Testosterone influences spatial cognition in older men

Intramuscular testosterone treatment in elderly men: evidence of memory decline and altered brain function

CONTEXT

Recent clinical trials of im testosterone in eugonadal men suggest positive effects on verbal memory, but other studies find no effect.

OBJECTIVE

Our objective was to determine whether supraphysiological testosterone influences verbal memory and brain function during a verbal memory task in healthy eugonadal older men.

PATIENTS, DESIGN, AND SETTING

Fifteen cognitively normal men, aged 66-86 yr, participated in a randomized, double-blind, placebo-controlled crossover trial involving 9 months of participation per participant at a hospital-based research facility.

INTERVENTION

We used testosterone enanthate (200 mg im every other week for 90 d) crossed over with placebo (sesame oil vehicle im) with a 90-d washout between treatments.

MAIN OUTCOME MEASURES

Performance was assessed on a standardized verbal memory test, and brain activity (relative glucose metabolic rates) in medial temporal and frontal regions was measured with positron emission tomography during a verbal memory task.

RESULTS

Treatment increased total testosterone by 241%. Behavioral results showed a significant decrease in short-delay verbal memory with treatment (P < 0.05, effect size = 0.59 sd) and a nonsignificant decrease on a composite verbal memory measure (P = 0.09, effect size = 0.48 sd). Positron emission tomography scans revealed decreased relative activity in ventromedial temporal cortex (i.e. right amygdala/entorhinal cortex) and increased relative activity in bilateral prefrontal cortex with treatment.

CONCLUSIONS

Decreased verbal memory and altered relative activity in medial temporal and prefrontal regions suggest possible detrimental effects of supraphysiological testosterone supplementation in elderly men. The results do not rule out potential benefits with other regimens, cognitive tests, or populations.

The sex specificity of navigational strategies in Alzheimer disease

Alzheimer disease (AD) is associated with navigational impairments that limit functional independence. We have now examined the role of cognitive and perceptual mechanisms in the navigational impairment of AD to test the hypothesis that men and women with AD may focus on different navigational cues. We conducted navigational, neuropsychologic, and psychophysical testing in men and women from 3 groups: older normal controls, patients with mild cognitive impairment, and patients with AD. Men and women showed parallel declines in navigational capacities from the older normal control, to the mild cognitive impairment, to the AD groups with men and women making similar numbers of errors but different types of errors. There were small sex differences in neuropsychologic and psychophysical performance but large sex differences in how those measures related to navigational capacity: men showed strong links between visual motion processing and navigation. Women showed strong links between verbal capacities and navigation. The findings of these cross-sectional comparisons suggest that there may be sex differences in the progressive navigational decline of AD: men and women who are impaired to the same degree may suffer somewhat different patterns of decline with men relying more on visuospatial processing and women relying more on verbal mediation.

Testosterone therapy in the aging male

The decline, with aging, in serum concentrations of biologically active forms of testosterone in men is an indisputable fact and some men will eventually develop symptoms of late-onset hypogonadism (LOH) with its clinical consequences. LOH reduces quality of life and may pose important risk factors for frailty, changes in body composition, cardiovascular disease, sexual dysfunction and osteoporosis. Testosterone supplementation in cases of LOH will restore serum testosterone levels into the physiologic range; will restore metabolic parameters to the eugonadal state, increase muscle mass, strength, and function; maintaine or improve BMD reducing fracture risk; will improve neuropsychological function (cognition and mood); libido and sexual functioning; and enhance quality of life. The ultimate goals, however, are to maintain or regain a high quality of life, to reduce disability, to compress major illnesses into a narrow age range and to add life to years. To achieve these goals men must also adjust their lifestyle to optimize dietary habits, as well as to exercise and to abstain from smoking life-long. Monitoring these patients is a shared responsibility that cannot be taken lightly. The physician must emphasize to the patient the need for periodic evaluations and the patient must agree to comply with these requirements. The physician's evaluation should include an assessment of the clinical response and monitoring must be tailored to the indications and individual needs of the patient.

Activation of the androgen receptor alters the intracellular calcium response to glutamate in primary hippocampal neurons and modulates sarco/endoplasmic reticulum calcium ATPase 2 transcription

Androgens have been shown to have a number of effects on hippocampal function. Although androgen receptors (AR) are found at high levels in hippocampal neurons, the intracellular mechanisms responsible for androgen's actions are unknown. If androgens were capable of altering internal calcium concentration ([Ca(2+)](i)), they could influence a variety of intracellular signaling pathways, maintain neuronal homeostasis and Ca(2+) induced excitotoxicity. In the present study, calcium imaging was used to measure the [Ca(2+)](i) in rat primary hippocampal neurons treated with either the AR agonist dihydrotestosterone (DHT), DHT+flutamide (AR antagonist), flutamide alone, or vehicle for 24 h and subsequently presented with an excitatory glutamate stimulus. In the absence of glutamate stimulation, DHT treatment caused a significant upward shift in baseline [Ca(2+)](i) when compared with neurons from all other groups. Glutamate had a greater effect on [Ca(2+)](i) in DHT-treated neurons and DHT-treated neurons returned to baseline levels significantly faster than all other groups. Cyclopiazonic acid, an inhibitor of sarco/endoplasmic reticulum calcium ATPase (SERCA) had a larger response in DHT-treated neurons compared with controls, suggesting increased Ca(2+) stores in DHT-treated neurons. In all cases the effects of DHT were blocked by treatment with flutamide indicating an AR-mediated mechanism. To determine a possible mechanism by which AR activation could be influencing [Ca(2+)](i), SERCA2 mRNA levels were measured in primary hippocampal neurons. SERCA2 is inserted into the endoplasmic reticulum (ER) membrane and functions to rapidly pump [Ca(2+)](i) into the ER. Following treatment of primary hippocampal neurons with DHT, SERCA2 mRNA was increased, an effect that was blocked in the presence of flutamide. Taken together these results indicate that DHT, working through AR, causes an up-regulation of SERCA2, which increases the sequestering of [Ca(2+)](i) in the endoplasmic reticulum of hippocampal neurons. Such changes may allow the neurons to respond more robustly to a stimulus and recover more quickly following a highly stimulatory challenge.

Effects of sex and APOE epsilon4 on object recognition and spatial navigation in the elderly

To determine effects of APOE epsilon4 (epsilon4) on cognitive performance of healthy elderly, 116 nondemented elders (mean age 81 years) were cognitive tested. The established tests Faces, Family Pictures, Spatial Span Forward and Backward, and the object recognition and spatial navigation tests developed in our laboratory were used as cognitive tests. Salivary samples were collected to determine APOE genotype and salivary testosterone and cortisol levels. Non-epsilon4- and epsilon4-carrying men and women did not differ in age, Mini-Mental State Examination, Wide Range Achievement Test-Reading, Beck Anxiety Inventory, or reaction time scores. There was an effect of epsilon4 on the object recognition and spatial navigation tests, with non-epsilon4 carriers outperforming epsilon4 carriers, but not in the other cognitive tests. No relationship was found for sex and epsilon4 status or sex and performance during the hidden session of Memory Island. In men, salivary cortisol levels correlated with object recognition. These results show that object recognition and spatial navigation tests are useful to assess cognitive function in the elderly.

Evidence for the influence of testosterone in the performance of spatial navigation in a virtual water maze in women but not in men

Testosterone (T) may be associated with enhanced spatial navigation in a number of rodent species, although the nature of the relation is equivocal. Similarly, numerous studies in humans generally have found that T is associated with enhanced spatial ability on a variety of paper and pencil tasks that may relate to navigational ability. However, relatively few studies have reported effects of T on navigational ability in humans. We investigated the relationship between endogenous T and performance on a virtual water maze (vWM) and mental rotations test (MROT). ELISA for T was performed on salivary samples that were obtained from participants before and after completion of both spatial tasks. Results indicated that women with low T required more time to locate the hidden platform in the vWM than either group of men or women with high T. Significant negative correlations were found for the entire sample between vWM performance and T, and between vWM latency to escape and MROT. Similar significant correlations were found in women but not men. Thus, our data support the position that T improves performance in the vWM in a linear fashion, most strongly in women. However, further work is needed to confirm this hypothesis in humans.

Gonadal steroids and visuo-spatial abilities in adult males: implications for generalized age-related cognitive decline

The relationship between the gonadal steroids, testosterone and estrogen, and individual and group differences in performance on some cognitive tasks remains unclear but sex differences favoring males on some tests of visuo-spatial ability are large and robust. This aim of this review is to assess evidence for both organizational and activational effects of gonadal steroids as the principle cause of sex difference in visuo-spatial ability. Additionally, the implications of this relationship are discussed in the context of decreasing levels of gonadal steroids in aging males and psychological theories of generalized age-related cognitive decline. Based upon human and non-human research gonadal steroids have organizational effects on visuo-spatial ability in adulthood. Activational effects of gonadal steroids on visuo-spatial ability appear most dominant in older men and are necessary for maintaining optimal visuo-spatial ability; randomized clinical trials show that testosterone supplementation improves performance. Additionally, decreasing gonadal steroid levels in aging males may contribute to generalized age-related cognitive decline. Future supplementation studies in men should attempt to control for constituent abilities related to visuo-spatial task performance, and investigate interactions between dosage levels and baseline gonadal status. Further future animal research is required to investigate changes in gonadal steroid levels and their relationship to neurotransmitter systems, neural plasticity, and behavioral correlates.

Testosterone and cognitive function in ageing men: data from the Florey Adelaide Male Ageing Study (FAMAS)

OBJECTIVES

Recent evidence suggests that declining testosterone levels in ageing males may be associated with both normal and pathological cognitive ageing. The aim of the present analyses was to investigate whether endogenous gonadal steroid levels in males mediate or moderate the associations between age and performance on neuropsychological measures of verbal memory, executive function, and processing speed.

METHODS

A cross-sectional analysis of the baseline data from 1046 community-dwelling men aged 35-80 years participating in the Florey Adelaide Male Ageing Study (FAMAS). Multiply adjusted analyses included participants' history of medical conditions, anthropometric measurements, medication use, smoking status, alcohol use and mood. Hormone measurements included total testosterone (TT), bioavailable testosterone (BT), calculated free testosterone (cEFT), oestradiol (E2), sex hormone binding globulin (SHBG), follicle stimulating hormone (FSH), and lutenising hormone (LH). Neuropsychological tests included the Fuld Object Memory Evaluation (FOME), Trails A and Trails B.

RESULTS

In multiply adjusted analyses, higher cEFT and TT levels were associated with both poorer verbal memory and executive function performance and faster processing speed. cEFT levels were found to moderate the relationship between age and verbal memory performance quadratically and to mediate the relationship between age and processing speed.

CONCLUSION

The results from this study suggest that higher levels of endogenous testosterone, particularly in the elderly, may have deleterious effects on cognitive functioning in men.

Androgens’ performance-enhancing effects in the inhibitory avoidance and water maze tasks may involve actions at intracellular androgen receptors in the dorsal hippocampus

Androgens can have performance-enhancing effects in some cognitive tasks, but the mechanism of these effects has not been established. Experiments examined whether androgens' actions to bind to intracellular androgen receptors (ARs) in the hippocampus are necessary to enhance cognitive performance in the inhibitory avoidance and water maze tasks. If androgens' binding at ARs are essential, then blocking them through intrahippocampal administration of flutamide, an AR receptor antagonist, should attenuate androgens' performance-enhancing effects in the inhibitory avoidance and water maze tasks. In Experiments 1 and 2, flutamide was administered through intrahippocampal inserts to intact male rats immediately pre- and post-training in the inhibitory avoidance and water maze tasks. Both pre- and post-training administration of flutamide to the dorsal hippocampus, but not missed sites, produced significantly poorer performance in the inhibitory avoidance and water maze tasks, without influencing control measures such as flinch/jump threshold or swim speed. In Experiment 3, flutamide administration to the hippocampus was delayed two hours following training in the inhibitory avoidance and water maze tasks. There was no significant effect of delayed administration of flutamide on performance in either of these tasks. Together, these findings suggest that blocking ARs in the dorsal hippocampus with flutamide administration immediately pre- or post-training can produce decrements in cognitive performance, which implies that androgens' performance-enhancing effects may occur, in part, through binding at intracellular androgen receptors in the dorsal hippocampus.

Maternal effects and the evolution of brain size in birds: overlooked developmental constraints

A central dogma for the evolution of brain size posits that the maintenance of large brains incurs developmental costs, because they need prolonged periods to grow during the early ontogeny. Such constraints are supported by the interspecific relationship between ontological differences and relative brain size in birds and mammals. Given that mothers can strongly influence the development of the offspring via maternal effects that potentially involve substances essential for growing brains, we argue that such effects may represent an important but overlooked component of developmental constraints on brain size. To demonstrate the importance of maternal effect on the evolution of brains, we investigated the interspecific relationship between relative brain size and maternal effects, as reflected by yolk testosterone, carotenoids, and vitamins A and E in a phylogenetic study of birds. Females of species with relatively large brains invested more in eggs in terms of testosterone and vitamin E than females of species with small brains. The effects of carotenoid and vitamin A levels on the evolution of relative brain size were weaker and non-significant. The association between relative brain size and yolk testosterone was curvilinear, suggesting that very high testosterone levels can be suppressive. However, at least in moderate physiological ranges, the positive relationship between components of maternal effects and relative brain size may imply one aspect of developmental costs of large brains. The relationship between vitamin E and relative brain size was weakened when we controlled for developmental mode, and thus the effect of this antioxidant may be indirect. Testosterone-enhanced neurogenesis and vitamin E-mediated defence against oxidative stress may have key functions when the brain of the embryo develops, with evolutionary consequences for relative brain size.

Androgens' effects to enhance learning may be mediated in part through actions at estrogen receptor-beta in the hippocampus

Testosterone (T) may enhance cognitive performance. However, its mechanisms are not well understood. First, we hypothesized that if T's effects are mediated in part through actions of its 5alpha-reduced metabolites, dihydrotestosterone (DHT) and/or 3alpha-androstanediol (3alpha-diol) in the hippocampus, then T, DHT, and 3alpha-diol-administration directly to the hippocampus should enhance learning and memory in the inhibitory avoidance task. In order to test this hypothesis, gonadectomized (GDX) male rats were administered T, DHT, or 3alpha-diol via intrahippocampal inserts immediately following training in the inhibitory avoidance task. We found that T tended to increase, and DHT and 3alpha-diol significantly increased, performance in the inhibitory avoidance task compared to vehicle-administered GDX rats. Second, we hypothesized that, if androgens' effects are due in part to actions of 3alpha-diol in the hippocampus, then systemic or intrahippocampal administration of 3alpha-diol should significantly enhance cognitive performance of GDX male rats. Third, we hypothesized that, if androgen metabolites can have actions at estrogen receptors (ERs) in the hippocampus, then administration of ER antisense oligonucleotides (AS-ODNs) directly to the hippocampus of GDX, 3alpha-diol replaced, rats would decrease learning in the inhibitory avoidance task. We found that intrahippocampal administration of AS-ODNs for ERbeta, but not ERalpha, significantly decreased learning and memory of 3alpha-diol replaced rats. Together, these findings suggest that T's effects to enhance learning and memory may take place, in part, through actions of its metabolite, 3alpha-diol, at ERbeta in the dorsal hippocampus.

Characterization of verbal and spatial memory changes from moderate to supraphysiological increases in serum testosterone in healthy older men

BACKGROUND

It has been suggested that cognitive changes in response to T supplementation may occur within an ideal range. The objective of this study was to compare the cognitive responses of older, eugonadal men in whom moderate or large increases in serum testosterone levels was induced by exogenous testosterone supplementation.

DESIGN

Randomized, double-blind, placebo-controlled study with subsequent grouping of participants according to average increase in circulating T from baseline.

SETTING

Community dwelling participants.

PARTICIPANTS

Fifty-seven healthy, eugonadal, community dwelling male volunteers, mean age 67 years (+/-11 years).

INTERVENTIONS

Participants were randomized to receive weekly intramuscular (i.m.) injections of either 50, 100 or 300 mg T enanthate or placebo (saline) injection for 6 weeks. Cognitive evaluations using a battery of neuropsychological tests were conducted at baseline, weeks 3 and 6 of treatment and after 6 weeks of wash-out.

MAIN OUTCOME MEASURES

Performance on cognitive tests of verbal and spatial memory.

RESULTS

Men with moderate increases in serum T and/or its metabolites demonstrated significant improvements in verbal and spatial memory. In contrast, men with large or low increases in circulating T levels, failed to demonstrate significant changes in memory.

CONCLUSION

These results suggest that in healthy older men, beneficial changes in cognitive function induced by T supplementation are most evident with moderate changes in cognition from moderate to high T supplementation increases in T levels. Large or no to low increases in T levels do not appear to appreciably effect cognition.

Anastrozole improved testosterone-induced impairment acquisition of spatial learning and memory in the hippocampal CA1 region in adult male rats

Neurohormones like testosterone and estrogen have an important role in learning and memory. Many biological effects of androgens in the brain require the local conversion of these steroids to an estrogen. The current research has conducted to assess the effect of testosterone, estrogen and aromatase inhibitor (anastrozole) on spatial discrimination of rats, using Morris water maze and also the pathway of the effect of testosterone by using anastrozole. Adult male rats were bilaterally cannulated into CA1 region of hippocampus and divided into 15 groups. Different groups received DMSO 0.5 microl and DMSO 0.5 microl + DMSO 0.5 microl as control groups and different doses of testosterone enanthate (TE) (20, 40 and 80 microg/0.5 microl), estradiol valerat (EV) (1, 2.5, 5, 10, and 15 microg/0.5 microl), anastrozole (An) (0.25, 0.5, 1 microg/0.5 microl), TE 80 microg/0.5 microl + anastrozole 0.5 microg/0.5 microl and EV 15 microg/0.5 microl + anastrozole 0.5 microg/0.5 microl all days before training. TE and EV were injected 30-35 min before training and anastrozole was injected 25-30 min before training. Our results have shown both TE 80 microg/0.5 microl and EV 15 microg/0.5 microl groups increase in escape latency and traveled distance to find invisible platform. Also we have shown that anastrozole dose dependently decreases escape latency and traveled distance. We resulted that both TE and EN impaired acquisition of spatial learning and memory but anastrozole improved it. Anastrozole also could be buffered TE-induced impairment effect but not EV.

Testosterone and the brain

Gender differences in spatial recognition, and age-related declines in cognition and mood, point towards testosterone as an important modulator of cerebral functions. Testosterone appears to activate a distributed cortical network, the ventral processing stream, during spatial cognition tasks, and addition of testosterone improves spatial cognition in younger and older hypogonadal men. In addition, reduced testosterone is associated with depressive disorders. The relationship between depression and testosterone appears to partly depend upon the androgen receptor genotype of the patient, and in appropriate patients with low testosterone levels, testosterone substitution can increase positive mood and decrease negative mood. The much publicized link between testosterone and aggression is probably only of importance in athletes who supplement their testosterone levels to excessively high levels, whereas in hypogonadal men, testosterone supplementation only enhances the positive aspects of aggression such as vigour and energy. Current data suggest that testosterone supplementation in hypogonadal men of all ages will enhance many aspects of mood and cognition.

Testosterone and cognitive function: current clinical evidence of a relationship

BACKGROUND

Testosterone levels decline as men age, as does cognitive function. Whether there is more than a temporal relationship between testosterone and cognitive function is unclear. Chemical castration studies in men with prostate cancer suggest that low serum testosterone may be associated with cognitive dysfunction. Low testosterone levels have also been observed in patients with Alzheimer's disease (AD) and mild cognitive impairment (MCI). This paper reviews the current clinical evidence of the relationship between serum testosterone levels and cognitive function in older men.

METHODS

A systematic literature search was conducted using PubMed and EMBASE to identify clinical studies and relevant reviews that evaluated cognitive function and endogenous testosterone levels or the effects of testosterone substitution in older men.

RESULTS

Low levels of endogenous testosterone in healthy older men may be associated with poor performance on at least some cognitive tests. The results of randomized, placebo-controlled studies have been mixed, but generally indicate that testosterone substitution may have moderate positive effects on selective cognitive domains (e.g. spatial ability) in older men with and without hypogonadism. Similar results have been found in studies in patients with existing AD or MCI.

CONCLUSIONS

Low endogenous levels of testosterone may be related to reduced cognitive ability, and testosterone substitution may improve some aspects of cognitive ability. Measurement of serum testosterone should be considered in older men with cognitive dysfunction. For men with both cognitive impairment and low testosterone, testosterone substitution may be considered. Large, long-term studies evaluating the effects of testosterone substitution on cognitive function in older men are warranted.

Endogenous sex hormone levels and risk of cognitive decline in an older biracial cohort

BACKGROUND

Older women treated with conjugated estrogens may have an increased risk of dementia, but the effect of naturally occurring sex hormones on cognition is not certain.

METHODS

Bioavailable estradiol and free testosterone level were obtained from 792 (55% men, 51% black) participants. We assessed cognition with the Modified Mini-Mental State Examination (3MS), Selective Reminding Test (SRT) and CLOX 1 at baseline and 2 years later.

RESULTS

Women in the lowest estradiol tertile were more likely than those in the highest tertile to decline (> or = 1.0 S.D. of change) on 3MS (25% versus 9%, adjusted odds ratio [OR] = 3.9; 95% confidence interval [CI] = 1.6-9.6) and on SRT (28% versus 12%, adjusted OR [95% CI] = 3.3 [1.4-7.9]) but not CLOX 1. There was a borderline association between low estradiol tertile and decline on SRT in men (22% versus 14%, adjusted OR [95% CI] = 1.9 [0.9-3.9]). Testosterone level was not associated with decline in cognition in either men or women. Findings did not differ by race.

CONCLUSIONS

Older women with low estradiol levels were more likely to experience decline in global cognitive function and verbal memory, and a similar trend was observed for verbal memory in men. This supports the hypothesis that endogenous sex hormones may play an important role in the maintenance of cognitive function in older adults.

Reproductive hormones modulate oxidative stress in Alzheimer's disease

Alzheimer's disease (AD) is a neurodegenerative disease characterized by gradual cognitive decline, impairments in speech and language, and dysfunction in the sensorimotor systems, culminating in complete reliance on nursing care. Oxidative stress, caused by an imbalance in the pro-oxidant/antioxidant mechanisms in the body, has been implicated in AD pathogenesis, as in many other age-associated diseases such as atherosclerosis, Parkinson disease, and amyotrophic lateral sclerosis. Although the hormones estrogen, progesterone, testosterone, and luteinizing hormone are best known for their roles in reproduction, many studies show these hormones have other roles, including neuroprotection. Changes in the levels of these hormones that occur in reproductive senescence are hypothesized to increase risk of AD, as a result of reduced protection against oxidative insults. The Abeta peptide, overproduction of which is thought to be a key pathogenic event in the development of AD, is neurotoxic, most likely due to its ability to promote oxidative stress. The reproductive hormones are known to influence Abeta metabolism, and this review discusses the beneficial and detrimental effects these hormones have on Abeta production and oxidative stress, and their relevance in potential AD therapies.

Treatment of androgen deficiency in the aging male

Although guidelines for androgen replacement therapy for older men have been developed by several groups, the data to support treatment are based on the results of only a small number of clinical trials. It has not been definitively established that the decline in testosterone seen in most aging men results in an androgen deficient state with health-related outcomes that can be improved by androgen therapy.

Age or factors associated with aging attenuate testosterone's concentration-dependent enhancement of the regularity of luteinizing hormone secretion in healthy men

BACKGROUND

Healthy older men have reduced testosterone (Te) production and frequent, small irregular LH pulses. Which is cause and which is effect are not known.

RATIONALE

In model systems, frequent and irregular LH pulses reflect attenuated feedback inhibition by Te.

HYPOTHESIS

Factors associated with aging impair negative feedback by Te.

SUBJECTS AND SETTING

Healthy men at an academic medical center were studied.

METHODS

The study used quantification of the regularity of LH release patterns during blockade of gonadal steroidogenesis and graded transdermal Te addback in 18 healthy men aged 18-65 yr.

RESULTS

In the cohort as a whole, stepwise Te repletion repressed LH concentrations (P = 0.001) and enhanced the quantifiable orderliness of LH release patterns (P < 0.001). By regression analysis, age attenuated the capability of increasing Te concentrations to regularize LH secretion patterns (P = 0.019). However, after a fixed GnRH stimulus, the effect of Te on LH regularity was invariant of the age factor (P = 0.16), thus pointing to a hypothalamic locus of impaired Te feedback.

SUMMARY

Aging disrupts the capability of systemic Te concentrations to maintain orderly LH secretion under endogenous, but not exogenous, GnRH drive.

CONCLUSIONS

Age or factors associated with increased age reduce negative feedback by any given total Te concentration on hypothalamopituitary GnRH-LH outflow, thus contributing to disorderly LH secretion.

Testosterone modulates performance on a spatial working memory task in male rats

Gonadal hormones have been shown to modulate memory retention in female rats. The current experiments examine the role of testicular hormones in modulating the performance of male rats on two spatial water maze tasks. In the first study, castrated and intact rats were trained on the visible platform and hidden platform versions of the Morris water maze task. Castration did not affect performance on either version of this reference memory task with castrated and intact rats demonstrating similar performance both during acquisition and on post-training probe trials. In the second experiment, castrated and intact rats were tested on a delayed-matching-to-place version of the water maze. Rats received a series of trial pairs in the maze with a hidden platform located in the same pool location on the exposure and retention trials of each pair; between pairs of trials, however, the platform was repositioned to a novel pool location. The interval between trials was either 10- or 60-min and memory retention, taken as the difference between the pathlengths on the exposure and retention trials, declined as the interval increased. Relative to intact males, castrated males demonstrated impaired working memory retention at 60-min but not at 10-min retention intervals. This interval-dependent impairment in working memory retention was reversed by physiologic levels of testosterone replacement. These findings indicate that castration does not significantly affect acquisition or probe trial performance on a classic reference memory task but does impair spatial working memory retention, an effect that is reversed by exogenous testosterone.

Androgen deprivation impairs memory in older men

Androgen deprivation leads to a profound loss of synaptic density in the hippocampus and changes in learning and memory in animal models. The authors examined group differences in verbal memory between men on androgen deprivation therapy (ADT), a commonly used treatment for prostate cancer, and healthy men. The authors found that men on ADT have a specific impairment of retention but normal encoding and retrieval processes on a word list-learning task. Speed and accuracy for both perceptual and semantic encoding, as well as retrieval at a very short retention interval, were not affected; however, recognition fell to chance after a 2-min retention interval in men on ADT. Healthy men showed only moderate forgetting, and performance was still above chance at 12 min. This pattern of preserved encoding and retrieval but impaired retention suggests that androgens play a role in hippocampally mediated memory processes, possibly having a specific affect on consolidation.

Gonadotropins: potential targets for preventive and therapeutic interventions in Alzheimer’s disease

Increased prevalence of Alzheimer’s disease (AD) in women has led to an interest in the role of hormonal changes in the neurodegenerative process. In particular, research has been directed towards investigating the effect of changes in sex hormone levels following reproductive senescence. Clinical trials of hormone-replacement therapy for the prevention of AD are proving contentious, and considerably more research is necessary before the benefit of the hormone replacement strategy can be ascertained. However, evidence is now emerging to support the notion that increased gonadotropin levels may confer an increased risk of AD. Gonadotropins have been implicated in the metabolism of β-amyloid, a key protein that is central to the pathogenesis of AD. Gonadotropin reduction represents a promising new target for therapeutic intervention in AD and, potentially, dementia in general. In this review, the authors discuss the therapeutic and preventive potential of gonadotropin-reducing agents in the management of AD.

Comparison of screening questionnaires for the diagnosis of hypogonadism

Three questionnaires, the St. Louis University Androgen Deficiency in Aging Male (ADAM), the Aging Male Survey (AMS) and the Massachusetts Male Aging Study (MMAS), have been developed as potential screening tools for hypogonadism in older males. We compared these questionnaires in 148 males aged 23-80 years using bioavailable testosterone as the "biochemical gold standard" for diagnosis of hypogonadism. The sensitivity for the ADAM was 97%, for the AMS 83% and the MMAS 60%. Specificity was 30% for the ADAM, 59% for the MMAS and 39% for AMS. Both bioavailable testosterone and the calculated free testosterone correlated significantly with a number of the individual questions. Total testosterone correlated poorly with most of the questions. In conclusion, the ADAM and AMS may be useful screening tools for hypogonadism across the adult lifespan, but both are relatively nonspecific.

Age-dependent measures of anxiety and cognition in male histidine decarboxylase knockout (Hdc−/−) mice

Histidine decarboxylase deficient (Hdc(-/-)) and wild-type male mice on the C57Bl6/J background were used to determine the role of histamine in brain function. 3-5 (Y) and 12-14 (MA) month-old Hdc(-/-) mice showed hypoactivity and increased measures of anxiety in the open field, light-dark, elevated plus-maze, and elevated zero maze tests. Y Hdc(-/-) mice showed superior performance in the hidden sessions of the water maze and passive avoidance memory retention. In contrast, Y Hdc(-/-) mice were impaired in novel location recognition, spent less time searching in the target quadrant and more time searching in the outer zone of the water maze during the probe trials. These behaviors are likely due to increased measures of anxiety and are not found in MA Hdc(-/-) mice. These data support a role for histamine in anxiety and cognition and underline the importance of considering age and potential effects on measures of anxiety in the interpretation of the role of histaminergic neurotransmission in cognitive function.

Testosterone improves spatial memory in men with Alzheimer disease and mild cognitive impairment

OBJECTIVE

To determine the efficacy of testosterone (T) supplementation on cognition in a sample of men with Alzheimer disease (AD) or mild cognitive impairment (MCI).

METHODS

Fifteen patients with AD and 17 patients with MCI aged 63 to 85 years completed a randomized, double-blind, placebo-controlled study. Nineteen participants received weekly intramuscular (IM) injections of 100 mg T enanthate and 13 participants received weekly injections of placebo (saline) for 6 weeks. Cognitive evaluations using a battery of neuropsychological tests were conducted at baseline, week 3, and week 6 of treatment and again after 6 weeks of washout.

RESULTS

Peak serum total T levels were raised from baseline an average of 295% in the active treatment group. Improvements in spatial memory (p < 0.05) and constructional abilities (p < 0.05) and verbal memory were evident in the T group. No changes were noted for selective and divided attention or language. Prostate specific antigen did not significantly change during this brief treatment.

CONCLUSION

Testosterone supplementation may benefit selective cognitive functions in men with Alzheimer disease and mild cognitive impairment.

Normative hypogonadism and depression: does ‘andropause’ exist?

The progressive decline in testosterone level has been demonstrated in both cross-sectional and longitudinal studies, and overall at least 25% of men over the age of 70 years meet laboratory criteria for hypogonadism (i.e., testosterone deficiency). Such age-associated HPG hypofunctioning, which has been termed 'andropause', is thought to be responsible for a variety of symptoms experienced by elderly men, including sexual dysfunction and depression. Although, it has been difficult to establish correlations between 'andropausal' symptoms and plasma testosterone levels, there is some evidence that testosterone replacement leads to improvement in muscle strength, bone mineral density, and erectile dysfunction. There is little evidence of a link between HPG-axis dysfunction and depressive illness, and exogenous androgens have not been consistently shown to be antidepressant. This article reviews the relationship between androgens and depression in aging men.

Negative Association of Testosterone on Spatial Visualization in 35 to 80 Year Old Men

Androgens have been linked to visuospatial ability. We examined the relationship between serum free testosterone (T) levels and spatial visualization ability in a population-based sample of 450 healthy men between the ages of 35 and 80 years. They were tested on block design and Mini Mental State Examination (MMSE) draw-a-figure, as well as tasks assessing episodic memory, semantic memory, procedural memory, and verbal fluency. Blood was analyzed for free T and estradiol. Participants were grouped into high or low free T based on age-specific median values. Participants with low free T performed at a superior level on both the block design task and draw-a-figure task as compared to participants with high free T. The results are discussed within the scant body of research on androgens and cognition in men.

Anti-epileptic drug phenytoin enhances androgen metabolism and androgen receptor expression in murine hippocampus

Epilepsy is very often related to strong impairment of neuronal networks, particularly in the hippocampus. Previous studies of brain tissue have demonstrated that long-term administration of the anti-epileptic drug (AED) phenytoin leads to enhanced metabolism of testosterone mediated by cytochrome P450 (CYP) isoforms. Thus, we speculate that AEDs affect androgen signalling in the hippocampus. In the present study, we investigated how the AED phenytoin influences the levels of testosterone, 17beta-oestradiol, and androgen receptor (AR) in the hippocampus of male C57Bl/6J mice. Phenytoin administration led to a 61.24% decreased hippocampal testosterone level as compared with controls, while serum levels were slightly enhanced. 17beta-Oestradiol serum level was elevated 2.6-fold. Concomitantly, the testosterone metabolizing CYP isoforms CYP3A11 and CYP19 (aromatase) have been found to be induced 2.4- and 4.2-fold, respectively. CYP3A-mediated depletion of testosterone-forming 2beta-, and 6beta-hydroxytestosterone was significantly enhanced. Additionally, AR expression was increased 2-fold (mRNA) and 1.8-fold (protein), predominantly in the CA1 region. AR was shown to concentrate in nuclei of CA1 pyramidal neurons. We conclude that phenytoin affects testosterone metabolism via induction of CYP isoforms. The increased metabolism of testosterone leading to augmented androgen metabolite formation most likely led to enhanced expression of CYP19 and AR in hippocampus. Phenytoin obviously modulates the androgen signalling in the hippocampus.

Men, women, and ghosts in science

Science suffers because, by favouring the self-confident of both sexes, we discriminate against women.

Aging attenuates both the regularity and joint synchrony of LH and testosterone secretion in normal men: analyses via a model of graded GnRH receptor blockade

Testosterone (T) secretion declines in the aging male, albeit for unknown reasons. From an ensemble perspective, repeated incremental signaling among gonadotropin-releasing hormone (GnRH), luteinizing hormone (LH), and T is required to maintain physiological androgen availability. Pattern-regularity statistics, such as univariate approximate entropy (ApEn) and bivariate cross-ApEn, provide specific and sensitive model-free measurement of altered multi-pathway control. The present study exploits partial muting of one pathway (GnRH drive) to appraise adaptive regulation of LH and T secretion in young and aging individuals. Analyses comprised 100 paired 18-h LH and T concentration time series obtained in 25 healthy men ages 20-72 yr each administered placebo and three graded doses of a specific GnRH-receptor antagonist. Graded blockade of GnRH drive increased the individual regularity of LH and T secretion and the synchrony of LH-T feedforward and T-LH feedback in the cohort as a whole (P<0.001 for each). However, age markedly attenuated ganirelix-induced enhancement of univariate T orderliness and bivariate LH-T feedback and T-LH feedback synchrony (P <or= 0.0025). In summary, the present analyses support the thesis that aging disrupts coordinate control of T secretion, LH-T feedforward, and T-LH feedback in healthy men. Thus the experimental strategy of stepwise silencing of an agonistic pathway may have utility in dissecting the bases of altered neurohormonal linkages in other systems.

Hormone replacement therapy and cognitive function in postmenopausal women

OBJECTIVES

The study investigated the effect of hormone replacement therapy (HRT) on cognitive processes in healthy, naturally postmenopausal women.

METHOD

Participants were 64 volunteer postmenopausal women (27 in HRT, 37 in non-HRT group). Groups were matched for age, level of education and postmenopausal period. Duration of HRT was more than 12 months. Cognitive processes were measured through 44 scores obtained from Wechsler Memory Scale-Revised, Line Orientation Test, Cancellation Test and Raven Standard Progressive Matrices. All of these tests had been studied with respect to their psychometric properties in the Turkish culture [for review, Karakaş S. BILNOT battery: research and development of neuropsychological tests. Ankara, Turkey: Dizayn Ofset; 2004].

RESULTS

Multivariate analysis of variance was performed where HRT and estradiol level were predictive (independent) variables and test scores were predicted (dependent) variables. The studied variables did not have a significant effect on a broad spectrum of neuropsychological scores that measured immediate and delayed visual and verbal memory, visuospatial perception and orientation, sustained attention/vigilance, visual search and scan, impulsivity and response speed, executive functions and general intelligence. Logistic regression analysis demonstrated a prediction rate of 86.89% of HRT status; the model was, however, based on four scores whose scientific relevance could not at this point be ascertained.

CONCLUSION

The research design of the present observational study applied control techniques to demographic (age, level of education), menopausal (length of menopausal period, duration of HRT), and hormonal variables. The cognitive changes that some studies found concerning the effect of replacement therapy could not be found when the potentially confounding variables were thus controlled.

Cross-sex hormone treatment does not change sex-sensitive cognitive performance in gender identity disorder patients

Cognitive performance in untreated early onset gender identity disorder (GID) patients might correspond to their born sex and not to their perceived gender. As a current mode of intervention, cross-sex hormone treatment causes considerable physical changes in GID patients. We asked, as has been suggested, whether this treatment skews cognitive performance towards that of the acquired sex. Somatically healthy male and female early onset GID patients were neuropsychologically tested before, 3 and 12 months after initiating cross-sex hormone treatment, whereas untreated healthy subjects without GID served as controls (C). Performance was assessed by testing six cognitive abilities (perception, arithmetic, rotation, visualization, logic, and verbalization), and controlled for age, education, born sex, endocrine differences and treatment by means of repeated measures analysis of variance. GID patients and controls showed an identical time-dependent improvement in cognitive performance. The slopes were essentially parallel for males and females. There was no significant three-way interaction of born sex by group by time for the six investigated cognitive abilities. Only education and age significantly influenced this improvement. Despite the substantial somatic cross-sex changes in GID patients, no differential effect on cognition over time was found between C and GID participants. The cognitive performance of cross-sex hormone-treated GID patients was virtually identical to that of the control group. The documented test-retest effect should be taken into consideration when evaluating treatment effects generally in psychiatry.

Complications of androgen-deprivation therapy in men with prostate cancer

Androgen-deprivation therapy (ADT) is indicated for the treatment of metastatic prostate cancer and locally advanced disease. In addition to sexual side effects, long-term ADT results in several other changes, including hot flashes; gynecomastia; changes in body composition, metabolism, and the cardiovascular system; osteoporosis; anemia; psychiatric and cognitive problems; and fatigue and diminished quality of life. This review discusses these complications of ADT and treatments aimed at reducing them. It is important for clinicians to anticipate these effects and to initiate measures to prevent or minimize them in order to maintain quality of life in prostate cancer survivors.

The role of androgens in cognition and brain aging in men

Losses of working and long-term memory are hallmarks of human aging and may signal impending neurodegenerative disease. The maintenance of neural elements in brain systems that support memory, such as synapse formation in prefrontal cortex and hippocampus, are critical for cognitive health in aging. This paper reviews the biological basis for androgens as neuroprotectants or neuromodulators in aging and the importance of androgens on the brain systems important for memory. We relate biological effects to cognitive outcomes in elderly men under a variety of androgen conditions. In brief, androgen deprivation causes significant loss of synapses in the hippocampus in rodent and nonhuman primates, increases amyloid deposition in human and rodent models and causes changes in neurotransmission in prefrontal cortex in rodent models. Recent work suggests that these changes modify age-related cognitive loss, particularly to memory in men. In addition, the conversion of testosterone to its androgen metabolites or to estradiol may play a special role in the preservation of memory in aging. This paper reviews discrepancies between studies using animal models and studies of human cognition, and suggests new directions that are likely to be fruitful in the future for understanding the role of androgens in brain aging. This review suggests that studies of low androgen levels in older men may not index the same biological mechanisms and behavioral effects as the studies of gonadectomy in animal models.

Androgen Deficiency in the Etiology and Treatment of Erectile Dysfunction

The evaluation and management of erectile dysfunction (ED) has evolved dramatically following the introduction of oral phosphodiesterase-5 inhibitors. Despite the limited role of directed diagnostic testing in the evaluation of the impotent patient, routine de-termination of a serum testosterone likely is indicated based on evidence that testosterone modulates erectile function, that hypogonadism is prevalent among elderly men and men with ED, and that symptomatology alone rarely detects hypogonadism. Forms of testosterone commonly used include oral, parenteral, transdermal, and implantable preparations, each with significant advantages and disadvantages. The risks and benefits of testosterone supplementation have been characterized incompletely and will require further validation before widespread use of testosterone as hormone replacement therapy in aging men.

Role of circulating androgen levels in effects of apoE4 on cognitive function

Compared with apoE2 and E3, apoE4 increases the risk of cognitive impairments and of developing Alzheimer's disease (AD). ApoE4 interacts with female sex, further increasing AD risk. Previously, we showed that female Apoe-/- mice are more susceptible to apoE4-induced cognitive deficits than male mice. Androgens protect against these deficits and apoE4 male mice are more sensitive to acute blockade of androgen receptors than apoE3 male mice. To determine the chronic effects of reduced circulating androgen levels on susceptibility to the effects of apoE4 on cognitive function in males, we castrated and sham-castrated apoE4, apoE3, and Apoe-/- male mice and behaviorally compared them 3 months later. Castration impaired novel location recognition in apoE4, but not apoE3 or Apoe-/-, mice. In contrast, castration impaired novel object recognition and spatial memory retention in the water maze in Apoe-/-, but not apoE3 or apoE4, mice. On the contrary, castrated, but not sham-castrated, apoE4 mice showed improved acquisition over the first two hidden platform sessions and spatial memory retention in the first probe trial. While apoE3 and Apoe-/- mice increased their exploratory times with the objects in the trial with the novel object, apoE4 mice did not. ApoE4 mice required more trials than apoE3 or Apoe-/- mice to reach criterion during passive avoidance training, but castration did not modulate passive avoidance learning or memory. Thus, androgens have differential roles in object recognition and spatial learning and memory in the water maze, depending on whether or not apoE4 is present.

The decline of androgen levels in elderly men and its clinical and therapeutic implications

Aging in men is accompanied by a progressive, but individually variable decline of serum testosterone production, more than 20% of healthy men over 60 yr of age presenting with serum levels below the range for young men. Albeit the clinical picture of aging in men is reminiscent of that of hypogonadism in young men and decreased testosterone production appears to play a role in part of these clinical changes in at least some elderly men, the clinical relevancy of the age-related decline in sex steroid levels in men has not been unequivocally established. In fact, minimal androgen requirements for elderly men remain poorly defined and are likely to vary between individuals. Consequently, borderline androgen deficiency cannot be reliably diagnosed in the elderly, and strict differentiation between "substitutive" and "pharmacological" androgen administration is not possible. To date, only a few hundred elderly men have received androgen therapy in the setting of a randomized, controlled study, and many of these men were not androgen deficient. Most consistent effects of treatment have been on body composition, but to date there is no evidence-based documentation of clinical benefits of androgen administration to elderly men with normal or moderately low serum testosterone in terms of diminished morbidity or of improved survival or quality of life. Until the long-term risk-benefit ratio for androgen administration to elderly is established in adequately powered trials of longer duration, androgen administration to elderly men should be reserved for the minority of elderly men who have both clear clinical symptoms of hypogonadism and frankly low serum testosterone levels.

Male hypogonadism. Part II: etiology, pathophysiology, and diagnosis

Male hypogonadism has a multifactorial etiology that includes genetic conditions, anatomic abnormalities, infection, tumor, and injury. Defects in the hypothalamic-pituitary-gonadal axis may also result from type II diabetes mellitus and treatment with a range of medications. Circulating testosterone levels have been associated with sexual function, cognitive function, and body composition. Apart from reduced levels of testosterone, clinical hallmarks of hypogonadism include absence or regression of secondary sex characteristics, reduced fertility (oligospermia, azoospermia), anemia, muscle wasting, reduced bone mass (and bone mineral density), and/or abdominal adiposity. Some patients, particularly those with partial androgen deficiency of the aging male, also experience sexual dysfunction, reduced sense of vitality, depressed mood, increased irritability, difficulty concentrating, and/or hot flushes in certain cases of acute onset. As many patients with male hypogonadism-like patients with erectile dysfunction-do not seek medical attention, it is important for clinicians to be acquainted with the signs and symptoms of hypogonadism, and to conduct appropriate laboratory testing and other assessments to determine the causes and inform the treatment of this condition.

Advances in male hormone substitution therapy

Increased awareness of the clinical diagnosis of male hypogonadism has resulted in the wider use of androgen substitution therapy. Clinical signs and symptoms together with a low serum testosterone level confirm the diagnosis of male hypogonadism. Androgen replacement results in improved sexual function, mood, muscle mass and bone density in most hypogonadal men. Such benefits must be assessed against potential risks. In older men, the potential risks of androgen treatment of hypogonadism are not known. Many delivery systems for androgen substitution are now available; the preparation chosen depends on the choice of the patient and his physician. Selective androgen receptor modulators offer tissue selective biological effects and the possibility of attaining maximum efficacy and minimum adverse effects.

Cognitive abilities, androgen levels, and body mass index in 5-year-old children

This study explores the potential relationship between a series of cognitive abilities and testosterone, dehydroepiandrosterone (DHEA), androstenedione, and body mass index (BMI) measurements in 5-year-old children. 60 boys and 69 girls were administered a test (K-BIT) which provided measurements of fluid intelligence (Matrices subtest), crystallized intelligence (Vocabulary subtest), and IQ composite (the combination of the two subtests); a sub-sample of 48 boys and 61 girls was also subjected to diverse tests related to theory of mind (affective labeling, appearance-reality distinction, display rules, and false belief). Testosterone, DHEA, and androstenedione levels were measured using an enzyme immunoassay technique in saliva samples. An analysis of variance failed to reveal any significant differences between boys and girls in any of the cognitive abilities assessed. The correlation analysis revealed a positive relationship between fluid intelligence and testosterone levels in boys, a negative relationship between crystallized intelligence and androstenedione levels in girls, and between affective labeling and androstenedione levels in boys. A multiple regression analysis indicated that androstenedione and BMI were the best predictors for some of the cognitive abilities assessed.

Age, hormones, and cognitive functioning among middle-aged and elderly men: cross-sectional evidence from the Massachusetts Male Aging Study

BACKGROUND

This study examines interrelationships among age, hormones, and cognition for middle-aged and elderly men, and tests whether hormones predict lower cognitive functioning and mediate the age-cognition relationship.

METHODS

We analyzed Time 2 data from the Massachusetts Male Aging Study, a population-based cohort study. Selection criteria included complete information on cognition and hormones (n = 981). Cognitive measures included working memory (Backward Digit Span test), speed/attention (Digit Symbol Substitution test), and spatial ability (Figural Relations test). Hormones included free testosterone, total testosterone, dehydroepiandrosterone (DHEA), dehydroepiandrosterone sulfate (DHEAS), androstanediol glucuronide (3 alpha-A-diol-gluc), luteinizing hormone (LH), follicle-stimulating hormone (FSH), sex hormone-binding globulin (alternatively known as a "binding protein") (SHBG), prolactin (PRL), estrone (E1), and cortisol (CRT). Age was measured in years. Adjusted analyses added educational attainment, health conditions and behaviors, body mass index, and depression.

RESULTS

Older age was associated with lower cognitive functioning. In unadjusted models, logged free and total testosterone, DHEA, and DHEAS related to higher functioning in at least one cognitive domain; logged FSH, SHBG, and LH related to lower functioning in at least one cognitive domain; and logged E1, CRT, and PRL were not significant. In adjusted models, logged hormones did not relate to cognitive function except for logged E1 and CRT, which had negative effects. Logged hormones did not mediate the age-cognition relationship.

CONCLUSIONS

The direct effects of hormones on cognition are not significant when salient factors are considered. Further, hormones do not mediate the age-cognition relationship; it is necessary to look to other explanatory pathways.

ISA, ISSAM and EAU recommendations for the investigation, treatment and monitoring of late-onset hypogonadism in males: scientific background and rationale

Prescription sales for testosterone products have substantially increased over the last several years reflecting the growing awareness of physicians for the potential benefits of testosterone replacement therapy in men with hypogonadism. Indiscriminate administration of testosterone poses a risk and has to be deprecated. Testosterone supplementation to treat late-onset hypogonadism (LOH), a term for androgen deficiency in elderly men, is still controversially discussed mainly due to a lack of large, controlled clinical trials on efficacy and safety. To provide guidance for physicians primarily dealing with aging men, ISSAM is periodically updating and publishing its recommendations as new data become available [Morales A, Lunenfeld B. International Society for the Study of the Aging Male. Investigation, treatment and monitoring of late-onset hypogonadism in males. Official recommendations of ISSAM. International Society for the Study of the Aging Male. Aging Male 2002;5:74-86 and Morales A, Lunenfeld B. Androgen replacement therapy in aging men with secondary hypogonadism. Draft recommendations for endorsement by ISSAM. Aging Male 2001;4:1]. Following a panel discussion at the 4th ISSAM Congress in Prague in February 2004, the International Society of Andrology (ISA), the International Society for the Study of the Aging Male (ISSAM) and the European Association of Urology (EAU) revised existing recommendations on the definition, diagnosis and management of LOH. The recommendations are based on the currently available scientific data on androgen supplementation therapy and should be regarded as provisional until larger-scale, long-term studies are available. While certainly not intending to be exhaustive, this review will highlight some relevant background information and provide the underlying scientific rationale for the ISA, ISSAM and EAU recommendations on LOH published in this issue.

Behavioral performance of tfm mice supports the beneficial role of androgen receptors in spatial learning and memory

In adulthood, androgens and androgen receptors might contribute to the sexually dimorphic performance in spatial learning and memory, but their roles seem complex. To study the potential role of androgen receptors in spatial learning and memory, we tested adult 6-8-month-old mutant mice with a naturally occurring defect in the androgen receptor gene (testicular feminization mutant or tfm) and C57Bl/6J wild-type mice. Because the trait is X-linked, only tfm males are completely androgen insensitive while female tfm mice are heterozygous, carrying one wild-type and one tfm copy of the androgen receptor. Here we show that female tfm carrier mice outperform tfm male mice in the water maze, while there are no gender differences in water maze performance in wild-type mice. In tfm mice, there were no gender differences in measures of anxiety in the open field or plus maze or sensorimotor function, indicating that potential differences in these measures did not contribute to the differences observed in the water maze. There were no differences in tfm and wild-type female and male mice in emotional learning and memory in the passive avoidance test. These findings support a beneficial role for androgen receptors in spatial learning and memory.

Associations between serum testosterone fall and cognitive function in prostate cancer patients

Data on the association between cognition and testosterone levels in elderly men are inconclusive. Androgen deprivation therapy is commonly used in the treatment of prostate cancer with the aim of achieving castration levels of serum testosterone. The study group comprised 26 elderly men (mean age 65 years) with newly diagnosed prostate cancer. Cognitive testing was done at baseline and at 6 and 12 months on androgen deprivation therapy. Cognitive performances were evaluated using verbal, visuomotor, and memory tests as well as tests of processing speed and attention. Castration levels of testosterone were achieved in all patients by 6 months. Significant associations between cognitive performances and testosterone decline were documented: visuomotor slowing, slowed reaction times in some attentional domains including working memory and impaired hit rate in a vigilance test, impaired delayed recall and recognition speed of letters, but improvement in object recall. The results suggest selective associations between testosterone decline and cognition. Documentation of cognitive performance with changes in serum testosterone levels has substantial implications for informed patient support in prostate cancer.

Estradiol and cognition during androgen deprivation in men with prostate carcinoma

BACKGROUND

The adverse effects of hormonal manipulation in prostate carcinoma need to be established in view of its increasing use as an adjuvant treatment. This prospective study investigated the association of androgen deprivation-induced estradiol decline with cognition in prostate carcinoma.

METHODS

Cognitive testing of prostate carcinoma patients was carried out at baseline and at 6 and 12 months on androgen deprivation (AD). Cognitive performances were evaluated with standardized measures of information processing, including working memory and attention, visual and verbal skills, and memory performances in 31 tests. Testosterone and estradiol changes during AD were measured with the DELFIA (PerkinElmer, Inc., Wellesley, MA) system. Associations between changes in cognitive performances and estradiol decline were studied.

RESULTS

Cognitive performances, which were significantly associated with decline in estradiol, included visual memory of figures (r = -0.52; P = 0.022) and recognition speed of numbers, which were impaired, (r = -0.57; P = 0.030) at 6 months, and improvement in verbal fluency (r = -0.52; P = 0.019) at 12 months. Other cognitive domains appeared unaffected by estradiol decline. The character of change (impairment or improvement) depended on the magnitude of estradiol decline.

CONCLUSIONS

The cognitive domains of verbal fluency, visual recognition, and visual memory were associated with decline in estradiol during androgen deprivation. The results suggest selective associations among testosterone decline, estradiol, and cognitive performance. Documentation of these associations has implications for informed patient support in hormonally treated prostate carcinoma.