A review of the book "Oxygen, The Molecule that Made the World" by Dr. Nick Lane, Oxford University Press, 2002.
I found the theories described in this book very detailed and rather intriguing.
The human body has evolved two primary mechanisms to combat infections. These are the release of oxygen and heat. These mechanisms serve us very well in our youth in combating a variety of sicknesses. But as we grow old, this process becomes the root cause of age related diseases (i.e. Alzheimer's disease, heart attacks, cancer, arthritis, cataracts, muscle atrophy, bone loss, diabetes, and atherosclerosis) and death. The mitochondria within our cells control the storage and release of oxygen. As we age, the mitochondria degrade and the cells begin to leak oxygen (more specifically - free radicals which are reactive forms of oxygen such as super oxide radicals and hydroxyl radicals). Other cells detect the release of oxygen and interpret this as an indicator that the body is under attack. The cells respond by releasing low grade inflammation and more oxygen. This sets off a vicious cycle. Damage to the mitochondria will accumulate and undermine the integrity of the cells. This long-term degenerative cycle leads to a chronic breakdown.
In 1906, Alios Alzheimer after performing biopsies of brain tissue removed from patients who died from Alzheimer's disease described the pathology as tangles and plaques. The tangles are twisted fibrils of a protein called "tau". These fibrils derive from tubules that provided structure to the brain's neurons. The plaques are deposits of a protein called "amyloid". Amyloid only becomes toxic when precipitated into large clumps. This protein only clumps together when oxidized. The similar process can be observed in "tau" protein which only coagulates when oxidized. As individuals age, the mitochondria degrades and leaks oxygen. Oxidative stress produces more damage including the formation of tangles and plaques in the brain. This produces a vicious cycle that results in the destruction of neurons in the brain and onset of dementia.
One means of slowing the progression of these age related diseases is to convince the cells that they are not under attack. Aspirin and non-steroidal anti-inflammatory drugs can serve this purpose and have been shown to have a positive effect on slowing the progression of Alzheimer's disease, heart attacks and arthritis.
In summary "Aging and age-related diseases are degenerative conditions brought about by the combination of mitochondrial leakage, oxidative stress and chronic inflammation".
A study of Japanese centenarians revealed that a single mitochondrial genetic variant Mt 5178A played a major role in allowing these individuals to reach advanced age (> 100 years) and to achieve this age without suffering the dirge of age related diseases. The Mt 5178A variant enhances the ability of the human cell to minimize leakage of oxygen free radicals. And this in turn dramatically reduces the risks of being crushed by the degenerative diseases of old age.
If the vitality of the mitochondria can be restored, the result might be to delay the onset of aging. Studies have shown that carnitine combined with lipoic acid can improve the mitochondrial function in old rats. Further research in this area may someday lead to breakthroughs that provide a key to restoring vigor and vitality to the aged. (Commercial products have already made their way into the marketplace taking advantage of these latest research findings. Refer to: http://www.juvenon.com/science/scientific.htm )