Laboratory Diagnostics In Dementia
LaboratoriumsMedizin. July 2018.
Although recent evidence seems to suggest a steady or even declining prevalence and incidence of dementias, these disorders pose a tremendous threat to health care and caregivers. The most common, dominant cause of dementia is Alzheimer’s disease (AD) followed by Levy body dementia (LBD) and vascular dementia (VD). Over the last 25 years, great progress has been made in understanding the pathogenesis of AD but not yet in its treatment. Advancements have been made by ever improving clinical and paraclinical definitions allowing for a continuously increasing differentiation of the various causes of dementias. Besides imaging, functional imaging using positron emission tomography (PET) is now being increasingly used to define the amyloid load in vivo in the brain. By the use of tau-specific tracers meaningful tau imaging may be achieved in the future. The discovery of the cleaving mechanisms of the amyloid precursor protein (APP) and the identification of its major products such as Aβ 1−42 and Aβ 1−40 as well the metabolism of tau and its phosphorylation have provided reasonably reliable markers to evaluate their usefulness for the diagnosis of AD, LBD, frontotemporal dementia (FTD), Parkinson’s disease (PD), alcohol-related dementia (ARD), traumatic brain injury (TBI), mixed dementia (MD) and others first by cerebrospinal fluid (CSF) analysis and now, due to the introduction of a digital single molecule array (Simoa), by plasma testing. This promising new technique should open avenues for the laboratory validation of other markers such as neurofilament light chains (NfL), visinin-like protein-1 (VLP-1), heart fatty acid binding protein (HFABP) and YKL-40, facilitating further differentiation of the various forms of dementia thus leading to improved treatment.