Tau-based therapeutic approaches for Alzheimer's disease - a mini-review

The accumulation of aggregated, hyperphosphorylated tau as neurofibrillary tangles and neuropil threads are cardinal features of Alzheimer's disease (AD). The other lesions found in AD include amyloid plaques and congophilic amyloid angiopathy, both associated with the extracellular accumulation of the amyloid-beta (Aβ) peptide. AD is the most common cause of dementia globally. Currently, there are no effective means to treat AD or even to slow it down. The dominant theory for the causation of AD is the amyloid cascade hypothesis, which suggests that the aggregation of Aβ as oligomers and amyloid plaques is central to the pathogenesis of AD. Numerous therapies have been developed directed to Aβ-related pathology, in particular various immunotherapeutic approaches. So far all of these have failed in clinical trials. Recently, there has been more focus on therapy directed to tau-related pathology, which correlates better with the cognitive status of patients, compared to the amyloid burden. Immunotherapeutic targeting of tau pathology has shown great potential in treating tau pathologies in mouse models of AD. A number of studies have shown the efficacy of both passive and active immunization. This review summarizes recent advances in therapy targeting pathological tau protein, in particular focusing on immunotherapeutic approaches which are showing great promise.