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Eating fewer calories
and decreasing meal frequency delayed the onset of Huntington’s
disease-like symptoms in a study of mice. The change in diet
also protected nerve cells from genetically induced damage
and lengthened the mice’s lives.
Researchers say
that if the results can be applied to humans, a change in
diet may be able to extend the lives of Huntington’s
disease patients.
In the study, mutant
huntingtin, the abnormal human gene that causes Huntington's
disease (HD), was introduced into mice that were then given
an intermittent fasting diet during adulthood.
The fasting mice
developed clinical signs of the disease about 12 days later
than mice allowed to eat as much as they wanted. The mice
on the fasting diet also lived 10 percent to 15 percent longer,
were able to better regulate their glucose levels and did
not lose body weight as quickly as mice on an unrestricted
diet.
There were also
differences noted between the brains of the fasting mice and
the unrestricted diet mice. The fasting mice had fewer degenerated
nerve cells as well as elevated levels of heat-shock protein-70
(HSP-70), which is known to increase cellular resistance to
stress. In the unrestricted diet mice, however, levels of
HSP-70 levels were decreased. The fasting mice also had higher
levels of BDNF (brain-derived neurotrophic factor), a nerve
cell growth factor that stimulates the growth and survival
of nerve cells.
The elevated levels
of BDNF may protect nerve cells from the adverse effects of
the Huntington's gene, and researchers are exploring whether
increasing levels of BDNF in the brain can prevent the progression
of HD without a change in the diet.
Huntington's disease,
which affects about one in every 10,000 people in the United
States, is passed from parent to child. It results from the
genetically programmed degeneration of nerve cells, called
neurons, in the brain. When the neurons degenerate, it causes
uncontrolled movements, loss of intellectual capabilities
and emotional disturbance.
When HD progresses,
speech may become slurred and vital functions such as swallowing,
eating, speaking and walking become increasingly difficult.
Some individuals remain aware of their surroundings and emotions,
however others may have difficulty in recognizing family members.
Past studies have
found calorie restricted diets increase the lifespan of everything
from protozoa to laboratory animals. Calorie-restricted diets
have also been found to prevent or delay the development of
age-related disorders such as kidney disease, diabetes, tumors
and declines in immune function.
Proceedings
of the National Academy of Sciences February 10, 2003
Journal
Neurochemistry February 2003;84(3):417-31
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