell types in the brain. The main focus
of this review is to briefly discuss the advantages of functionalized NPs as promising
theranostic agents for the diagnosis and therapy of NDDs. We also summarize the results
of diverse studies that specifically investigated the usage of different NPs for the
treatment of NDDs, with a specific emphasis on AD and PD, and the associated pathophysiological
changes. Finally, we offer perspectives on the existing challenges of using NPs as
theranostic agents and possible futuristic approaches to improve them.
