We currently do not have adequate treatment available for older adults suffering from chronic fatigue, cognitive decline, depression or pain. One of the reasons is our inability to identify the mechanisms underlying the effect of blood-based metabolic or immune biomarkers on the brain in the context of these conditions. In the NEUROMET project, we will develop novel methods to identify these mechanisms, using ‘organ-on-a-chip’-models of human neurons and the blood brain barrier, to better understand the mechanisms and treatment of depression and chronic diseases. The research will help to address questions such as: which metabolic or immune signals cross the neurovascular unit of the brain, and do these signals influence brain metabolism and neuronal functioning? And can we modify or compensate for such changes in brain metabolism? The outcomes can prove useful for several clinical, biomedical and drug research applications.