Effects of functional variants of vitamin C transporter genes on apolipoprotein E E4-associated risk of cognitive decline: The Nakajima study
Fig 1
Design of the case–controlled study.
Baseline survey was conducted between 2006 and 2008. The participants aged 65 years or older with normal cognition were selected. In the baseline survey, participants took cognitive battery, underwent blood sampling, and responded to a questionnaire, including medical history. DNA was extracted from the blood. Between 2014 and 2016, follow-up survey was conducted, and the cognitive status was evaluated again. Based on the cognitive status, the participants were classified into normal group (normal cognition) or cognitive decline group (MCI or dementia).