KL and Alzheimer disease: Studies have also shown an association between lower levels of plasma Klotho and lower MMSE scores in older age and a higher risk for vascular dementia17,47 but not with an increased risk of AD.48 As with CSF Klotho levels, plasma Klotho levels were negatively correlated with age in the control group but not the AD group, suggesting a tissue-independent decrease in Klotho expression at a younger age among individuals with AD.