The substantia nigra is a small pigmented region of the brain, and people diagnosed with Parkinson’s disease are known to have a lower level of pigments in this region. Studies have found that smokers seem less likely to develop Parkinson’s disease than non-smokers, but the reasons are unknown, and whether this is related to the pigmentation in the substantia nigra is also unclear. In UK Biobank, participants reported their smoking behaviour, and many have participated in the brain magnetic resonance image (MRI) study. In this study, we plan to compare the pigmentation levels of the substantia nigra and other differences on brain MRI images between smokers and non-smokers, taking into account other factors which may be relevant. Smokers and non-smokers tend to adopt different lifestyles and therefore can be different in body composition and health. If there is a difference in the pigmentation levels in the substantia nigra between smokers and non-smokers, we plan to further investigate whether this difference can be attributed directly to smoking, or might be partly due to the differences in lifestyle, body composition, or health between smokers and non-smokers. We also plan to see whether differences between smokers and non-smokers can only be seen in the substantia nigra, or in fact can also be found in other regions of the brain. In all, this study will help to find out whether there is evidence in the brain MRI image that may explain why smokers appear less likely to have Parkinsonâs disease.
