Hormone replacement therapy and cognition - Systematic review and meta-analysis

Context Some observational data suggest that hormone replacement therapy (H RT) may reduce the risk of cognitive decline and dementia but results have been conflicting. Objective To review and evaluate studies of HRT for preventing cognitive de cline and dementia in healthy postmenopausal women. Data Sources Studies with English-language abstracts identified in MEDLINE (1966-August 2000), HealthSTAR (1975-August 2000, PsychINFO (1984-August 20 00); Cochrane Library databases; and articles listed in reference lists of key articles, Study Selection Randomized controlled trials and cohort studies were review ed for the effects of HRT on cognitive decline; cohort and case-control stu dies were reviewed for dementia risk. No randomized controlled trials regar ding dementia risk were identified. Data Extraction Twenty-nine studies met inclusion criteria and were rated, Two reviewers rated study quality independently and 100% agreement was reac hed on Jadad scores and 80% agreement was reached on US Preventive Services Task Force quality scores. A final score was reached th rough consensus if reviewers disagreed. Data Synthesis Studies of cognition were not combined quantitatively becaus e of heterogeneous study design. Women symptomatic from menopause had impro vements in verbal memory, vigilance, reasoning, and motor speed, but no enh ancement of other cognitive functions. Generally, no benefits were observed in asymptomatic women. A meta-analysis of observational studies suggested that HRT was associated with a decreased risk of dementia (summary odds rat io, 0.66; 95% confidence interval, 0.53-0.82). However, possible biases and lack of control for potential confounders limit interpretation of these st udies. Studies did not contain enough information to assess adequately the effects of progestin use, various estrogen preparations or doses, or durati on of therapy. Conclusions in women with menopausal symptoms, HRT may have specific cognit ive effects, and future studies should target these effects, The meta-analy sis found a decreased risk of dementia in HRT users but most studies had im portant methodological limitations.