MECHANISMS IN ENDOCRINOLOGY: Cushing's syndrome causes irreversible effects on the human brain: a systematic review of structural and functional magnetic resonance imaging studies

Prolonged corticosterone exposure induces dendritic spine remodeling and attrition in the rat medial prefrontal cortex

The stress-responsive hypothalamo-pituitary-adrenal (HPA) axis plays a central role in promoting adaptations acutely, whereas adverse effects on physiology and behavior following chronic challenges may result from overactivity of this system. Elevations in glucocorticoids, the end-products of HPA activation, play roles in adaptive and maladaptive processes by targeting cognate receptors throughout neurons in limbic cortical networks to alter synaptic functioning. Because previous work has shown that chronic stress leads to functionally relevant regressive alterations in dendritic spine shape and number in pyramidal neurons in the medial prefrontal cortex (mPFC), this study examines the capacity of sustained increases in circulating corticosterone (B) alone to alter dendritic spine morphology and density in this region. Subcutaneous B pellets were implanted in rats to provide continuous exposure to levels approximating the circadian mean or peak of the steroid for 1, 2, or 3 weeks. Pyramidal neurons in the prelimbic area of the mPFC were selected for intracellular fluorescent dye filling, followed by high-resolution three-dimensional imaging and analysis of dendritic arborization and spine morphometry. Two or more weeks of B exposure decreased dendritic spine volume in the mPFC, whereas higher dose exposure of the steroid resulted in apical dendritic retraction and spine loss in the same cell population, with thin spine subtypes showing the greatest degree of attrition. Finally, these structural alterations were noted to persist following a 3-week washout period and corresponding restoration of circadian HPA rhythmicity. These studies suggest that prolonged disruptions in adrenocortical functioning may be sufficient to induce enduring regressive structural and functional alterations in the mPFC. J. Comp. Neurol. 524:3729-3746, 2016. © 2016 Wiley Periodicals, Inc.

The risks of overlooking the diagnosis of secreting pituitary adenomas

Secreting pituitary adenomas that cause acromegaly and Cushing’s disease, as well as prolactinomas and thyrotroph adenomas, are uncommon, usually benign, slow-growing tumours. The rarity of these conditions means that their diagnosis is not familiar to most non-specialist physicians. Consequently, pituitary adenomas may be overlooked and remain untreated, and affected individuals may develop serious comorbidities that reduce their quality of life and life expectancy. Because many signs and symptoms of pituitary adenomas overlap with those of other, more common disorders, general practitioners and non-endocrinology specialists need to be aware of the “red flags” suggestive of these conditions. A long duration of active disease in patients with secreting pituitary adenomas is associated with an increased risk of comorbidities and reduced quality of life. Appropriate treatment can lead to disease remission, and, although some symptoms may persist in some patients, treatment usually reduces the incidence and severity of comorbidities and improves quality of life. Therefore, correct, early diagnosis and characterization of a pituitary adenoma is crucial for patients, to trigger timely, appropriate treatment and to optimize outcome. This article provides an overview of the epidemiology of hormonal syndromes associated with pituitary adenomas, discusses the difficulties of and considerations for their diagnosis, and reviews the comorbidities that may develop, but can be prevented, by accurate diagnosis and appropriate treatment. We hope this review will help general practitioners and non-endocrinology specialists to suspect secreting pituitary adenomas and refer patients to an endocrinologist for confirmation of the diagnosis and treatment.

Quality of life in patients with adrenal insufficiency correlates stronger with hydrocortisone dosage, than with long-term systemic cortisol levels

In patients with adrenal insufficiency (AI) a higher hydrocortisone intake has been associated with more impairment in quality of life (QoL). Irrespective of age, sex and severity of AI the dosage of hydrocortisone is titrated around 20mg/D in all patients with AI based on physical and mental signs and symptoms. However, until now it is unknown whether these QoL impairments are related to increased systemic cortisol exposure. Measurement of hair cortisol levels (CORThair) can be used to assess chronic systemic cortisol exposure. This study aimed to explore whether QoL in patients with AI is associated with CORThair and daily hydrocortisone intake. We performed a cross-sectional study in 120 patients with AI on stable hydrocortisone replacement, in whom hair samples and QoL data were collected. CORThair were measured with ELISA, and QoL was assessed with validated questionnaires (SF-36, EQ-5D, HADS, MFI-20). Patients reported impairments in 14 of 15 QoL subscales (p<0.001). More impairments in physical aspects of QoL correlated with higher CORThair and higher daily hydrocortisone intake (p<0.05), an effect that was more pronounced in female patients. Regression analyses including both CORThair and hydrocortisone intake revealed a significant negative contribution of higher hydrocortisone intake on physical aspects of QoL (p≤0.046), whereas no significant contribution was found for CORThair. The present study showed that patients with AI report several impairments in QoL which are associated with hydrocortisone intake, and to a lesser extent reflected by chronic systemic cortisol exposure as measured by hair cortisol. This suggests that QoL impairments in patients with AI are not per se the effect of prolonged exposure to elevated systemic cortisol levels.

Brain metabolite abnormalities in ventromedial prefrontal cortex are related to duration of hypercortisolism and anxiety in patients with Cushing's syndrome

Chronic exposure to excessive glucocorticoid (GC) concentration in Cushing's syndrome (CS) can affect the brain structurally and functionally; ventromedial prefrontal cortex (vmPFC) is rich in GC receptors and therefore particularly vulnerable to excessive GC concentration. Proton magnetic resonance spectroscopy ((1)H-MRS) is a sensitive, non-invasive imaging technique that provides information on brain metabolites in vivo. Our aim was to investigate metabolite concentrations in vmPFC of CS patients and their relationship with clinical outcome. Twenty-two right-handed CS patients (7 active/15 in remission, 19 females, 41.6 ± 12.3 years) and 22 right-handed healthy controls (14 females, 41.7 ± 11 years) underwent brain MRI and (1)H-MRS exams at 3 Tesla. Concentrations of glutamate (Glu), glutamate + glutamine (Glx), creatine (Cr), N-Acetyl-aspartate (NAA), N-Acetyl-aspartate + N-acetylaspartylglutamate (total NAA), choline-containing compounds (Cho) and myoinositol (MI) were determined. Moreover, anxiety and depressive symptoms were evaluated with the State-Trait Anxiety Inventory (STAI) and the Beck Depression Inventory-II (BDI-II) test, respectively. CS patients had lower concentrations of glutamate and total NAA in the vmPFC than healthy controls (8.6 ± 1.2 vs. 9.3 ± 0.7 mmol/L, and 6.4 ± 0.8 vs. 6.8 ± 0.4 mmol/L, respectively; p < 0.05). Duration of hypercortisolism was negatively correlated with total NAA (r = -0.488, p < 0.05). Moreover, the concentration of total NAA was negatively correlated with anxiety state (r = -0.359, p < 0.05). Brain metabolites are abnormal in the vmPFC of patients with CS. Decreased total NAA and glutamate concentrations indicate neuronal dysfunction that appear to be related with duration of hypercortisolism and anxiety.

The chronic syndromes after previous treatment of pituitary tumours

Ultimately, almost all patients who are appropriately treated for pituitary tumours enter a chronic phase with control or cure of hormonal excess, adequate treatment of pituitary insufficiency and relief of mass effects. This phase is associated with improvement of initial signs and symptoms, but also with the persistent consequences of the initial disease and associated treatments. Pituitary insufficiency is a common denominator in many of these patients, and is associated with a reduction in quality of life, despite adequate endocrine substitution. Hypothalamic dysfunction can be present in patients previously treated for visual impairments caused by large suprasellar adenomas, or craniopharyngiomas. In addition to hypopituitarism, these patients can have multisystem morbidities caused by altered hypothalamic function, including weight gain and disturbed regulation of sleep-wake cycles. Mortality can also be affected. Patients cured of Cushing disease or acromegaly have chronic multisystem morbidities (in the case of Cushing disease, also affecting mortality) caused by irreversible effects of the previous excesses of cortisol in Cushing disease and growth hormone and insulin-like growth factor 1 in acromegaly. In addition to early diagnosis and treatment of pituitary tumours, research should focus on the amenability of these chronic post-treatment syndromes to therapeutic intervention, to improve quality of life and clinical outcomes.

Long-term cognitive effects of glucocorticoid excess in Cushing's syndrome

CONTEXT AND OBJECTIVE

We previously found that patients with Cushing's syndrome (CS) scored lower than controls in several domains of cognitive function and that correction of hypercortisolism is not necessarily correlated with short-term improvement in intellectual performance. Here, we examined the long-term outcome in patients treated for CS by assessing the extent to which the detrimental effects of glucocorticoid (GC) excess on cognition can be reversed three years after corrective surgery.

DESIGN

A battery of neuropsychological tests, including tests of attention, visuospatial processing, learning and memory, and executive functioning were administered pre-treatment and 12, 24 and 36 months post-treatment.

PATIENTS AND CONTROL SUBJECTS

We included 18 patients with endogenous CS recruited before surgical treatment and 18 controls matched for age, sex and education.

RESULTS

CS patients performed worse than controls on tests of attention, executive functioning and nonverbal aspects of memory. Moreover, at 36 months following eucortisolism, executive function performance and, to a lesser extent, attention tasks showed limited change compared to pre-treatment testing.

CONCLUSION

Chronic hypercortisolism is accompanied by a deleterious impact on aspects of cognitive function. This negative effect on attention, executive performance and nonverbal memory seen in patients with CS suggests a differential effect of excess GCs upon different brain areas and networks. This influence persists years after the return to normal cortisol secretion levels.

Bilateral adrenalectomy in the 21st century: when to use it for hypercortisolism?

Therapeutic options available for the treatment of Cushing's syndrome (CS) have expanded over the last 5 years. For instance, the efficient management of severe hypercortisolism using a combination of fast-acting steroidogenesis inhibitors has been reported. Recent publications on the long-term efficacy of drugs or radiation techniques have also demonstrated low toxicity. These data should encourage endocrinologists to reconsider the place of bilateral adrenalectomy in patients with ACTH-dependent aetiologies of CS; similarly, the indication of bilateral adrenalectomy is reassessed in primary bilateral macronodular adrenal hyperplasia. The objective of this review is to compare the efficacy and side effects of the various therapeutic options of hypercortisolism with those of bilateral adrenalectomy, in order to better define its indications in the 21st century.

Genetic Moderation of Stress Effects on Corticolimbic Circuitry

Stress exposure is associated with individual differences in corticolimbic structure and function that often mirror patterns observed in psychopathology. Gene x environment interaction research suggests that genetic variation moderates the impact of stress on risk for psychopathology. On the basis of these findings, imaging genetics, which attempts to link variability in DNA sequence and structure to neural phenotypes, has begun to incorporate measures of the environment. This research paradigm, known as imaging gene x environment interaction (iGxE), is beginning to contribute to our understanding of the neural mechanisms through which genetic variation and stress increase psychopathology risk. Although awaiting replication, evidence suggests that genetic variation within the canonical neuroendocrine stress hormone system, the hypothalamic-pituitary-adrenal axis, contributes to variability in stress-related corticolimbic structure and function, which, in turn, confers risk for psychopathology. For iGxE research to reach its full potential it will have to address many challenges, of which we discuss: (i) small effects, (ii) measuring the environment and neural phenotypes, (iii) the absence of detailed mechanisms, and (iv) incorporating development. By actively addressing these challenges, iGxE research is poised to help identify the neural mechanisms underlying genetic and environmental associations with psychopathology.

The HPA axis in bipolar disorder: Systematic review and meta-analysis

OBJECTIVES

To provide a quantitative and qualitative synthesis of the available evidence on the role of Hypothalamic-Pituitary-Adrenal (HPA) axis in the pathophysiology of Bipolar Disorder (BD).

METHODS

Meta-analysis and meta-regression of case-control studies examining the levels of cortisol, ACTH, CRH levels. Systematic review of stress reactivity, genetic, molecular and neuroimaging studies related to HPA axis activity in BD.

RESULTS

Forty-one studies were included in the meta-analyses. BD was associated with significantly increased levels of cortisol (basal and post-dexamethasone) and ACTH, but not of CRH. In the meta-regression, case-control differences in cortisol levels were positively associated with the manic phase (p=0.005) and participants' age (p=0.08), and negatively with antipsychotics use (p=0.001). Reviewed studies suggest that BD is associated with abnormalities of stress-related molecular pathways in several brain areas. Variants of HPA axis-related genes seem not associated with a direct risk of developing BD, but with different clinical presentations. Also, studies on unaffected relatives suggest that HPA axis dysregulation is not an endophenotype of BD, but seems related to environmental risk factors, such as childhood trauma. Progressive HPA axis dysfunction is a putative mechanism that might underlie the clinical and cognitive deterioration of patients with BD.

CONCLUSIONS

BD is associated with dysfunction of HPA axis activity, with important pathophysiological implications. Targeting HPA axis dysfunctions might be a novel strategy to improve the outcomes of BD.

Mild cognitive deficits in patients with primary adrenal insufficiency

BACKGROUND

The brain is a major target organ for cortisol considering its high density of glucocorticoid receptors. Several states of hypothalamus-pituitary-adrenal dysregulation point towards impairments in cognitive functioning. However, there is a very limited body of research on the effects of hypocortisolism on cognitive functioning.

AIM

To evaluate cognitive functioning in patients with hypocortisolism (i.e., primary adrenal insufficiency (PAI)) and to examine the possible effect of postponing early-morning hydrocortisone intake on cognitive functioning.

METHODS

Thirty-one patients with PAI on regular morning hydrocortisone intake and 31 healthy matched controls underwent nine neuropsychological tests, evaluating memory and executive functioning. In addition, the effect of normal timing and postponement of morning hydrocortisone intake on neuropsychological tests were assessed in an additional 29 patients with PAI.

RESULTS

Compared to controls, patients with PAI performed worse on auditory and visual memory tasks (all P ≤ 0.024) and executive functioning tasks (all P ≤ 0.012). In contrast, patients performed better on a concentration and an attention task (both P<0.05). Postponement of hydrocortisone intake in the morning did not affect the outcomes of neuropsychological tests.

CONCLUSION

Patients on long-term hydrocortisone replacement for PAI show mild cognitive deficits compared to controls. There was no effect of postponement of regular hydrocortisone intake on cognition.

Cardiovascular risk and white matter lesions after endocrine control of Cushing's syndrome

OBJECTIVE

Cushing's syndrome (CS) is associated with high cardiovascular risk. White matter lesions (WML) are common on brain magnetic resonance imaging (MRI) in patients with increased cardiovascular risk.

AIM

To investigate the relationship between cardiovascular risk, WML, neuropsychological performance and brain volume in CS.

DESIGN/METHODS

Thirty-eight patients with CS (23 in remission, 15 active) and 38 controls sex-, age- and education-level matched underwent a neuropsychological and clinical evaluation, blood and urine tests and 3Tesla brain MRI. WML were analysed with the Scheltens scale. Ten-year cardiovascular risk (10CVR) and vascular age (VA) were calculated according to an algorithm based on the Framingham heart study.

RESULTS

Patients in remission had a higher degree of WML than controls and active patients (P<0.001 and P=0.008 respectively), which did not correlate with cognitive performance in any group. WML severity positively correlated with diastolic blood pressure (r=0.659, P=0.001) and duration of hypertension (r=0.478, P=0.021) in patients in remission. Both patient groups (active and in remission) had higher 10CVR (P=0.030, P=0.041) and VA than controls (P=0.013, P=0.039). Neither the 10CVR nor the VA correlated with WML, although both negatively correlated with cognitive function and brain volume in patients in remission (P<0.05). Total brain volume and grey matter volume in both CS patient groups were reduced compared to controls (total volume: active P=0.006, in remission P=0.012; grey matter: active P=0.001, in remission P=0.003), with no differences in white matter volume between groups.

CONCLUSIONS

Patients in remission of Cushing's syndrome (but not active patients) have more severe white matter lesions than controls, positively correlated with diastolic pressure and duration of hypertension. Ten-year cardiovascular risk and vascular age appear to be negatively correlated with the cognitive function and brain volume in patients in remission of Cushing's syndrome.

Altered neural processing of emotional faces in remitted Cushing's disease

Patients with long-term remission of Cushing's disease (CD) demonstrate residual psychological complaints. At present, it is not known how previous exposure to hypercortisolism affects psychological functioning in the long-term. Earlier magnetic resonance imaging (MRI) studies demonstrated abnormalities of brain structure and resting-state connectivity in patients with long-term remission of CD, but no data are available on functional alterations in the brain during the performance of emotional or cognitive tasks in these patients. We performed a cross-sectional functional MRI study, investigating brain activation during emotion processing in patients with long-term remission of CD. Processing of emotional faces versus a non-emotional control condition was examined in 21 patients and 21 matched healthy controls. Analyses focused on activation and connectivity of two a priori determined regions of interest: the amygdala and the medial prefrontal-orbitofrontal cortex (mPFC-OFC). We also assessed psychological functioning, cognitive failure, and clinical disease severity. Patients showed less mPFC activation during processing of emotional faces compared to controls, whereas no differences were found in amygdala activation. An exploratory psychophysiological interaction analysis demonstrated decreased functional coupling between the ventromedial PFC and posterior cingulate cortex (a region structurally connected to the PFC) in CD-patients. The present study is the first to show alterations in brain function and task-related functional coupling in patients with long-term remission of CD relative to matched healthy controls. These alterations may, together with abnormalities in brain structure, be related to the persisting psychological morbidity in patients with CD after long-term remission.