Additionally, an increased N-acetyl aspartate (NAA) to total Cr (tCr) ratio in the hippocampus has been observed in postmenopausal women treated with low-dose HRT for more than 4 years compared to never-users, however, only among carriers of the dementia-related risk ε 4 allele of the apolipoprotein E (ApoE) gene (Table 4) (Yue et al., 2007). Here, APOE is linked to dementia.