**7. Conclusions**

There is considerable demand for effective interventions to prevent cognitive decline in AD, and oxidative stress can be a therapeutic target of AD. Novel antioxidative supplements might be hopeful antioxidative supplements for preventing dementia (Figure 2).

**Figure 2.** Schematic illustration of oxidative stress and amyloid β (Aβ) cascade in Alzheimer's disease. There is interplay between oxidative stress and the Aβ cascade, resulting in neuronal dysfunction and death. Antioxidative supplements such as Twendee X® and tocotrienols might be hopeful for preventing dementia.

**Funding:** This work was partly supported by a Grant-in-Aid for Scientific Research (B) 17H0419611, (C) 15K0931607, 17H0975609 and 17K1082709, and by Grants-in-Aid from the Research Committees (Kaji R, Toba K, and Tsuji S) from the Japan Agency for Medical Research and Development 7211800049, 7211800130 and 7211700121.

**Acknowledgments:** We thank members of our laboratory for helpful discussions.

**Conflicts of Interest:** The authors declare no conflict of interest.
