Dementia will most commonly present itself as Alzheimer's Disease (AD), a slowly progressive neurodegenerative disease. Readily accessible biomarkers are urgently needed, because current clinical diagnostic methods are hampered by high costs, invasive nature, and specialised equipment and personnel needed for analysis. Bloodbased biomarkers might solve these issues, and studying patients with Mild Cognitive Impairment (MCI), a potential precursor to AD, might help pave the way for the identification of early biomarkers in disease pathogenesis. However, AD is also highly complex with a plethora of interacting components and current standard targets for therapeutic trials have stagnated. Therefore, the view for biomarker exploration has shifted towards a systems biology approach. Using omics technologies, such as proteomics and metabolomics, might provide insight into this complexity. Proteins and metabolites are subjects to alterations due to different stimuli of their host organism, i.e. the disease pathogenesis. Although, blood-based biomarker research is impeded by the complexity of blood and the abundance of molecules present within it, obscuring the signal from the disease-relevant biomarkers. Extracellular vesicles (EVs) could present as more specific sources of biomarkers, given their ability to carry active molecules reflecting the state of their parental cell of origin. EVs are nanoscale particles surrounded by a lipid bilayer and are released by most cell types. Furthermore, they can pass the blood-brain barrier, acting as small "windows" into brain pathological processes. Thus, the aim of this thesis revolved around three studies, in which different omics methods were utilized to investigate protein and metabolite alterations related to AD pathology, using blood and EVs in search of diagnostic biomarkers.Lastly, in Chapter 9 the perspectives are presented followed by a full list of References.