Cortisol suppression by dexamethasone in the healthy elderly: effects of age, dexamethasone levels, and cognitive function

Dynamic Tests in Pituitary Endocrinology: Pitfalls in Interpretation during Aging

Aging and age-related diseases represent hot topics of current research. Progressive damage in morphology and function of cells and tissue characterizes the normal process of aging that is influenced by both genetic and environmental factors. The ability of each individual to adapt to these stressors defines the type of aging and the onset of age-related diseases (i.e., metabolic syndrome, inflammatory disorders, cancer, and neurodegenerative diseases). The endocrine system plays a critical role in this process because of its complex relationships with brain, immune system, and skeletal muscle; thus, alterations in hormonal networks occur during aging to maintain homeostasis, with consequent under- or overactivity of specific hypothalamic-pituitary-peripheral hormone axes. On the other hand, the increase in life expectancy has led to increasing incidence of age-related diseases, including endocrine disorders, which may prompt assessment of endocrine function in aging individuals. In this context, there is growing awareness that natural changes of endocrine physiology and physiopathology occurring with increasing age may necessitate age-driven diagnostic cutoffs requiring validation in the elderly. This review aims to analyze the available literature on the hormone response to the most important dynamic tests currently used in the clinical practice for the screening of anterior pituitary-related diseases to underline pitfalls in interpretation during aging.

The Age-Dependent Changes of the Human Adrenal Cortical Zones Are Not Congruent

BACKGROUND

While previous studies indicate that the zonae reticularis (ZR) and glomerulosa (ZG) diminish with aging, little is known about age-related transformations of the zona fasciculata (ZF).

OBJECTIVES

To investigate the morphological and functional changes of the adrenal cortex across adulthood, with emphasis on (i) the understudied ZF and (ii) sexual dimorphisms.

METHODS

We used immunohistochemistry to evaluate the expression of aldosterone synthase (CYP11B2), visinin-like protein 1 (VSNL1), 3β-hydroxysteroid dehydrogenase type II (HSD3B2), 11β-hydroxylase (CYP11B1), and cytochrome b5 type A (CYB5A) in adrenal glands from 60 adults (30 men), aged 18 to 86. Additionally, we employed mass spectrometry to quantify the morning serum concentrations of cortisol, 11-deoxycortisol (11dF), 17α-hydroxyprogesterone, 11-deoxycorticosterone, corticosterone, and androstenedione in 149 pairs of age- and body mass index-matched men and women, age 21 to 95 years.

RESULTS

The total cortical area was positively correlated with age (r = 0.34, P = 0.008). Both the total (VSNL1-positive) and functional ZG (CYP11B2-positive) areas declined with aging in men (r = -0.57 and -0.67, P < 0.01), but not in women. The CYB5A-positive area declined with age in both sexes (r = -0.76, P < 0.0001). In contrast, the estimated ZF area correlated positively with age in men (r = 0.59, P = 0.0006) and women (r = 0.49, P = 0.007), while CYP11B1-positive area remained unchanged across ages. Serum cortisol, corticosterone, and 11-deoxycorticosterone levels were stable across ages, while 11dF levels increased slightly with age (r = 0.16, P = 0.007).

CONCLUSION

Unlike the ZG and ZR, the ZF and the total adrenal cortex areas enlarge with aging. An abrupt decline of the ZG occurs with age in men only, possibly contributing to sexual dimorphism in cardiovascular risk.

Sleep, Cognition and Cortisol in Addison's Disease: A Mechanistic Relationship

Sleep is a critical biological process, essential for cognitive well-being. Neuroscientific literature suggests there are mechanistic relations between sleep disruption and memory deficits, and that varying concentrations of cortisol may play an important role in mediating those relations. Patients with Addison's disease (AD) experience consistent and predictable periods of sub- and supra-physiological cortisol concentrations due to lifelong glucocorticoid replacement therapy, and they frequently report disrupted sleep and impaired memory. These disruptions and impairments may be related to the failure of replacement regimens to restore a normal circadian rhythm of cortisol secretion. Available data provides support for existing theoretical frameworks which postulate that in AD and other neuroendocrine, neurological, or psychiatric disorders, disrupted sleep is an important biological mechanism that underlies, at least partially, the memory impairments that patients frequently report experiencing. Given the literature linking sleep disruption and cognitive impairment in AD, future initiatives should aim to improve patients' cognitive performance (and, indeed, their overall quality of life) by prioritizing and optimizing sleep. This review summarizes the literature on sleep and cognition in AD, and the role that cortisol concentrations play in the relationship between the two.

Serum cortisol level after low dose dexamethasone suppression test may be predictive for diabetes mellitus and hypertension presence in obese patients: A retrospective study

AIMS

Obesity, a remarkably increased healthcare problem, accompanies with morbidities including type 2 diabetes mellitus (DM), hypertension, and cardiovascular diseases. Hypothalamic-pituitary-adrenal (HPA) axis alteration is thought to be effective on the background of obesity, even concomitant with DM and hypertension. We aimed to evaluate the negative feedback mechanism of the HPA axis via overnight 1 mg dexamethasone suppression test (DST) and the association of post-1 mg DST cortisol level with DM and hypertension presence in obesity.

METHODS

This study consisted of 402 obese patients who provide suppression after DST. Post-1 mg DST cortisol level and its association with other variables including anthropometric measurements, laboratory test results, hypertension, prediabetes, and DM presence were evaluated. Predictivity of post-1 mg DST for hypertension and DM was investigated.

RESULTS

We established a significant difference in post-1 mg DST cortisol level when compared patients with and without DM, patients without DM and with prediabetes, patients with prediabetes and DM (p < 0.001 vs. p = 0.003 vs. p = 0.022 respectively). Post-1 mg DST cortisol level was significantly higher in hypertensive patients (p < 0.001). Post-1 mg DST cortisol level had positive correlation with age (r = 0.319, p < 0.001), fasting plasma glucose (r = 0.168, p = 0.001), and HbA1c (r = 0.278, p < 0.001) levels. Logistic regression analyses demonstrated that post-1 mg DST cortisol level is an independent predictor of DM and hypertension presence.

CONCLUSION

Cortisol negative feedback mechanism may be altered in obese patients who are complicated with hypertension and DM. Therefore, post-1 mg DST cortisol level can be predictive for hypertension and DM presence in obesity.

Stress induced neural reorganization: A conceptual framework linking depression and Alzheimer's disease

Chronic stress is a risk factor for a number of physiological disorders including cardiovascular disease, obesity and gastrointestinal disorders, as well as psychiatric and neurodegenerative disorders. There are a number of underlying molecular and cellular mechanisms altered in the course of chronic stress, which may increase the vulnerability of individuals to develop psychiatric disorders such as depression, and neurodegenerative disorders such as Alzheimer's Disease (AD). This is evident in the influence of stress on large-scale brain networks, including the resting state Default Mode Network (DMN), the effects of stress on neuronal circuitry and architecture, and the cellular and molecular adaptations to stress, which may render individuals with stress related psychiatric disorders more vulnerable to neurodegenerative disease later in life. These alterations include decreased negative feedback inhibition of the hypothalamic pituitary axis (HPA) axis, decreased dendritic arborization and spine density in the prefrontal cortex (PFC) and hippocampus, and the release of proinflammatory cytokines, which may suppress neurogenesis and promote neuronal cell death. Each of these factors are thought to play a role in stress-related psychiatric disease as well as AD, and have been observed in clinical and post-mortem studies of individuals with depression and AD. The goal of the current review is to summarize clinical and preclinical evidence supporting a role for chronic stress as a putative link between neuropsychiatric and neurodegenerative disease. Moreover, we provide a rationale for the importance of taking a medical history of stress-related psychiatric diseases into consideration during clinical trial design, as they may play an important role in the etiology of AD in stratified patient populations.

Simultaneous assay of cortisol and dexamethasone improved diagnostic accuracy of the dexamethasone suppression test

OBJECTIVES

The overnight dexamethasone (DXM) suppression test (DST) has high sensitivity, but moderate specificity, for diagnosing hypercortisolism. We have evaluated if simultaneous measurement of S-DXM may correct for variable DXM bioavailability and increase the diagnostic performance of DST, and if saliva (sa) is a feasible adjunct or alternative to serum.

DESIGN AND METHODS

Prospective study of DST was carried out in patients with suspected Cushing's syndrome (CS) (n = 49), incidentaloma (n = 152) and healthy controls (n = 101). Cortisol, cortisone and DXM were assayed by liquid chromatography-tandem mass spectrometry (LC-MS/MS).

RESULTS

Three hundred and two subjects underwent DST; S-cortisol was ≥50 nmol/L in 83 patients, of whom 11 had CS and 27 had autonomous cortisol secretion. The lower 2.5 percentile of S-DXM in subjects with negative DST (n = 208) was 3.3 nmol/L, which was selected as the DXM cut-off level. Nine patients had the combination of low S-DXM and positive DST. Of these, three had been misdiagnosed as having autonomous cortisol secretion. DST results were highly reproducible and confirmed in a replication cohort (n = 58). Patients with overt CS had significantly elevated post-DST sa-cortisol and sa-cortisone levels compared with controls; 23 of 25 with autonomous cortisol secretion had elevated sa-cortisone and 14 had elevated sa-cortisol.

CONCLUSIONS

Simultaneous measurement of serum DXM and cortisol reduced false-positive DSTs by 20% and improved the specificity. S-DXM >3.3 nmol/L is sufficient for the suppression of cortisol <50 nmol/L. Measurement of glucocorticoids in saliva is a non-invasive and easy procedure and post-DST sa-cortisone was found particularly useful in the diagnosis of CS.

Hypothalamic-Pituitary--Adrenal Axis-Feedback Control

The hypothalamo-pituitary-adrenal axis (HPA) is responsible for stimulation of adrenal corticosteroids in response to stress. Negative feedback control by corticosteroids limits pituitary secretion of corticotropin, ACTH, and hypothalamic secretion of corticotropin-releasing hormone, CRH, and vasopressin, AVP, resulting in regulation of both basal and stress-induced ACTH secretion. The negative feedback effect of corticosteroids occurs by action of corticosteroids at mineralocorticoid receptors (MR) and/or glucocorticoid receptors (GRs) located in multiple sites in the brain and in the pituitary. The mechanisms of negative feedback vary according to the receptor type and location within the brain-hypothalmo-pituitary axis. A very rapid nongenomic action has been demonstrated for GR action on CRH neurons in the hypothalamus, and somewhat slower nongenomic effects are observed in the pituitary or other brain sites mediated by GR and/or MR. Corticosteroids also have genomic actions, including repression of the pro-opiomelanocortin (POMC) gene in the pituitary and CRH and AVP genes in the hypothalamus. The rapid effect inhibits stimulated secretion, but requires a rapidly rising corticosteroid concentration. The more delayed inhibitory effect on stimulated secretion is dependent on the intensity of the stimulus and the magnitude of the corticosteroid feedback signal, but also the neuroanatomical pathways responsible for activating the HPA. The pathways for activation of some stressors may partially bypass hypothalamic feedback sites at the CRH neuron, whereas others may not involve forebrain sites; therefore, some physiological stressors may override or bypass negative feedback, and other psychological stressors may facilitate responses to subsequent stress.

Age-dependent and gender-dependent regulation of hypothalamic-adrenocorticotropic-adrenal axis

Tightly regulated output of glucocorticoids is critical to maintaining immune competence, the structure of neurons, muscle, and bone, blood pressure, glucose homeostasis, work capacity, and vitality in the human and experimental animal. Age, sex steroids, gender, stress, body composition, and disease govern glucocorticoid availability through incompletely understood mechanisms. According to an ensemble concept of neuroendocrine regulation, successful stress adaptations require repeated incremental signaling adjustments among hypothalamic corticotropin-releasing hormone and arginine vasopressin, pituitary adrenocorticotropic hormone, and adrenal corticosteroids. Signals are transduced via (positive) feedforward and (negative) feedback effects. Age and gonadal steroids strongly modulate stress-adaptive glucocorticoid secretion by such interlinked pathways.

Age-dependent and -independent associations between depression, anxiety, DHEAS, and cortisol: from the MIPH Industrial Cohort Studies (MICS)

There is a well-established link between dysphoric mood and endocrine dysregulation, but the strength of this association may vary with age. In order to investigate this possibility we assessed anxiety and depression with overnight urinary cortisol and plasma dehydroepiandrosterone-sulphate (DHEAS) in 608 factory employees ranging between 21 and 62 years. As expected, DHEAS declined with age (r=-0.54, P<0.001) while there was a modest age-related increase in nocturnal cortisol (r=0.17, P<0.001). Depressive symptoms were associated with higher nocturnal cortisol (β=0.19, P<0.001), independent of age. While the association between anxiety and cortisol (age by anxiety interaction: β=0.11, P<0.05) became stronger with age, there was a similar decline in the DHEAS/cortisol ratio in high-anxious middle-aged adults (β=-0.10, P=0.018). The current findings suggest that dysphoric mood, and in particular anxiety, may exacerbate the effects of aging on cortisol release. Prospective studies are needed to determine the causal relations between dysphoric mood, cortisol and DHEAS across the lifespan.

Effects of stress hormones on the brain and cognition: Evidence from normal to pathological aging

Several studies have demonstrated a wide cognitive variability among aged individuals. One factor thought to be associated with this heterogeneity is exposure to chronic stress throughout life. Animal and human evidence demonstrates that glucocorticoids (GCs), the main class of stress hormones, are strongly linked to memory performance whereby elevated GC levels are associated with memory performance decline in both normal and pathological cognitive aging. Accordingly, it is believed that GCs may increase the brain's vulnerability to the effects of internal and external insults, and thus may play a role in the development of age-related cognitive disorders such as Alzheimer's disease (AD). The aim of this review article was to investigate the effects of GCs on normal and pathological cognitive aging by showing how these hormones interact with different brain structures involved in cognitive abilities, subsequently worsen memory performance, and increase the risk for developing dementia.

Dynamics of social and energetic stress in wild female chimpanzees

Stress hormone measurements can reinforce and refine hypotheses about the costs of particular contexts or behaviors in wild animals. For social species, this is complicated because potential stressors may come from the physical environment, social environment, or some combination of both, while the stress response itself is generalized. Here, we present a multivariate examination of urinary cortisol dynamics over 6 years in the lives of wild female chimpanzees in the Kanyawara community of Kibale National Park, Uganda. We hypothesized that chimpanzee socioecology provides strong indications of both energetic and social stress to females, but that the salience of these stressors might vary over a female's life history in accordance with their changing reproductive costs and social interactions. Using linear mixed models, we found that urinary cortisol levels increased significantly with age but were also elevated in young immigrants to the community. Across reproductive states, cycling, non-estrous females had relatively low cortisol compared to lactating, estrous, or pregnant females. Aggression from males led to higher cortisol levels among estrous females, frequent targets of aggressive sexual coercion. In contrast, energetic stress was most salient to lactating females, who experienced higher cortisol during months of low fruit consumption. Low dominance rank was associated with increased cortisol, particularly during the energetically demanding period of lactation. The effects of female conflict were felt widely, even among those who were the primary aggressors, providing further evidence that long-term resource competition, while apparently muted, exerts a far-reaching impact on the lives of chimpanzee females.

Dehydroepiandrosterone sulfate and cognitive function in the elderly: The InCHIANTI Study

DHEA and its sulfate derivative (DHEAS) decline with age. The decline in DHEAS levels has been associated with many physiological impairments in older persons including cognitive dysfunction. However, data regarding the possible relationship between DHEAS and cognition are scant. We investigated whether DHEAS levels are associated with presence and development of lower cognitive function measured by the Mini Mental State Examination (MMSE) in older men and women. One thousand and thirty-four residents aged > or =65 yr of the InCHIANTI Study with data available on DHEAS and MMSE were randomly selected. MMSE was administered at baseline and 3 yr later. Among these, 841 completed a 3-yr follow-up. Parsimonious models obtained by backward selection from initial fully-adjusted models were used to identify independent factors associated with MMSE and DHEAS. The final analysis was performed in 755 participants (410 men and 345 women) with MMSE score > or =21. A significant age-related decline of both DHEAS levels (p<0.001) and MMSE score (p<0.001) was found over the 3-yr follow-up. At enrolment, DHEAS was significantly and positively associated with MMSE score, independently of age and other potential confounders (beta+/-SE 0.003+/-0.001, p<0.005). Low baseline DHEAS levels were predictive of larger decline of MMSE and this relationship was significant after adjusting for covariates (beta+/-SE -0.004+/-0.002, p<0.03). Our data show a significant and positive association between DHEAS and cognitive function, assessed by MMSE test. Low DHEAS levels predict accelerated decline in MMSE score during the 3-yr follow-up period.

Basal, pulsatile, entropic (patterned), and spiky (staccato-like) properties of ACTH secretion: impact of age, gender, and body mass index

BACKGROUND

Age, gender, and BMI determine ultradian modes of LH and GH secretion, viz., pulsatile, basal, pattern-defined regularity [approximate entropy (ApEn)] and spikiness (sharp, brief excursions). Whether the same determinants apply to ACTH secretion is not known.

SETTING

The study was conducted at a tertiary medical center.

SUBJECTS

We studied normal women (n = 22) and men (n = 26) [ages, 23-77 yr; body mass index (BMI), 21-32 kg/m(2)].

METHODS

Volunteers underwent 10-min blood sampling to create 24-h ACTH concentration profiles.

OUTCOMES

Dynamic measures of ACTH secretion were studied.

RESULTS

Mean ACTH concentrations (R(2) = 0.15; P = 0.006) and both pulsatile (R(2) = 0.12; P = 0.018) and basal (nonpulsatile) (R(2) = 0.16; P = 0.005) ACTH secretion correlated directly with BMI (n = 48). Men had greater basal (P = 0.047), pulsatile (P = 0.031), and total (P = 0.010) 24-h ACTH secretion than women, including when total secretion was normalized for BMI (P = 0.019). In men, both ACTH-cortisol feedforward and cortisol-ACTH feedback asynchrony (cross-ApEn) increased with age (R(2) = 0.20 and 0.22; P = 0.021 and 0.018). ACTH spikiness rose with age (P = 0.046), principally in women. Irregularity of cortisol secretion (ApEn) increased with age (n = 48; P = 0.010), especially in men. In both sexes, percentage pulsatile ACTH secretion predicted 24-h mean cortisol concentrations (R(2) = 0.14; P = 0.009).

CONCLUSION

Valid comparisons of ultradian ACTH dynamics will require cohorts matched for age, gender, and BMI, conditions hitherto not satisfied in most physiological studies of this axis.

Effect of aging on 24-hour pattern of stress hormones and leptin in rats

This work analyzes the 24-hour changes of hypothalamic-pituitary-adrenal (HPA) axis activity and leptin release in aged rats. Three- and 22-month-old male Wistar rats were killed at 6 time intervals during a 24-hour cycle (n=8-10 rats/group). Aging augmented plasma ACTH while it decreased plasma and adrenal gland corticosterone levels. Plasma and adrenal corticosterone levels attained high levels during all the scotophase, concomitantly with the maxima in ACTH levels, whereas in aged rats only a brief plasma corticosterone peak at the early scotophase and no time of day variations of adrenal corticosterone were observed. Aging augmented circulating leptin, with a significant interaction "agextime" in the factorial ANOVA, i.e. only in young rats time of day changes were significant, with the lowest values of leptin at the middle of the light period and higher values at night. When plasma leptin was expressed on body weight basis, the age-related differences became not significant but the daily pattern of plasma leptin found in young rats persisted. Plasma and adrenal corticosterone levels correlated significantly with plasma ACTH only in young rats. Likewise, plasma leptin correlated with plasma corticosterone only in young rats. These changes can be attributed to a disrupting effect of aging on the homeostatic mechanisms modulating HPA activity and leptin release.

Distinguishing between depression and dementia in older persons: neuropsychological and neuropathological correlates

Dementia and depression are frequently comorbid among older adult patients. Depression is related to cognitive decrement and can even represent the first signs of a neurodegenerative process. It can be difficult to distinguish depressed patients exhibiting the first signs of dementia from those whose cognition will improve with treatment. In this article, studies from the neuropsychological literature are reviewed that aid in accurate diagnosis and prognosis. Furthermore, the relationship between depression and dementia is explored by examining potential neurobiological mechanisms that may potentiate both syndromes in the context of the ongoing debate on depression as a prodrome and/or a risk factor for dementia. This article is concluded with suggestions for clinicians when deciding who to refer for neuropsychological assessment and with ideas for further research that might promote a better understanding of the complex association between depression and dementia during old age.

Neuropsychological impairment in major depression: its nature, origin and clinical significance

Neuropsychological impairment is well established as a feature of major depressive disorder (MDD) but studies have shown a variable pattern of impairment. This paper seeks first to clarify this by examining methodological and clinical factors that give rise to variability in study findings. Second, it examines theories of the origin of these neuropsychological abnormalities. Third, it reviews evidence regarding the clinical significance of different patterns of deficit. A selective review was undertaken of the literature with a particular emphasis on methodological factors, the influence of clinical subtypes and prevalent theories of neuropsychological abnormality. Methodological issues and the heterogeneity of MDD account for considerable variability in results. Specific investigation of the subtypes of psychotic MDD, melancholic MDD and bipolar depression reduces this heterogeneity and results are more consistent in the elderly. Hypothalamic-pituitary-adrenal axis dysfunction is associated with neuropsychological dysfunction in MDD although evidence of direct causation is not definitive at present. Impairment of executive and psychomotor function is a consistent finding, particularly in the elderly, and may reflect frontostriatal-limbic dysfunction. There is growing evidence that this may have clinical significance. It is suggested that future research take very careful account of the exact phenotype of MDD. Classification based on neuropsychological profile may, in fact, be useful. Further research should examine further the clinical importance of patterns of neuropsychological impairment.

Glucocorticoid receptor variant and risk of dementia and white matter lesions

OBJECTIVE

Elevated glucocorticoid levels are associated with dementia. A glucocorticoid receptor gene variant (ER22/23EK) is related to relative glucocorticoid resistance. We investigated whether the ER22/23EK allele is associated with dementia and structural brain abnormalities.

METHODS

This study was performed in two prospective population-based cohort studies among elderly. The first study included 6034 participants who were screened for dementia (mean follow-up 5.8 years). The second study included 1011 elderly subjects with an MRI at baseline and follow-up. The ER22/23EK allele was assessed for association with dementia, cognitive function and white matter lesions.

RESULTS

The ER22/23EK allele was associated with a decreased risk of dementia. Among non-demented participants, ER22/23EK-carriers had a better performance on psychomotor speed tests than non-carriers. No differences were found in memory function between genotypes. In addition, both presence and progression of white matter lesions was lower in ER22/23EK-carriers. No association was found with brain atrophy on MRI.

CONCLUSIONS

Our findings suggest a protective effect of the ER22/23EK allele on the risk of dementia and white matter lesions.

Abnormalities of the HPA axis in affective disorders: clinical subtypes and potential treatments

BACKGROUND

New evidence is emerging regarding abnormalities of hypothalamic-pituitary-adrenal (HPA) axis function in subtypes of affective disorders. Adverse effects of HPA axis dysregulation may include dysfunction of monoaminergic transmitter systems, cognitive impairment and peripheral effects. Newer treatments specifically targeting the HPA axis are being developed.

OBJECTIVE

To review these developments focusing particularly on the glucocorticoid receptor (GR) antagonist mifepristone.

METHOD

A selective review of the literature.

RESULTS

The function of GRs is increasingly being defined. The role of corticotrophin-releasing hormone (CRH) and dehydroepiandrosterone (DHEA) in the brain is also increasingly understood. HPA axis function is particularly likely to be abnormal in psychotic depression and bipolar disorder, and it is in these conditions that trials of the GR antagonist mifepristone are being focused. CRH antagonists and DHEA are also being investigated as potential treatments.

CONCLUSION

Initial studies of mifepristone and other HPA-axis-targeting agents in psychotic depression and bipolar disorder are encouraging and confirmatory studies are awaited.

Type D personality: the heart, stress, and cortisol

Many studies have demonstrated the role of psychosocial and behavioural risk factors in the aetiology and pathogenesis of cardiovascular disorders. Recently, a new personality construct, the type D or 'distressed' personality, has been proposed. Type D behaviour is characterized by the joint tendency to experience negative emotions and to inhibit these emotions while avoiding social contacts with others. The observation that cardiac patients with type D personality are at increased risk for cardiovascular morbidity and mortality underlines the importance of examining both acute (e.g. major depression) and chronic (e.g. certain personality features) factors in patients at risk for coronary events. Both type D dimensions (negative affectivity and social inhibition) are associated with greater cortisol reactivity to stress. Elevated cortisol may be a mediating factor in the association between type D personality and the increased risk for coronary heart disease and, possibly, other medical disorders. Studies of the effect of age on hypothalamic-pituitary-adrenal (HPA) function in healthy humans have produced inconsistent results. This may relate to a different prevalence of type D individuals in study samples (i.e. some type D individuals may have alterations within the HPA axis that are similar to HPA axis changes in depressed patients). Further studies of the psychological and biological features of type D individuals may help develop treatment approaches to improve the psychological and physical health of individuals with type D personality.

Cortisol, DHEAS and aging: resistance to cortisol suppression in frail institutionalized elderly

Convincing evidences has linked the hypothalamus-pituitary-adrenal (HPA) axis to aging patterns. F excess is implicated in the development of frailty characteristics whereas DHEAS is positively correlated to successful aging. We compared serum F and DHEAS levels of independent community-living (successful group, 19 M and 28 F, 69 to 87 yr) with those of institutionalized elderly (frail group, 20 M and 30 F, 65 to 95 yr). Serum F was determined at 1) baseline (08:00 h, 16:00 h and 23:00 h), 2) after 2 overnight dexamethasone (DEX) suppression tests (DST, using 0.25 and 1.0 mg doses), and 3) 60 min after ACTH stimulation (250 microg i.v. bolus); serum DHEAS was determined at 08:00 h. Basal serum F at 08:00 h, 16:00 h and 23:00 h and serum DHEAS levels were similar in both groups; however F: DHEAS ratio at 08:00 h was higher in the frail, compared to the successful group (mean +/- SD: 0.55 +/- 0.53 and 0.35 +/- 0.41, respectively; p = 0.04). In response to DST, F suppression was less effective in frail elderly after either 0.25 or 1.0 mg doses (9.0 +/- 6.0 and 2.0 +/- 0.9 microg/dl), as compared to the successful group (5.8 +/- 4.4 and 1.5 +/- 0.5 microg/dl) (p = 0.01). In addition, a significant correlation was observed between post-DEX F levels (both doses) and parameters of cognitive and physical frailty. Normal and similar F levels were observed after ACTH stimulation in both groups. Our data suggest a deficient feedback regulation of the HPA axis in frail institutionalized elderly, as demonstrated by a higher set point for F suppression. This augmented HPA tonus enforces the hypothesis that even milder F excess may be related to characteristics of frailty in the elderly.

Corticosteroids: sculptors of the hippocampal formation

The influence of corticosteroids on hippocampus-dependent learning and memory processes is now indisputable. On the other hand, closer scrutiny of early studies together with interpretations from newer studies would suggest that the proposition that corticosteroid-induced hippocampal cell death accounts fully for the associated cognitive deficits is only partially correct. Firstly, it is now clear that a specific sub-population of hippocampal neurons, the granule cells of the dentate gyrus, is more sensitive to changes in the corticosteroid environment; this fact raises the interesting question of what might be the unique properties of granule cells that render them more vulnerable to these hormones, since virtually all hippocampal cells express corticosteroid receptors. Secondly, from a critical analysis of the available data, the picture that emerges is that corticosteroids, by acting through two distinct receptors, influence not only cell birth and death, but probably also cell differentiation. Mineralocorticoid receptor (MR) occupation appears to be essential for the survival of existing and newly generated granule neurons. In contrast, while glucocorticoid receptors (GR) can induce loss of neurons in the absence of MR activation, it appears that their occupation usually results in less drastic effects involving only dendritic atrophy and loss of synaptic contacts. This revised scheme of corticosteroid actions on hippocampal structure should explain earlier observations that many of the cognition- impairing effects of corticosteroids are reversible.

Salivary cortisol day profiles in elderly with mild cognitive impairment

It is unknown whether hypothalamus-pituitary-adrenal (HPA) axis dysfunction is associated with the memory impairments observed among elderly participants with mild cognitive impairment (MCI), a group considered at increased risk for Alzheimer's disease (AD). Therefore, salivary cortisol levels were measured at six points over the course of the day while at-home in MCI participants (n=16), normal elderly (n=28), and young controls (n=14). Results revealed that MCI participants did not show elevated salivary cortisol levels. The 9 a.m. cortisol level of the MCI group was significantly lower than the 9 a.m. level of the young controls, but did not differ from those of the normal elderly group. In contrast to the other two groups, within the MCI group mean cortisol levels were inversely related to immediate recall of paragraphs. No association was observed between mean cortisol levels and performance in paired associates and digit span. Whether cortisol levels, in conjunction with other factors, such as hippocampal volume, will lead to improved prediction of future decline to AD in participants with MCI remains to be established in longitudinal studies.

Basal hypothalamo-pituitary-adrenal axis activity and corticotropin feedback in young and older men: relationships to magnetic resonance imaging-derived hippocampus and cingulate gyrus volumes

Alterations in basal cortisol secretion and feedback sensitivity are reported in aging. However, it is not known whether these hypothalamus-pituitary-adrenal (HPA) axis alterations are related to structural brain changes. This study was designed to investigate these relationships in the human. Nine young (24.0 +/- 1.2 years; mean +/- SE; range: 19-30) and 11 older (69.0 +/- 1.8 years; range: 59-76) men, in addition to having standardized magnetic resonance imaging of their brains, were given 0.5 mg/kg cortisol or placebo intravenously in a double-blind, crossover study. As expected, older men had significantly smaller volumes for all brain regions. Although the groups did not differ in baseline HPA axis activity, there were significant and specific relationships between the brain volumes and the baseline measures of HPA activity. Namely, for young and older subjects combined and after controlling for age and cerebral vault size, hippocampal volumes were inversely associated with 24-hour urinary cortisol and basal corticotropin (ACTH) levels, and the anterior cingulate gyrus volume was negatively correlated with baseline ACTH. Elderly subjects had a slower decrease in ACTH levels (percent of baseline level) during the first 30 min after cortisol administration. However, no associations were observed between the ACTH feedback indices and any brain measure. This report, although based on a small number of subjects, supports previous studies showing a blunted ACTH fast feedback during normal aging. Hippocampal atrophy appears to be related to increased basal measures of HPA axis activity, but not to fast ACTH feedback. It remains possible that age-associated changes in fast feedback may be related to changes to other brain sites, such as hypothalamus or pituitary.

Effects of rapid tryptophan depletion on salivary and plasma cortisol in Alzheimer's disease and the healthy elderly

Serotonergic function is reduced in dementia of Alzheimer type (DAT) and abnormalities in the hypothalamic-pituitary-adrenal (HPA) axis are also common. There is considerable interaction between the two systems. Effects of lowering brain serotonin on salivary and plasma cortisol were assessed in patients with DAT and in control subjects. A double-blind, cross-over design involving administration of two nutritionally balanced amino acid mixtures with or without tryptophan was used. Salivary and plasma cortisol were measured at intervals before and after the drink. DAT patients had higher salivary cortisol than controls. Despite a reduction of approximately 70% in plasma free tryptophan after 4 h in both groups, there was no effect on salivary or plasma cortisol. We conclude that, in subjects with DAT and healthy elderly subjects, acute tryptophan depletion had no effect on cortisol secretion.

Effects of hydrocortisone administration on cognitive function in the elderly

Previous studies have found adverse effects of both acute and chronic elevations of corticosteroids on cognitive function in humans and that cortisol levels may predict cognitive decline in elderly subjects. However, no previous studies have directly investigated the effects of hydrocortisone on cognitive functioning in the healthy elderly. Sixteen healthy elderly subjects took part in a placebo-controlled, double-blind, cross-over trial. Hydrocortisone 20 mg or placebo was administered twice, 12 h and 1 h before cognitive testing. On each occasion, a battery of neuropsychological tests was performed which included tests of attention, working memory, declarative memory and executive function. Salivary cortisol levels at the time of testing were elevated approximately 10-fold following hydrocortisone compared with placebo. No significant effects were found on memory or a range of other cognitive functions. The lack of effect of this regime of hydrocortisone is in contrast to studies in younger subjects. The elderly may be less sensitive to cognitive effects of short-term increases in cortisol levels, possibly due to an age-related downregulation of hippocampal glucocorticoid receptors.

Dementia: a neuroendocrine perspective

The etiology of Alzheimer's disease (AD) has not been as yet completely defined. Genetic, environmental and neurophysiological aspects should all be taken into account. The disease has also neuroendocrine implications, some of which are discussed in this review. It is known that stress and glucocorticoids may affect neurone survival. On the contrary, some data indicate that DHEA and DHEAS exert a neuroprotective action. In AD, changes in hypothalamic-pituitary-adrenal axis function have been reported. Experimental and clinical evidence indicates that glucocorticoid hypersecretion and DHEAS levels decrement may add to hippocampal dysfunction in aging and in AD. Glucocorticoid and beta-amyloid concur in the mechanism of neurone damage, as well as excitatory amino acids (EAA), Ca++ and reactive oxygen species (ROS). The neuroprotective effects exerted by IGFs are also hindered in aging and even more in AD. Production and biological actions of IGFs are negatively influenced by cortisol hypersecretion and DHEAS decrease in patients with AD.

Corticosteroids and cognition

The brain is a major target organ for corticosteroids. It has been observed that excessive circulatory levels of endogenous and exogenous corticosteroids are frequently associated with cognitive impairment in a wide variety of clinical disease states. Cognition and low levels of corticosteroids have been less well studied. In this paper we review the literature on glucocorticosteroid effects on cognition and delineate specific functions that appear to be causally affected. We draw a possible connection to specific areas of brain perturbation, including the hippocampus and frontal lobe regions. The possibility that cognitive dysfunction caused by glucocorticoids can be pharmacologically managed is introduced.

Relationships between cortisol, dehydroepiandrosterone sulphate and insulin-like growth factor-I system in dementia

Changes in the hypothalamus-pituitary-adrenal axis (HPAA) function, entailing elevated cortisol circulating titres, occur in aging and in some neurological conditions, such as Alzheimer's disease (AD). Excess cortisol has neurotoxic effects which affect hippocampal neurones. Dehydroepiandrosterone sulphate (DHEAS) has an antiglucocorticoid activity and neuroprotective effects, but its levels decrease with aging. Glucocorticoids influence the production of insulin-like growth factor-I (IGF-I) and modify its systemic and neurotrophic biological activity by inducing changes in IGF-binding proteins (IGFBPs). We looked for relationships between cortisol, DHEAS levels, and IGF-I - IGFBPs system in AD. Cortisol, DHEAS and GH levels at 02:00, 08:00, 14:00, 20:00 h, basal IGF-I, IGFBP-1 and IGFBP-3 levels were determined by RIAs or IRMA in 25 AD patients, aged 58-89 yr, and in 12 age-matched healthy controls. AD subjects had higher cortisol, lower DHEAS levels and increased cortisol/DHEAS ratio (C/Dr) than controls. In AD cases, total IGF-I, IGFBP-3, and IGF-I/IGFBP ratios were significantly lowered, while IGFBP-1 levels were significantly higher than in controls. We found a significant inverse correlation between IGF-I and IGFBP-3 levels vs C/Dr, and between both IGF-I/IGFBPs ratios vs mean cortisol levels. IGFBP-3 correlated directly with DHEAS. Cortisol was directly and IGF-I inversely correlated with cognitive impairment. In AD patients we found that alterations in HPAA function and elevated C/Dr are related to lowered total and free IGF-I levels. These findings and their relationship to cognitive impairment suggest that changes in hormonal set-up might influence the clinical presentation of the disease.

Dexamethasone effects on cortisol secretion in Alzheimer's disease: some clinical and hormonal features in suppressor and nonsuppressor patients

Alterations in the hypothalamic-pituitary-adrenal axis (HPAA) and failure of dexamethasone (DXT) to suppress cortisol secretion occur in Alzheimer's disease (AD). This study was aimed to settle possible differences in some clinical (age, body weight, body mass index, dementia severity) and hormonal parameters in AD patients non-responders to overnight 1 mg-DXT suppression test compared with the responder subjects. ACTH, cortisol and dehydroepiandrosterone sulphate (DHEAS) day-time levels were assessed in 25 AD patients and in 12 age-matched healthy controls before DXT administration. In view of their neuroprotective effects, plasma levels of Insulin-like Growth Factor-I (IGF-I) and of IGF-Binding Proteins (IGFBPs) were also determined. After DXT, 8 AD subjects (32%) showed cortisol levels above the conventional cut-off of 140 nmol/L. No significant differences were found in clinical parameters in suppressor vs nonsuppressor patients. AD subjects showed higher cortisol, cortisol/DHEAS ratios, and lower DHEAS levels in comparison with controls. Both ACTH and cortisol levels were not different in suppressor and nonsuppressor patients, but DHEAS levels were significantly lower in nonsuppressor cases, who also exhibited ACTH and cortisol periodicities more altered than in suppressor and in control subjects. IGF-I and IGFBP-3 levels were lower and those of IGFBP-1 higher in nonsuppressor than in suppressor cases and in healthy controls. IGF-I/IGFBPs system data were correlated with cognitive impairment and adrenal steroid levels in AD patients.

Estrogens normalize the hypothalamic-pituitary-adrenal axis response to stress and increase glucocorticoid receptor immuno-reactivity in hippocampus of aging male rats

Aging is associated with a disturbance in the regulation of the hypothalamic-pituitary-adrenal axis (HPA) and reduced levels of glucocorticoid receptors (GR) in the hippocampus. To compensate for these effects, we have investigated whether estrogen therapy normalized the HPA response to stress and GR in hippocampus and paraventricular (PVN) nucleus. Young (3-4 months) and old (20 months) male Sprague-Dawley rats were bled by tail cut in the basal state and following ether stress. While basal and ether-stimulated levels of plasma corticosterone (CORT) were similar in the two groups, old animals presented a delayed termination of the response to ether stress. A dexamethasone inhibition test carried out in old animals, showed a failure to completely block plasma CORT after ether stimulation. Furthermore, in old rats GR-immunoreactive levels were reduced in CA1-CA2 hippocampal subfields and subiculum, while normal levels were obtained in CA3-CA4 and PVN. We observed that prolonged estrogen treatment (6 weeks) of old rats normalized the termination of the stress response, restored dexamethasone inhibition of plasma CORT, and increased GR immunoreactivity in CA1 and CA2 hippocampal subfields and subiculum. The results suggest that estrogen treatment enhanced the glucocorticoid feedback signal by increasing GR in hippocampus, and corrected the disturbances in HPA axis regulation. These animal experiments may be important to elucidate the effects of estrogenic on the hippocampal and HPA dysfunction associated with aging and Alzheimer's disease in humans.

A prospective study on cortisol, dehydroepiandrosterone sulfate, and cognitive function in the elderly

The objective of this study was to investigate the relation between the peripheral concentrations of the adrenal steroid hormones cortisol and dehydroepiandrosterone sulfate (DHEAS) and cognitive impairment and decline. A prospective study design was used. The setting was a suburb of Rotterdam, The Netherlands. The study population consisted of a sample of 189 healthy participants from the population-based Rotterdam Study, aged 55-80 yr, who were invited for an additional examination. Follow-up examinations took place 1.9 yr after baseline, on the average. We determined fasting blood levels of DHEAS before dexamethasone administration and of cortisol and corticosteroid-binding globulin before and after the administration of 1 mg dexamethasone overnight. The 30-point Mini-Mental State Examination (MMSE) was used to assess cognition. The associations with cognitive impairment (MMSE score of <26; 6% of the sample) and cognitive decline (drop in MMSE score of >1 point/yr; 24%) were estimated using logistic regression, with adjustment for age, sex, education, and depressive symptoms. An increase of 1 SD in the estimate of free cortisol (SD = 30.3) was associated with cognitive impairment, although not significantly [odds ratio (OR) = 1.5; 95% confidence interval (CI), 0.9-2.4]. A 1 SD increase in the natural logarithm of cortisol after the administration of 1 mg dexamethasone (SD = 0.68) was associated with an OR for cognitive decline of 1.5 (95% CI, 1.0-2.3). A 1 SD increase in DHEAS (SD = 2.10 micromol/L) was inversely, but nonsignificantly, related to cognitive impairment (OR = 0.5; 95% CI, 0.2-1.1) and cognitive decline (OR = 0.6; 95% CI, 0.4-1.1). The ratio of free cortisol over DHEAS was significantly related to cognitive impairment (OR = 1.8; 95% CI, 1.0-3.2). This prospective study among healthy elderly subjects suggested that basal free cortisol levels were positively related to cognitive impairment, and cortisol levels after dexamethasone treatment were related to cognitive decline. There was an inverse, but nonsignificant, association between DHEAS and cognitive impairment and decline.

Corticotropin-dependent Cushing's syndrome in older people: presentation of five cases and therapeutical use of ketoconazole

BACKGROUND

Cushing's syndrome is a rare disorder. The corticotropin (ACTH)-dependent form of this syndrome generally results either from excessive ACTH secretion by a pituitary adenoma or ectopic secretion by a malignant tumor. Theoretically, the latter type can be assumed to occur more frequently in old age as the incidence of malignancy increases.

METHODS

Diagnostic procedures for these five cases of Cushing's syndrome consisted of 24-hour urinary cortisol excretion, plasma ACTH and serum cortisol levels, oCRH stimulatory test, low-dose and high-dose dexamethasone suppression tests, CT scan or MR imaging of the pituitary region, and bilateral inferior petrosal sinus sampling. Patients were treated with ketoconazole, if possible, and evaluated according to clinical response and 24-hour urinary cortisol excretion.

PATIENTS

The five cases presented were selected on the basis of age--75 years or older--from a total of about 100 patients presenting with Cushing's syndrome. In only three cases were signs of hypercorticism found on clinical examination. The other two patients were evaluated for adrenocortical excess because of severe hypokalemia and the fortuitous finding of enlarged adrenal glands on CT scan, respectively.

RESULTS

As a result of endocrine testing, pituitary-dependent Cushing's disease was suspected in three patients and ectopic Cushing's syndrome in two patients. Imaging techniques demonstrated only one pituitary adenoma in the first three patients and a lung tumor in one of the latter two patients. Inferior petrosal sinus sampling confirmed the suspected origin of the Cushing's syndrome in the three patients in which this procedure was performed. All three patients with pituitary-dependent Cushing's disease underwent successful clinical and biochemical treatment with ketoconazole.

CONCLUSION

Pituitary-dependent Cushing's disease may occur more frequently in patients older than 75 years of age than has previously been assumed. Because surgical treatment is not always easily tolerated by older patients, the steroidogenesis inhibitor, ketoconazole, can be a valuable alternative for the control of hypercorticism.

With aging in humans the activity of the hypothalamus-pituitary-adrenal system increases and its diurnal amplitude flattens

There is compelling evidence for feedback disturbances in the hypothalamus-pituitary-adrenal system associated with human aging as assessed by challenge tests. However, reports about age-related changes in human basal activity are ambiguous and to date little is known about changes in the pulsatile features of the HPA system. To investigate these changes we studied twenty-two healthy male and eleven healthy female subjects ranging from 23 to 85 and 24 to 81 years respectively. 24-hour blood sampling with 30 minute sampling intervals was performed. From 18.00 to 24.00 hours blood was sampled every 10 minutes for analysis of pulsatile features of HPA activity. Statistical analysis revealed that age in particular had major effects upon basal HPA-system activity: there was a significant age-associated increase in minimal (p < 0.0001) and mean (p < 0.02) cortisol plasma concentrations, but no alteration in pulsatile features. We found no age-cortisol correlation during daytime, but were able to demonstrate a strong impact of age upon cortisol plasma levels from 20.00 to 1.30 hours. The diurnal amplitude of cortisol (p < 0.005) and ACTH (p < 0.006), relative to the 24-hour mean of the hormones, showed an age-associated decline. Additionally, the evening cortisol quiescent period (p < 0.01) was shortened in the elderly, suggesting increasingly impaired circadian function in aging. Our results suggest an increased basal activity and a flattened diurnal amplitude of the HPA system in the elderly.

Neuropsychological deficits among older depressed patients with predominantly psychological or vegetative symptoms

Depressed outpatients having primarily psychological or vegetative symptoms, as defined by the factor analytically developed Hamilton Depression Scale superfactors described by Rhoades and Overall (1983), were compared with similarly aged normal controls on a comprehensive neuropsychological battery. The vegetative group evidenced poorer performance than controls on several measures associated with right hemisphere functioning and on a task associated with executive functioning. In contrast, the psychological group did not significantly differ from controls on any measure, and had significantly better performance than the vegetative group on several tasks. These findings suggest that neuropsychological deficits associated with depression may be limited to those patients with primarily vegetative symptoms.

Do glucocorticoids contribute to the abnormalities in serotonin transporter expression and function seen in depression? An animal model

Adrenocorticosteroids and serotonergic neurons exert reciprocal regulatory actions, and both are abnormal in depression. We evaluated whether glucocorticoids influence the serotonin transporter in rat platelets and brain by infusing dexamethasone for 26 days, sufficient for replacement of the entire platelet population. Effectiveness was verified by measurement of plasma dexamethasone levels, adrenal atrophy, and growth inhibition. At the end of the infusion, we examined [3H]paroxetine binding to platelet, hippocampal, and cerebrocortical membranes, and [3H]serotonin uptake into platelets and synaptosomes. Dexamethasone slightly reduced platelet [3H]paroxetine binding (12%) and had no effect on binding in brain. Platelet [3H]serotonin uptake was unaffected, but synaptosomal uptake was significantly reduced. In neither platelets nor synaptosomes did dexamethasone alter imipramine's ability to inhibit uptake. Thus, elevated glucocorticoids are not responsible for reduced platelet serotonin transporter expression in depression, nor for resistance to imipramine's effect in platelets in elderly depression; however, reduced synaptosomal [3H]serotonin uptake indicates that glucocorticoids can affect transport efficiency, even when the number of transporter molecules is unaltered.

Anterior pituitary function during critical illness and dopamine treatment

OBJECTIVE

To summarize the available data on anterior pituitary function in critical illness and to focus on the endocrine effects of dopamine infusion. The analogy with anterior pituitary function in the elderly is highlighted, and the potential importance of these observations for recovery from critical illness is discussed.

DATA SOURCES

Computerized search of published research and reference list review.

STUDY SELECTION

Review of 178 citations. Included are seven original studies on the effect of dopamine on pituitary function in adult and pediatric critical illness performed by the authors.

DATA EXTRACTION

Studies on the endocrinology of illness, chronic stress, aging, and dopamine, or on the clinical importance of endocrine changes.

DATA SYNTHESIS

The different pituitary axes are important determinants of normal anabolism and immune function. Continuously increased serum cortisol concentrations, insulin resistance, blunted prolactin release, and attenuated pulsatility of growth hormone and luteinizing hormone secretory patterns, as well as multiple anomalies in the thyroid axis, characterize the endocrine profile of prolonged critical illness. Dopamine, a natural catecholamine with hypophysiotropic properties, which has been used for more than two decades as an inotropic and vasoactive drug in intensive care, suppresses the circulating concentrations of all anterior pituitary-dependent hormones, except for cortisol. Available evidence suggests that the major effect of dopamine administration on the endocrine system is unlikely to be beneficial for the threatened metabolic and immunologic homeostasis of the severely ill patient. This pattern of hypopituitarism induced by chronic, severe illness and exogenous dopamine administration is reminiscent of the hormonal profiles obtained in experimental models of chronic stress, suggesting that endogenous dopamine may play a role in the endocrine and metabolic response to critical illness.

CONCLUSIONS

The dopamine-induced or aggravated pituitary dysfunction in critical illness warrants caution with prolonged infusion of this catecholamine as a so-called supportive agent, particularly in early life. The potential of combined hormonal therapy to improve the metabolic and immune status of the critically ill patient deserves thorough investigation.

Clinical and magnetic resonance imaging correlates of hypothalamic-pituitary-adrenal axis function in depression and Alzheimer's disease

BACKGROUND

An age-related dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis is well recognised in animals, but still remains controversial in humans. There is increasing interest that raised corticosteroid levels, due to activation of the HPA axis, may cause both depressive symptoms and cognitive impairments. Steroid effects on cognition may be via the hippocampus, a major site of corticosteroid action and an important structure involved in learning and memory.

METHOD

To investigate this further, we examined the relationship between the dexamethasone suppression test, cognitive function, depressive symptoms and hippocampal atrophy on magnetic resonance imaging (MRI) in 32 normal controls, 49 subjects with NINCDS/ADRDA Alzheimer's disease and 51 patients with DSM-III-R Major Depression.

RESULTS

Controlling for differences in dexamethasone concentrations, post-dexamethasone cortisol levels were related to advancing age in controls and depressed subjects. However, among subjects with Alzheimer's disease, post-dexamethasone cortisol levels were independently associated with both minor depressive symptoms and hippocampal atrophy on MRI.

CONCLUSION

An association between advancing age and increased HPA axis dysregulation is supported for controls and depressed subjects. In Alzheimer's disease, HPA axis changes were associated with depressive symptoms and hippocampal atrophy. Longitudinal studies are now needed to determine the causal direction of these associations.

Enhanced adrenal sensitivity to adrenocorticotrophic hormone (ACTH) is evidence of HPA axis hyperactivity in Alzheimer's disease

Adrenal sensitivity was assessed in 16 non-depressed patients with NINCDS/ADRDA Alzheimer's disease (AD) and 18 control subjects by measuring cortisol response to low dose (0.05 microgram/kg i.v.) exogenous adrenocorticotrophic hormone (ACTH). Controlling for sex and medication, both peak cortisol level (peak-baseline) and area under cortisol response curve (AUC above baseline) were significantly greater in AD subjects. This shows that HPA axis hyperactivity, as demonstrated by enhanced adrenal sensitivity to ACTH, occurs in AD. Similar findings have been reported to occur in depression. Among AD subjects, AUC cortisol response correlated with current age (r = 0.70, P = 0.001) and age at onset of dementia (r = 0.73, P = 0.001) and an inverse correlation was seen between cortisol AUC and cognitive test (CAMCOG) score (r = -0.51, P = 0.044). Our findings suggest that HPA axis hyperactivity in AD is associated with advancing age and cognitive dysfunction. Such changes may be cause, or consequence, of neuronal loss.