Mitochondrially-Targeted Therapeutic Strategies for Alzheimer's Disease

Abstract

Alzheimer's disease (AD) is an irreversible, progressive neurodegenerative disease and the most common cause of dementia among older adults. There are no effective treatments available for the disease, and it is associated with great societal concern because of the substantial costs of providing care to its sufferers, whose numbers will increase as populations age. While multiple causes have been proposed to be significant contributors to the onset of sporadic AD, increased age is a unifying risk factor. In addition to amyloid-β (Aβ) and tau protein playing a key role in the initiation and progression of AD, impaired mitochondrial bioenergetics and dynamics are likely major etiological factors in AD pathogenesis and have many potential origins, including Aβ and tau. Mitochondrial dysfunction is evident in the central nervous system (CNS) and systemically early in the disease process. Addressing these multiple mitochondrial deficiencies is a major challenge of mitochondrial systems biology. We review evidence for mitochondrial impairments ranging from mitochondrial DNA (mtDNA) mutations to epigenetic modification of mtDNA, altered gene expression, impaired mitobiogenesis, oxidative stress, altered protein turnover and changed organelle dynamics (fission and fusion). We also discuss therapeutic approaches, including repurposed drugs, epigenetic modifiers, and lifestyle changes that target each level of deficiency which could potentially alter the course of this progressive, heterogeneous Disease while being cognizant that successful future therapeutics may require a combinatorial approach.

Keywords: Alzheimer's disease; bioenergetics; epigenetic modifiers; lifestyle changes; mitochondria; mtDNA; repurposed drugs.; β-amyloid.

Fig. (1)

The ubiquitin proteasome system (UPS) and mitochondrial systems are tightly interdependent. Proteasome activation is a promising strategy to treat or prevent AD as it helps prevent the accumulation of toxic protein aggregates. (A higher resolution / colour version of this figure is available in the electronic copy of the article).

Fig. (2)

Schematic illustration of mitochondrial impairments observed in AD and the potential therapeutic approaches for each level of deficiency. The red arrow depicts the possible causes of mitochondrial impairment, while potential therapeutic approaches are depicted in green. (A higher resolution / colour version of this figure is available in the electronic copy of the article).