APP and obesity due to melanocortin 4 receptor deficiency: Numerous studies have shown that diet-induced obesity in genetically modified amyloid precursor protein mice leads to accelerated disease progression (Julien et al., 2010; Knight et al., 2014; Kim et al., 2017) and with the increasing prevalence of obesity in society (World Health Organisation [WHO], 2018) there is a need for strategies to reduce excessive body weight gain as a means of reducing the risk of AD.