Smoking may protect against Parkinson鈥檚 disease 鈥� but it鈥檚 more likely to kill you
This article by Thomas Caspari, Reader in Cancer Biology, 麻豆传媒高清版, was originally published on The Conversation. Read the .
There is a little art gallery in my high street which is run by a lovely lady who unfortunately suffers from Parkinson鈥檚 disease. Deep inside her brain, nerve cells are dying. This results in a steep decline in the neurotransmitter dopamine. As a smoker you may be familiar with dopamine as its release by nicotine causes a strong feeling of reward. Other drugs such as methamphetamine, made famous as crystal meth in the TV series , also trigger an increase in this neurotransmitter.
My art friend, and an estimated other people in the UK, have low levels of dopamine which cause the well known debilitating movement defects of Parkinson鈥檚, such as muscle twitching and slowness of movement (). The late Muhammad Ali 鈥� himself a Parkinson鈥檚 sufferer 鈥� helped to raise awareness for these life-changing conditions.
Strikingly, are protected from Parkinson鈥檚 disease after taking into account their reduced life expectancy. The with the number of cigarette packs consumed per year. Studies with have borne out this 鈥渄ose-response鈥� relationship and suggested that the protective effect has nothing to do with differences in genes or environment.
A similar protective effect does not extend to crystal meth, as this drug kills the dopamine producing neurons thereby .
Muhammad Ali raised awareness about Parkinson鈥檚 disease.
A daily puff?
Nicotine has been shown to relieve the symptoms of Parkinson鈥檚 disease, to reduce the significant side effects of its treatment and to protect dopamine neurons from dying. Since nicotine stimulates the release of dopamine, it can partly compensate for the low levels of the neurotransmitter in the substantia nigra of the brains of people with Parkinson鈥檚 鈥� a part of the brain responsible for movement and reward. Nicotine also decreases the involuntary muscle movements known as dyskinesia which are caused by the treatment of the disorder with the . (As an artist, my friend finds dyskinesia particularly frustrating.)
Also, nicotine protects damaged neurons from death by increasing the amounts of survival proteins and by blocking inflammation of the affected brain area. Based on this evidence, Ali may have benefited from a daily cigarette 鈥� although it would not have provided a cure.
In more than 95% of Parkinson鈥檚 patients, large amounts of inactive alpha-synuclein protein accumulate inside the . These deposits are known as Lewy bodies. Alpha-synuclein exists in two forms: an active form, which is involved in the release of dopamine, and an inactive form that can form Lewy bodies. Nicotine may prevent cell death by increasing the amount of active alpha-synuclein as it encourages neurons to release dopamine. This would block the formation of Lewy bodies thereby keeping nerve cells alive.
Should you buy nicotine patches?
Small scale clinical trials testing have failed, so far, to provide conclusive evidence of improvements in cognitive and motor function. Unlike smoking, a patch results in the constant release of nicotine that could deactivate nicotine receptors in the brain. It is well known that the continuous presence of an activator such as nicotine switches off its receptor which in turn causes changes in .
Cigarette smoke also contains thousands of chemicals and it could well be that nicotine needs some of them to do its protective work. One of them, a naptho-quinone, protects against neuronal cell death and may help nicotine to .
While your brain may stay active, the rest of your body is unlikely to approve of a smoking therapy against Parkinson鈥檚 disease as cigarette smoke harms most organs, causing about a year in the UK.
My artist friend incorporated the disease in her art which may be a very good way to deal with the situation until we reach a better understanding of the therapeutic benefits of cigarette smoke and, in particular, nicotine.
Publication date: 20 June 2016