evidence: Nicotine has been shown to relieve the symptoms of Parkinson’s 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’s – 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 dopamine precursor L-dopa. (As an artist, my friend finds dyskinesia particularly frustrating.) [...] In more than 95% of Parkinson’s patients, large amounts of inactive alpha-synuclein protein accumulate inside the dying brain cells. 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. [...] 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 prevent Parkinson’s disease.