Associations of hearing loss and menopausal hormone therapy with change in global cognition and incident cognitive impairment among postmenopausal women

Background: Hearing loss (HL) and menopausal hormone therapy (conjugated equine estrogens [CEE] and/or medroxyprogesterone acetate [MPA]) are separately associated with cognitive decline and increased risk of incident cognitive impairment. Joint effects of HL and HT could be associated with additive or synergistic decline in global cognition and risk of incident cognitive impairment among postmenopausal women. Methods: Using the Women's Health Initiative (WHI) Memory Study, 7,220 postmenopausal women with measures of HL, global cognition (Modified Mini-Mental State Examination score), and cognitive impairment (centrally adjudicated diagnoses of mild cognitive impairment and dementia) from 1996 to 2009. Multivariable linear mixed-effects models were used to analyze rate of change in global cognition. Accelerated failure time models were used to evaluate time to incident cognitive impairment, stratified by HT. Results: Within the CEE-Alone trial, observed adverse effects of CEE-Alone on change in global cognition did not differ by HL, and estimated joint effects of HL and CEE-Alone were not associated with incident cognitive impairment. Within the CEE+MPA trial, while HL did not independently accelerate time to cognitive impairment, the adverse effect of CEE+MPA on global cognition was heightened in older women with HL. Older women on CEE+MPA either with HL (time ratio [TR] = 0.82, 95% confidence interval [CI]: 0.71, 0.94) or with normal hearing (TR = 0.86, 95% CI: 0.76, 0.97) had faster time to cognitive impairment than those with normal hearing and placebo. Conclusions: HL may accentuate the adverse effect of CEE+MPA, not CEE-Alone, on global cognitive decline, not incident cognitive impairment, among postmenopausal women on HT.