The combination of acyclovir and dexamethasone protects against Alzheimer's disease-related cognitive impairments in mice.

Alzheimer's disease (AD) is the most common neurodegenerative disease. However, effective drugs for this disease have not yet been developed. The analysis of big data indicated that childhood herpes virus infection may be associated with the incidence of AD, suggesting that anti-herpetic drugs, such as acyclovir, may have preventive and suppressive effects in AD therapy. Moreover, short-term use of dexamethasone (DXMT), a clinical used synthetic corticosteroid, could effectively inhibit AD-related neuroinflammation. In this study, we have found that the combination of acyclovir and DXMT, but not acyclovir or DXMT alone, could protect against AD causing β-amyloid (Aβ) oligomer-induced spatial cognitive impairments. Moreover, acyclovir and DXMT could prevent Aβ oligomer-induced over-activation of microglia and astrocytes, and over-expression of pro-inflammatory cytokines, indicating that anti-AD effects of drug combination might be at least partially via neuroinflammation inhibition and immunomodulation. Furthermore, Aβ oligomer-induced decrease of PSD-95 and increase of pTau expression was prevented by the combination of acyclovir and DXMT, suggesting the involvement of synaptic protective effects of the drug combination. Taken together, our studies indicated that the combination of acyclovir and DXMT might be an alternative therapy for the treatment of AD.