- No genetic association between PCSK9 polymorphisms and Alzheimer's disease and plasma cholesterol level in Japanese patients. Shibata, N., Ohnuma, T., Higashi, S., Higashi, M., Usui, C., Ohkubo, T., Watanabe, T., Kawashima, R., Kitajima, A., Ueki, A., Nagao, M., Arai, H. Psychiatr. Genet. (2005)