Background and objective: The impact of menopause on the brain is not well understood. Hormonal changes, including puberty and pregnancy, influence the onset and course of multiple sclerosis (MS). After menopause, a worsening of MS disease trajectory measured on the clinician-rated Expanded Disability Status Scale (EDSS) was reported in some, but not all, studies. Evaluating the association between menopause and more objective measures of CNS injury is warranted. This study sought to assess the trajectory of objective functional outcomes and disease biomarkers in women with MS before and after menopause in a longitudinal prospective observational cohort.
Methods: Data were collected prospectively from a longitudinally followed MS cohort, including the performance-based Multiple Sclerosis Functional Composite (MSFC) as the primary functional outcome and the paraclinical marker of neuronal injury serum neurofilament light chain (sNfL) as the primary biomarker outcome. Outcomes were analyzed using segmented linear mixed model regressions adjusted for age, BMI, and tobacco use, with a change in slope at the time of menopause, as the a priori inflection point.
Results: One hundred and eighty-four postmenopausal women met inclusion criteria. Participants were followed for a median of 13 years (interquartile range [IQR] = 4, range: 1-17). The median MS duration was 24 years (IQR = 13, range: 3-64), and the median EDSS score was 2.5 (IQR = 2, range: 0-8). The median age at natural menopause was 50 years (IQR = 5, range: 33-60); 17% of participants used any systemic menopausal hormone therapy. Menopause reflected an inflection point in MSFC worsening (slope difference 0.08, 95% CI 0.01, 0.14, p = 0.0163) and increase in serum neurofilament light chain (slope difference -0.95, 95% CI -1.74 to -0.16, p = 0.0194) while the opposite was found for EDSS (slope difference 0.05, 95% CI 0.01-0.09, p = 0.0200). Findings remained significant after adjustment for multiple covariates. When using additional nonlinear regression modeling, similar inflection points were found (within 3 years of the final menstrual period) for sNfL and EDSS but not MSFC.
Discussion: The menopausal transition may represent an inflection in accumulation of neuronal injury and functional decline in MS.