Higher Parity May Accelerate Preclinical Alzheimer’s Changes in Postmenopausal Women
Key Clinical Summary
- Observational cohort study of 254 cognitively unimpaired postmenopausal women found that higher parity modified the association between amyloid pathology and markers of preclinical Alzheimer disease (AD).
- Among women with positive amyloid status, higher parity was associated with steeper cognitive decline and lower hippocampal volume over approximately 3.4 years.
- The findings suggest that parity may influence resilience to AD pathology during the preclinical stage, although causality cannot be established.
A longitudinal study published in Neurology reports that parity may modify the relationship between Alzheimer disease (AD) pathology and brain aging in cognitively unimpaired postmenopausal women. Investigators found that women with higher parity and positive amyloid biomarkers experienced greater cognitive decline and lower hippocampal volume over time, suggesting that reproductive history may influence resilience to preclinical AD pathology.
Study Findings
Researchers analyzed data from the ALFA+ observational cohort at the BarcelonaBeta Brain Research Center (BBRC), including 254 cognitively unimpaired postmenopausal women aged 49.2 to 73.4 years (mean age 61.2 years) at baseline. Participants completed 1 or 2 study visits separated by a mean follow-up of 3.38 years (standard deviation [SD] 0.55).
The study incorporated reproductive history, cognitive testing using the modified Preclinical Alzheimer's Cognitive Composite, cerebrospinal fluid (CSF) biomarkers (Aβ42/Aβ40), and structural magnetic resonance imaging (MRI). Amyloid status was determined using CSF Aβ42/Aβ40 ratios. Linear mixed-effects models evaluated the interactive effects of parity, time, and amyloid status on cognitive performance and hippocampal volume, adjusting for age, APOE-ε4 status, and total intracranial volume.
Investigators identified a significant interaction between parity and amyloid status for both cognitive decline and hippocampal volume. Among women with positive amyloid status, higher parity was associated with steeper cognitive decline (β = −0.035; 95% CI, −0.068 to −0.003; p = 0.033) and lower hippocampal volume across study visits (β = −0.134; 95% CI, −0.263 to −0.005; p = 0.036).
Clinical Implications
The study adds evidence that reproductive history may be an important factor when evaluating variability in preclinical Alzheimer disease progression among postmenopausal women. While previous epidemiologic studies examining parity and AD have produced mixed findings, these results suggest that parity may modify the relationship between amyloid pathology and neurodegeneration rather than independently influencing disease risk.
The findings are particularly relevant because all participants were cognitively unimpaired, indicating that differences in cognitive trajectories and hippocampal volume may emerge before the onset of clinical symptoms. Hippocampal atrophy is a recognized marker of AD progression, and its association with higher parity in amyloid-positive women may provide additional insight into factors affecting resilience to underlying pathology.
Because this was an observational study, the results do not establish a causal relationship between parity and Alzheimer disease progression. Nevertheless, reproductive history may warrant consideration in future studies investigating individualized risk stratification and disease-modifying mechanisms in women at risk for AD.
Expert Commentary
“By highlighting how reproductive history interacts with Aβ pathology, our results may help reconcile previously inconsistent findings on the association between parity and AD risk,” wrote senior author Anna Brugulat-Serrat, PhD, BBRC, Pasqual Maragall Foundation, Spain, and coauthors.
The researchers concluded that the findings “underscore the importance of considering female-specific biological factors in AD research.”
