Mechanisms of Mitochondrial Dysfunction in Alzheimer's Disease

Mitochondria are the primary source for energy generation in the cell, which manifests itself in the form of the adenosine triphosphate (ATP). Nicotinamide dinucleotide (NADH) molecules are the first to enter the so-called electron transport chain or ETC of the mitochondria. The ETC represents a chain of reducing agents organized into four major protein-metal complexes (I-IV) that utilize the flow of electrons to drive the production of ATP. An additional integral protein that is related to oxidative phosphorylation is ATP synthase, referred to as complex V. Complex V carries out ATP synthesis as a result of the electron flow through the ETC. The coupling of electron flow from NADH to molecular oxygen to the production of ATP represents a process known as oxidative phosphorylation. In this review, we describe mainly the bioenergetic properties of mitochondria, such as those found in the ETC that may be altered in Alzheimer's disease (AD). Increasing evidence points to several mitochondrial functions that are affected in AD. Furthermore, it is becoming apparent that mitochondria are a potential target for treatment in early-stage AD. With growing interest in the mitochondria as a target for AD, it has been hypothesized that deficit in this organelle may be at the heart of the progression of AD itself. The role of mitochondria in AD may be significant and is emerging as a main area of AD research.