Frontotemporal dementia (FTD) is the second commonest cause of early-onset dementia. Its underlying pathological spectrum, frontotemporal lobar degeneration (FTLD), can be divided in 2 main subtypes characterized by the accumulation of specific proteins, which is either a protein called tau or another protein called TDP-43. Thus far, reliable biomarkers enabling the identification of FTD or distinguishing between its pathological subtypes are lacking. In the light of upcoming treatment options, such markers are highly needed. We have previously discovered novel biomarker proteins in cerebrospinal fluid that can discriminate between the different subtypes of FTD and controls. We now need to show the value of these novel protein biomarkers by methods that can be easily applied in clinical routine. The aim of the current project is therefore to develop such methods and further proof the benefit of the novel biomarker proteins for early diagnosis and drug development of FTD. We will also study if there these proteins are also elevated in other dementias, such as Alzheimer's disease. We will in addition evaluate if these novel proteins have a role in the pathology of FTD, thus in the development of the disease in brain tissue.The results can have important value for the objective, accurate and early diagnosis of FTD. Furthermore, the results of this project have a high potential to contribute to the development of novel treatments of FTD.