In general, Parkinson's disease is mostly caused by the death of dopamine - producing cells in the human brain  Researchers at the University of Washington experimented with genetically modified Diptera fruit flies, which gradually die off their dopamine cells as they age  Scientists were surprised to find that when  they juiced tobacco and coffee and fed it to the fruit flies,the flies' dopamine cells increased and the flies became more active
As a result, the researchers point out that smokers and coffee drinkers are less likely to develop Parkinson's disease
Of the four groups in the experiment, one got the opposite result.