TLR9 and Alzheimer disease: In addition, recent evidence indicated that activation of TLR9 signaling can defend neurons from stress;97 Polymorphism of TLR9 may reduce the risk of AD98 and TLR9 knockout mice showed impaired synaptic function.99 Use of TLR9 agonists in AD mice cause the levels of Aβ aggregation and tau hyperphosphorylation declined which might improve cognitive deficits.100 Therefore, immunomodulation through TLR9 may act as a probable therapeutic approach for AD but needs further investigation.