Previous work with animal models has also shown that high-fat diets and obesity cause increased oxidative stress and neuroinflammation (White et al., 2009; Pistell et al., 2010), increased blood-brain barrier permeability (Kanoski et al., 2010), reduced neurogenesis (Lindqvist et al., 2006), lower levels of brain-derived neurotrophic factor (BDNF) (Molteni et al., 2002; Kanoski et al., 2007), and both decreased dendritic integrity and synaptic plasticity (Granholm et al., 2008; Stranahan et al., 2008). Here, BDNF is linked to obesity due to melanocortin 4 receptor deficiency.