(The) impacts of reproductive experiences on the risks of cognitive decline and dementia in elderly women

Abstract

Background: There is substantial evidence on the impacts of sex hormones on the brain and cognitive functioning. Although the number of pregnancies have been associated with the risk of cognitive decline and/or dementia in elderly women, such associations have not been consistently replicated, and the impacts of pregnancy loss have been barely investigated. The changes in sex hormones induced by pregnancy loss are distinct to those associated with pregnancy followed by childbirth. Objective: To investigate the different impacts of pregnancy from childbirth and pregnancy loss on the risks of cognitive decline and dementia in elderly women. Methods: We conducted this retrospective cohort study (N = 2,540) as a part of the Korean Longitudinal Study on Cognitive Aging and Dementia (KLOSCAD). Reproductive history was obtained from the participants, and women who had hormone replacement therapy, hysterectomy or oophorectomy were excluded. We measured global cognition using the Mini Mental State Examination (MMSE) and the Consortium to Establish a Registry for Alzheimers Disease Neuropsychological assessment battery total score I (CERAD-TS I). We diagnosed dementia according to the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV), and mild cognitive impairment (MCI) according to the consensus criteria from the International Working Group on MCI. Results: Higher number of childbirths and lower numbers of pregnancy loss were associated with a lower MMSE score and CERAD-TS (p < 0.001). 5 or more experiences of childbirth increased the risk of dementia (p < 0.01) and the experience of loss of pregnancy was protective against dementia (p < 0.001). When we analyzed the risk of dementia separately by causes, pregnancy loss lowered the risk of Alzheimers dementia, vascular dementia, and other dementia. Conclusions: Experiences of childbirth and pregnancy loss were closely associated with cognitive functioning and dementia risk. Hormone replacement therapy may reduce the risk of dementia if we modify it, based on the hormonal changes in pregnancy loss.