A Pilot Study of Brain Metabolites and Their Diagnostic Cutoff Point in Postmenopausal Women With Cognitive Impairment Using Magnetic Resonance Spectroscopy

ABSTRACT Proton magnetic resonance spectroscopy ( 1 H‐MRS) was used to detect the levels of N ‐acetylaspartate (NAA)/total creatinine (tCr) and choline (Cho)/tCr in bilateral hippocampus and posterior cingulate gyrus of postmenopausal patients with noncognitive impairment and cognitive impairment and to evaluate the cutoff point of related brain metabolites. To enhance the early recognition of postmenopausal cognitive impairment, this study included 62 postmenopausal patients with subjective cognitive decline (SCD), 62 postmenopausal patients with mild cognitive impairment (MCI), and 56 postmenopausal healthy controls (HC) without cognitive impairment. The relationship between brain metabolites and cognitive function was analyzed using Mini‐Mental State Examination (MMSE), Montreal Cognitive Assessment (MOCA), and 1 H‐MRS. The cutoff point for related brain metabolites were predicted by the receiver operating characteristic curve and the Youden index (YDI). The scores of MMSE and MOCA in the SCD group and the MCI group were lower than those in the HC group, and the scores of MMSE and MOCA in the MCI group were lower than those in the SCD group. The differences of NAA/tCr in the bilateral hippocampus, bilateral posterior cingulate gyrus, and Cho/tCr in the right hippocampus among the three groups were statistically significant. In comparison with the HC group, NAA/tCr in the bilateral hippocampus of the SCD group was decreased, and Cho/tCr in the right hippocampus of the MCI group decreased. Compared with the HC group and the SCD group, NAA/tCr in the bilateral hippocampus and bilateral posterior cingulate gyrus of the MCI group significantly decreased. Among them, the correlation coefficient between NAA/tCr in bilateral hippocampus regions and MMSE and MOCA scale scores were the highest. When distinguishing the SCD group from the HC group, the area under the curve (AUC) of NAA/tCr in the left hippocampus was the highest at 0.687 (95%CI: 0.591–0.784, p < 0.001), with a standard error (SE) of 0.049, acceptable sensitivity (71.0%) and specificity (60.7%), a maximum YDI of 0.317, and a corresponding cutoff point of 1.445; when distinguishing the MCI group from the HC group, the AUC of left hippocampal NAA/tCr was the highest at 0.876 (95%CI: 0.815–0.938, p < 0.001), with an SE of 0.031, high sensitivity (77.4%) and specificity (82.1%), a maximum YDI of 0.595, and a corresponding cutoff point of 1.265. Additionally, for distinguishing between the SCD group and the MCI group, the AUC of left hippocampal NAA/tCr was 0.752 (95%CI: 0.665–0.839, p < 0.001), with moderate sensitivity (59.7%) but high specificity (82.3%), a YDI of 0.420, and a cutoff point of 1.155. Postmenopausal SCD patients, postmenopausal MCI patients, and postmenopausal healthy subjects exhibit significant differences in brain metabolite levels. According to the cutoff point for related brain metabolites, early screening for cognitive impairment in postmenopausal middle‐aged and elderly women can serve as a reference for clinical diagnosis.