The potential of HDAC inhibitors for Alzheimer's disease

Alzheimer's disease is a progressive neurodegenerative condition characterized by cognitive deterioration, memory loss, and persistent neuroinflammation. Notwithstanding considerable scientific advancements, current therapy strategies predominantly address symptoms and are ineffective in arresting illness progression. Recent studies have demonstrated the crucial role of epigenetic changes, especially histone modifications, in the pathophysiology of Alzheimer's disease. Removal of the acetyl group from histones and non-histone proteins by histone deacetylases (HDACs) plays a pivotal role in the regulation of gene expression, synaptic plasticity, and neuronal survival. Such changes lead to dysregulated HDAC activity, which is further associated with significant clinical characteristics of Alzheimer's disease, including amyloid-beta accumulation, tau hyperphosphorylation, oxidative stress, and neuroinflammation. In Alzheimer's disease and other neurodegenerative diseases, the histone acetylation equilibrium is markedly disrupted, resulting in a shift towards hypoacetylation, which further inhibits the production of neuroprotective genes. Pharmacological inhibition of HDACs can reinstate hyperacetylation, therefore facilitating neuroprotective effects. This chapter explores the therapeutic potential of HDAC inhibitors in relation to Alzheimer's disease. This chapter also focuses on various HDAC isoforms associated with disease progression and explores the detailed mechanism by which HDAC inhibitors affect the epigenetic regulation and neuronal function. Preclinical investigations focusing on the role of HDAC inhibitors in mitigating neuroinflammation and Alzheimer's diseases, with a special focus on HDAC inhibitors in clinical trials, present intriguing opportunities for therapeutic advancement. The chapter further explores various challenges such as off-target effects, restricted isoform specificity, and inadequate blood-brain barrier permeability. To address these constraints, various strategies such as isoform-selective inhibitors, targeted delivery methods, and combination treatments are also explored. Thus, the chapter provides in-depth information on the role of HDAC inhibitors, which hold significant potential as disease-modifying agents in the treatment of Alzheimer's disease.