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Estrogen- and tamoxifen-associated effects on brain structure and function
Jamie L Eberling1, Christine Wu, Regina Tong-Turnbeaugh
1Department of Neurology and Center for Neuroscience, University of California, Davis, CA 95616, USA. jleberling@lbl.gov
Neuroimage
|January 27, 2004
Summary
Estrogen therapy (ERT+) appears neuroprotective, showing higher brain metabolism and larger hippocampal volumes compared to tamoxifen (TAM) users. Tamoxifen users exhibited reduced brain metabolism and memory function.
Area of Science:
- Neuroscience
- Endocrinology
- Radiology
Background:
- Estrogen plays a role in brain function and may have neuroprotective effects.
- Tamoxifen, a selective estrogen receptor modulator, is used in breast cancer treatment and may have different effects on the brain.
- Postmenopausal women are a key demographic for studying hormonal effects on the brain.
Purpose of the Study:
- To investigate the differential effects of estrogen replacement therapy (ERT+) and tamoxifen (TAM) on brain glucose metabolism and hippocampal volume in postmenopausal women.
- To compare brain activity and structure between women taking ERT+, TAM, and those not taking either (ERT-).
- To assess the impact of these treatments on cognitive function, specifically semantic memory.
Main Methods:
- Positron emission tomography (PET) was used to measure brain glucose metabolism.
- Magnetic resonance imaging (MRI) was employed to assess hippocampal atrophy.
- Cognitive testing, including semantic memory assessment, was conducted on all participants.
- Three groups of postmenopausal women were studied: ERT+, TAM, and ERT-.
Main Results:
- The TAM group exhibited widespread hypometabolism in frontal lobes and significantly lower semantic memory scores compared to ERT+ and ERT- groups.
- The ERT- group showed reduced metabolism in frontal and temporal cortex compared to the ERT+ group.
- The TAM group displayed smaller right hippocampal volumes, with both hemispheres being significantly smaller than the ERT+ group after outlier removal; ERT- group volumes were intermediate.
Conclusions:
- Findings suggest estrogen replacement therapy has neuroprotective effects, indicated by higher brain metabolism and larger hippocampal volumes.
- Tamoxifen use is associated with decreased brain metabolism, impaired semantic memory, and reduced hippocampal volume.
- Estrogen's positive impact on brain physiology and anatomy is highlighted, contrasting with tamoxifen's effects.