Hypercortisolism and its possible neural bases

The Effect of Physical Exercise on Cognitive Impairment in Neurodegenerative Disease: From Pathophysiology to Clinical and Rehabilitative Aspects

Neurodegenerative diseases are a group of pathologies that cause severe disability due to motor and cognitive limitations. In particular, cognitive impairment is a growing health and socioeconomic problem which is still difficult to deal with today. As there are no pharmacologically effective treatments for cognitive deficits, scientific interest is growing regarding the possible impacts of healthy lifestyles on them. In this context, physical activity is gaining more and more evidence as a primary prevention intervention, a nonpharmacological therapy and a rehabilitation tool for improving cognitive functions in neurodegenerative diseases. In this descriptive overview we highlight the neurobiological effects of physical exercise, which is able to promote neuroplasticity and neuroprotection by acting at the cytokine and hormonal level, and the consequent positive clinical effects on patients suffering from cognitive impairment.

Increased serum cortisol is associated with alterations in cross-sectional and topographic OCT parameters in diabetic retinopathy: a preliminary study

PURPOSE

Cortisol, a steroid hormone, plays an essential role in metabolic processes of diabetes mellitus. This study for the first time evaluated the association of serum cortisol with spectral domain optical coherence tomography (SD-OCT)-based cross-sectional and topographic parameters with severity of diabetic retinopathy (DR).

METHODS

A tertiary care center-based preliminary study was undertaken. Fourteen consecutive cases of DR and fifteen healthy controls were included. Cases were graded according to ETDRS classification: non-proliferative DR (NPDR, n = 8) and proliferative DR (PDR, n = 6). All study subjects underwent complete ophthalmological evaluation. Serum cortisol was analyzed using chemiluminescence microparticle assay method. Central subfield thickness (CST), cube average thickness (CAT), cube volume (CV), retinal nerve fiber layer (RNFL) thickness, disorganization of inner retinal layers (DRIL), grade of retinal photoreceptor ellipsoid zone (EZ) disruption and grade of retinal pigment epithelium (RPE) alterations were evaluated using SD-OCT. Statistical analysis was done using ANOVA and Pearson's correlation analysis.

RESULTS

Mean serum cortisol levels (µg/dL) were NPDR = 11.59 ± 0.42, PDR = 14.50 ± 0.26 and controls = 8.22 ± 0.77. With increasing severity of DR, mean CST, CAT, CV showed positive correlation, whereas mean RNFL thickness showed negative correlation with serum cortisol levels (p < 0.01). DRIL, EZ disruption and RPE alterations showed positive correlation with serum cortisol levels (p < 0.001).

CONCLUSION

Serum cortisol levels are significantly associated with severity of DR and correlate positively with CST, CAT, CV, DRIL, EZ disruption and RPE alterations and negatively with RNFL thickness.

Circulating cortisol and cognitive and structural brain measures: The Framingham Heart Study

OBJECTIVE

To assess the association of early morning serum cortisol with cognitive performance and brain structural integrity in community-dwelling young and middle-aged adults without dementia.

METHODS

We evaluated dementia-free Framingham Heart Study (generation 3) participants (mean age 48.5 years, 46.8% men) who underwent cognitive testing for memory, abstract reasoning, visual perception, attention, and executive function (n = 2,231) and brain MRI (n = 2018) to assess total white matter, lobar gray matter, and white matter hyperintensity volumes and fractional anisotropy (FA) measures. We used linear and logistic regression to assess the relations of cortisol (categorized in tertiles, with the middle tertile as referent) to measures of cognition, MRI volumes, presence of covert brain infarcts and cerebral microbleeds, and voxel-based microstructural white matter integrity and gray matter density, adjusting for age, sex, APOE, and vascular risk factors.

RESULTS

Higher cortisol (highest tertile vs middle tertile) was associated with worse memory and visual perception, as well as lower total cerebral brain and occipital and frontal lobar gray matter volumes. Higher cortisol was associated with multiple areas of microstructural changes (decreased regional FA), especially in the splenium of corpus callosum and the posterior corona radiata. The association of cortisol with total cerebral brain volume varied by sex (p for interaction = 0.048); higher cortisol was inversely associated with cerebral brain volume in women (p = 0.001) but not in men (p = 0.717). There was no effect modification by the APOE4 genotype of the relations of cortisol and cognition or imaging traits.

CONCLUSION

Higher serum cortisol was associated with lower brain volumes and impaired memory in asymptomatic younger to middle-aged adults, with the association being evident particularly in women.

Melatonin attenuates phenotypic flexibility of energy metabolism in a photoresponsive mammal, the Siberian hamster

The duration of melatonin (MEL) secretion conveys information about day length and initiates a cascade of seasonal phenotypic adjustments in photoresponsive mammals. With shortening days, animals cease reproduction, minimize energy expenditure, enhance thermoregulatory capacity and adjust functioning of the hypothalamic-pituitary-adrenal (HPA) axis to match the winter increase in energy demands. Within each season, stress plays an important role in the flexible adjustments of a phenotype to environmental perturbations. Recent studies have shown that thermal reaction norms of energy metabolism were narrower in winter-acclimated Siberian hamsters, Phodopus sungorus We tested the hypothesis that physiological changes occurring in response to prolonged MEL signals, including changes in the secretion of stress hormones, are responsible for the seasonal decrease in phenotypic flexibility of energy metabolism in photoresponsive mammals. To quantify reaction norms for basal metabolic rate (BMR) and cortisol (CORT) secretion, male Siberian hamsters maintained at a long (16 h:8 h light:dark) photoperiod were acclimated repeatedly for 12 days to 10 and 28°C. As predicted, the phenotypic flexibility of BMR decreased when animals were supplemented with MEL. However, at the same time, mean CORT concentration and the reaction norm for its secretion in response to changes in acclimation temperature increased. These results suggest that decreased sensitivity of HPA axis to CORT signal, rather than changes in CORT level itself, is responsible for the decreased phenotypic flexibility in photoresponsive species. Our results suggest that decreased phenotypic flexibility in winter, together with increased stress hormone secretion, make photosensitive species more vulnerable to climate change.

Biological markers for anxiety disorders, OCD and PTSD: A consensus statement. Part II: Neurochemistry, neurophysiology and neurocognition

OBJECTIVE

Biomarkers are defined as anatomical, biochemical or physiological traits that are specific to certain disorders or syndromes. The objective of this paper is to summarise the current knowledge of biomarkers for anxiety disorders, obsessive-compulsive disorder (OCD) and posttraumatic stress disorder (PTSD).

METHODS

Findings in biomarker research were reviewed by a task force of international experts in the field, consisting of members of the World Federation of Societies for Biological Psychiatry Task Force on Biological Markers and of the European College of Neuropsychopharmacology Anxiety Disorders Research Network.

RESULTS

The present article (Part II) summarises findings on potential biomarkers in neurochemistry (neurotransmitters such as serotonin, norepinephrine, dopamine or GABA, neuropeptides such as cholecystokinin, neurokinins, atrial natriuretic peptide, or oxytocin, the HPA axis, neurotrophic factors such as NGF and BDNF, immunology and CO2 hypersensitivity), neurophysiology (EEG, heart rate variability) and neurocognition. The accompanying paper (Part I) focuses on neuroimaging and genetics.

CONCLUSIONS

Although at present, none of the putative biomarkers is sufficient and specific as a diagnostic tool, an abundance of high quality research has accumulated that should improve our understanding of the neurobiological causes of anxiety disorders, OCD and PTSD.

Aging and the HPA axis: Stress and resilience in older adults

Hypothalamic-pituitary-adrenal (HPA) axis function may change over the course of aging, and altered diurnal or stress-induced secretion of the hormone cortisol could predispose older adults to negative health outcomes. We propose that psychological resilience may interact with diurnal cortisol to affect health outcomes later in life. Emotion regulation and social support are two constructs that contribute to resilience and exhibit age-specific patterns in older adults. Determining how the use of resilience resources interacts with age-related diurnal cortisol will improve our understanding of the pathways between stress, resilience, and well-being. In this review, we assess published studies evaluating diurnal cortisol in older adults to better understand differences in their HPA axis functioning. Evidence thus far suggests that diurnal cortisol may increase with age, although cross-sectional studies limit the conclusions that can be drawn. We also review extant evidence connecting age-specific signatures of emotion regulation and social support with diurnal cortisol. Conclusions are used to propose a preliminary model demonstrating how resilience resources may modulate the effects of cortisol on health in aging.

Prolonged secretion of cortisol as a possible mechanism underlying stress and depressive behaviour

Stress is associated with the onset of depressive episodes, and cortisol hypersecretion is considered a biological risk factor of depression. However, the possible mechanisms underlying stress, cortisol and depressive behaviours are inconsistent in the literature. This study examined the interrelationships among stress, cortisol and observed depressive behaviours in female rhesus macaques for the first time and explored the possible mechanism underlying stress and depressive behaviour. Female monkeys were video-recorded, and the frequencies of life events and the duration of huddling were analysed to measure stress and depressive behaviour. Hair samples were used to measure chronic cortisol levels, and the interactions between stress and cortisol in the development of depressive behaviour were further evaluated. Significant correlations were found between stress and depressive behaviour measures and between cortisol levels and depressive behaviour. Stress was positively correlated with cortisol levels, and these two factors interacted with each other to predict the monkeys’ depressive behaviours. This finding extends the current understanding of stress/cortisol interactions in depression, especially pertaining to females.

Salivary cortisol, brain volumes, and cognition in community-dwelling elderly without dementia

OBJECTIVE

We investigated the associations of morning and evening salivary cortisol levels with regional brain volumes and cognitive functioning in community-dwelling older persons without dementia.

METHOD

From the Age, Gene/Environment Susceptibility (AGES)-Reykjavik Study, we included 4,244 persons without dementia (age 76 ± 5 years, 58% women) who had 1.5T brain MRI, assessment of cognitive functioning, and saliva collected at home 45 minutes after awakening and at night. Linear regression analysis was used to estimate the cross-sectional relationship among cortisol levels, brain volumes, and cognitive functioning, adjusting for covariates.

RESULTS

Higher evening cortisol was associated with smaller total brain volume (highest vs lowest tertile -16.0 mL; 95% confidence interval -19.7 to -12.2 mL, adjusted for age, sex, education, intracranial volume, smoking, steroid use, white matter lesions, and brain infarcts on MRI). The smaller volumes were observed in all brain regions, but were significantly smaller in gray matter than in white matter regions. Poorer cognitive functioning across all domains was also associated with higher evening cortisol. Higher levels of morning cortisol were associated with slightly greater normal white matter volume and better processing speed and executive functioning, but not with gray matter volume or with memory performance.

CONCLUSIONS

In older persons, evening and morning cortisol levels may be differentially associated with tissue volume in gray and white matter structures and cognitive function. Understanding these differential associations may aid in developing strategies to reduce the effects of hypothalamic-pituitary-adrenal axis dysfunction on late-life cognitive impairment.

Cross-cultural gene- environment interactions in depression, post-traumatic stress disorder, and the cortisol awakening response: FKBP5 polymorphisms and childhood trauma in South Asia

Despite increased attention to global mental health, psychiatric genetic research has been dominated by studies in high-income countries, especially with populations of European descent. The objective of this study was to assess single nucleotide polymorphisms (SNPs) in the FKBP5 gene in a population living in South Asia. Among adults in Nepal, depression was assessed with the Beck Depression Inventory (BDI), post-traumatic stress disorder (PTSD) with the PTSD Checklist-Civilian Version (PCL-C), and childhood maltreatment with the Childhood Trauma Questionnaire (CTQ). FKBP5 SNPs were genotyped for 682 participants. Cortisol awakening response (CAR) was assessed in a subsample of 118 participants over 3 days. The FKBP5 tag-SNP rs9296158 showed a main effect on depressive symptoms (p = 0.03). Interaction of rs9296158 and childhood maltreatment predicted adult depressive symptoms (p = 0.02) but not PTSD. Childhood maltreatment associated with endocrine response in individuals homozygous for the A allele, demonstrated by a negative CAR and overall hypocortisolaemia in the rs9296158 AA genotype and childhood maltreatment group (p < 0.001). This study replicated findings related to FKBP5 and depression but not PTSD. Gene-environment studies should take differences in prevalence and cultural significance of phenotypes and exposures into account when interpreting cross-cultural findings.

Long-term effects of maternal separation on the responsiveness of the circadian system to melatonin in the diurnal nonhuman primate (Macaca mulatta)

Depression is often linked to early-life adversity and circadian disturbances. Here, we assessed the long-term impact of early-life adversity, particularly preweaning mother-infant separation, on the circadian system's responsiveness to a time giver or synchronizer (Zeitgeber). Mother-reared (MR) and peer-reared (PR) rhesus monkeys were subjected to chronic jet-lag, a forced desynchrony protocol of 22 hr T-cycles [11:11 hr light:dark (LD) cycles] to destabilize the central circadian organization. MR and PR monkeys subjected to the T-cycles showed split locomotor activity rhythms with periods of ~22 hr (entrained) and ~24 hr (free-running), simultaneously. Continuous melatonin treatment in the drinking water (20 μg/mL) gradually increased the amplitude of the entrained rhythm at the expense of the free-running rhythm, reaching complete entrainment by 1 wk. Upon release into constant dim light, a rearing effect on anticipation for both the predicted light onset and food presentation was observed. In MR monkeys, melatonin did not affect the amplitude of anticipatory behavior. Interestingly, however, PR macaques showed light onset and food anticipatory activities in response to melatonin treatment. These results demonstrate for the first time a rearing-dependent effect of maternal separation in macaques, imprinting long-term plastic changes on the circadian system well into late adulthood. These effects could be counteracted by the synchronizer molecule melatonin. We conclude that the melatonergic system is targeted by early-life adversity of maternal separation and that melatonin supplementation ameliorates the negative impact of stress on the circadian system.

Effect of selective serotonin reuptake inhibitors and immunomodulator on cytokines levels: an alternative therapy for patients with major depressive disorder

Major depressive disorder (MDD) is a psychiatric illness that presents as a deficit of serotonergic neurotransmission in the central nervous system. MDD patients also experience alterations in cortisol and cytokines levels. Treatment with selective serotonin reuptake inhibitors (SSRIs) is the first-line antidepressant regimen for MDD. The aim of this study was to determine the effect of a combination of SSRIs and an immunomodulator-human dialyzable leukocyte extract (hDLE)-on cortisol and cytokines levels. Patients received SSRIs or SSRIs plus hDLE. The proinflammatory cytokines IL-1 β , IL-2, and IFN- γ ; anti-inflammatory cytokines IL-13 and IL-10; and 24-h urine cortisol were measured at weeks (W) 0, 5, 20, 36, and 52 of treatment. The reduction in cortisol levels in the SSRI-treated group was 30% until W52, in contrast, the combined treatment induced a 54% decrease at W36. The decline in cortisol in patients who were treated with SSRI plus hDLE correlated with reduction of anti-inflammatory cytokines and increases levels of proinflammatory cytokines at the study conclusion. These results suggest that the immune-stimulating activity of hDLE, in combination with SSRIs, restored the pro- and anti-inflammatory cytokine balance and cortisol levels in depressed patients versus those who were given SSRIs alone.

Chronic deep brain stimulation of the hypothalamic nucleus in wistar rats alters circulatory levels of corticosterone and proinflammatory cytokines

Deep brain stimulation (DBS) is a therapeutic option for several diseases, but its effects on HPA axis activity and systemic inflammation are unknown. This study aimed to detect circulatory variations of corticosterone and cytokines levels in Wistar rats, after 21 days of DBS-at the ventrolateral part of the ventromedial hypothalamic nucleus (VMHvl), unilateral cervical vagotomy (UCVgX), or UCVgX plus DBS. We included the respective control (C) and sham (S) groups (n = 6 rats per group). DBS treated rats had higher levels of TNF-α (120%; P < 0.01) and IFN-γ (305%; P < 0.001) but lower corticosterone concentration (48%; P < 0.001) than C and S. UCVgX animals showed increased corticosterone levels (154%; P < 0.001) versus C and S. UCVgX plus DBS increased IL-1β (402%; P < 0.001), IL-6 (160%; P < 0.001), and corsticosterone (178%; P < 0.001 versus 48%; P < 0.001) compared with the C and S groups. Chronic DBS at VMHvl induced a systemic inflammatory response accompanied by a decrease of HPA axis function. UCVgX rats experienced HPA axis hyperactivity as result of vagus nerve injury; however, DBS was unable to block the HPA axis hyperactivity induced by unilateral cervical vagotomy. Further studies are necessary to explore these findings and their clinical implication.

Validation of a fecal glucocorticoid metabolite assay for collared peccaries (Pecari tajacu)

The possibility of assessing endogenous adrenal activity in the collared peccary (Pecari tajacu) was tested by using an adrenocorticotropic hormone (ACTH) challenge in a fecal glucocorticoid metabolite (FGM) assay. Feces were collected from 12 captive adult male peccaries beginning 48 hr prior to challenge; six of these animals received the challenge as an ACTH injection and the other six were injected with saline solution. Feces collection ended 120 hr after injections. As a control, feces were collected for eight consecutive days from another six adult male peccaries that remained in their original mixed-sex herds in semiconfined paddocks. All feces samples were freeze-dried, extracted by an ethanol vortex method, and assayed for glucocorticoids by means of an enzyme immunoassay. FGM concentrations were compared between the treatments by a repeated measures analysis of variance (ANOVA) followed by a post hoc Tukey test. The assay is reliable but, instead of the usual proportion of 1:50 in ethanol (fecal mass:solvent), 1:10 is recommended for best extraction of FGM. Baseline FGM concentrations were similar among the ACTH, saline, and control treatments (29.7 +/- 11.2 ng/g(-1) dry feces) during the 48 hr before the challenge. The ACTH group reached an FGM excretion peak at 24 hr post-treatment, followed by a decline, while in the control and saline groups FGM levels remained relatively constant. Therefore, the fecal glucocorticoid metabolite assay reflects endogenous adrenal activity in the collared peccary and is a powerful tool for noninvasive stress monitoring in peccaries.

Corticosteroids: way upstream

Studies into the mechanisms of corticosteroid action continue to be a rich bed of research, spanning the fields of neuroscience and endocrinology through to immunology and metabolism. However, the vast literature generated, in particular with respect to corticosteroid actions in the brain, tends to be contentious, with some aspects suffering from loose definitions, poorly-defined models, and appropriate dissection kits. Here, rather than presenting a comprehensive review of the subject, we aim to present a critique of key concepts that have emerged over the years so as to stimulate new thoughts in the field by identifying apparent shortcomings. This article will draw on experience and knowledge derived from studies of the neural actions of other steroid hormones, in particular estrogens, not only because there are many parallels but also because 'learning from differences' can be a fruitful approach. The core purpose of this review is to consider the mechanisms through which corticosteroids might act rapidly to alter neural signaling.

Differential expression of immunophilins FKBP51 and FKBP52 in the frontal cortex of HIV-infected patients with major depressive disorder

Patients infected with human immunodeficiency virus (HIV) have a higher risk of developing major depressive disorder (MDD) than the general population. Immunophilins FKBP51 and FKBP52 are expressed in cortical neurons and regulate the function of the glucocorticoid receptor (GR). Previous reports have shown that genetic variants in the FKBP5 gene encoding FKBP51 are linked to psychiatric disorders. We sought to determine whether immunophilins are upregulated in HIV infection. To determine whether FKBP52 and FKBP51 are associated with MDD and/or HIV, we compared protein and gene expression in autopsy tissues from the frontal cortical gray matter. The study cases were divided into five groups: control, MDD, MDD with psychosis, HIV(+), and HIV(+) with MDD. Gene expression and protein levels were determined by real-time PCR and Western blot analysis of fresh frozen tissues. Genotyping of previously published alleles of the FKBP5 gene was also performed. We found correlation of upregulation of both immunophilins in the HIV-infected groups. In the HIV(+) population with MDD, FKBP4 expression is significantly higher while FKBP5 is more variable. After analyzing the FKBP5 gene for single nucleotide polymorphisms, we found that rs3800373 CC genotype is more frequent in the MDD and MDD/Psychosis groups. We hypothesized that the levels of FKBP51, as modulator of the nuclear translocation of GR, would be lower in MDD. Instead, an increase in FKBP51 at both the transcript (FKBP5) and protein level correlated with MDD. Increased FKBP4 expression of correlated to HIV(+)MDD but not to HIV without MDD.

Variations in circulating cytokine levels during 52 week course of treatment with SSRI for major depressive disorder

Major depressive disorder (MDD) is a psychiatric condition characterized by hypercortisolism and variations in circulatory cytokines. Previously it has been reported that administration of selective serotonin reuptake inhibitors (SSRI) in MDD patients modify cortisol and cytokine levels but these studies only evaluated changes over a short time period. This work reports the long-term effects of administration of SSRI on the cortisol levels and pro-/anti-inflammatory cytokine profile in a group of MDD patients treated for 52 weeks. A total of 31 patients diagnosed with MDD received anti depressant treatment with SSRI. HDRS and BDI were administered over a year, and levels of interleukin IL-1beta, IL-10, IL-2, IFN-gamma, IL-4, IL-13, and 24-h urine cortisol were determined at weeks (W) 0, 5, 20, 36 and 52 of treatment. Before treatment we found high levels of cortisol, IL-4, IL-13 (Th2) and IL-10 in MDD patients when compared with healthy volunteers. At W20 psychiatric scales indicated a remission of the depressive episode concomitantly with increments in IL-2 and IL-1beta but without changes in cortisol. Towards the end of the treatment (W52) we observed a significant reduction (p<0.01) in cortisol levels, with an increment in IL-1beta and IFN-gamma and a decrease in Th2 cytokines. Our results suggest that depressed patients only reach a partial reestablishment of HPA axis function after the long-term administration of SSRI.

Stress-induced changes in corticosteroid receptor expression in primate hippocampus and prefrontal cortex

Neurobiological studies of stress often focus on the hippocampus where cortisol binds with different affinities to two types of corticosteroid receptors, i.e., mineralocorticoid receptor (MR) and glucocorticoid receptor (GR). The hippocampus is involved in learning and memory, and regulates the neuroendocrine stress response, but other brain regions also play a role, especially prefrontal cortex. Here, we examine MR and GR expression in adult squirrel monkey prefrontal cortex and hippocampus after exposure to social stress in infancy or adulthood. In situ hybridization histochemistry with (35)S-labeled squirrel monkey riboprobes and quantitative film autoradiography were used to measure the relative distributions of MR and GR mRNA. Distinct cortical cell layer-specific patterns of MR expression differed from GR expression in three prefrontal regions. The relative distributions of MR and GR also differed in hippocampal Cornu Ammonis (CA) regions. In monkeys exposed to adult social stress compared to the no-stress control, GR expression was diminished in hippocampal CA1 (P=0.021), whereas MR was diminished in cell layer III of ventrolateral prefrontal cortex (P=0.049). In contrast, exposure to early life stress diminished GR but not MR expression in cell layers I and II of dorsolateral prefrontal cortex (P's<0.048). Similar reductions likewise occurred in ventrolateral prefrontal cortex, but the effects of early life stress on GR expression in this region were marginally not significant (P=0.053). These results provide new information on regional differences and the long-term effects of stress on MR and GR distributions in corticolimbic regions that control cognitive and neuroendocrine functions.

Preliminary evidence that hippocampal volumes in monkeys predict stress levels of adrenocorticotropic hormone

BACKGROUND

Hippocampal volumes previously determined in monkeys by magnetic resonance imaging are used to test the hypothesis that small hippocampi predict increased stress levels of adrenocorticotropic hormone (ACTH).

METHODS

Plasma ACTH levels were measured after restraint stress in 19 male monkeys pretreated with saline or hydrocortisone. Monkeys were then randomized to an undisturbed control condition or intermittent social separations followed by new pair formations. After 17 months of exposure to the intermittent social manipulations, restraint stress tests were repeated to determine test/retest correlations.

RESULTS

Individual differences in postrestraint stress ACTH levels over the 17-month test/retest interval were remarkably consistent for the saline (r(s) = .82, p = .0004) and hydrocortisone (r(s) = .78, p = .001) pretreatments. Social manipulations did not affect postrestraint stress ACTH levels, but monkeys with smaller hippocampal volumes responded to restraint after saline pretreatment with greater increases in ACTH levels with total brain volume variation controlled as a statistical covariate (beta = -.58, p = .031). Monkeys with smaller hippocampal volumes also responded with diminished sensitivity to glucocorticoid feedback determined by greater postrestraint ACTH levels after pretreatment with hydrocortisone (beta = -.68, p = .010).

CONCLUSIONS

These findings support clinical reports that small hippocampi may be a risk factor for impaired regulation of the hypothalamic-pituitary-adrenal axis in humans with stress-related psychiatric disorders.

Intrahypothalamic neuroendocrine actions of corticotropin-releasing factor

Most studies of the neuroendocrine effects of corticotropin-releasing factor (CRF) have focused on its role in the regulation of the pituitary-adrenal axis; activation of this axis follows release of the peptide from CRF-containing terminals in the median eminence. However, a sizeable proportion of CRF fibres terminate within the hypothalamus itself, where synaptic contacts with other hypothalamic neuropeptidergic neurons (e.g. gonadotropin-releasing hormone-containing and opioidergic neurons) have been identified. Here, we summarize physiological and pharmacological data which provide insights into the nature and significance of these intrahypothalamic connections. It is now clear that CRF is a potent secretagogue of the three major endogenous opioid peptides (beta-endorphin, Met-enkephalin and dynorphin) and that it stimulates opioidergic neurons tonically. In the case of beta-endorphin, another hypothalamic peptide, arginine vasopressin, appears to be an essential mediator of CRF's effect, suggesting the occurrence of CRF synapses on, or in the vicinity of, vasopressin neurons; morphological support for this assumption is still wanting. Evidence for direct and indirect inhibitory effects of CRF on sexual behaviour and secretion of reproductive hormones is also presented; the indirect pathways include opioidergic neurons. An important conclusion from all these studies is that, in addition to its better known functions in producing adaptive responses during stressful situations, CRF might also contribute to the coordinated functioning of various components of the neuroendocrine system under basal conditions. Although feedback regulation of hypothalamic neuronal activity by peripheral steroids is a well-established tenet of endocrinology, data on modulation of the intrahypothalamic actions of CRF by adrenal and sex steroids are just emerging. Some of these newer findings may be useful in framing questions related to the mechanisms underlying disease states (such as depressive illness) in which CRF has been strongly implicated.

Hormonal differences between psychotic and non-psychotic melancholic depression

BACKGROUND

The dexamethasone suppression test (DST) is the main hormonal disturbance in psychotic depression compared to non-psychotic depression. However, although there have been many studies of individual hormonal axes in depression, few multi-axial studies have been reported. This study aims to examine hormonal differences between these groups of patients through three functional hormonal tests: DST, thyroid stimulating hormone response to thyroid releasing hormone (TSH-TRF) and growth hormone response to growth hormone releasing factor (GH-GRF).

METHODS

Forty inpatients meeting DSM-III-R criteria for major depressive episode with melancholia (21 non-psychotic and 19 psychotic) were studied. Dexamethasone suppression test, TSH-TRF and GH-GRF tests were undertaken for all patients.

RESULTS

In the whole melancholic sample, 80.0% showed disturbances in at least one hormonal axis, 40.0% in two axes and 5.0% in all three axes. Basal and post-dexamethasone cortisol levels were significantly higher in psychotic than in non-psychotic patients. An association between post-dexamethasone cortisol and blunted GH-GRF response was demonstrated in those with psychotic depression. In the whole sample, GH blunting was found in 62.5% of patients, DST non-suppression in 37.5% and TSH blunting in 25.0% (no differences were found between psychotic and non-psychotic patients).

LIMITATIONS

Sample was restricted to melancholia and unknown factors may influence hormonal responses to stress.

CONCLUSIONS

Hormonal disturbances in depression are more evident when studying several axes, being the HPA and the GH axes the most prominents. Psychotic depression showed more HPA disturbance than non-psychotic depression. Influence of the HPA on the GH axis is discussed.

Is depression different in older adults?

Psychiatric disorders such as depression are common conditions in older adults. Depression presents similarly to younger adults, but with more psychotic symptoms and apathy. Research has suggested that genetics play a less important role in the etiology of depression in the elderly, but that other biological factors may be more significant. Vascular pathology in particular is thought to be especially important. White-matter hyperintensities are found in the frontal lobes and basal ganglia in greater numbers in older adults with depression, with damage to the frontal–subcortical circuits thought to be particularly important. It is associated with treatment resistance. Prognosis is poor if depression is not detected and treated adequately and this may lead to a higher risk of dementia and death. However, treatment with selective serotonin reuptake inhibitors and other antidepressants, plus psychological therapies, are effective in the older depressed patient and reduce morbidity and mortality.

Schizophrenia and violence: a search for neurobiological correlates

PURPOSE OF REVIEW

Compelling evidence suggests that a small group of men who develop schizophrenia display a stable pattern of antisocial behaviour from childhood onwards, causing considerable suffering to victims and to themselves and imposing a significant financial burden on society. We reviewed the literature on the neurobiological correlates of antisocial behaviour and violence to further the understanding of this subgroup of persons with schizophrenia and develop testable hypotheses for future research.

RECENT FINDINGS

Few studies have been conducted, sample sizes are small and measures vary greatly. Taken together, the results suggest that among men with schizophrenia, those who have displayed a stable pattern of antisocial and aggressive behaviour since childhood, as compared with those with no such history, perform better on neuropsychological tests tapping specific executive functions and more poorly on assessments of orbitofrontal functions. We hypothesize that individuals in this subgroup are less compromised neurologically and display structural brain abnormalities in the amygdala-orbitofrontal system and in the prefrontal cortex and hippocampus.

SUMMARY

A better understanding of the distinctive neurobiological characteristics of this subgroup of men with schizophrenia will contribute to developing treatments tailored to their needs, to prevent antisocial behaviours and to reduce the symptoms of schizophrenia.

Neurobiological correlates of violent behavior among persons with schizophrenia

Men and women who develop schizophrenia are at increased risk, compared with the general population, to engage in violence toward others. The reasons for this robust finding remain obscure. We undertook a review of studies comparing neuropsychological test performance, neurological soft signs, and structural brain images of persons with schizophrenia with and without a history of violence. Our search identified 17 studies. The results are inconsistent and contradictory, mainly due to varying definitions of violence, differences in sample characteristics, and the use of diverse measures to tap the neurobiological correlates of violent behavior. The results suggest, however, that among men with schizophrenia, those who have displayed a stable pattern of antisocial and aggressive behavior since childhood, as compared with those with no such history, perform better on neuropsychological tests tapping specific executive functions and more poorly on assessments of orbitofrontal functions, show fewer neurological soft signs, and display larger reductions in volume of the amygdalae, more structural abnormalities of the orbitofrontal system, more abnormalities of white matter in the amygdala-orbitofrontal system, and smaller reductions in volumes of the hippocampus.

The HPA and immune axes in stress: the involvement of the serotonergic system

The impact of acute and chronic stress on the hypothalamic-pituitary-adrenal (HPA) axis is reviewed and evidence presented that corticotrophin releasing factor (CRF) is the stress neurotransmitter which plays an important role in the activation of the central sympathetic and serotonergic systems. The activity of CRF is expressed through specific receptors (CRF 1 and 2) that are antagonistic in their actions and widely distributed in the limbic regions of the brain, as well as in the hypothalamus, and on immune cells. The mechanism whereby chronic stress, via the CRF induced activation of the dorsal raphe nucleus, can induce a change in the serotonergic system, involves an increase in the 5HT2A and a decrease in the 5HT1A receptor mediated function. Such changes contribute to the onset of anxiety and depression. In addition, the hypersecretion of glucocorticoids that is associated with chronic stress and depression desensitises the central glucocorticoid receptors to the negative feedback inhibition of the HPA axis. This indirectly results in the further activation of the HPA axis. The rise in pro-inflammatory cytokines that usually accompanies the chronic stress response results in a further stimulation of the HPA axis thereby adding to the stress response. While CRF would appear to play a pivotal role, evidence is provided that simultaneous changes in the serotonergic and noradrenergic systems, combined with the activation of peripheral and central macrophages that increase the pro-inflammatory cytokine concentrations in the brain and blood, also play a critical role in predisposing to anxiety and depression. Neurodegenerative changes in the brain that frequently occur in the elderly patient with major depression, could result from the activation of indoleaminedioxygenase (IDO), a widely distributed enzyme that converts tryptophan via the kynenine pathway to for the neurotoxic end product quinolinic acid.

Choline exposure reduces potentiation of N-methyl-D-aspartate toxicity by corticosterone in the developing hippocampus

Exposure to high levels of glucocorticoids (GCs) may adversely affect neuronal viability, particularly in the developing hippocampus, via increased function or sensitivity of N-methyl-D-aspartate (NMDA)-type glutamate receptors. Conversely, choline supplementation in the developing brain may reduce the severity of subsequent insult. The present studies aimed to examine the extent to which short-term exposure to high concentrations of corticosterone would produce neuronal injury mediated by NMDA receptor activity. These studies also assessed the ability of choline to prevent this form of injury via interactions with nicotinic acetylcholine receptors (nAChRs) expressing the alpha7 subunit. Organotypic hippocampal slice cultures derived from neonatal rat were pre-treated for 72 h with corticosterone (100 nM) alone or with choline (0.1-10 mM), prior to a brief (1 h) NMDA exposure (5 microM). NMDA exposure produced significant cellular damage, reflected as increased fluorescence of the non-vital marker propidium iodide, in the CA1 region. While exposure to corticosterone alone did not produce damage, pre-treatment of cultures with corticosterone markedly exacerbated NMDA-induced toxicity. Pre-treatment with choline (> or =1 mM) alone or in combination with corticosterone markedly reduced subsequent NMDA toxicity, effects blocked by co-exposure to methyllycaconitine (100 nM), an antagonist active at nAChRs expressing the alpha7 subunit. These data suggest that even short-term exposure to high concentrations of GCs may adversely affect neuronal viability and that choline supplementation protects the brain from NMDA receptor-mediated damage, including that associated with hypercortisolemia.

Neurotropic action of androgens: principles, mechanisms and novel targets

The importance of androgen signaling is well recognized for numerous aspects of central nervous system (CNS) function, ranging from sex-specific organization of neuroendocrine and behavioral circuits to adaptive capacity, resistance and repair. Nonetheless, concepts for the therapeutic use of androgens in neurological and mental disorders are far from being established. This review outlines some critical issues which interfere with decisions on the suitability of androgens as therapeutic agents for CNS conditions. Among these, sex-specific organization of neural substrates and resulting differential responsiveness to endogenous gonadal steroids, convergence of steroid hormone actions on common molecular targets, co-presence of different sex steroid receptors in target neuronal populations, and in situ biotransformation of natural androgens apparently pose the principal obstacles for the characterization of specific neurotropic effects of androgens. Additional important, albeit less explored aspects consist in insufficient knowledge about molecular targets in the CNS which are under exclusive or predominant androgen control. Own experimental data illustrate the variability of pharmacological effects of natural and synthetic androgens on CNS functions of adaptive relevance, such as sexual behavior, anxiety and endocrine responsiveness to stress. Finally, we present results from an analysis of the consequences of aging for the rat brain transcriptome and examination of the influence of androgens on differentially expressed genes with presumable significance in neuropathology.

Endocrine response to surgical stress and postoperative confusion in depressed patients with alcohol abuse

Both alcohol drinking and depression are risk factors for postoperative confusion and are associated with alteration of pituitary-adrenal function. We investigated the incidence of postoperative confusion, plasma cortisol and ACTH response to surgical stress in depressed patients with alcohol abuse. We studied sixty depressed patients with and without alcohol abuse who underwent abdominal surgery. Postoperative confusion occurred in 4 of 30 patients (13%) in depressed patients without alcohol abuse, 10 of 30 patients (33%) in depressed patients with alcohol abuse. Plasma cortisol concentrations (27.2 +/- 7.0, 28.3 +/- 8.2, 29.2 +/- 4.1, 28.0 +/- 6.3 and 27.9 +/- 5.7 microg dl(-1)) 15, 60 min after the skin incision, 60 min after the end of surgery, the next day and the third day after surgery in depressed patients with alcohol abuse were significantly higher than that (20.1 +/- 6.4, 21.7 +/- 9.6, 22.3 +/- 8.0, 21.9 +/- 6.7 and 20.3 +/- 5.4 microg dl(-1)) in depressed patients without alcohol abuse. In depressed patients with alcohol abuse, plasma cortisol concentrations (34.9 +/- 7.1, 33.2 +/- 5.8 and 33.4 +/- 5.5 microg dl(-1)) 60 min after the end of surgery, the next day and third day after surgery in postoperatively confused depressed patients were significantly higher than those (26.4 +/- 6.3, 25.4 +/- 5.0 and 25.2 +/- 4.9 microg dl(-1)) of nonconfused depressed patients. In conclusion, the incidence of postoperative confusion was significantly higher in depressed patients with alcohol abuse than in depressed patients without alcohol abuse. Increased plasma cortisol concentrations after surgery were associated with postoperative confusion in depressed patients with alcohol abuse.

Neuroanatomical circuits modulating fear and anxiety behaviors

OBJECTIVE

Our understanding of the neurobiology of anxiety disorders, although not complete, has advanced significantly with the development and application of genetic, neuroimaging and neurochemical approaches.

METHOD

The neuroanatomical basis of anxiety disorders is reviewed with particular focus on the amygdala and the temporal and prefrontal cortex. The functional anatomical correlates of anxiety disorders such as panic disorder, specific phobias and post-traumatic stress disorder are also discussed.

RESULTS

Functional neuroimaging studies in patients with anxiety disorders have shown neurophysiological abnormalities during symptom provocation tests, implicating the limbic, paralimbic and sensory association regions. The involvement of neurotransmitters such as serotonin and norepinephrine in depressive disorders is well established. Antidepressants that affect these neurotransmitter systems have also been shown to be useful in the treatment and management of patients with anxiety disorders. The role of serotonin and norepinephrine in the pathophysiology of anxiety disorders is reviewed. In addition, the involvement of the stress hormone corticotropin-releasing hormone, the peptide cholecystokinin and the amino acid transmitter gamma-amino butyric acid in anxiety disorders is reviewed.

CONCLUSION

The inconsistency in the results of biologic investigations of anxiety disorders highlights the importance of addressing the neurobiologic heterogeneity inherent within criteria-based, psychiatric diagnoses. Understanding of this heterogeneity will be facilitated by the continued development and application of genetic, neuroimaging and neurochemical approaches that can refine anxiety disorder phenotypes and elucidate the genotypes associated with these disorders. Application of these experimental approaches will also facilitate research aimed at clarifying the mechanisms of anti-anxiety therapies.

(−)-nicotine ameliorates corticosterone's potentiation of N-methyl-d-aspartate receptor-mediated cornu ammonis 1 toxicity

Hypercortisolemia, long-term exposure of the brain to high concentrations of stress hormones (i.e. cortisol), may occur in patients suffering from depression, alcoholism, and other disorders. This has been suggested to produce neuropathological effects, in part, via increased function or sensitivity of N-methyl-d-aspartate (NMDA)-type glutamate receptors. Given that cigarette smoking is highly prevalent in some of these patient groups and nicotine has been shown to reduce toxic consequences of NMDA receptor function, it may be suggested that nicotine intake may attenuate the neurotoxic effects of hypercortisolemia. To investigate this possibility, organotypic hippocampal slice cultures derived from rat were pre-treated with corticosterone (0.001-1 microM) alone or in combination with selective glucocorticoid receptor antagonists for 72-h prior to a brief (1-h) NMDA exposure (5 microM). Pre-treatment with corticosterone (0.001-1 microM) alone did not cause hippocampal damage, while NMDA exposure produced significant cellular damage in the cornu ammonis (CA)1 subregion. No significant damage was observed in the dentate gyrus or CA3 regions following NMDA exposure. Pre-treatment of cultures with corticosterone (0.1-1 microM) markedly exacerbated NMDA-induced CA1 and dentate gyrus region damage. This effect in the CA1 region was prevented by co-administration of the glucocorticoid receptor antagonist RU486 (>or=1 microM), but not spironolactone (1-10 microM), a mineralocorticoid receptor antagonist. In a second series of studies, both acute and pre-exposure of cultures to (-)-nicotine (1-10 microM) significantly reduced NMDA toxicity in the CA1 region. Co-administration of cultures to (-)-nicotine (1-10 microM) with 100 nM corticosterone prevented corticosterone's exacerbation of subsequent CA1 insult. This protective effect of (-)-nicotine was not altered by co-exposure of cultures to 10 microM dihydro-beta-erythroidine but was blocked by co-exposure to 100 nM methyllycaconitine, suggesting the involvement of nicotinic acetylcholine receptors possessing the alpha7* subunit. The present studies suggest a role for hypercortisolemia in sensitizing the hippocampal NMDA receptor system to pathological activation and indicate that prolonged nicotine exposure attenuates this sensitization. Thus, it is possible that one consequence of heavy smoking in those suffering from hypercortisolemia may be a reduction of neuronal injury and sparing of cellular function.

Neuroendocrine aspects of hypercortisolism in major depression

A consistent finding in biological psychiatry is that hypothalamic-pituitary-adrenal (HPA) axis physiology is altered in humans with major depression. These findings include hypersecretion of cortisol at baseline and on the dexamethasone suppression test. In this review, we present a process-oriented model for HPA axis regulation in major depression. Specifically, we suggest that acute depressions are characterized by hypersecretion of hypothalamic corticotropin-releasing factor, pituitary adrenocorticotropic hormone (ACTH), and adrenal cortisol. In chronic depressions, however, enhanced adrenal responsiveness to ACTH and glucocorticoid negative feedback work in complementary fashion so that cortisol levels remain elevated while ACTH levels are reduced. In considering the evidence for hypercortisolism in humans, studies of nonhuman primates are presented and their utility and limitations as comparative models of human depression are discussed.

Metyrapone-induced glucocorticoid depletion modulates tyrosine hydroxylase and phenylethanolamine N-methyltransferase gene expression in the rat adrenal gland by a noncholinergic transsynaptic activation

The hypothalamic corticotropin-releasing hormone system and the sympathetic nervous system are anatomically and functionally interconnected and hormones of the hypothalamic-pituitary-adrenocortical axis contribute to the regulation of catecholaminergic systems. To investigate the role of glucocorticoids on activity of the adrenal gland, we analysed plasma and adrenal catecholamines, tyrosine hydroxylase (TH) and phenylethanolamine N-methyltransferase (PNMT) mRNA expression in rats injected with metyrapone or dexamethasone. Metyrapone-treated rats had significantly lower epinephrine and higher norepinephrine production than control rats. Metyrapone increased TH protein synthesis and TH mRNA expression whereas its administration did not affect PNMT mRNA expression. Dexamethasone restored plasma and adrenal epinephrine concentrations and increased PNMT mRNA levels, which is consistent with an absolute requirement of glucocorticoids for PNMT expression. Adrenal denervation completely abolished the metyrapone-induced TH mRNA expression. Blockage of cholinergic neurotransmission by nicotinic or muscarinic receptor antagonists did not prevent the metyrapone-induced rise in TH mRNA. Finally, pituitary adenylate cyclase activating polypeptide (PACAP) adrenal content was not affected by metyrapone. These results provide evidence that metyrapone-induced corticosterone depletion elicits transsynaptic TH activation, implying noncholinergic neurotransmission. This may involve neuropeptides other than PACAP.

Anxious-retarded depression: relation with plasma vasopressin and cortisol

Dysregulation of the hypothalamus-pituitary-adrenal (HPA) axis is related to melancholic or endogenous depression; however, the strength of this relationship depends on the definition of the specific depression subcategory. A two-dimensionally defined subcategory, anxious-retarded depression, is related to melancholic depression. Since arginine vasopressin (AVP) activates the HPA axis, and both major depression and the melancholic subcategory are associated with elevated plasma AVP levels, we investigated whether the plasma AVP level is also elevated in anxious-retarded depression, melancholic depression and anxious-retarded melancholic depression, and whether plasma AVP and cortisol levels are correlated in these subcategories. A total of 66 patients with major depression not using oral contraception were investigated. Patients with anxious-retarded depression had a highly significant AVP-cortisol correlation, while no such correlation was found in patients with nonanxious-retarded depression. Log-transformed mean plasma AVP values were higher in patients with anxious-retarded depression than in patients with nonanxious-retarded depression. Patients with anxious-retarded melancholic depression also had a significantly elevated level of plasma AVP and a highly significant correlation between plasma AVP and cortisol levels. The correlation was low in patients with melancholic depression. Anxious-retarded depression may be a useful refinement of the melancholic subcategory with regard to dysregulation of the HPA axis and plasma AVP release.

Further evidence for the central effect of dexamethasone at the hypothalamic level in the negative feedback mechanism

The site of action of glucocorticoids (GC) in exerting negative feedback upon the hypothalamo-pituitary-adrenocortical (HPA) axis is not yet clear. In the present study we have examined whether dexamethasone (Dex) can inhibit the HPA axis stress responses by acting locally at the hypothalamic level in freely moving male rats. Local micro-injection of Dex in the paraventricular nuclei (PVN; 1 microg) prevented a decrease of CRH-41 content in the median eminence. The PVN Dex injections (0.25-1 microg) also inhibited the rise in plasma ACTH and corticosterone (CS) following short photic stimulation in a dose dependent manner. In PVN Dex-injected rats, i.v. injection of CRH-41 increased serum ACTH and CS levels similar to that observed in rats injected with saline into the PVN indicating normal sensitivity of the pituitary gland to CRH-41. Local injection of [3H]Dex in the PVN showed that only a negligible amount of radioactivity was found in the pituitary. These data indicate that minute amounts of Dex in the PVN, which did not affect the pituitary, blocked the HPA axis responses to photic stimulation. It is suggested that Dex may exert its inhibitory effect on the HPA axis at least in part at the hypothalamic level.

Forensic evaluation of trauma syndromes in children

There are significant differences between a clinical evaluation and a forensic evaluation [289-291]. These differences must be kept solidly in mind in performing the evaluation. The forensic evaluator needs to assess the validity of complaints, including the possibility of malingering and the child's ability to describe symptoms accurately, the connection between the symptoms and a given incident, and the potential long-term sequelae of a trauma. The goal of the interview is not to treat, but to obtain information. Assessing the validity of complaints is perhaps the greatest challenge. This requires obtaining and reconciling data from numerous sources, including interviews with the child and parents, and information from other sources, as well as rating scales and validity testing. One must be very cautious in asking leading questions and using standardized PTSD protocols, lest they teach the parents and child about the symptoms of PTSD and thereby distort the information they provide as a result. The forensic interviewer should consider what will be needed when called to testify in court. What data will convince the jury? How might the opposing attorney challenge the assessment? What scientific studies support the findings and conclusions concerning the diagnosis, functional impairment, and validity. The precise DSM-IV-TR diagnosis is not always key in a forensic evaluation. What is essential is establishing the connection between the trauma and ensuing emotional problems. All of the symptoms the individual has as a result of the trauma become important, whether or not they contribute to fulfillment of DSM-IV-TR criteria. This contrasts with a clinical evaluation in which one needs to demonstrate the existence of a DSM-IV-TR diagnosis for reimbursement purposes. Finally, the forensic evaluator should be familiar with current practice guidelines for examination of children with PTSD. Any deviation may need to be explained in court [264,292].

Hydrocortisone induced regional cerebral activity changes in schizophrenia: a PET scan study

BACKGROUND

There is evidence that, even during remission, schizophrenia (SZ) patients are especially vulnerable to de-compensate under stress, and that they tend to have a high baseline serum cortisol levels. This study was undertaken to determine whether raising serum cortisol by the infusion of hydrocortisone, in the absence of additional psychological stress, would result in different cerebral activity changes in schizophrenic patients compared to normal controls (CON). We were especially interested in cerebral activity in regions such as the medial temporal lobe and hippocampus, since structural abnormalities in these brain regions were frequent in association with schizophrenia.

METHODS

Serum cortisol levels were raised, by infusing hydrocortisone, in 8 pairwise-matched SZ patients and 8 CONs. The associated regional cerebral activity changes were analyzed using statistical parametric mapping (SPM).

RESULTS

There was increased regional cerebral activity in response to elevated cortisol in the left hippocampal region in the SZ group, while the controls showed evidence of decreased regional cerebral activity in the same anatomical location. For the rest of the brain regions, cerebral activity increases and decreases, in response to raised serum cortisol, in the SZ followed the same regional pattern as in the control group, but with a smaller overall magnitude of change. The blunted response in SZ was most marked in the regions that showed greatest regional cerebral activity changes in normal subjects.

CONCLUSION

Patients with schizophrenia showed an abnormal increased regional cerebral activity response to cortisol infusion in the left hippocampal region, and similar but attenuated regional cerebral activity response in other regions, when compared to matched controls.

Delirium after coronary bypass surgery evaluated by the organic brain syndrome protocol

OBJECTIVE

The aim was to evaluate symptoms of delirium from a psychogeriatric perspective occurring postoperative to coronary bypass surgery.

DESIGN

Patients, > or = 60 years, scheduled for coronary bypass surgery (n = 52) were enrolled in a prospective descriptive study. The patients were evaluated before and several times after surgery by the Organic Brain Syndrome scale, and delirium was diagnosed according to psychiatric codes.

RESULTS

Of the 52 patients, 23% presented delirium. These patients were older than the control group, 73.5 +/- 4.2 and 69.3 +/- 5.9 years, respectively (mean +/- SD, p < 0.01), and had more frequently a history of previous stroke (p < 0.05). Emotional delirium was seen in 83%, hyperactive delirium in about 40%, and 25% were classified to have a psychotic delirium. A major finding was a 58% frequency of hallucinations and illusions among patients with delirium, and a similar rate among those without delirium.

CONCLUSION

Delirium is common after cardiac surgery in particular in older patients, but is often under-diagnosed. Hallucinations were common in both delirious and non-delirious patients.

Circuits and systems in stress. I. Preclinical studies

This paper reviews the preclinical literature related to the effects of stress on neurobiological and neuroendocrine systems. Preclinical studies of stress provide a comprehensive model for understanding neurobiological alterations in post-traumatic stress disorder (PTSD). The pathophysiology of stress reflects long-standing changes in biological stress response systems and in systems involved in stress responsivity, learning, and memory. The neural circuitry involved includes systems mediating hypothalamic-pituitary-adrenal (HPA) axis, norepinephrine (locus coeruleus), and benzodiazepine, serotonergic, dopaminergic, neuropeptide, and central amino acid systems. These systems interact with brain structures involved in memory, including hippocampus, amygdala, and prefrontal cortex. Stress responses are of vital importance in living organisms; however excessive and/or repeated stress can lead to long-lasting alterations in these circuits and systems involved in stress responsiveness. Intensity and duration of the stressor, and timing of the stressor in life, have strong impact in this respect.

Mood, cognition and Alzheimer's disease

There is good evidence for sex differences in brain disease, and that oestrogen modulates brain development and ageing. For example, females are significantly more likely to suffer from Alzheimer's disease, depression and late-onset psychosis than are men. Moreover, hormone replacement therapy may reduce the rate of cognitive decline in post-menopausal women and reduce their risk of developing Alzheimer's disease (as compared to post-menopausal women who do not take hormone replacement therapy). The neurobiological basis of these differences in brain disease and ageing was unknown until relatively recently. In this chapter we discuss results of studies demonstrating that sex steroids (i) are crucial for development and ageing of brain regions affected in Alzheimer's disease; (ii) interact with neuronal networks and chemical systems at many different levels in brain, and (iii) affect mood and cognitive function in elderly women without Alzheimer's disease. The current literature supports the hypothesis that sex steroids can modulate brain ageing and provides a number of potential neurobiological explanations for the cognitive effects of hormone replacement therapy. There is only limited evidence that hormone replacement therapy is effective in women already suffering from Alzheimer's disease. Nonetheless, recent work may lead to new prevention strategies for age-related cognitive decline and brain diseases such as Alzheimer's disease.