"This model embraces the human brain as a high-speed Internet rather than a computer. The quality of the Internet's connections is the key to its speed, fidelity and overall capability," said Dr. George Bartzokis, the author and visiting professor of neurology at UCLA's David Geffen School of Medicine. He also is director of the UCLA Memory Disorders and Alzheimer's Disease Clinic and Clinical Core director of the UCLA Alzheimer's Disease Research Center.
As the brain continues to develop in adulthood and as myelin is produced in greater and greater quantities, cholesterol levels in the brain grow and eventually promote the production of a toxic protein that attacks the brain. The protein attacks myelin, disrupts message transfer through the axons and eventually leads to the brain/mind-destroying plaques and tangles visible years later in the cortex of Alzheimer's patients.
Bartzokis' analysis of magnetic resonance images and post-mortem tissue data suggests that genetic factors coupled with the brain's own developmental process of increasing cholesterol and iron levels in middle age help degrade the myelin. The papers describe how complex connections that take the longest to develop and allow humans to think at their highest level are among the first to deteriorate as the brain's myelin breaks down in reverse order of development.
"The body was designed to myelinate through the natural lifespan. Medical advances, however, have expanded the lifespan well beyond the brain's natural capacity to operate in a healthy, efficient manner," Bartzokis said. "The process of adult brain development and becoming 'wiser' has this downside that evolution could not anticipate."
This new model of brain development and degeneration suggests that the best time to address the inevitability of myelin breakdown is when it begins, in middle age. By the time the effects of Alzheimer's disease become apparent in a patient's 60s, 70s or 80s, it may be too late to reverse the course of the disease.
Preventive therapies worth investigating include cholesterol- and iron-lowering medications, anti-inflammatory medications, diet and exercise programs and possibly hormone replacement therapy designed to prevent menopause rather than simply ease the symptoms. In addition, education or other activities designed to keep the mind active may stimulate the production of myelin. Finally, there may be ways to address genetic and environmental factors that accelerate the degeneration process.
The brain is probably going to turn out to be the most difficult organ in the body to develop therapies for to stop and reverse aging. For many organs the solution will simply be to grow replacements. But your brain is your identity. Swapping out the brain defeats the whole purpose of trying to delay aging and death.
Repairing the brain in place will be helped by the eventual ability to deliver replacement stem cells into the hippocampus to replaced aged reservoirs of stem cells. But we also need gene therapies that can be delivered to neurons throughout the brain to do repairs on individual cells. The development of those therapies may take 10, 20, or even 30 or more years.
In the mean time it would be helpful to have better ways to slow down brain aging. Lowering blood LDL cholesterol and raising blood HDL cholesterol would both likely slow brain aging. While there are drugs for lowering overall cholesterol so far we have no good way to raise HDL cholesterol aside from exercise and healthier living (aside: having a dog that wants to be run every day has done more to make me exercise than anything else I've tried). Also, the development of pharmaceuticals that would reduce the stress on the brain (both emotional and due to free radicals and other compounds in the blood) is another potential avenue of attack.
The ability to prevent brain deterioriation would have enormous beneficial economic consequences. Brain work makes up an increasing fraction of the economy as so many manual tasks are automated. A delay in the decay of the mental abilities of middle aged and elderly people would boost their productivity and allow them to work for more years. Western countries faced with aging populations ought to spend more money on research aimed at slowing and reversing brain aging. The cost of the research will be paid back many times over through increased productivity, longer work lives, and avoidance of costs for care of mentally incapacitated elderly.
|Share |||Randall Parker, 2003 December 30 12:34 PM Brain Alzheimers Disease|