Concurrent Mutations of Germline GPR101 and Somatic USP8 in a Pediatric Giant Pituitary ACTH Adenoma

Abstract

Background

Cushing’s disease (CD) is rare in pediatric patients. It is characterized by elevated plasma adrenocorticotropic hormone (ACTH) from pituitary adenomas, with damage to multiple systems and development. In recent years, genetic studies have shed light on the etiology and several mutations have been identified in patients with CD.

Case presentation

A girl presented at the age of 10 years and 9 months with facial plethora, hirsutism and acne. Her vision and eye movements were impaired. A quick weight gain and slow growth were also observed. Physical examination revealed central obesity, moon face, buffalo hump, supra-clavicular fat pads and bruising. Her plasma ACTH level ranged between 118 and 151 pg/ml, and sella enhanced MRI showed a giant pituitary tumor of 51.8 × 29.3 × 14.0 mm. Transsphenoidal pituitary debulk adenomectomy was performed and immunohistochemical staining confirmed an ACTH-secreting adenoma. Genetic analysis identified a novel germline GPR101 (p.G169R) and a somatic USP8 (p. S719del) mutation. They were hypothesized to impact tumor growth and function, respectively.

Conclusions

We reported a rare case of pediatric giant pituitary ACTH adenoma and pointed out that unusual concurrent mutations might contribute to its early onset and large volume.

Peer Review reports

Background

Cushing’s disease (CD) is caused by the overproduction of adrenocorticotropic hormone (ATCH) by pituitary adenomas (PAs). It is rare in children and accounts for approximately 75% of pediatric Cushing’s syndrome from 7 to 17 years of age [1]. Weight gain and facial changes are more common in children than in adults [2]. Growth retardation is also a characteristic of children with hypercortisolemia [3]. Genetic alterations such as somatic USP8RASD1TP53 mutations, and germline AIPMEN1, and CABLES1 mutations have been identified in CD patients [4]. Here we report a case of pediatric invasive pituitary ACTH macroadenoma associated with a novel germline GPR101 (p. G169R) and a somatic USP8 (p. S719del) mutation.

Case presentation

The girl was born at full term with a length of 48 cm and a weight of 2900 g. Her neuromotor and cognitive development was comparable to those of children of the same age. At the age of 9 years and 4 months she developed plethora, hirsutism, facial acne, rapid weight gain, and increased abdominal circumference. Her skin darkened, and purple striae appeared on thighs and in the armpits. She became dull and less talkative, as indicated by her parents. At 10 years and 3 months, the patient complained of pain around the left orbit with an intensity of 4–5 points on a numerical rating scale (NRS). Five months later bilateral blepharoptosis appeared, with significantly impaired vision of the left eye. Soon both eyes failed to rotate in all directions.

On admission the patient was 10 years and 9 months, with a height of 144 cm (90–97th percentile) and a weight of 48 kg (25–50th percentile). Her weight gain was 20 kg, while the height increased by only 2–3 cm in 18 months. Her blood pressure was 115/76mmHg, and her heart rate was 80 bpm. Apart from the signs mentioned above, physical examination revealed central obesity (BMI 23.1 kg/m2), moon face, buffalo hump, supra-clavicular fat pads and bruising at the left fossa cubitalis. Her pupils were 7 mm in diameter and barely reacted to light. There was a fan-shaped visual field defect in the left eye. Her breasts were Tanner stage III and pubic hair was Tanner stage II, although menarche had not yet occurred. The parents and her younger brother at 6 years of age did not have symptoms related to Cushing syndrome, acromegaly or gigantism. There was no family history of pituitary tumor or other endocrine tumors.

She had increased midnight serum cortisol (24.35 µg/dL, normal range < 1.8 µg/mL) and 24-hour urine free cortisol (24hUFC) (308.0 µg, normal range 12.3–103.5). The plasma ACTH level ranged from 118 to 151 pg/mL (< 46pg/mL). The 24hUFC was not suppressed (79.2 µg) after 48 h low-dose dexamethasone suppression test (LDDST), but suppressed to 32.8 µg (suppression rate 89.4%) after 48 h high-dose dexamethasone. Sella enhanced MRI showed a giant pituitary tumor measured 51.8 × 29.3 × 14.0 mm with heterogeneous density (Fig. 1). The mass compressed the optic chiasma and surrounded the bilateral cavernous sinus (Knosp 4). Therefore, an invasive giant pituitary ACTH adenoma was clinically diagnosed. The morning growth hormone (GH) was 1.0ng/ml (< 2 ng/ml) and insulin-like growth factor 1 416 ng/ml (88–452 ng/ml). The prolactin (PRL), luteinizing hormone (LH), follicle-stimulating hormone (FSH) and thyroid stimulating hormone (TSH) were all in normal ranges, as well as serum sodium, potassium, blood glucose and urine osmolality. Abdominal ultrasonography revealed a fatty liver. Tests concerning type 1 multiple endocrine neoplasia included serum calcium, phosphate, parathyroid hormone, gastrin and glucagon, which were all unremarkable (Table 1).

Fig. 1

figure 1

Contrast-enhanced coronal (A) and sagittal (B) T1-weighted MRI on admission. The sellar mass measured 51.8 × 29.3 × 14.0 cm (TD × VD × APD) with a heterogeneous density in the enhanced scan. The diaphragma sellea was dramatically elevated, with optic chiasm compressed. The sellar floor was sunken and bilateral cavernous sinus was surrounded (Knosp 4)

Table 1 Laboratory data on admission

Transsphenoidal pituitary debulk adenomectomy was performed immediately due to multiple cranial nerve involvement and the negative results of Sandostatin loading test. A decompression resection was done. The plasma ACTH level declined to 77 pg/ml and serum cortisol 30.2 µg/dl three days after the operation. Vision, pupil dilation, eye movements and blepharoptosis also partially improved. Histopathology and immunohistochemical staining confirmed a densely–granulated corticotroph adenoma (Fig. 2, NanoZoomer S360 digital slide scanner and NDP.view 2.9.25 software, Hamamatsu, Japan). Neither necrosis nor mitotic activity was observed. The immunostaining for somatostatin receptor SSTR2A was positive with a cytoplasmic pattern, while GH, PRL, TSH, FSH, LH and PIT were all negative. The Ki 67 index was found to be 10%. One month after the operation the ACTH level increased to 132 pg/mL again, and the parents agreed to refer their child for radiotherapy to control the residual tumor.

Fig. 2

figure 2

Histopathology and immunohistochemistry staining results of the pituitary tumor. By light microscopy, the tumor cells were mostly basophilic and arranged in papillary architecture. Neither necrosis nor mitotic activity was observed (A hematoxylin-eosin, ×200). Immunohistochemistry staining was positive for ACTH (B immunoperoxidase, ×200) and transcription factor T-PIT (C immunoperoxidase, ×200). Cytoplasmic staining of SSTR2A was observed in around 1/3 tumor cells besides the strong staining of endothelial cells (D immunoperoxidase, ×200). The Ki-67 index was 10% (E immunoperoxidase, ×200). Cytokeratin CAM5.2 was diffusely positive in the cytoplasm (F immunoperoxidase, ×200). The positive control for ACTH and T-PIT was the human anterior pituitary gland, and for SSRT2, Ki-67 and CAM5.2 were cerebral cortex, tonsil and colonic mucosa, respectively

The early onset and invasive behavior of this tumor led to the consideration of whether there was a genetic defect. Genetic studies were recommended for the families and they all agreed and signed the written informed consent forms. Whole exome sequencing (WES) was performed on the patient’s blood sample using an Illumina HiSeq sequencer to an average read depth of at least 90 times per individual. Raw sequence files were mapped to the GRCH37 human reference genome and analyzed using the Sentieon software. The results revealed a germline heterozygous GPR101 gene mutation c.505G > C (p.Gly169Arg), which was subsequently confirmed to be of maternal origin by Sanger sequencing. Meanwhile WES of the tumor tissue identified an additional somatic heterozygous c.2155_2157delTCC (p.S719del) mutation of the USP8 gene .

Discussion and conclusions

In this report, we described an extremely giant and invasive pituitary ACTH adenoma in a 10-year-old girl. According to Trouillas et al., invasive and proliferative pituitary tumors have a poor prognosis [5]. CD is rare among children, and the fast-growing and invasive nature of the tumor in this case led to the investigation of genetic causes. The somatic USP8 gene mutation has been recently reported to be associated with the pathogenesis of CD [67]. This gene encodes ubiquitin-specific protease 8 (USP8). S718, S719 and P720 are hotspots in different studies [6,7,8,9,10,11,12,13,14]. They are located at the 14-3-3 binding motif, and the mutations disrupt the binding between USP8 and 14-3-3 protein, which leads to increased deubiquitination and EGFR signaling. High levels of EGFR consequently trigger proopiomelanocortin (POMC) transcription and ACTH secretion [67]. The p.S719del mutation has been previously reported and its pathogenicity has been confirmed [7]. Thus, we speculate the p.S719del mutation plays a role in this patient with CD.

It is noteworthy that in our case, the pituitary corticotrophin adenoma was extremely giant and bilaterally invasive. USP8 mutations have been found in 31% of pediatric CD patients [10]. It is well known that microadenomas are most common in adult and pediatric CD patients. Previously, the Chinese and Japanese cohorts observed smaller sizes of USP8-mutated PAs than wild-type PAs [79]. The Chinese cohort also reported a lower rate of invasive adenomas in USP8-mutated PAs [7]. This may be explained by the finding that UPS8 mutations did not significantly promote cell proliferation more than the wild-type ones [6]. Other cohorts suggested no difference in tumor size or invasiveness between USP8-mutated and wild-type PAs [81012,13,14], which may be partially explained by the differences in sample sizes and ethnic backgrounds. Owing to the lack of evidence of USP8 mutations significantly contributing to tumor growth and invasiveness, additional pathogenesis should be investigated in this case.

The p.Gly169Arg mutation of the GPR101 gene has not been reported in patients with pituitary tumors. In silico predictions were performed using Polyphen-2, Mutation Taster and PROVEAN, and all of the programs reported it to be pathogenic. The GPR101 gene encodes an orphan G protein-coupled receptor (GPCR) and microduplication encompassing the gene has been proven to be the cause of X-linked acrogigantism (XLAG) [15]. XLAG is characterized by the early onset of pituitary GH-secreting macroadenomas. Point mutations of GPR101 have been found in patients with PAs that are mostly GH-secreting [15,16,17]. Although their prevalence is very low, an in vitro study supported the pathogenic role of p.E308D, the most common mutation of GPR101. This led to increased cell proliferation and GH production in rat pituitary GH3 cells [15]. Rare cases of PRL, ACTH or TSH-secreting PAs with GPR101 variants were also documented [1618]. To date, there have been five cases of ACTH-secreting PAs with four different germline GPR101 mutations: two cases of p.E308D, p.I122T, p.T293I and p.G31S, although in silico predictions and in vitro evaluations using AtT-20 cells have respectively determined the latter two mutations to be non-pathogenic [1618]. These patients were mainly children and young adults. Unlike pituitary GH-secreting tumors, the role of GPR101 mutations in the pathophysiology of CD is still questionable. Trivellin et al. demonstrated no statistically significant difference in GPR101 expression between corticotropinomas and normal human pituitaries. No significant correlation between GPR101 and POMC expression levels was found neither [18].

Given the evidences above, we hypothesize that the somatic USP8 mutation is responsible for the overexpression of ACTH in this CD girl while the germline GPR101 mutation contributes to the early onset and fast-growing nature of the tumor. Similarly, a 27-year-old woman with Nelson’s syndrome originally considered to be associated with a germline AIP variant (p.Arg304Gln) was recently reported to have a somatic USP8 mutation. The patient progressed rapidly and underwent multiple transsphenoidal surgeries [19]. Since germline AIP mutations are more commonly seen in GH-secreting PAs [20], the authors proposed that the USP8 mutation might have shifted the tumor towards ACTH-secreting [19]. Further investigations into the pathogenicity of GPR101 p.Gly169Arg and AIP p.Arg304Gln mutations are required to support the hypothesis.

In summary, we report a novel germline GPR101 and somatic USP8 mutation in a girl with an extremely giant pituitary ACTH adenoma. The concurrent mutations may lead to the growth and function of the tumor, respectively. Further investigations should be carried out to verify the role of the concurrent mutations in the pathogenesis of pediatric CD.

Availability of data and materials

The WES data of the blood sample of the patient is available in the NGDC repository (https://ngdc.cncb.ac.cn/gsa-human/) and the accession number is HRA002396. Any additional information is available from the authors upon reasonable request.

Abbreviations

CD:
Cushing’s disease
ACTH:
adrenocorticotropic hormone
PA:
pituitary adenoma
NRS:
numerical rating scale
24hUFC:
24-hour urine free cortisol
LDDST:
low-dose dexamethasone suppression test
USP8:
ubiquitin-specific protease 8
POMC:
proopiomelanocortin
GPCR:
G protein-coupled receptor
XLAG:
X-linked acrogigantism

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Acknowledgements

We thanked Dr. Xiaohua Shi and Dr. Yu Xiao from the Department of Pathology, Peking Union Medical College Hospital for their expertise in pituitary pathology and critical help in accomplishment of our manuscript.

Funding

This research was supported by “The National Key Research and Development Program of China” (No. 2016YFC0901501), “CAMS Innovation Fund for Medical Science” (CAMS-2017-I2M–1–011). They mainly covered the fees for genetic analysis and publications.

Author information

Authors and Affiliations

  1. Department of Pediatrics, Peking Union Medical College Hospital, Chinese Academy of Medical Science and Peking Union Medical College, Beijing, 100730, China

    Xu-dong Bao

  2. Department of Endocrinology, Key Laboratory of Endocrinology of National Health Commission, Peking Union Medical College Hospital, Chinese Academy of Medical Science and Peking Union Medical College, Beijing, 100730, China

    Lin Lu, Hui-juan Zhu, Xiao Zhai, Yong Fu, Feng-ying Gong & Zhao-lin Lu

  3. Department of Neurosurgery, Peking Union Medical College Hospital, Chinese Academy of Medical Science and Peking Union Medical College, Beijing, 100730, China

    Yong Yao, Ming Feng & Ren-zhi Wang

Contributions

XB and LL contributed to the study design and manuscript writing. HZ and FG performed genetic analysis. XZ and YF collected the clinical data. YY, MF and RW provided the tumor tissue and histopathology data. ZL revised the manuscript. All authors have read and approved the final manuscript.

Corresponding author

Correspondence to Lin Lu.

Ethics declarations

Ethics approval and consent to participate

This study was approved by the Ethics Committee of Peking Union Medical College Hospital. The parents of the patient provided written informed consent for research participation.

Consent for publication

The parents of the patient provided written informed consent for the publication of indirectly identifiable data in this research.

Competing interests

The authors declare that they have no competing interests.

Additional information

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Results Reinforce Efficacy of Recordati’s Isturisa in Cushing’s Disease

Recordati Rare Diseases, a US biopharma that forms part of the wider Italian group, has presented multiple positive data sets on Isturisa (osilodrostat) at the annual ENDO 2022 meeting in Atlanta, Georgia.

Isturisa is a cortisol synthesis inhibitor indicated for the treatment of adult patients with Cushing’s disease for whom pituitary surgery is not an option or has not been curative.

Among the data presented, the Phase III LINC 4 study demonstrated that Isturisa maintained normal mean urinary free cortisol long-term in patients with Cushing’s disease while the Phase III LINC 3 study found adrenal hormone levels changed during early treatment with the drug while stabilizing during long-term treatment.

The ILLUSTRATE study also showed patients treated with a prolonged titration interval tended to have greater persistence with therapy.

Mohamed Ladha, president and general manager for North America, Recordati Rare Diseases, said: “The data from these studies reinforces the efficacy and safety of Isturisa as a treatment for patients with Cushing’s disease.

“We are pleased to share these data with the endocrine community and are excited to provide patients with a much-needed step forward in the management of this rare, debilitating, and potentially life-threatening condition.”

Cushing’s disease is a rare, serious illness caused by a pituitary tumor that leads to overproduction of cortisol by the adrenal glands. Excess cortisol can contribute to an increased risk of morbidity and mortality. Treatment for the condition seeks to lower cortisol levels to a normal range.

Isturisa, which was approved by the US Food and Drug Administration in March 2020, works by inhibiting 11-beta-hydroxylase, an enzyme responsible for the final step of cortisol biosynthesis in the adrenal gland.

From https://www.thepharmaletter.com/article/results-reinforce-efficacy-of-recordati-s-isturisa-in-cushing-s-disease

Transsphenoidal Surgery in an Older Patient with Cushing’s Disease

Abstract

Cushing’s disease causes numerous metabolic disorders, cognitive decline, and sarcopenia, leading to deterioration of the general health in older individuals. Cushing’s disease can be treated with transsphenoidal surgery, but thus far, surgery has often been avoided in older patients. We herein report an older woman with Cushing’s disease whose cognitive impairment and sarcopenia improved after transsphenoidal surgery. Although cognitive impairment and sarcopenia in most older patients show resistance to treatment, our case indicates that normalization of the cortisol level by transsphenoidal surgery can be effective in improving the cognitive impairment and muscle mass loss caused by Cushing’s disease.

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From https://www.jstage.jst.go.jp/article/internalmedicine/advpub/0/advpub_8326-21/_article

Medications Used to Treat Cushing’s

Dr. Friedman uses several medications to treat Cushing’s syndrome that are summarized in this table. Dr. Friedman especially recommends ketoconazole. An in-depth article on ketoconazole can be found on goodhormonehealth.com.

 

 

 Drug How it works Dosing Side effects
Ketoconazole  (Generic, not FDA approved in US) blocks several steps in cortisol biosynthesis Start 200 mg at 8 and 10 PM, can up titrate to 1200 mg/day • Transient increase in LFTs
• Decreased testosterone levels
• Adrenal insufficiency
Levoketoconazole (Recorlev) L-isomer of Ketoconazole Start at 150 mg at 8 and 10 PM, can uptitrate up to 1200 mg nausea, vomiting, increased blood pressure, low potassium, fatigue, headache, abdominal pain, and unusual bleeding
Isturisa (osilodrostat) blocks 11-hydroxylase 2 mg at bedtime, then go up to 2 mg at 8 and 10 pm, can go up to 30 mg  Dr. Friedman often gives with spironolactone or ketoconazole. • high testosterone (extra facial hair, acne, hair loss, irregular periods)  • low potassium
• hypertension
Cabergoline (generic, not FDA approved) D2-receptor agonist 0.5 to 7 mg • nausea,  • headache  • dizziness
Korlym (Mifepristone) glucocorticoid receptor antagonist 300-1200 mg per day • cortisol insufficiency (fatigue, nausea, vomiting, arthralgias, and headache)
• increased mineralocorticoid effects (hypertension, hypokalemia, and edema
• antiprogesterone effects (endometrial thickening)
Pasireotide (Signafor) somatostatin receptor ligand 600 μg or 900 μg twice a day Diabetes, hyperglycemia, gallbladder issues

For more information or to schedule an appointment with Dr. Friedman, go to goodhormonehealth.com

Altered Hippocampal Volume and Functional Connectivity in Patients with Cushing’s Disease

Abstract

Introduction

Stress-related brain disorders can be associated with glucocorticoid disturbance and hippocampal alteration. However, it remains largely unknown how cortisol affects the structure and function of hippocampus. Cushing’s disease (CD) provides a unique “hyperexpression model” to explore the effects of excessive cortisol on hippocampus as well as the relation between these effects and neuropsychological deficits.

Methods

We acquired high-resolution T1-weighted and resting-state functional magnetic resonance imaging in 47 CD patients and 53 healthy controls. We obtained the volume and functional connectivity of the hippocampal rostral and caudal subregions in both groups. Relationships between hippocampal alterations, neuroendocrine, and neuropsychological assessments were identified.

Results

Relative to control subjects, the CD patients had smaller volumes of all four hippocampal subregions. Furthermore, whole brain resting-state functional connectivity analyses with these four different hippocampal regions as seeds revealed altered hippocampal functional connectivity with high-order networks, involving the DMN, frontoparietal, and limbic networks in CD patients. The intrinsic hippocampal functional connectivity was associated with the quality of life of the CD patients.

Conclusions

Our findings elucidate the cumulative effect of excess cortisol on the morphology and function of hippocampus and reinforce the need for effective interventions in stress-related brain disease to halt potential hippocampal damage.

1 INTRODUCTION

Converging evidence has pointed to a strong linkage between the cortisol and human brain and stress-related neuropsychiatry disorders, such as major depression disorder and posttraumatic stress disorder (de Kloet et al., 2005). However, it remains to be established how this stress hormone influences specific brain structures and functions, particularly in humans, which is of particular importance for both treatment of stress-related disorders and research on cortisol effects in the brain.

Cushing’s disease (CD) is caused by an adrenocorticotropic hormone pituitary adenoma and characterized by chronic hypercortisolism. This condition is therefore a unique and natural “hyperexpression model” to investigate the chronic effects of cortisol on brain physiology and cognition (Zhang et al., 2021). By applying multimodal neuroimaging techniques to CD patients, previous studies have observed that chronic hypercortisolism could cause a number of abnormalities in various brain phenotypes. Among these neural changes of CD patients, hippocampal anomalies are the most replicated findings. Studies on CD patients report hippocampal changes that converge with morphologic alterations such as reduction in volume (Burkhardt et al., 2015; Toffanin et al., 2011). Moreover, abnormal cerebral blood flow and glucose metabolism in hippocampus have also been found in CD patients. Both structural and functional alterations in the hippocampus might contribute to the psychotic symptoms in CD patients (Frimodt-Møller et al., 2019). However, it is well established that psychosis is better described as a brain connectional diaschisis rather than isolated regional dysfunctions (Matthews & Hampshire, 2016). These current hippocampus-related findings were mainly obtained by voxel-based or regional analyses of brain volume or metabolism properties, and researchers have not determined whether the organizational patterns of hippocampal functional connectivity are disrupted in CD patients.

The hippocampus is easily targeted by long-term hypercortisolism because this area is a part of the stress response system and is abundant in mineralocorticoid receptors and glucocorticoid receptors (McEwen et al., 2016). Also recently, studies on macaques and humans have observed that hippocampus is an anatomically and functionally heterogeneous region along the rostral/caudal-dorsal/ventral axis (Schultz & Engelhardt, 2014). Specifically, the rostral hippocampus has connections with prefrontal regions and relates to stress, emotion, and affect. In contrast, the caudal hippocampus mainly connects to sensory cortical areas and performs primarily cognitive functions (Fanselow & Dong, 2010). Therefore, the hippocampus should be studied in a set of separate structures with rostral and caudal hippocampus. Whether the hippocampal subregions exhibit differentially altered connectivity patterns responding to chronic hypercortisolism remains largely unknown.

The present study further extends this work by examining the relationship between hippocampal subregions and resting-state functional connectivity in large-scale brain networks, as measured by resting-state fMRI (rs-fMRI) (Park & Friston, 2013). We focus on default mode network (DMN), frontoparietal, and limbic networks, given their involvement in stress related psychiatric illnesses. The first is the DMN, which supports self-related cognitive functions. Complementing the DMN is the frontoparietal network, which supports the cognitive regulation of behavior and emotion. Finally, the limbic networks play a key role in emotion regulation.

In this study, first, to explore the structural changes of hippocampal subregions in CD patients, we performed a volumetric MRI analysis of the four subregions (left rostral hippocampus, left caudal hippocampus, right rostral hippocampus, and right caudal hippocampus). Given the known direct neurotoxic effects of cortisol on hippocampus, we predicted that chronic hypercortisolism caused smaller hippocampal volumes in CD patients. Second, we used these four subregions as seed regions separately and mapped whole-brain functional connectivity patterns associated with each subregion to examine alterations in hippocampal functional connectivity in CD patients. Considering the psychiatric symptoms in CD patients, it is reasonable to expect the presence of altered hippocampal functional connectivity with high-order networks.

2 MATERIAL AND METHODS

2.1 Participants

A total of 47 participants with a diagnosis of CD and 53 healthy control (HC) subjects were included in this study. The CD patients underwent transsphenoidal surgery at the Department of Neurosurgery, The First Medical Center of Chinese People’s Liberation Army (PLA) General Hospital between May 2017 and November 2019. According to the clinical practice guideline (Nieman et al., 2015), CD was diagnosed by experienced endocrinologists and confirmed by postsurgical pathology. The detailed preoperative assessments of diagnostic criteria have been reported in our previous study. HCs were recruited from the local community and were controlled for any history of psychopathology abnormalities. All participants were right-handed and had normal vision and auditory sensation. The study was approved by the local ethics committee of the Chinese PLA General Hospital and written informed consent was obtained from each participant. The data of these 47 CD and 53 HC subjects have been partially used in our previous studies (Wang et al., 2019; Zhang et al., 2021).

2.2 Neuroendocrine and neuropsychological assessment

All participants underwent biochemical evaluation to assess their cortisol level. We quantified the levels of 24-h urinary free cortisol (24hUFC, nmol/24h); serum cortisol (nmol/L) at 0:00, 8:00, and 16:00. Cortisol was detected with an ADVIA Centaur Analyzer (Siemens Healthcare Diagnostics, Tarrytown, NY, USA). Cortisol levels at 8:00 as well as 24hUFC were also measured in 51 HC subjects.

All participants underwent a comprehensive neuropsychological assessment with an expert psychiatrist, including Self-Rating Depression Scale (SDS), Self-Rating Anxiety Scale (SAS), Mini-mental State Examination (MMSE), and Montreal Cognitive Assessment (MoCA). Moreover, health-related quality of life and neuropsychiatric symptoms of CD patients were evaluated with the Cushing’s Quality-of-Life (CushingQoL) questionnaire (Nelson et al., 2013) and Chinese version of the neuropsychiatric inventory (CNPI) (Leung et al., 2001), respectively.

2.3 Image acquisition

Structural and functional MRI data were acquired on a 3.0-Tesla MR system (Discovery MR750, General Electric) with an 8-channel head coil. High-resolution structural 3D T1-weighted images were conducted using a sagittal Fast Spoiled Gradient-Echo (FSPGR) sequence with the following parameters: repetition time = 6.7 ms, echo time = 2.9 ms, flip angle = 7°, field of view = 250 × 250 mm2, number of slices = 192, voxel size = 1 × 1 × 1 mm3 with no gap. The functional images were acquired using an echo-planar imaging (EPI) sequence with repetition time = 2000 ms, echo time = 30 ms, flip angle = 90°, thickness/gap = 3.5 mm/0.5 mm, slices = 36, field of view = 224 × 224 mm2, voxel size = 3.5 × 3.5 × 3.5 mm3, number of total volumes = 240. Soft earplugs were used to attenuate scanner noise and head motion was restrained with foam padding. During functional scanning, all participants were requested to keep their eyes closed and stay awake.

2.4 rs-fMRI data preprocessing

Preprocessing of the rs-fMRI images was conducted using SPM12 and Data Processing Assistant for Resting-State fMRI (DPABI, http://www.restfmri.net/forum/DPARSF). The first 10 volume of the functional images were removed to avoid initial steady-state problems. Then functional images were spatially realigned to the first image for motion correction, and reslicing for acquisition temporal delay. The head motion of all participants in this study had no more than 2-mm translation or 2° rotation in any direction. Next, functional images were coregistered to each participant’s segmented gray matter T1 image, and then spatially normalized to the MNI space, resampled to 3-mm isotropic voxels. Subsequently, the global signal, white matter signal, cerebrospinal fluid signal and 24-motion vectors were regressed from the data. Finally, linear detrending and bandpass filter (0.01−0.08 Hz) were carried out to reduce the effects of low-frequency drift and high-frequency physiological noise.

2.5 Hippocampal functional connectivity

The hippocampus has been functionally parcellated into four subregions (left rostral hippocampus, left caudal hippocampus, right rostral hippocampus, and right caudal hippocampus) based on Human Brainnetome Atlas (Fan et al., 2016). On each hippocampal subregion, we performed seed-based functional connectivity analysis. Briefly, hippocampal functional connectivity maps were obtained by computing the Pearson correlation coefficient for each voxel’s time course with the average time course inside the region of interest. Notably, the computation was constrained within a gray-matter mask which was generated by thresholding (a threshold of 0.2) a prior gray-matter probability map in SPM12. The resulting correlation coefficients were further converted to z scores using Fisher’s r-to-z transform to improve normality. For each subject, we obtained 4 z-score maps indicative of the intrinsic functional connectivity patterns of the four hippocampal subregions. To exclude the possible confounding effect of hippocampal volume in CD patients, we performed a voxel-based morphometry analysis on structural MRI images and took the volume of hippocampal subregions as a covariate in the functional connectivity statistical analyses.

2.6 Statistical analysis

All demographic and clinical variables including neuroendocrine and neuropsychological scores were compared by two-sample t-tests. Sex composition of the two groups was compared using a Pearson’s chi-square test (two-tailed). To explore differences in hippocampal functional connectivity between CD patients and HCs, general linear models were performed in a voxel-wise fashion. To exclude the possible confounding effects of age, gender, education level, and volume of hippocampal subregions, we used these measures as covariates in the general linear models. Multiple comparison correction was performed using a FDR of 0.05 within the grey matter mask.

In CD patients group, a linear regression analysis was further performed to explore the relationship between functional connectivity of the clusters showing significant group differences and neuropsychological scores as well as the endocrinological indicators (cortisol and 24hUFC). Multiple comparisons were also corrected using the FDR method with a corrected threshold of q < 0.05.

3 RESULTS

3.1 Demographic, endocrinological, and neuropsychological results

Table 1 shows the demographic characteristics of the CD patients and the HCs. There were no significant differences in terms of age, sex distribution, and years of education between groups. Compared with HCs, CD patients had significantly lower MoCA scores and higher SDS and SAS scores (Table 1). As expected, the CD patients had significantly higher levels of serum cortisol and 24hUFC (p < .001). Moreover, we calculated the volumes of the four hippocampal subregions and found smaller volumes of all four hippocampal subregions in the CD patients.

TABLE 1. Participant characteristics
CDs (n = 47) HCs (n = 53) p Value
Age (years) 37.38 ± 10.61 (20–59) 34.79 ± 10.72 (21–63) .113
Gender (male/female) 4/43 4/49 .859
Education (years) 11.00 ± 4.11 11.74 ± 3.10 .311
Illness duration (months) 41.62 ± 53.71
Neuropsychological tests
MoCA 22.47 ± 3.98 (n = 45) 27.72 ± 2.00 <.001
SDS 40.18 ± 9.96 (n = 45) 27.13 ± 4.42 <.001
SAS 38.27 ± 7.90 (n = 45) 26.98 ± 4.47 <.001
CNPI 11.93 ± 9.68 (n = 45)
Cushing QOL 37.76 ± 8.29 (n = 45)
Endocrinological tests
Serum cortisol (nmol/L)
0:00 am 633.81 ± 237.59 (n = 46)
8:00 am 735.34 ± 279.44 (n = 47) 358.51 ± 107.43 (n = 51) <.001
16:00 pm 671.05 ± 273.56 (n = 47)
24hUFC (nmol/24 h) 2381.59 ± 1653.16 (n = 41) 252.03 ± 119.47 (n = 47) <.001
Volume of hippocampal subregions (mm3)
Left rostral hippocampus 343.75 ± 39.15 (257.18–423.27) 365.69 ± 27.19 (313.21–442.06) .001
Left caudal hippocampus 272.69 ± 32.74 (206.63–339.04) 296.39 ± 23.13 (249.62–347.61) <.001
Right rostral hippocampus 305.10 ± 33.71 (229.67–396.89) 336.76 ± 25.98 (274.95–415.16) <.001
Right caudal hippocampus 320.42 ± 32.60 (238.16–396.58) 347.87 ± 27.16 (294.00–415.80) <.001
  • Abbreviations: 24hUFC, 24-h urinary free cortisol.; CDs, Cushing’s disease patients; CNPI, Chinese version of neuropsychiatric inventory; Cushing QOL, Cushing Quality of Life Scale; HCs, healthy controls; MoCA, Montreal Cognitive Assessment; SAS, Self-Rating Anxiety Scale; SDS, Self-Rating Depression Scale.
  • Note: All values are expressed as mean ± SD. Group differences in sex between CDs and HCs were examined using chi-square test. Group differences in the other demographic and clinical characteristics between CDs and HCs were examined using two-sample t-tests (two-tailed).

3.2 Spatial distribution of hippocampal functional connectivity

The hippocampal functional connectivity maps of both CD patients and HCs are presented in Figure 1. Visually, the spatial distributions of hippocampal functional connectivity were highly similar between groups, in spite of some differences in strength. We observed that the brain regions significantly positively connecting to hippocampus were primarily distributed in several limbic network regions (the orbital frontal cortex, bilateral medial temporal regions, and temporal pole) and DMN regions (bilateral medial frontal cortex, posterior cingulate gyrus/precuneus, and anterior cingulate cortex). Brain regions with negative connectivity to hippocampus were chiefly distributed in the frontoparietal network regions (dorsolateral prefrontal cortex, supramarginal gyrus, and angular gyrus).

Details are in the caption following the image

Between-group differences in functional connectivity of the hippocampal subregions. The first column shows the hippocampal functional connectivity subregions. The second and third columns show the hippocampal functional connectivity maps within CD and HC groups, respectively. Further between-group comparisons showed that CD patients had significantly altered hippocampal functional connectivities relative to HCs, with a corrected statistical threshold of < .05. ROI1, left rostral hippocampus; ROI2, left caudal hippocampus; ROI3, right rostral hippocampus; ROI4, right caudal hippocampus; ROI, region of interest; CD, Cushing’s disease; HC, healthy control

3.3 Altered hippocampal functional connectivity in CD patients

The significant differences in functional connectivity with each hippocampal subregion between the CD patients and HCs groups are illustrated in third column of Figure 1. Both the right and left rostral hippocampus exhibited significantly decreased functional connectivity with the superior parietal lobe (SPL), a component of the frontoparietal network. Moreover, right rostral hippocampus exhibited additional increased functional connectivity with right inferior frontal gyrus, a component of DMN. For the left caudal hippocampus, significantly altered functional connectivity was found to the DMN regions, including (bilateral medial frontal cortex, angular gyrus, anterior, and posterior cingulate cortex). We also observed decreased functional connectivity between the right caudal hippocampus and anterior cingulate cortex. Additionally, the right caudal hippocampus exhibited increased functional connectivity with some limbic regions including the right orbital frontal cortex and temporal pole (Table 2).

TABLE 2. Brain regions showing changed RSFC between CDs and HCs groups
Peak MNI coordinate
Brain regions BA Cluster size (voxels) x y z Peak T
ROI-based RSFC
ROI1 R IFG 48 219 57 21 —3 4.598
L angular 39 423 −27 −72 51 −5.530
RIO2 R thalamus 114 9 −6 3 −5.905
L angular 39 195 −27 −72 54 −4.830
R angular 39 384 36 −66 48 −5.607
ROI3 R MTG 20 633 39 6 −21 4.410
L angular 39 195 −27 −72 54 −4.830
R angular 39 384 36 −66 48 −5.607
MFG/ACC 10/32 572 −3 42 −3 −4.033
PCC/PreCUN 26/23 709 12 −45 27 −4.502
ROI4 MFG/ACC 32 465 3 48 6 −4.670
R MTG/OFC 48/21 747 30 3 −21 4.208
  • Note: Statistical threshold was set at p < .05, corrected.
  • Abbreviations: CDs, Cushing’s disease patients; HCs, healthy controls; ROI, regions of interest; BA, Brodmann areas; MNI, Montreal Neurological Institute; RSFC, resting-state functional connectivity; SFG, superior frontal gyrus; MFG, middle frontal gyrus; dMFG, dorsal medial frontal gyrus; IPL, inferior parietal lobule; AG, angular gyrus; ROL, rolandic operculum; Ins, insular; PrCG, precentral gyrus; L, left; R, right; ROI1, left rostral hippocampus; ROI2, left caudal hippocampus; ROI3, right rostral hippocampus; ROI4, right caudal hippocampus.

3.4 Brain–behavior relationships in the CD patients

In the correlation analyses of CD patients, the mean values of the functional connectivity between the left caudal hippocampus and anterior cingulate cortex correlated positively with the Cushing’s QoL scores (r = .327, p < .05) (Figure 2). No other correlations were found for volumes and functional connectivity of the four hippocampal subregions with neuroendocrine and neuropsychological assessment in the CD patients.

Details are in the caption following the image

Significant correlations between left hippocampal functional connectivity and the quality of life in CD patients. CD, Cushing’s disease; Hip, hippocampus; ACC, anterior cingulate cortex

4 DISCUSSION

Using a cohort of CD patients and HCs, the present study performed a comprehensive investigation to reveal how the chronic hypercortisolism affects the morphology and connectivity of hippocampal subregions and their relationships with neuroendocrine and neuropsychological assessment. Compared with the HCs, the CD patients had smaller volumes of all four hippocampal subregions. Furthermore, CD patients exhibited differential patterns of altered hippocampal functional connectivity with high-order networks, involving the DMN, frontoparietal, and limbic networks. The intrinsic hippocampal functional connectivity was associated with the quality of life of the CD patients. Together, these findings elucidate the cumulative effect of cortisol on the morphology and function of hippocampus and provide important information to further understand the role of hippocampus in stress-related brain disease.

Cortisol, the end product of the hypothalamic–pituitary–adrenal axis, plays a critical role in the body’s response to stress and maintenance of homeostasis (Sapolsky et al., 2000); however, chronic hypercortisolism is known to impair neurons in the hippocampus. CD patients naturally demonstrate chronic excessive amounts of cortisol; therefore these patients serve as a natural “hyperexpression model” to investigate the chronic effects of cortisol on human hippocampus. Importantly, we showed the CD patients are associated with smaller hippocampal volumes in all four subregions. In line with our study, previous structural imaging studies have shown hippocampal volume decreases in CD patients (Frimodt-Møller et al., 2019; Toffanin et al., 2011). Furthermore, Brown et al. found that healthy volunteers were associated with a significant reduction in hippocampal volume following only 3-day stress doses of corticosteroid administration, strongly suggesting the effects of cortisol on hippocampal size. It is important to note that chronic hypercortisolism can affect the hippocampus in at least two ways: by direct neurotoxic effects on the hippocampus (Lupien et al., 2018; Uno et al., 1994) and by reduction in hippocampal neurogenesis (Saaltink & Vreugdenhil, 2014). Moreover, cortisol stimulates the release of excitatory amino acids glutamate on hippocampal cells (de Kloet et al., 2005). On the other hand, chronic elevations of cortisol also reduce neurotrophic factors that includes nerve growth factor and brain-derived neurotrophic factor (McEwen et al., 2015).

The different patterns of functional connectivity in rostral hippocampus versus caudal hippocampus might be associated to the specific cytoarchitecture along the rostral/caudal hippocampus. Accumulated evidence from both animal and human studies suggests that different parts of the hippocampus display distinctive gene expression and anatomical projections patterns (Fanselow & Dong, 2010). In detail, gene expression in the rostral hippocampus correlates with regions involved in emotion and stress (amygdala and hypothalamus). Moreover, the rostral hippocampus has connections with prefrontal regions, exerts strong regulatory control of the hypothalamic–pituitary–adrenal axis with a negative feedback (Toffanin et al., 2011). Accordingly, as demonstrated in this study, chronic hypercortisolism predominantly disrupted the functional connectivity in rostral hippocampus.

Another major finding in this study was altered hippocampal functional connectivity with DMN, frontoparietal, and limbic networks in CD individuals relative to that in HCs. Emerging evidence proposes that interactions within and between these large-scale brain networks play important roles on brain functions and may be affected in multiple psychiatric disorders (Menon, 2011; Sha et al., 2019). Among these brain networks, the DMN is anchored in the medial prefrontal cortex and posterior cingulate cortex and is implicated in internally directed attention and self-referential processing (Raichle, 2015), while the frontoparietal and limbic networks support the cognitive regulation of emotion, attention, and behavior (Buhle et al., 2014; Kohn et al., 2014). The engagement of these high-level functional networks may suggest the linkage of abnormal stress hormone cortisol to cognitive deficits in CD patients. In line with our study, previous studies have shown stress-induced cortisol increase was associated with altered connectivity within the major brain networks (Zhang et al., 2019, 20202020). Meanwhile, structural and functional alterations in these brain systems are also found in CD patients. For example, many functional imaging studies have consistently demonstrated altered brain activities and functional connectivity involving in DMN, frontoparietal, and limbic networks (Jiang et al., 2017; Wang et al., 2019; Zhang et al., 2021), even in the patients with long-term remission of CD (van der Werff et al., 2015). Importantly, previous studies have shown that the CD patients had widespread reductions of white matter integrity, which provide further evidence for the structural substrate for the persistence of these functional deficits (Pires et al., 2015; van der Werff et al., 2014). Here, we propose that by altering hippocampal processes via the abundant glucocorticoid and mineralocorticoid receptors, exposure to hypercortisolism disrupts the interactions with DMN, frontoparietal, and limbic networks in CD patients, thus engender vulnerability for emotional and cognitive problems. In line with this view is evidence that altered hippocampal functional connectivity is associated with the quality of life in CD patients. Because impaired quality of life is a persistent complaint from CD patients (Webb et al., 2018), it is important to accurately assess which aspects of QoL are affected in order to better understand the severity of hypercortisolism on patients and the potential efficacy of treatment. CushingQoL questionnaire has proven to be a valuable resource for assessing health-related QoL in CD patients, based on the combination of psychosocial issues and physical problems (Nelson et al., 2013). A better understanding of the neuroplasticity and continuing quality of life change may in turn facilitate advances in management and intervention.

Several issues need to be addressed further. First, although the sample size of this study was relatively large, the findings still need to be further replicated in an independent sample. Second, the cross-sectional, observational nature of our study design precludes any causal conclusions. Therefore, studies tracking dynamic changes in hippocampal functional connectivity following the remission of hypercortisolism are needed. We are currently following up participants as part of a longitudinal study. Finally, a combined analysis of multimodal imaging including structural and metabolic data would provide integrated information on the effect of cortisol excess on human brain.

In short, we demonstrate that CD patients present atypical morphology and functional connectivity of hippocampus. Here we observed the chronic hypercortisolism caused smaller volumes of all hippocampal subregions. This volume change was in line with the preclinical research that excess cortisol cause dendritic shrinkage and loss of spines in the hippocampus. Functionally, CD patients demonstrated altered hippocampal connectivity whose nodes include key components of the DMN, frontoparietal, and limbic networks. These multimodal results reinforce the need for effective therapeutic interventions in stress-related brain disease to halt possible hippocampal damage.

ACKNOWLEDGMENTS

This study was supported by the National Natural Science Foundation of China (No. 82001798 and No. 81871087), Military Young Scholar Medical Research Fund of Chinese PLA General Hospital (No. QNF19071), and Medical Big Data and Artificial Intelligence Development Fund of Chinese PLA general Hospital (No. 2019MBD-039).

CONFLICT OF INTEREST

The authors report no biomedical financial interests or potential conflicts of interest.

Read more, including references, at https://onlinelibrary.wiley.com/doi/10.1002/brb3.2507

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