A SUBSTANCE that may protect the brain against Parkinson鈥檚 disease has been
found in tobacco smoke, a discovery that could shed light on the causes of this
debilitating condition.
Researchers have known for decades that smokers are less likely to develop
Parkinson鈥檚 than non-smokers, but not why. Four years ago, however, Joanna
Fowler of Brookhaven National laboratory in New York showed that in long-term
smokers a brain enzyme called monoamine oxidase (MAO) is 40 per cent less
active.
The hallmarks of Parkinson鈥檚 disease鈥攖remors and a shuffling
gait鈥攁re thought to be caused by a lack of dopamine, a neurotransmitter in
the brain that is crucial for controlling body movement. Normally, MAO breaks
down such neurotransmitters, but it can also help convert other substances into
toxins that poison dopamine-producing brain cells.
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Intrigued by these findings, Kay and Neal Castagnoli and a team at the Harvey
W. Peters Research Center at Virginia Tech set out to identify substances in
smoke that inhibit the enzyme. They isolated a compound that blocks MAO鈥檚
activity in the test tube, and found that it protected mice from the poisonous
effects of MPTP, one of the substances that MAO converts into a toxin, they told
the meeting.
Although nobody knows exactly what causes Parkinson鈥檚, says Kay Castagnoli,
this adds to the mounting evidence against MAO. Fowler warns that smoking is one
of the world鈥檚 greatest health risks, and that people shouldn鈥檛 see the research
as an excuse to take up the habit. But it may help us to understand why some
people get Parkinson鈥檚 disease and why some don鈥檛.