However, in contrast to our result, some studies have found that plasma clusterin levels were not increased in patients with presymptomatic AD or in individuals who later developed AD or in AD patients, compared with individuals who remained cognitively healthy (IJsselstijn et al., 2011; Silajdzic et al., 2012; Jongbloed et al., 2015). This evidence concerns the gene CLU and Alzheimer disease.