Estrogen replacement therapy for treatment of mild to moderate Alzheimer disease: a randomized controlled trial. Alzheimer's Disease Cooperative Study

Interactions of estrogens and insulin-like growth factor-I in the brain: implications for neuroprotection

Data from epidemiological studies suggest that the decline in estrogen following menopause could increase the risk of neurodegenerative diseases. Furthermore, experimental studies on different animal models have shown that estrogen is neuroprotective. The mechanisms involved in the neuroprotective effects of estrogen are still unclear. Anti-oxidant effects, activation of different membrane-associated intracellular signaling pathways, and activation of classical nuclear estrogen receptors (ERs) could contribute to neuroprotection. Interactions with neurotrophins and other growth factors may also be important for the neuroprotective effects of estradiol. In this review we focus on the interaction between insulin-like growth factor-I (IGF-I) and estrogen signaling in the brain and on the implications of this interaction for neuroprotection. During the development of the nervous system, IGF-I promotes the differentiation and survival of specific neuronal populations. In the adult brain, IGF-I is a neuromodulator, regulates synaptic plasticity, is involved in the response of neural tissue to injury and protects neurons against different neurodegenerative stimuli. As an endocrine signal, IGF-I represents a link between the growth and reproductive axes and the interaction between estradiol and IGF-I is of particular physiological relevance for the regulation of growth, sexual maturation and adult neuroendocrine function. There are several potential points of convergence between estradiol and IGF-I receptor (IGF-IR) signaling in the brain. Estrogen activates the mitogen-activated protein kinase (MAPK) pathway and has a synergistic effect with IGF-I on the activation of Akt, a kinase downstream of phosphoinositol-3 kinase. In addition, IGF-IR is necessary for the estradiol induced expression of the anti-apoptotic molecule Bcl-2 in hypothalamic neurons. The interaction of ERs and IGF-IR in the brain may depend on interactions between neural cells expressing ERs with neural cells expressing IGF-IR, or on direct interactions of the signaling pathways of alpha and beta ERs and IGF-IR in the same cell, since most neurons expressing IGF-IR also express at least one of the ER subtypes. In addition, studies on adult ovariectomized rats given intracerebroventricular (i.c.v.) infusions with antagonists for ERs or IGF-IR or with IGF-I have shown that there is a cross-regulation of the expression of ERs and IGF-IR in the brain. The interaction of estradiol and IGF-I and their receptors may be involved in different neural events. In the developing brain, ERs and IGF-IR are interdependent in the promotion of neuronal differentiation. In the adult, ERs and IGF-IR interact in the induction of synaptic plasticity. Furthermore, both in vitro and in vivo studies have shown that there is an interaction between ERs and IGF-IR in the promotion of neuronal survival and in the response of neural tissue to injury, suggesting that a parallel activation or co-activation of ERs and IGF-IR mediates neuroprotection.

Hormone replacement in women with a history of breast cancer

Estrogen used alone (estrogen replacement therapy [ERT]) or with the addition of progesterone (hormone replacement therapy [HRT]) is known to be effective in reducing menopausal symptoms including hot flashes, vaginal dryness and urinary symptoms. It has been traditionally contraindicated, however, in women with a previous diagnosis of breast cancer because of fear that it may increase the risk of recurrence. There are considerable basic scientific data but little methodologically strong observational data and none from randomized studies concerning the use of ERT in women with a prior diagnosis of breast cancer. From our knowledge of the physiology of breast cancer, however, estrogen and/or progestational agents should be used with caution in women with a previous diagnosis of breast cancer. There are currently many alternatives to ERT/HRT in the prevention of menopausal symptoms such as vitamin E, clonidine and selective serotonin reuptake inhibitor antidepressants such as venlafaxine. There are also a variety of other approaches to the prevention of osteoporosis and cardiovascular disease including bisphosphonates, diet, and exercise; and diet, exercise, and statins, respectively. Other suggested beneficial effects of estrogen such as colon cancer prevention can be approached by the use of aspirin or the non-steroidals. Several trials of ERT/HRT used for 2 years versus no therapy in menopausal women with a previous diagnosis of breast cancer are ongoing in Europe and Britain, and should give us stronger data as to the role of HRT in this setting.

Detangling Alzheimer's disease

Alzheimer's disease (AD) afflicts 4 million people in the United States and is expected to strike 14 million by the year 2050, as the population ages. Researchers are scrambling to find genetic risk factors, decipher disease mechanisms, and develop reliable diagnostic tests that detect the illness at its earliest, potentially most treatable stage. Using these findings, they hope to devise new therapeutic approaches. Current clinical trials are testing novel techniques that stall or reverse AD-like neuropathology in mice.

Effects of estrogen on patterns of brain activity at rest and during cognitive activity: a review of neuroimaging studies

Animal and human studies provide evidence of systematic effects of estrogen on cerebral activity and cognitive function. In this article, we review studies of the activational effects of estrogen on cerebral activity during rest and during the performance of cognitive tasks in pre- and postmenopausal women. The goal is twofold--to better understand evidence suggesting that estrogen influences brain functioning and argue for the importance of considering hormone effects when designing neuroimaging studies. Hormone-related increases in blood flow during the resting state have been documented in healthy elderly women, elderly women with cerebrovascular disease, and middle-aged postmenopausal women with early menopause. There is no reliable influence of estrogen on blood flow during the resting state in women with Alzheimer's disease. Hormone therapy has been associated with changes in brain activation patterns in middle-aged and elderly postmenopausal women during performance of verbal and figural memory tasks, providing critical biological support for the view that estrogen might protect against age-associated changes in cognition and lower the risk of Alzheimer's disease. There is a paucity of studies examining changes in brain activation patterns across the menstrual cycle and a need for randomized studies of hormone therapy in postmenopausal women to confirm findings from observational studies. General procedural guidelines for controlling and investigating hormone effects in neuroimaging studies are discussed.

Investigations of a CA repeat in the oestrogen receptor beta gene in patients with Alzheimer's disease

Several studies have shown that oestrogen treatment after menopause decreases the risk for Alzheimer's disease (AD). It is also known that oestrogen stimulates the outgrowth of nerve cells and that apolipoprotein E (Apo E) synthesis and amyloid precursor protein (APP) metabolism are regulated by oestrogen. Recently a new oestrogen receptor was identified, oestrogen receptor beta (ERbeta), located at chromosome 14q22-24. Several genes close to this chromosomal region have been implicated in AD, but the results are conflicting. Our hypothesis was that variations in the ERbeta gene could be the underlying cause to the positive findings in these genes and we have therefore investigated a CA repeat(1) in intron 5 of the ERbeta gene. Three hundred and thirty-six AD cases and 110 healthy age-matched controls were included in this study. Fourteen different alleles were found with frequencies between 0.1 and 37%. There was no significant difference between AD cases and controls when all alleles were compared. However, allele 5 was seen in 13.6% of the controls but only in 8.0% of AD cases (P=0.014; odds ratio (OR)=0.55). No AD patient homozygous for this allele was seen but three controls were homozygous. In conclusion, our findings suggest the ERbeta allele 5 to be a protective factor. However, this has to be confirmed in a larger population.

In-vitro activity of S. lavandulaefolia (Spanish sage) relevant to treatment of Alzheimer's disease

Salvia lavandulaefolia Vahl. (Spanish sage) essential oil and individual monoterpenoid constituents have been shown to inhibit the enzyme acetylcholinesterase in-vitro and in-vivo. This activity is relevant to the treatment of Alzheimer's disease, since anticholinesterase drugs are currently the only drugs available to treat Alzheimer's disease. Other activities relevant to Alzheimer's disease include antioxidant, anti-inflammatory and estrogenic effects. Results of in-vitro tests for these activities are reported here for S. lavandulaefolia extracts, the essential oil and its major constituents. Antioxidant activity (inhibition of bovine brain liposome peroxidation) was found in the EtOH extract of the dried herb (5 mg mL(-1)) and the monoterpenoids (0.1 M) alpha- and beta-pinene and 1,8-cineole. Thujone and geraniol had lower antioxidant effects, while camphor had no antioxidant effects. Possible anti-inflammatory activity (eicosanoid inhibition in rat leucocytes) was found in the EtOH extract (50 microg mL(-1)) and was shown by the monoterpenoids alpha-pinene and geraniol (0.2 mM), but not 1,8-cineole, thujone or camphor. Possible estrogenic activity (via induction of beta-galactosidase activity in yeast cells) was found in the essential oil (0.01 mg mL(-1)) and the monoterpenoid geraniol (0.1-2 mM). 1,8-Cineole, alpha- and beta-pinene and thujone did not exhibit estrogenic activity in this analysis. These results demonstrate that S. lavandulaefolia, its essential oil and some chemical constituents have properties relevant to the treatment of Alzheimer's disease and provide further data supporting the value of carrying out clinical studies in patients with Alzheimer's disease using this plant species.

Neuroimaging of aging and estrogen effects on central nervous system physiology

OBJECTIVE

To review the literature on neuroimaging studies focusing on gender differences in the aging process and on the effects of postmenopausal estrogen use on the brain.

DESIGN

Pertinent studies were identified through a computer MEDLINE search. References of selected articles were hand-searched for additional citations.

CONCLUSION(S)

The current literature suggests that estrogen replacement may decrease brain white matter lesions, increase cerebral blood flow, alter regional brain activation patterns during cognitive processing, and have modulatory effects on various neurotransmitter systems. Overall, this points to a functional plasticity in higher order brain processing that can be altered by gonadal steroids.

Phytoestrogens and healthy aging: gaps in knowledge. A workshop report

There is an increasing public interest in foods and dietary supplements containing phytoestrogens for the maintenance of health. A workshop was convened to assess evidence for the potential benefits of phytoestrogen-containing foods or supplements on diseases or conditions affecting older populations. Preclinical, clinical, and epidemiologic data on the cardiovascular system, various cancers, bone diseases, and menopausal symptoms were the focus of the discussions. Research on the basis of consumer food choices as well as a presentation from the FDA regarding approval of the use of soy foods to reduce the risk of cardiovascular disease were also presented. Based on the information presented, isoflavone-containing soy foods may have favorable effects on the cardiovascular system, but major knowledge gaps still exist regarding effects ofphytoestrogen supplements on bone diseases, various cancers, menopausal symptoms, and cognitive function.

Pharmacotheraphy for Alzheimer's disease

In the past 2 years, substantive advances in therapy for Alzheimer's disease (AD) have occurred. The nature of the effects of cholinesterase inhibitors has been refined with the publication of several studies that have examined different aspects of the symptomatology of AD. Breakthroughs in the basic science of Alzheimer's disease have led to new insights into potential therapeutic strategies targeted at the secretases involved in the metabolism of the Alzheimer precursor protein. An immunization approach, in which the beta-amyloid protein itself was used as the immunizing agent, has also been presented and independently validated. Other areas of investigation with disappointing results, such as estrogen replacement therapy, anti-inflammatory approaches, and several other therapeutic agents, are also reviewed.

Relationships of sex hormone levels to dependence in activities of daily living in the frail elderly

OBJECTIVES

We undertook this nursing home study in order to determine the relationships between dependency in activities of daily living (ADL) and blood levels of estrone, testosterone, androstenedione, and dehydroepiandrosterone (DHEA). Little is known about this issue.

METHODS

cross-sectional study of 370 nursing home residents. Hormone levels in blood specimens drawn in 1997 and 1998 were correlated with degree of ADL dependency recorded in medical charts.

RESULTS

Because of multiple comparisons associations were deemed significant for P-values < or =0.017 for males and < or =0.0125 for females. In males, the following were inversely related: testosterone levels with dependency in transferring and eating; estrone with eating and a summary ADL index; and androstenedione with toileting and a summary ADL index (in all cases, r=-0.4; P=0.007-0.015). Inverse trends existed between testosterone levels and dependency in mobility and a summary ADL index; and androstenedione and eating (in all cases r=-0.3; P=0.030-0.055). Among females the following were directly related: estrone levels with dependence in mobility, toileting, transferring, and a summary ADL index; and DHEA with transferring and a summary ADL index (r=0.2-0.3, P=0.0001-0.01). Trends existed between estrone and eating, and DHEA and toileting (r=0.1-0.2, P=0.04).

CONCLUSION

In male residents, higher sex hormone levels are associated with better ADL performance. Among females the opposite is true. While further studies are needed to elucidate these relationships, our results and recent findings of others suggest sex hormone actions in older women differ from those in younger populations. A possible stress-related mechanism is also presented.

Exogenous estrogen in systemic lupus erythematosus: oral contraceptives and hormone replacement therapy

The role of exogenous estrogen in the initiation and maintenance of human SLE remains very controversial. Although cohort studies suggest an increase in the incidence of SLE with both oral contraceptives and hormone replacement therapy, recent retrospective studies suggest that the risk of flare is not increased with hormone replacement therapy. However, exogenous estrogen does increase hypercoagulability, an issue in SLE patients with antiphospholipid antibodies. The prospective SELENA study will ultimately address whether exogenous estrogen increases severe flares in SLE.

Current perspectives on benefits and risks of hormone replacement therapy

Hormone replacement therapy with estrogen alone or with added progestin relieves menopausal symptoms and physical changes associated with depleted endogenous estrogen levels. Estrogen replacement has also demonstrated a clear benefit in the prevention of osteoporosis. Hormone replacement therapy with added progestin maintains spinal bone density, protects against postmenopausal hip fractures, and provides these benefits even when therapy is started after age 60. More recently, additional benefits have emerged. Current estrogen and hormone replacement therapy users have a 34% reduction in the risk of colorectal cancer and a 20% to 60% reduction in the risk of Alzheimer's disease. Until recently, the body of evidence indicated that hormone replacement therapy with estrogen only reduced cardiovascular disease risk by 40% to 50% in healthy patients; whether the findings of 3 ongoing trials will change this conclusion is pending availability of the final results. The many benefits of estrogen and hormone replacement therapy must be weighed against a slight increase in the risk of breast cancer diagnosis with use for 5 or more years, but which disappears following cessation of therapy. Overall, estrogen and hormone replacement therapy improves the quality of life and increases life expectancy for most menopausal women.

Postmenopausal hormone replacement therapy use by older Mexican-American women

OBJECTIVES

To determine the prevalence of current hormone replacement therapy (HRT) use and describe its correlates among community-dwelling, Mexican-American women aged 67 and older.

DESIGN

A population-based survey of older Mexican-Americans conducted in 1995/1996.

SETTING

Five Southwestern states: Texas, New Mexico, California, Arizona, and Colorado.

PARTICIPANTS

An area probability sample of 1,424 noninstitutionalized Mexican-American women aged 67 and older (mean age = 75.1) completed the survey instrument via a 90-minute in-home interview, which included examination and recording of all medications taken.

MEASUREMENTS

Current use of HRT.

RESULTS

In this sample of older Mexican-American women, 4.7% were current users of HRT. Controlling for sociodemographic characteristics (age, marital status, living arrangements, years of education, income, language of interview), current HRT use is significantly related to years of education (per each year) (odds ratio (OR) = 1.13; 95% confidence interval (CI) = 1.05-1.20), having had a hysterectomy (OR = 4.37; 95% CI 2.50-7.64), a diagnosis of osteoporosis (OR = 3.40, 95% CI = 1.58-7.33), age at menopause (per each year) (OR = 1.07; 95% CI = 1.03-1.12), ever having a mammogram (OR = 3.72; 95% CI = 1.66-8.37), ever having a Pap test/pelvic examination (OR = 2.11; 95% CI = 1.08-4.12), having spoken with a pharmacist within the past year regarding health conditions (OR = 1.96; 95% CI = 1.06-3.65), and having Medicare plus private insurance (OR = 2.13; 95% CI = 1.14-3.97).

CONCLUSION

The prevalence of HRT use is lower than that reported in the older non-Hispanic white female population. In general, these findings indicate that access to and utilization of the traditional U.S. health care system are indicators of HRT use.

Fluctuations in spatial recognition memory across the menstrual cycle in female rhesus monkeys

Findings are inconsistent regarding whether women's cognitive performance fluctuates across phases of the menstrual cycle, but differences in methodology and the use of reported cycle phase rather than precise hormonal measures may underlie these disparities. Studies in monkeys may help resolve these discrepant findings, since hormonal status can be reliably determined. We tested four young (5-7 years old) female rhesus monkeys daily during one entire menstrual cycle on three cognitive tasks displayed on a computerized touch-screen system: a Matching to Sample task with a 30 s delay (MTS-30s), a Matching to Sample task without delay (MTS-no delay) and the spatial condition of the Delayed Recognition Span Test (spatial-DRST). Blood samples were collected at specific time intervals throughout the cycle and assayed for estradiol and progesterone in order to identify hormonal status. There was a nonsignificant trend for the MTS-30s scores to be better during the follicular and luteal phases, when estradiol levels were low, than during the peri-ovulatory phase, when estradiol levels were at their highest. MTS-no delay performance did not vary as a function of hormonal status. Spatial-DRST scores were significantly better during the follicular and luteal phases than during the peri-ovulatory phase of the cycle. These data in the female rhesus monkey support the hypothesis that spatial memory performance is sensitive to estradiol variations across the menstrual cycle, with better performance associated with low estradiol levels.

Assessing outcomes in Alzheimer disease

To gain a better overview of the effectiveness of treatment of patients with Alzheimer disease (AD), areas such as cognition, activities of daily living (ADL), behavior, caregiver burden, quality of life and economics need to be assessed. A number of instruments are available for assessing these domains, many of which are reviewed in this article. These include the cognitive subscale of the Alzheimer's Disease Assessment Scale (the standard instrument for the measurement of efficacy in dementia trials), scales that assess AD patients' abilities to perform ADL (including the Disability Assessment for Dementia scale and the Alzheimer's Disease Cooperative Study-Activities of Daily Living), scales to assess behavioral symptoms in dementia (including the Neuropsychiatric Inventory and the Behavioral Pathology in Alzheimer's Disease Rating Scale), scales for assessing global clinical change, and methods for assessing caregiver time, quality of life and health economics. Each instrument has its own advantages and disadvantages. However, the instruments used need to be selected carefully to provide credible and informative outcome data.

Reduced cerebrospinal fluid estradiol levels are associated with increased beta-amyloid levels in female patients with Alzheimer's disease

Recent in-vitro studies indicate that estrogens such as 17beta-estradiol (E2) may decrease the production of beta-amyloid 1-42 (Abeta42), a peptide central for the formation of senile plaques in Alzheimer's disease (AD). To test this hypothesis in a clinical study, cerebrospinal fluid levels of E2 were compared between 30 female AD patients and 11 female patients with non-dementing diseases such as major depression and investigated with respect to beta-amyloid 1-40 and Abeta42 levels. E2 levels were significantly (P<0.05) lower in the AD group than in controls; within the AD group E2 levels were inversely correlated with Abeta42 concentrations (r=-0.36, P=0.05). This is the first clinical study providing evidence for an influence of E2 on Abeta42 metabolism in vivo. This observation corresponds to the putative beneficial effects of estrogen replacement therapy on the development and course of AD.

New approaches to diagnose and treat Alzheimer's disease: a glimpse of the future

An explosion of scientific and clinical knowledge about Alzheimer's disease now provides a basis for selecting targets for treatment aimed at slowing progression of dementia or delaying the onset of or preventing Alzheimer's disease. The rationale that underlies several promising approaches to treatment are reviewed. Novel forms of treatment are most effective when combined with sensitive clinical methods to diagnose Alzheimer's disease as early as possible and to track its progression over time. Therefore, this article highlights findings concerning biological markers for Alzheimer's disease and the mild cognitive impairment syndrome and attempts to define a prodromal stage of Alzheimer's disease.

Brain aromatase is neuroprotective

The expression of aromatase, the enzyme that catalyzes the biosynthesis of estrogens from precursor androgens, is increased in the brain after injury, suggesting that aromatase may be involved in neuroprotection. In the present study, the effect of inactivating aromatase has been assessed in a model of neurodegeneration induced by the systemic administration of neurotoxins. Domoic acid, at a dose that is not neurotoxic in intact male mice, induced significant neuronal loss in the hilus of the hippocampal formation of mice with reduced levels of aromatase substrates as a result of gonadectomy. Furthermore, the aromatase substrate testosterone, as well as its metabolite estradiol, the product of aromatase, were able to protect hilar neurons from domoic acid. In contrast, dihydrotestosterone, the 5 alpha-reduced metabolite of testosterone and a nonaromatizable androgen, was not. These findings suggest that aromatization of testosterone to estradiol may be involved in the neuroprotective action of testosterone in this experimental model. In addition, aromatase knock-out mice showed significant neuronal loss after injection of a low dose of domoic acid, while control littermates did not, indicating that aromatase deficiency increases the vulnerability of hilar neurons to neurotoxic degeneration. The effect of aromatase on neuroprotection was also tested in male rats treated systemically with the specific aromatase inhibitor fadrozole and injected with kainic acid, a well characterized neurotoxin for hilar neurons in the rat. Fadrozole enhanced the neurodegenerative effect of kainic acid in intact male rats and this effect was counterbalanced by the administration of estradiol. Furthermore, the neuroprotective effect of testosterone against kainic acid in castrated male rats was blocked by fadrozole. These findings suggest that neuroprotection by aromatase is due to the formation of estradiol from its precursor testosterone. Finally, a role for local cerebral aromatase in neuroprotection is indicated by the fact that intracerebral administration of fadrozole enhanced kainic acid induced neurodegeneration in the hippocampus of intact male rats. These findings indicate that aromatase deficiency decreases the threshold for neurodegeneration and that local cerebral aromatase is neuroprotective. Brain aromatase may therefore represent a new target for therapeutic approaches to neurodegenerative diseases.

Pharmacotherapy of Alzheimer's disease: is there a need to redefine treatment success?

The traditional aim of Alzheimer's disease treatment in clinical trials has been to improve cognitive abilities. It has become increasingly clear, however, that other aspects are important in assessing treatment responses. A group of 10 physicians recently gathered to review the current criteria for assessing treatment success in Alzheimer's disease. While cognition has been previously viewed as the primary measure of efficacy, areas such as functional abilities, behaviour, caregiver burden, quality of life and resource utilization all need to be comprehensively assessed to fully evaluate treatment effects in patients with Alzheimer's disease, as well as their impacts on caregivers and society. Postponing or slowing decline in any of these areas may represent an important benefit and should be considered as an outcome measure in clinical trials, clinical practice and decision-making about healthcare budgets. Accepted instruments are available for assessing outcomes in each aspect of Alzheimer's disease, but they need to be selected carefully to provide valid, meaningful data. Some of the most frequently used outcome measures in Alzheimer's disease are reviewed. Using expanded criteria for treatment success and clinically relevant outcome measures, data from currently available studies show that cholinesterase inhibitors produce clinically meaningful long-term benefits in multiple domains in patients with Alzheimer's disease.

Estrogen prevents the lipopolysaccharide-induced inflammatory response in microglia

After neuronal injury and in several neurodegenerative diseases, activated microglia secrete proinflammatory molecules that can contribute to the progressive neural damage. The recent demonstration of a protective role of estrogen in neurodegenerative disorders in humans and experimental animal models led us to investigate whether this hormone regulates the inflammatory response in the CNS. We here show that estrogen exerts an anti-inflammatory activity on primary cultures of rat microglia, as suggested by the blockage of the phenotypic conversion associated with activation and by the prevention of lipopolysaccharide-induced production of inflammatory mediators: inducible form of NO synthase (iNOS), prostaglandin-E(2) (PGE(2)), and metalloproteinase-9 (MMP-9). These effects are dose-dependent, maximal at 1 nm 17beta-estradiol, and can be blocked by the estrogen receptor (ER) antagonist ICI 182,780. The demonstration of ERalpha and ERbeta expression in microglia and macrophages and the observation of estrogen blockade of MMP-9 mRNA accumulation and MMP-9 promoter induction further support the hypothesis of a genomic activity of estrogen via intracellular receptors. This is the first report showing an anti-inflammatory activity of estrogen in microglia. Our study proposes a novel explanation for the protective effects of estrogen in neurodegenerative and inflammatory diseases and provides new molecular and cellular targets for the screening of ER ligands acting in the CNS.

Differential mechanisms of neuroprotection by 17 beta-estradiol in apoptotic versus necrotic neurodegeneration

The major goal of this study was to compare mechanisms of the neuroprotective potential of 17 beta-estradiol in two models for oxidative stress-independent apoptotic neuronal cell death with that in necrotic neuronal cell death in primary neuronal cultures derived from rat hippocampus, septum, or cortex. Neuronal apoptosis was induced either by staurosporine or ethylcholine aziridinium (AF64A), as models for necrotic cell death glutamate exposure or oxygen-glucose deprivation (OGD) were applied. Long-term (20 hr) pretreatment (0.1 microm 17 beta-estradiol) was neuroprotective in apoptotic neuronal cell death induced by AF64A (40 microm) only in hippocampal and septal neuronal cultures and not in cortical cultures. The neuroprotective effect was blocked by the estrogen antagonists ICI 182,780 and tamoxifen and the phosphatidylinositol 3-kinase (PI3-K) inhibitor LY294002. In glutamate and OGD-induced neuronal damage, long-term pretreatment was not effective. In contrast, short-term (1 hr) pretreatment with 17 beta-estradiol in the dose range of 0.5-1.0 microm significantly reduced the release of lactate dehydrogenase and improved morphology of cortical cultures exposed to glutamate or OGD but was not effective in the AF64A model. Staurosporine-induced apoptosis was not prevented by either long- or short-term pretreatment. The strong expression of the estrogen receptor-alpha and the modulation of Bcl proteins by 17 beta-estradiol in hippocampal and septal but not in cortical cultures indicates that the prevention of apoptotic, but not of necrotic, neuronal cell death by 17 beta-estradiol possibly depends on the induction of Bcl proteins and the density of estrogen receptor-alpha.

Testosterone-mediated neuroprotection through the androgen receptor in human primary neurons

Estrogen is an active neuroprotectant and is presently investigated as a potential therapy against Alzheimer's disease for women. To determine if male hormones could also be neuroprotective, we investigated the effect of testosterone, methyltestosterone, and epitestosterone at physiological concentrations on primary cultures of human neurons induced to undergo apoptosis by serum deprivation. Serum deprivation significantly induces neuronal apoptosis in a protracted fashion. As expected, physiological concentrations of 17-beta-estradiol and transcriptionally inactive 17-alpha-estradiol protect neurons against apoptosis. Similar to 17-beta-estradiol, physiological concentrations of testosterone are also neuroprotective. Androgen receptors are present at 8 +/- 2 fmol/mg protein in the neuron cultures. The non-aromatizable androgen, mibolerone, is also neuroprotective and aromatase inhibitor, 4-androsten-4-OL-3,17-dione, does not prevent testosterone-mediated neuroprotection. In contrast, anti-androgen, flutamide, eliminates testosterone-mediated neuroprotection. Testosterone analog, methyltestosterone, showed androgen receptor-dependent neuroprotection that was delayed in time indicating that a metabolite may be the active agent. The endogenous anti-androgen, epitestosterone, also showed a slight neuroprotective effect but not through the androgen receptor. These results indicate that androgens induce neuroprotection directly through the androgen receptor. These data suggest that androgens may also be of therapeutic value against Alzheimer's disease in aging males.

Alzheimer's disease: insights from epidemiology

While a complete understanding of the pathogenesis of Alzheimer's disease (AD) remains elusive, many conclusions can be drawn from the numerous epidemiological studies undertaken to date. Prevalence and incidence estimates show consistency, following a roughly exponential pattern with a doubling of both parameters roughly every five years after age 65. Roughly 7% of the population aged 65 and over has AD. The clinical course of the disease is reasonably well established and mortality rates rise with increasing levels of cognitive deficit. Four risk factors for AD are firmly established: increasing age, the presence of the apolipoproteinE-epsilon4 allele, familial aggregation of cases, and Down's syndrome. Numerous other associations have been shown in some studies, but not in others. For example, women generally appear at higher risk than men, as do people with lower levels of education; depression is probably prodromal; head injury is an established risk factor, and may interact with the apoE gene; several occupational exposures appear hazardous, and exposure to aluminum in the water supply confers excess risk. Hypertension and other vascular symptoms appear to predispose to AD, which is now seen as nosologically closer to vascular dementia than was previously believed. Several apparently protective factors have been identified, although preventive trials based on these have so far shown minimal effectiveness. The use of non-steroidal anti-inflammatory drugs to treat arthritis is associated with a reduced risk of AD, as is estrogen use by post-menopausal women. Physical activity appears beneficial, as does a diet with high levels of vitamins B6, B12 and folate. while red wine in moderate quantities appears protective. This review concludes with a discussion of the strengths and limitations of current epidemiological methods for studying Alzheimer's disease.

Synthesis and reactivity of the catechol metabolites from the equine estrogen, 8,9-dehydroestrone

The risk factors for women developing breast and endometrial cancers are all associated with a lifetime of estrogen exposure. Estrogen replacement therapy in particular has been correlated with an increased cancer risk. Previously, we showed that the equine estrogens equilin and equilenin, which are major components of the widely prescribed estrogen replacement formulation Premarin, are metabolized to highly cytotoxic quinoids which caused oxidative stress and alkylation of DNA in vitro [Bolton, J. L., Pisha, E., Zhang, F., and Qiu, S. Chem. Res. Toxicol. 1998, 11, 1113-1127]. In this study, we have synthesized 8,9-dehydroestrone (a third equine estrogen component of Premarin) and its potential catechol metabolites, 4-hydroxy-8,9-dehydroestrone and 2-hydroxy-8,9-dehydroestrone. Both 2-hydroxy-8,9-dehydroestrone and 4-hydroxy-8,9-dehydroestrone were oxidized by tyrosinase or rat liver microsomes to o-quinones which reacted with GSH to give one mono-GSH conjugate and two di-GSH conjugates. Like endogenous estrogens, 8,9-dehydroestrone was primarily converted by rat liver microsomes to the 2-hydroxylated rather than the 4-hydroxylated o-quinone GSH conjugates; the ratio of 2-hydroxy-8,9-dehydroestrone versus 4-hydroxy-8,9-dehydroestrone was 6:1. Also in contrast to experiments with equilin, 4-hydroxyequilenin was not observed in microsomal incubations with 8,9-dehydroestrone or its catechols. The behavior of 2-hydroxy-8,9-dehydroestrone was found to be more complex than 4-hydroxy-8,9-dehydroestrone as GSH conjugates resulting from 2-hydroxy-8,9-dehydroestrone were detected even without oxidative enzyme catalysis. Under physiological conditions, 2-hydroxy-8,9-dehydroestrone isomerized to 2-hydroxyequilenin to form the very stable 2-hydroxyequilenin catechol; however, 4-hydroxy-8,9-dehydroestrone was found to be stable under similar conditions. Finally, preliminary studies conducted with the human breast tumor S-30 cell lines demonstrated that the catechol metabolites of 8,9-dehydroestrone were much less toxic than 4-hydroxyequilenin (20-40-fold). These results suggest that the catechol metabolites of 8,9-dehydroestrone may have the ability to cause cytotoxicity in vivo primarily through formation of o-quinones; however, most of the adverse effects of Premarin estrogens are likely due to formation of 4-hydroxyequilenin o-quinone from equilin and equilenin.

Combination Therapies and the Theoretical Limits of Evidence-Based Medicine

BACKGROUND

Advances in molecular pharmacology and surgical, endovascular, and radiation techniques have yielded multiple effective or promising, and potentially complementary, classes of treatments for virtually every major medical disorder. Consequently, determining the optimum combination of therapies for a condition is a burgeoning challenge to clinical trialists and practicing physicians.

METHODS

General phase III trial strategies for testing combination regimens are described, and then applied to two illustrative conditions, Alzheimer disease and ischemic stroke.

RESULTS

Strategies for testing combination regimens include: head to head trials of all combinations, which lead to unwieldy trial numbers; very large multi-arm trials, which impractically delay interval information on regimen utility; and hierarchical, serial clinical trials. Systematic literature review revealed seven classes of agents already approved or in late phase III testing for preventing the development or slowing the progression of Alzheimer disease and five for ischemic stroke prevention. Possible combination regimens number 128 (2(7)) for Alzheimer disease and 32 (2(5)) for ischemic stroke. Hierarchical, serial clinical trials would permit identification of the optimum combination of these agent classes for Alzheimer disease through 127 trials, enrolling 63,500 patients, requiring 286 years; for ischemic stroke through 31 trials, enrolling 186,000 patients, requiring 155 years.

CONCLUSIONS

Marked limitations in the ability of clinical trials to interrogate varied treatment combinations to determine the most effective ensemble exist, and their scope is widely underappreciated. Steps that may attenuate, though not eliminate, the challenge of a surfeit of combination treatment regimens include preclinical testing to identify the most promising regimens, use of surrogate outcome measures in exploratory clinical trials, and use of hierarchical, serial and factorial phase III trials.

Alzheimer's disease: a review for the ophthalmologist

Alzheimer's disease is the most prevalent dementia. Definitive diagnosis is made only at autopsy, although "probable" diagnoses are made using clinical criteria. Patients with Alzheimer's disease demonstrate severe deficits in memory with cortical features of language difficulty and visuomotor spatial deficits. They also may present with psychotic symptoms of delusions and hallucinations, and personality and behavioral changes. Advancing age, genetics, and environmental risk factors are important in the development of Alzheimer's disease. Visual abnormalities have been described in Alzheimer's disease and may be related to the development of visual hallucinations. Although palliative treatments exist for the cognitive loss and behavioral symptoms, future treatments will focus on both delay of onset and slowing of progression of the disease. Continued research is needed to further understand this devastating disorder, which may in turn lead to more successful treatments.

Alzheimer's disease and related disorders

The cholinesterase inhibitors provide the first clearly effective treatments for the cognitive deficits of AD and appear to have a beneficial effect on activities of daily living function and noncognitive behavior. There is increasing support for starting donepezil, rivastigmine, or galantamine early in the disease course and maintaining treatment at least during the early and middle stages of AD. Depressive signs and symptoms complicating AD are treated best with SSRIs. Placebo-controlled trials support the use of citalopram and sertraline in AD complicated by depression. The atypical antipsychotics are the first choice for managing psychosis and disruptive agitation in AD and particularly in the Lewy body variant of AD. Studies suggest that low-dose treatment with risperidone, 1 mg/d, or olanzapine, 5 mg/d, offers the optimal ratio of therapeutic to adverse effects.

Cellular and molecular mechanisms of estrogen regulation of memory function and neuroprotection against Alzheimer's disease: recent insights and remaining challenges

This review focuses on recent advances in our knowledge of estrogen action in the brain. The greatest amount of attention was devoted to those studies that impact our understanding of estrogen regulation of memory function and prevention of degenerative diseases associated with memory systems, such as Alzheimer's disease. A review of recent advances in our understanding of estrogen receptors, both nuclear and membrane, is also presented. Finally, these data are considered in regard to their relevancy to the use of estrogen replacement therapy for cognitive health throughout menopause and the development of an estrogen replacement therapy designed for the unique requirements of the brain.

Midlife women's attributions about perceived memory changes: observations from the Seattle Midlife Women's Health Study

Memory changes are of increasing interest as midlife women approach menopause. Recent studies of relationships between estrogen and Alzheimer's disease have prompted interest in memory experiences around the time of menopause. The purpose of this analysis, part of the larger Seattle Midlife Women's Health Study (SMWHS), was to describe the types of memory changes women perceived during midlife, to describe their attributions about the memory changes, and to describe the relationship among these types and attributions of memory changes and age, menopausal transition stage, hormone replacement therapy (HRT) use, stress, and major life roles. Women (n = 230) with a mean age of 46.7 years, enrolled in the SMWHS, described whether they had noticed any changes in their memory, when they noticed them first, the nature of the changes, and what they thought were the reasons for the changes. Types of memory changes were collapsed into five categories, which included difficulty recalling words or numbers, forgetting related to everyday behavior, concentration problems, need for memory aids, and forgetting events. Six categories describing attributions about the memory changes were increased role burden and stress, getting older, physical health, menstrual cycle changes/hormones, inadequate concentration, and emotional factors. Stress, physical health, and aging as attributions, rather than the menstrual cycle or hormone use, were linked to most types of memory change.

Evidence-based practice in women's health: hormone therapy for women at menopause

Women's health providers, especially midwives, must take into account the known benefits and risks, as well as the "unknown," when recommending the use of hormone therapy for menopausal women, especially as it relates to heart disease, breast cancer, impaired cognition, and osteoporosis. The most recent evidence available from various studies about the benefits and risks of estrogen and hormone therapy at menopause suggests that, although hormone therapy may be protective in some women against heart disease and osteoporosis, evidence is less certain about the benefits of hormone protection against impaired cognition and the risks of breast cancer with use. The clinical approach used by midwives in which individualizing care based on each woman's health status history as well as preferences is highly appropriate for women in the perimenopausal and menopausal period.

Reactive astrocytes express estrogen receptors in the injured primate brain

Previous studies have suggested that estrogen may regulate the expression of genes related to the inflammatory response within the nervous system, particularly within glia. In the present study, we examined whether injury induces estrogen sensitivity in reactive glia in the primate brain. Three adult Macaca fascicularis (cynomolgous) monkeys received unilateral fimbria fornix transections followed by chronic intracranial cannula implants through which a vehicle solution was infused intracerebroventricularly for a 4-week period. Astrocytes adjacent to areas of parenchymal disruption caused either by the lesion or by the instrumentation procedure became reactive, as evidenced by cellular hypertrophy and up-regulation of glial fibrillary acidic protein (GFAP) immunolabeling. Of note, specific estrogen receptor-alpha immunolabeling also was induced adjacent to injured regions, and this labeling strictly colocalized with GFAP immunoreactivity upon double fluorescent confocal immunolabeling. Induction of estrogen receptor immunoreactivity in reactive astrocytes occurred in all monkeys examined, whereas nonreactive glia distant from disrupted regions did not exhibit estrogen receptor labeling. Thus, expression of estrogen receptors is up-regulated in reactive astrocytes of the primate brain, potentially allowing estrogen to modulate aspects of the central nervous system's inflammatory response to injury.

Effects of hormone replacement therapy on cognitive performance in elderly women

OBJECTIVE

To determine the effects of 9 months of hormone replacement therapy (HRT) on cognitive performance in women aged 75 years and older.

METHODS

A 9-month randomized, double-blinded, placebo-controlled parallel trial. Fifty-two elderly postmenopausal women (age range 75-91 years) without known contraindications to HRT or evidence of dementia or depression were enrolled. Participants were randomly assigned in a 1:2 ratio to placebo or conjugated estrogens at 0.625 mg/d plus trimonthly medroxyprogesterone acetate at 5 mg/d for 13 days (HRT). Main outcome measures were change from baseline and rate of change from baseline for the following psychometric tests: Verbal Fluency Test, Weschler Paired Associate Learning and 20 min Delayed Recall, Trailmaking A and B Tests, Cancellation Random Letter and Random Form Tests.

RESULTS

At baseline, women in the HRT group reported a younger age of onset of menopause and a higher prevalence of hysterectomy, but otherwise did not differ from women in the placebo group. After 9 months of treatment, there were no significant group differences for any of the cognitive performance measures. The lack of an observed group-by-time difference for all cognitive tests remained after controlling for age of onset of menopause, education, and previous hysterectomy.

CONCLUSIONS

Although conclusions are limited by small sample size and the relatively short duration of treatment, results suggest that 9 months of estrogen replacement in combination with trimonthly progestin does not improve cognitive performance in women over 75 years who do not have dementia or depression.

Sex hormones and their impact on dementia and depression: a clinical perspective

Sex hormones have often been associated with changes in behavioural and mental abilities. This paper reviews the scientific literature published between 1990 and 2000 investigating the effects of oestrogen, testosterone and dehydroepiandrosterone (DHEA) on depression and dementia. Oestrogen seems to have a positive effect in preventing, but not treating, Alzheimer's disease. Oestrogen use may also improve mood amongst women with postnatal or perimenopausal depression; however, it may contribute to increasing depressive symptoms in women with premenstrual dysphoria. The behavioural effects of testosterone and DHEA remain unclear but the results of preliminary reports suggest that their use is associated with improved mood. At present, there is not enough hard data to support the use of sex hormones and DHEA for the treatment of depression or memory deficits.

Hormone replacement therapy: primary and secondary prevention

Researchers are far from understanding the mechanism(s) of action of hormone replacement therapy (HRT) on the cardiovascular system. Moreover, the results of clinical trials that can clarify these dilemmas will not be available for several years. As clients seek guidance in making the pivotal decision about taking HRT, it is important that practitioners understand what the current research reveals about its risks and benefits. This article addresses the role of HRT in primary and secondary prevention and includes observational research, clinical trials (completed and in progress), benefits and risks, and implications for clinical practice in counseling patients.

The nature of the effect of female gonadal hormone replacement therapy on cognitive function in post-menopausal women: a meta-analysis

We reviewed epidemiological and experimental studies of female gonadal hormone replacement therapy (HRT) on cognitive function in post-menopausal women and carried out meta-analyses. In healthy ageing women, HRT has small and inconsistent effects that include enhancement of verbal memory, abstract reasoning and information processing. Epidemiological studies show larger effects than experimental studies, which is not related to sample size. Important confounds may be that women who start using HRT are healthier than women who do not. Also, controlling for socio-economic status diminishes the effect of HRT. The effects of HRT may depend on the age and type of menopause and the therapeutic intervention used, with the most widely used drug, Premarin, having least effect. However, the effects are independent of mood and climacteric symptom alleviation. There is a paucity of experimental studies that include healthy elderly women. The evidence for an estrogen deficiency in women with dementia and cognitive dysfunction is inconsistent. Nevertheless, epidemiological studies suggest that HRT protects against the development of clinically diagnosed Alzheimer's disease. However, poor recall of HRT use by patients and altered physician behaviour may have confounded the effects. Surprisingly, both healthy and demented women with low education seem to benefit most from HRT. Three recent controlled experimental studies using Premarin showed no effects of HRT in preventing further cognitive decline in women who already have Alzheimer's disease. Duration of treatment seems to play an important role, with beneficial effects declining-and even reversing-with longer treatment in women with Alzheimer's disease.Future research should further investigate the cognitive effect of different HRT preparations, serum estrogen levels, and the interactions of HRT with age, menopausal status and existing protective (e.g. education) and risk factors (e.g. smoking and apolipoprotein E genotype) for cognitive decline and Alzheimer's disease.

The role of hormone replacement therapy in women with a previous diagnosis of breast cancer and a review of possible alternatives

Estrogen replacement therapy either with (HRT) or without (ERT) accompanying progesterone is routinely offered to well women at the time of menopause, in order to relieve vasomotor symptoms, (hot flashes), reduce urogenital atrophy and reduce the risks of cardiovascular disease, osteoporosis and perhaps colon cancer and Alzheimer's disease. It is generally felt however, that women with a previous diagnosis of breast cancer are not suitable candidates for such therapy since either estrogen or progesterone may be associated with an increased risk of cancer recurrence. There are however, a variety of approaches to menopausal therapy in such women. A careful history must first be taken in order to identify the symptoms or conditions of concern. Vasomotor symptoms can be reduced by the use of other medications such as the antidepressant venlafaxine (Effexor). Estring, a vaginal estrogen ring can be used to reduce genitourinary symptoms, with little systemic estrogen absorption. Osteoporosis can be prevented or treated with calcium supplements, exercise, improved diet, bisphosphonates and/or selective estrogen receptor modulators (SERMs) while cardiovascular risk can be reduced by diet and exercise, as well as the appropriate use of lipid lowering and antihypertensive medications.

Hormones after menopause?

The average life span of a woman is increasing and the age of menopausal onset has not changed much. The length of time that a woman spends in the postmenopausal state is thus increasing. This potential estrogen-deficient state may have certain physiologic and metabolic consequences. The onset of menopause is an excellent time to assess a women's overall health and to evaluate the benefit/risk equation of hormone replacement therapy (HRT).

Effects of estrogen on congnition mood, and degenerative brain diseases

OBJECTIVE

To review research findings on the effects of estrogen on cognition, mood, memory, and degenerative brain disease in women.

DATA SOURCES

English-language journal articles published primarily since 1995, retrieved from a MEDLINE search and from bibliographies of selected reviews.

STUDY SELECTION

Investigational studies, clinical trials, and review articles examining the effects of estrogen on the central nervous system.

DATA SYNTHESIS

Although scientific study of the brain is in its infancy, numerous studies indicate that estrogen is essential to optimal brain function. Estrogen has been shown to increase cerebral blood flow, act as an antiinflammatory agent, enhance activity at neuronal synapses, and exert direct neuroprotective and neurotrophic effects on brain tissue. Through these varied mechanisms, estrogen strongly influences mood and cognition, and the decline of this hormone at menopause can produce significant emotional and cognitive problems in women.

CONCLUSION

Pharmacists can educate women about the various mood and memory changes that can occur during perimenopause and how estrogen replacement therapy may lead to improvements in brain function. The potential use of estrogen replacement therapy to reduce the risk of Alzheimer's disease and ease the symptoms of Parkinson's disease could have a profound effect on women, their families, and society as a whole.

Augmented senile plaque load in aged female beta-amyloid precursor protein-transgenic mice

Transgenic mice (Tg2576) overexpressing human beta-amyloid precursor protein with the Swedish mutation (APP695SWE) develop Alzheimer's disease-like amyloid beta protein (Abeta) deposits by 8 to 10 months of age. These mice show elevated levels of Abeta40 and Abeta42, as well as an age-related increase in diffuse and compact senile plaques in the brain. Senile plaque load was quantitated in the hippocampus and neocortex of 8- to 19-month-old male and female Tg2576 mice. In all mice, plaque burden increased markedly after the age of 12 months. At 15 and 19 months of age, senile plaque load was significantly greater in females than in males; in 91 mice studied at 15 months of age, the area occupied by plaques in female Tg2576 mice was nearly three times that of males. By enzyme-linked immunosorbent assay, female mice also had more Abeta40 and Abeta42 in the brain than did males, although this difference was less pronounced than the difference in histological plaque load. These data show that senescent female Tg2576 mice deposit more amyloid in the brain than do male mice, and may provide an animal model in which the influence of sex differences on cerebral amyloid pathology can be evaluated.

Neurotrophin expression in the reproductively senescent forebrain is refractory to estrogen stimulation

The present studies compared the regulation of the neurotrophin ligands and receptors by estrogen in young adult and reproductively senescent rats. Both groups of animals were ovariectomized and replaced with 17beta-estradiol or placebo pellets for 4 weeks. Protein expression of specific neurotrophins and their receptors were measured in the olfactory bulb and its basal forebrain afferent, the horizontal limb of the diagonal band of Broca (hlDBB). Young-adult rats responded to estrogen with an increase in the expression of brain-derived neurotrophic factor (BDNF) in the olfactory bulb and hlDBB, as well as bulbar trkA and trkB receptors. Older rats did not respond to estrogen in this manner. Additionally, estrogen treatment decreased the expression of the universal neurotrophin receptor p75 in young adult animals, but increased expression of this receptor in reproductively senescent rats. The latter group, however, had significantly greater estrogen receptor alpha (ERalpha) expression in the olfactory bulb as compared to their younger counterparts, but very low expression of the steroid receptor coactivator, SRC-1. Changes in the proportion or ratio of steroid receptor/coactivator systems in the aging forebrain may contribute to the refractory response to estrogen in the reproductively senescent animals.

Understanding the role of estrogen on cognition and dementia

There is growing evidence that post menopausal use of estrogen may have a beneficial effect on cognition and may reduce the risk of dementia. In a vast majority of studies, the use of estrogen replacement in the postmenopausal period was associated with a reduced risk of dementia. Meta-analyses of both retrospective case controlled and prospective studies indicate a 30% reduction in the risk of dementia, with larger effect sizes (50% reduction) reported in the latter. Some, but not all, large epidemiological studies indicate that estrogen use is associated with better performance on both verbal and visual memory testing in later life. However, studies of the effect of estrogen on patients with Alzheimer's disease are less convincing with minimal effects reported in open trials and following brief exposure. Biological mechanisms, which could be responsible for some of these effects, include activation of the cholinergic system, anti-oxidant action, neurotrophic stimulation and anti-amyloidogenic properties. Beneficial effects of estrogen in primary prevention but not secondary prevention of heart disease indicates that the ability to observe beneficial effects may depend on the point at which intervention occurs. Ongoing double-blind randomized clinical trial to determine if estrogen is a safe and effective treatment for the prevention of memory loss and Alzheimer's disease will be described. Future work will undoubtedly include the identification of specific estrogenic receptors in the central nervous system that can be selectively activated without adverse involvement of other biologic systems.

Morphological abnormalities in the brains of estrogen receptor beta knockout mice

Estrogen receptor beta (ERbeta) is expressed at high levels in both neurons and glial cells of the central nervous system. The development of ERbeta knockout (BERKO) mice has provided a model to study the function of this nuclear receptor in the brain. We have found that the brains of BERKO mice show several morphological abnormalities. There is a regional neuronal hypocellularity in the brain, with a severe neuronal deficit in the somatosensory cortex, especially layers II, III, IV, and V, and a remarkable proliferation of astroglial cells in the limbic system but not in the cortex. These abnormalities are evident as early as 2 mo of age in BERKO mice. As BERKO mice age, the neuronal deficit becomes more pronounced, and, by 2 yr of age, there is degeneration of neuronal cell bodies throughout the brain. This is particularly evident in the substantia nigra. We conclude that ERbeta is necessary for neuronal survival and speculate that this gene could have an important influence on the development of degenerative diseases of the central nervous system, such as Alzheimer's disease and Parkinson's disease, as well as those resulting from trauma and stroke in the brain.

Galantamine, a cholinesterase inhibitor that allosterically modulates nicotinic receptors: effects on the course of Alzheimer's disease

Despite the proven efficacy of acetylcholinesterase inhibitors in Alzheimer's disease, there is a need for new and more effective treatments. Galantamine is a novel treatment for Alzheimer's disease that inhibits acetylcholinesterase and modulates nicotinic receptors. In randomized, double-blind, placebo-controlled studies of up to 6 months duration, galantamine significantly improved cognitive function. Galantamine also had beneficial effects on instrumental and basic activities of daily living, and postponed the progression of behavioral symptoms. Patients who completed one of the 6-month, placebo-controlled studies were eligible to enter a 6-month, open-extension study of the 24-mg/day dose of galantamine. At the end of 12 months, cognitive function and activities of daily living were preserved in those patients who had been treated throughout the study with galantamine 24 mg/day. At 12 months, this group of patients had significantly better cognitive functions than patients who had been treated with a placebo for 6 months before receiving galantamine. These studies indicate that galantamine postpones the progression of symptoms in Alzheimer's disease. Since galantamine shows the greatest benefits when treatment is started early, its long-term benefits may result from an effect on the underlying disease process; such an effect might be mediated by galantamine's concomitant action on nicotinic receptors.