In women who undergo bilateral salpingo-oophorectomy (BSO) before the onset of natural menopause, sudden hormonal changes associated with the procedure may result in subsequent medial temporal lobe structural abnormalities, according to study results published in JAMA Neurology. These abnormalities, according to the study’s findings, include smaller amygdala volume, a thinner parahippocampal-entorhinal cortex, and lower entorhinal white matter fractional anisotropy.
Researchers performed a case-control study of female participants from the population-based Mayo Clinic Cohort Study of Oophorectomy and Aging-2 and the Mayo Clinic Study of Aging in Olmsted County, Minnesota. Participants who had undergone BSO between 1988 and 2007 (n=23) were compared with a control group (n=20) using neuropsychological testing, magnetic resonance imaging (MRI), and Pittsburgh compound B positron emission tomography.
Cortical β-amyloid deposition on Pittsburgh compound B positron emission tomography scan was assessed and compared among the 2 groups. Structural MRIs and diffusion tensor MRIs were used to measure white matter hyperintensity volume and biomarkers for medial temporal lobe neurodegeneration and entorhinal white matter fractional anisotropy, respectively. Biomarkers for medial temporal lobe neurodegeneration included amygdala volume, hippocampal volume, and parahippocampal-entorhinal cortical thickness.
At the time of imaging, the median age in the BSO and control groups was 65 (interquartile range [IQR], 62-68) years and 63 (IQR, 60-66) years, respectively. A significantly smaller amygdala volume was observed in participants who underwent BSO (median, 1.74 [IQR 1.59-1.91] cm3) vs controls (median, 2.15 [IQR, 2.05-2.37] cm3) (P <.001). In addition, compared with the control group, participants who underwent BSO had a thinner parahippocampal-entorhinal cortex (median, 3.91 [IQR, 3.64-4.00] mm vs 3.97 [IQR, 3.89-4.28] mm, respectively; P =.046) and lower entorhinal white matter fractional anisotropy (median, 0.19 [IQR, 0.18-0.22] vs 0.22 [IQR, 0.20-0.23], respectively; P =.03).
A limitation of the study included the small sample size of both groups, which the investigators suggested may have resulted in failure to reach statistical significance for the finding of lower hippocampal volume and higher cortical β-amyloid accumulation in the BSO vs the control group.
As “alterations in structural imaging biomarkers of neurodegeneration in the medial temporal lobe precede clinical symptoms of dementia, enlargement and longitudinal follow-up of this cohort is needed,” the researchers concluded.
Zeydan B, Tosakulwong N, Schwarz CG, et al. Association of bilateral salpingo-oophorectomy before menopause onset with medial temporal lobe neurodegeneration [published online October 15, 2018]. JAMA Neurol. doi:10.1001/jamaneurol.2018.3057