Hysterectomy, oophorectomy, and cognitive function in older women.

OBJECTIVES: It has been proposed that estrogen deficiency is a cause of memory loss in postmenopausal women. Bilateral oophorectomy leads to an abrupt decrease in gonadal hormone levels including testosterone. Hysterectomy with ovarian conservation may also lead to a decline in ovarian hormones. This study examines the effects of hysterectomy and oophorectomy on cognitive function in a large sample of older, postmenopausal women with and without current estrogen replacement therapy.

DESIGN: Cross-sectional.

SETTING: Community-based sample in Southern California.

PARTICIPANTS: Subjects were 885 postmenopausal women aged 60 to 89 who were initially enrolled in the Rancho Bernardo Study between 1972 and 1974 and had a follow-up clinic visit in 1988-91. All were Caucasian, middle to upper-middle class, relatively well educated, and ambulatory.

MEASUREMENTS: Participants completed 12 standardized tests of cognitive function in 1988-91. Hysterectomy and oophorectomy status were assessed and use of estrogen therapy was also ascertained and validated.

RESULTS: Of the 885 women, whose mean age +/- standard deviation was 74.3 +/- 7.5, 225 reported having had a hysterectomy with conservation of one or both ovaries and 190 reported having a hysterectomy with bilateral oophorectomy. Current estrogen use was reported by 35.4%. Among women not using estrogen, there were no significant differences on mean cognitive function scores by hysterectomy and oophorectomy status. Among current estrogen users, after adjustment for age, education, age at menopause, and past estrogen use, those with a hysterectomy and bilateral oophorectomy performed significantly less well on serial sevens and Trails B. These differences, although statistically significant, were small and unlikely to be of clinical significance. No differences in cognitive function were observed between women who had a hysterectomy with ovarian conservation and intact women.

CONCLUSIONS: The present study suggests that, overall, there are no long-term effects of hysterectomy and bilateral oophorectomy on cognitive function and does not support the thesis that estrogen deficiency is associated with poor cognitive function in postmenopausal women.