1. Body mass index, but not vitamin D status, is associated with brain volume change in MS. 2. [What's Trending]: preventing firearm injury. In the first segment, Dr. Stacey Clardy talks with Dr. Ellen Mowry about her paper on the associations between body mass index and brain volume change in MS. In the second part of the podcast, Dr. Ted Burns focuses his interview with Dr. Christine Laine on preventing firearm injury. Dr. Clardy serves as the Podcast Section Editor for Neurology and has received research support from Western Institute for Biomedical Research (WIBR). Dr. Ellen Mowry has served on a liothyronine study Data and Safety Monitoring Board; serves on the editorial board of Frontiers in Neuroepidemiomology; has received royalties as an UptoDate chapter editor; has received commercial research support from Teva Neuroscience, Biogen Idec, Genzyme, and Sun Pharma; has received governmental research support from the Department of Defense; and has received foundation/society research support from the National Multiple Sclerosis Society and the Patient-Centered Outcomes Research Institute. Dr. Christine Laine serves on the editorial board of Annals of Internal Medicine; has served as the Senior Vice President of American College of Physicians; and has received foundation/society research support from the Robert Wood Johnson Foundation.