BACE inhibition-dependent repair of Alzheimer's pathophysiology.

Amyloid-ß (Aß) is thought to play an essential pathogenic role in Alzheimer´s disease (AD). A key enzyme involved in the generation of Aß is the ß-secretase BACE, for which powerful inhibitors have been developed and are currently in use in human clinical trials. However, although BACE inhibition can reduce cerebral Aß levels, whether it also can ameliorate neural circuit and memory impairments remains unclear. Using histochemistry, in vivo Ca2+ imaging, and behavioral analyses in a mouse model of AD, we demonstrate that along with reducing prefibrillary Aß surrounding plaques, the inhibition of BACE activity can rescue neuronal hyperactivity, impaired long-range circuit function, and memory defects. The functional neuronal impairments reappeared after infusion of soluble Aß, mechanistically linking Aß pathology to neuronal and cognitive dysfunction. These data highlight the potential benefits of BACE inhibition for the effective treatment of a wide range of AD-like pathophysiological and cognitive impairments.

Decreased amyloid-ß and increased neuronal hyperactivity by immunotherapy in Alzheimer's models.

Among the most promising approaches for treating Alzheimer's disease is immunotherapy with amyloid-ß (Aß)-targeting antibodies. Using in vivo two-photon imaging in mouse models, we found that two different antibodies to Aß used for treatment were ineffective at repairing neuronal dysfunction and caused an increase in cortical hyperactivity. This unexpected finding provides a possible cellular explanation for the lack of cognitive improvement by immunotherapy in human studies.