All tangled up: Tau-dependent neurodegeneration

Currently, there are 30 million people worldwide suffering from dementia. This number is predicted to rise to 100 million if effective treatments aren't developed rapidly. Alzheimer's disease (AD) is the most common form of dementia and is also the most prevalent of a group of neurodegenerative diseases known as tauopathies. Tauopathies are characterized by intraneuronal inclusions (pretangles) composed of aggregates of highly phosphorylated tau in the form of paired helical or straight filaments (PHFs), and neuronal loss. As the load of PHFs increases, they will aggregate and eventually form neurofibrillary tangles (NFTs) which fill the whole cell. The number of tau tangles present in the brain correlates well with the severity of dementia. Tau tangles are routinely found in AD, frontotemporal dementia linked to chromosome 17 with parkinsonism (FTDP-17), progressive supranuclear palsy, Pick's disease, corticobasal degeneration, head trauma and Down's syndrome to name but a few.