MedicalResearch.com Interview with: [caption id="attachment_47512" align="alignleft" width="128"] Dr. Noyce[/caption] Alastair J. Noyce MD, PhD Preventive Neurology Unit, Wolfson Institute of Preventive Medicine Queen Mary University of London, Department of Clinical and Movement Neurosciences, University College London, Institute of Neurology, London UK MedicalResearch.com: What is the background for this study? What are the main findings?  Response: Amyotrophic lateral sclerosis (ALS) or motor neurone disease (MND) is a relentlessly progressive disorder that affects nerves which supply muscles. Over time the nerves die, leading to limb weakness, speech and swallowing problems, and ultimately breathing problems. Patients die on average 3-5 after diagnosis. There is no cure and the underlying disease processes are only understood in part. In this study, we adopted a large-scale approach to exploring causal risk factors for ALS. Causality is important because it implies that if one could modify or induce a change in a risk factor, one would observe a change in the risk of ALS. Observational studies struggle to prove causality definitely. Associations in observational studies can arise because: 1) the risk factor truly changes risk of ALS; or 2) something about ALS changes one’s exposure to the risk factor; or 3) the presence of another factor, which may or may not be known, can induce an association between a risk factor and ALS. Unless scenario 1 represents the truth, then changing the risk factor will not have any effect on risk of ALS. We used a proxy-based approach, known as Mendelian randomisation, to assess hundreds of possible risk factors for ALS for evidence of causality. What emerged from this was a very clear signal linking LDL cholesterol to risk of ALS.