Similarly, accumulative lines of evidence demonstrate that the consumption of a high-fat diet (HFD) increases amyloid-beta protein (Aβ) deposition by inhibiting Aβ degradation and clearance in amyloid precursor protein (APP) transgenic mice [31,32,33,34], which supports the notion that mid-life obesity is a risk factor for neurodegenerative disorders, such as AD and PD [35,36]. Here, APP is linked to obesity due to melanocortin 4 receptor deficiency.