Considerable evidence suggests that estrogen can have neuroprotective effects. However, recent results raised important questions regarding the conditions under which hormone therapy (HT) following menopause can be beneficial. It has been suggested that variables such as time of initiation and duration of HT use are of critical importance for beneficial cognitive effects to be observed. The aim of the present study was to investigate the potential neuroprotective effects of estrogens in aging on brain regions with high levels of estrogen receptors, namely the hippocampus (HC) and the amygdala (AG). In order to better characterize the punctual and long-term effects of estrogens, we tested postmenopausal women currently using estrogen therapy alone (ET), past HT users, never users, and men. Age at menses, age at menopause, HT duration and age were included as covariates in the analysis. Results demonstrate that women using ET had larger left and right HC volumes compared to men, and larger right HC volumes compared to past users and never users. Importantly, we found a significant negative relationship between ET duration and HC volume in this group. The observed effects were region-specific since no significant differences could be observed for the AG. In summary, these findings support a treatment duration dependent neuroprotective role of estrogen on HC volume in aging.
"The discrepancies between these studies may be explained by the critical window theory, which posits that a positive effect on hippocampal structure will be limited to HT taken around the onset of menopause. Moreover, one study reported that duration of HT was negatively associated with hippocampal volume, pointing to a treatment duration effect (Lord, et al., 2008). "
"The most frequently studied measure has been HC volume, with some inconsistent findings (Eberling et al., 2003; Greenberg et al., 2006; Raz et al., 2004). A Canadian study reported that 16 women currently using HT had significantly larger right HC volume than 10 past users and 15 women who had never used HT (Lord et al., 2008). However, they also reported that, among current users, increased duration of treatment was associated with smaller total HC volume. "
[Show abstract][Hide abstract] ABSTRACT: Structural imaging studies suggest gender differences in brain volumes; however, whether hormone treatment (HT) can protect against age-related structural changes remains unknown, and no prior neuroimaging study has investigated potential interactions between HT and estrogen receptor (ESR) polymorphisms. Magnetic resonance imaging was used to measure gray and white matter, hippocampal volume, corpus callosum, cerebrospinal fluid (CSF), total intracranial volume (ICV) and white matter lesions (WML) in 582 non-demented older adults. In multivariable analysis, when compared to women who had never used HT, men and women currently on treatment, but not past users, had significantly smaller ratios of gray matter to ICV and increased atrophy (CSF/ICV ratio). Hippocampal and white matter volume as well as the corpus callosum area were not significantly different across groups. ESR2 variants were not significantly associated with brain measures, but women with the ESR1 rs2234693 C allele had significantly smaller WML. Furthermore this association was modified by HT use. Our results do not support a beneficial effect of HT on brain volumes in older women, but suggest the potential involvement of ESR1 in WML.
Neurobiology of aging 10/2013; 35(3). DOI:10.1016/j.neurobiolaging.2013.09.026 · 5.01 Impact Factor
"Decreased estrogen levels in healthy post-menopausal women have been associated with poorer verbal learning and memory [2,98,103]. Previous research suggests a “neuroprotective” role of estrogen in key memory structures such as the hippocampus . Growing recognition of the effects of estrogen on cognition has led to examination of the cognitive impact of adjuvant hormonal therapies for BC. "
[Show abstract][Hide abstract] ABSTRACT: As more chemotherapy-treated cancer patients are reaching survivorship, side-effects such as cognitive impairment warrant research attention. The advent of neuroimaging has helped uncover a neural basis for these deficits. This paper offers a review of neuroimaging investigations in chemotherapy-treated adult cancer patients, discussing the benefits and limitations of each technique and study design. Additionally, despite the assumption given by the chemobrain label that chemotherapy is the only causative agent of these deficits, other factors will be considered. Suggestions are made on how to more comprehensively study these cognitive changes using imaging techniques, thereby promoting generalizability of the results to clinical applications. Continued investigations may yield better long-term quality of life outcomes by supporting patients' self-reports, and revealing brain regions being affected by chemotherapy.
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