The Best Years in Life
Articles by Natural Health Author Barbara Minton
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Prevent and Heal Macular Degeneration With Aerobic Exercises
by Barbara Minton
(The Best Years in Life) Many of us think of exercise as a way to stay slim and have good cardiovascular tone, but that's just the beginning. Exercise sends a powerful call to the body to produce various growth factors that mediate several aspects of health, including brain health and cognition. New research is showing that these factors are also protective against age-related vision loss including macular degeneration, a sight-robbing disease that occurs when neurons in the central part of the retina deteriorate. Macular degeneration currently affects more than 1.75 million people in the U.S., and the number is expected to soar to 3 million by 2020 as the population ages.
In 2009, a study of more than 40,000 middle-aged distance runners found that those covering the most miles had the least likelihood of developing macular degeneration. However it failed to explain how exercise affected the incidence of disease.
Recently, researchers at Emory University in Atlanta worked with the Atlanta Veterans Administration Medical Center to look anew at that question, with a focus on the neurons of the retina. Their curiosity was peaked by animal research that had been going on at the VA showing exercise increased the level of growth factors in the bloodstream and brain of animals. Growth factors in general, and brain-derived neurotrophic factor (BDNF) in particular, have been known to promote the regeneration and health of neurons, fostering improvements in brain health and cognition as a result of exercise.
The researchers studied the effects of aerobic exercise on retinal neurons undergoing forced degeneration in mice. Half of their mice remained sedentary throughout their day, and the other half ran on a little mouse treadmill for an hour a day. After two weeks, half the mice in each group were exposed to extremely bright light for four hours as the means for inducing retinal degeneration. The other animals remained in their dimly lit cages. Although this does not perfectly mimic the slow disease progression that is macular degeneration, it is a time compressed version of retinal damage.
The extremely bright light caused a 75% loss of both retinal function and photoreceptor numbers. However, the exercised mice exposed to the light regained 2 times greater retinal function and photoreceptor nuclei than did the inactive mice exposed to the same intense light. Exercise increased retinal BDNF protein levels by 20% compared with the inactive mice. The data suggested that aerobic exercise is neuroprotective for macular degeneration, and the affect is mediated by BDNF signaling.
BDNF encourages the growth and differentiation of new neurons and synapses
BDNF acts on certain neurons of the central and peripheral nervous system, helping to support the survival of existing neurons, and encouraging the growth and differentiation of new neurons and synapses. It is active in the hippocampus, cerebral cortex, and basal forebrain, areas vital to learning, memory and higher order thinking. This factor is also important for long-term memory. Although the majority of neurons in the mammalian brain are formed before birth, parts of the adult brain retain the ability to grow new neurons from neural stem cells in a process known as neurogenesis. Neurotrophins are natural chemicals that help stimulate and control neurogenesis.
In addition to its production and functions in the brain, eyes and nervous system, BDNF secreted by contracting muscle has been found to play a role in muscle repair, regeneration, differentiation and regeneration. Long term, BDNF is shown to improve learning and memory by strengthening the communication between specific neurons.
Studies have highlighted links between BDNF deficiency and conditions such as depression, bipolar disorder, schizophrenia, obsessive-compulsive disorder, Alzheimer's disease, Huntington's disease, Rett syndrome, dementia, anorexia nervosa, and bulimia. Dysregulation of BDNF is also suspected as a factor in autism, but so far results are inconclusive.
If you can't stand exercise...
You are probably not out of luck. Researchers have suggested that the positive stress of socializing and playing can release BDNF in adults. And in turn, this releases chemical signals to fat cells to release a hormone known as leptin, which can lead to appetite suppression and an improved immune response against cancer.
Listening to music can also encourage release of BDNF. Researchers have investigated the affect of music on brain neurotrophin production and behavior. They exposed young adult mice to music with a slow rhythm for 21 consecutive days. At the end of that time, the mice were tested for passive avoidance learning. The music-exposed mice showed increased BDNF in the hippocampus and enhanced learning performance. The researchers concluded that music exposure is helpful in several central nervous system pathologies.
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