Perceived Occupational Stress is associated with Decreased Cortical Activity of the Prefrontal Cortex: A Multichannel Near-infrared Spectroscopy Study

Lateral prefrontal cortex thickness is associated with stress but not cognitive fatigue in exhaustion disorder

Introduction

Impaired executive functioning, including cognitive fatigue, is a core feature of the long-term stress-related condition exhaustion disorder (ED). Recent research suggests that a key area for executive control, the lateral prefrontal cortex (LPFC), may be mechanistically linked to cognitive fatigue due to stress. Here, we therefore asked if and how stress, the LPFC and cognitive fatigue may be related in ED.

Methods

We used a multimodal cross-sectional study design with high-resolution structural magnetic resonance imaging (MRI), self-reported measures, and path analysis modeling in 300 participants with ED.

Results

We found positive associations between stress and cognitive fatigue, and stress and LPFC thickness,but no association between LPFC thickness and cognitive fatigue. Furthermore, LPFC thickness did not mediate or moderate the association between stress and cognitive fatigue.

Discussion

These findings suggest that LPFC brain morphology is related to perceived stress levels but not cognitive fatigue, expanding previous research on the role of the LPFC in executive functioning. Moreover, the results support the notion that the LPFC may be mechanistically involved in stress-related executive function impairment but prompt further research into if and how this may be related to cognitive symptoms in ED.

NIRS-aided differential diagnosis among patients with major depressive disorder, bipolar disorder, and schizophrenia

BACKGROUND

To establish a clinically applicable neuroimaging-guided diagnostic support system that uses near-infrared spectroscopy (NIRS) for differential diagnosis at the individual level among major depressive disorder (MDD), bipolar disorder (BPD), and schizophrenia (SZ).

METHODS

A total of 192 participants were recruited, including 40 patients with MDD, 38 patients with BPD, 65 patients with SZ, and 49 healthy individuals. We analyzed the spatiotemporal characteristics of hemodynamic responses in the frontotemporal cortex during a verbal fluency test (VFT) measured by NIRS to assess the accuracy of single-subject classification for differential diagnosis among the three psychiatric disorders. The optimal threshold of the frontal centroid value (54 seconds) was utilized on the basis of the findings of the Japanese study.

RESULTS

The application of the optimal threshold of the frontal centroid value (54 seconds) allowed for the accurate differentiation of patients with unipolar MDD (72.5%) from BPD (78.9%) or SZ (84.6%).

CONCLUSION

These results suggest that the NIRS-aided differential diagnosis of major psychiatric disorders can be a promising biomarker in Taiwan. Future multi-site studies are needed to validate our findings.

Associations between frontal lobe activity and depressive symptoms in patients with major depressive disorder receiving rTMS treatment: a near-infrared spectroscopy study

Introduction

The effects of repetitive transcranial magnetic stimulation (rTMS) on the left dorsolateral prefrontal cortex (DLPFC) in patients with major depressive disorder (MDD) have been proved to have antidepressant effects. However, the absence of biomarkers to assess treatment response remains a challenge. This research aims to explore the relationship between frontal lobe activity, measured using near infrared spectroscopy (NIRS), and changes in symptoms among MDD patients following rTMS treatment.

Methods

A total of 26 MDD patients underwent 20 sessions of 10  Hz rTMS targeting the left DLPFC. NIRS was used to measure frontal lobe activity during a verbal fluency test at baseline, after 10 rTMS sessions, and after 20 rTMS sessions. Responders were defined as individuals with more than a 50% reduction in symptoms based on the 21-item Hamilton Depression Rating Scale after 20 rTMS sessions.

Results

Among the 14 responders, an increase in frontal lobe activity was significantly correlated with improvements in depressive symptoms following 10 (p = 0.0001) and 20 rTMS sessions (p = 0.007). Additionally, frontal lobe activity after 10 rTMS sessions was significantly associated with symptom improvement after 20 sessions (p = 0.001). These associations were not observed among non-responders.

Conclusion

The findings from this study indicate distinct patterns of frontal lobe activity between responders and non-responders to rTMS treatment, suggesting that NIRS has the potential to serve as a biomarker for monitoring treatment response in MDD patients undergoing rTMS.

Prolonged Physiological Stress Is Associated With a Lower Rate of Exploratory Learning That Is Compounded by Depression

BACKGROUND

Stress is a major risk factor for depression, and both are associated with important changes in decision-making patterns. However, decades of research have only weakly connected physiological measurements of stress to the subjective experience of depression. Here, we examined the relationship between prolonged physiological stress, mood, and explore-exploit decision making in a population navigating a dynamic environment under stress: health care workers during the COVID-19 pandemic.

METHODS

We measured hair cortisol levels in health care workers who completed symptom surveys and performed an explore-exploit restless-bandit decision-making task; 32 participants were included in the final analysis. Hidden Markov and reinforcement learning models assessed task behavior.

RESULTS

Participants with higher hair cortisol exhibited less exploration (r = -0.36, p = .046). Higher cortisol levels predicted less learning during exploration (β = -0.42, false discovery rate [FDR]-corrected p [pFDR] = .022). Importantly, mood did not independently correlate with cortisol concentration, but rather explained additional variance (β = 0.46, pFDR = .022) and strengthened the relationship between higher cortisol and lower levels of exploratory learning (β = -0.47, pFDR = .022) in a joint model. These results were corroborated by a reinforcement learning model, which revealed less learning with higher hair cortisol and low mood (β = -0.67, pFDR = .002).

CONCLUSIONS

These results imply that prolonged physiological stress may limit learning from new information and lead to cognitive rigidity, potentially contributing to burnout. Decision-making measures link subjective mood states to measured physiological stress, suggesting that they should be incorporated into future biomarker studies of mood and stress conditions.

Differentiating people with schizophrenia from healthy controls in a developing Country: An evaluation of portable functional near infrared spectroscopy (fNIRS) as an adjunct diagnostic tool

INTRODUCTION

This study aimed to evaluate portable functional near-infrared spectroscopy (fNIRS) device as an adjunct diagnostic tool in Vietnam to assess hemodynamics when people with schizophrenia and healthy controls performed cognitive tasks.

METHODS

One hundred fifty-seven participants were divided into schizophrenia (n = 110) and healthy controls group (n = 47), which were recruited by match of age, and gender. Hemodynamic responses in the frontal cortex were monitored with a 48-channel portable device during the Stroop Color-Word Test (SCWT) and Verbal Fluency Test (VFT). General linear model compared the differences in oxyhemoglobin (HbO₂) levels between the two groups. The Receiver Operating Characteristic (ROC) graph was generated for each neuroanatomical area.

RESULTS

People with schizophrenia did not show significant activation in the frontal lobe during the SCWT and VFT as compared to pre-task. During the VFT, the area under the ROC curve of the bilateral dorsolateral prefrontal cortex, bilateral orbitofrontal cortex, bilateral frontopolar prefrontal cortex, and bilateral ventrolateral prefrontal cortex were greater than 0.7 (p < 0.001). The area under the ROC curve (AUC) for the right orbitofrontal cortex was maximal during the VFT (AUC = 0.802, 95%CI = 0.731-0.872). The Youden's index reached a peak (0.57) at the optimal cut-point value (HbO₂ cutoff <0.209 μmol/ml for schizophrenia) in which the sensitivity was 85%; specificity was 72%; positive predictive value (PPV) was 0.88; negative predictive value (NPV) was 0.68 and correct classification rate was 76%.

DISCUSSION

Assessing hemodynamics during VFT by portable fNIRS offers the potential as an adjunct diagnostic tool for schizophrenia in developing countries.

Bilateral theta-burst stimulation on emotional processing in major depressive disorder: A functional neuroimaging study from a randomized, double-blind, sham-controlled trial

AIM

Bilateral theta-burst stimulation (biTBS; intermittent TBS over the left dorsolateral prefrontal cortex [DLPFC] and continuous TBS over the right DLPFC) has demonstrated efficacy in improving symptoms in patients with major depressive disorder (MDD). However, the underlying brain mechanisms remain unknown. The authors aimed to investigate the antidepressant efficacy of biTBS monotherapy and its effects on the brain responses measured by functional magnetic resonance imaging (fMRI) during emotional processing in MDD.

METHODS

The authors conducted a double-blind, randomized, sham-controlled trial of patients with MDD who exhibited no responses to at least one adequate antidepressant treatment for the prevailing episode. Recruited patients were randomly assigned to 10 biTBS monotherapy or sham stimulation sessions. The fMRI scans during performing emotional recognition task were obtained at baseline and after 10 sessions of treatment. Depressive symptoms were assessed using the 21-item Hamilton Rating Scale for Depression at baseline and the weeks 4, 8, 12, 16, 20, and 24 week.

RESULTS

The biTBS group (n = 17) exhibited significant decreases in depression scores compared with the sham group (n = 11) at week 8 (70% vs 40%; P = 0.02), and the significant differences persisted during the 24-week follow-up periods. At week 4, when the treatment course was completed, patients in the biTBS group, but not in the sham group, exhibited increased brain activities over the left superior and middle frontal gyrus during negative emotional stimuli.

CONCLUSION

The authors' findings provide the first evidence regarding the underlying neural mechanisms of biTBS therapy to improve clinical symptoms in patients with MDD.

Shared functional impairment in the prefrontal cortex affects symptom severity across psychiatric disorders

BACKGROUND

The prefrontal deficits in psychiatric disorders have been investigated using functional neuroimaging tools; however, no studies have tested the related characteristics across psychiatric disorders considering various demographic and clinical confounders.

METHODS

We analyzed 1558 functional brain measurements using a functional near-infrared spectroscopy during a verbal fluency task from 1200 participants with three disease spectra [196 schizophrenia, 189 bipolar disorder (BPD), and 394 major depressive disorder (MDD)] and 369 healthy controls along with demographic characteristics (age, gender, premorbid IQ, and handedness), task performance during the measurements, clinical assessments, and medication equivalent doses (chlorpromazine, diazepam, biperiden, and imipramine) in a consistent manner. The association between brain functions and demographic and clinical variables was tested using a general linear mixed model (GLMM). Then, the direction of relationship between brain activity and symptom severity, controlling for any other associations, was estimated using a model comparison of structural equation models (SEMs).

RESULTS

The GLMM showed a shared functional deficit of brain activity and a schizophrenia-specific delayed activity timing in the prefrontal cortex (false discovery rate-corrected p < 0.05). Comparison of SEMs showed that brain activity was associated with the global assessment of functioning scores in the left inferior frontal gyrus opercularis (IFGOp) in BPD group and the bilateral superior temporal gyrus and middle temporal gyrus, and the left superior frontal gyrus, inferior frontal gyrus triangularis, and IFGOp in MDD group.

CONCLUSION

This cross-disease large-sample neuroimaging study with high-quality clinical data reveals a robust relationship between prefrontal function and behavioral outcomes across three major psychiatric disorders.

A Bayesian network based study on determining the relationship between job stress and safety climate factors in occurrence of accidents

BACKGROUND

Job stress and safety climate have been recognized as two crucial factors that can increase the risk of occupational accidents. This study was performed to determine the relationship between job stress and safety climate factors in the occurrence of accidents using the Bayesian network model.

METHODS

This cross-sectional study was performed on 1530 male workers of Asaluyeh petrochemical company in Iran. The participants were asked to complete the questionnaires, including demographical information and accident history questionnaire, NIOSH generic job stress questionnaire, and Nordic safety climate questionnaire. Also, work experience and the accident history data were inquired from the petrochemical health unit. Finally, the relationships between the variables were investigated using the Bayesian network model.

RESULTS

A high job stress condition could decrease the high safety climate from 53 to 37% and increase the accident occurrence from 72 to 94%. Moreover, a low safety climate condition could increase the accident occurrence from 72 to 93%. Also, the concurrent high job stress and low safety climate could raise the accident occurrence from 72 to 93%. Among the associations between the job stress factor and safety climate dimensions, the job stress and worker's safety priority and risk non-acceptance (0.19) had the highest mean influence value.

CONCLUSION

The adverse effect of high job stress conditions on accident occurrence is twofold. It can directly increase the accident occurrence probability and in another way, it can indirectly increase the accident occurrence probability by causing the safety climate to go to a lower level.

Workplace design-related stress effects on prefrontal cortex connectivity and neurovascular coupling

This study aims to evaluate the effect of workstation type on the neural and vascular networks of the prefrontal cortex (PFC) underlying the cognitive activity involved during mental stress. Workstation design has been reported to affect the physical and mental health of employees. However, while the functional effects of ergonomic workstations have been documented, there is little research on the influence of workstation design on the executive function of the brain. In this study, 23 healthy volunteers in ergonomic and non-ergonomic workstations completed the Montreal imaging stress task, while their brain activity was recorded using the synchronized measurement of electroencephalography and functional near-infrared spectroscopy. The results revealed desynchronization in alpha rhythms and oxygenated hemoglobin, as well as decreased functional connectivity in the PFC networks at the non-ergonomic workstations. Additionally, a significant increase in salivary alpha-amylase activity was observed in all participants at the non-ergonomic workstations, confirming the presence of induced stress. These findings suggest that workstation design can significantly impact cognitive functioning and human capabilities at work. Therefore, the use of functional neuroimaging in workplace design can provide critical information on the causes of workplace-related stress.

Personalization of Repetitive Transcranial Magnetic Stimulation for the Treatment of Major Depressive Disorder According to the Existing Psychiatric Comorbidity

Repetitive transcranial magnetic stimulation (rTMS) and intermittent theta-burst stimulation (iTBS) are evidenced-based treatments for patients with major depressive disorder (MDD) who fail to respond to standard first-line therapies. However, although various TMS protocols have been proven to be clinically effective, the response rate varies across clinical applications due to the heterogeneity of real-world psychiatric comorbidities, such as generalized anxiety disorder, posttraumatic stress disorder, panic disorder, or substance use disorder, which are often observed in patients with MDD. Therefore, individualized treatment approaches are important to increase treatment response by assigning a given patient to the most optimal TMS treatment protocol based on his or her individual profile. This literature review summarizes different rTMS or TBS protocols that have been applied in researches investigating MDD patients with certain psychiatric comorbidities and discusses biomarkers that may be used to predict rTMS treatment response. Furthermore, we highlight the need for the validation of neuroimaging and electrophysiological biomarkers associated with rTMS treatment responses. Finally, we discuss on which directions future efforts should focus for developing the personalization of the treatment of depression with rTMS or iTBS.

The slope of cerebral oxyhemoglobin oscillation is associated with vascular reserve capacity in large artery steno-occlusion

Inadequate cerebral perfusion is a risk factor for cerebral ischemia in patients with large artery steno-occlusion. We investigated whether prefrontal oxyhemoglobin oscillation (ΔHbO₂, 0.6-2 Hz) was associated with decreased vascular reserve in patients with steno-occlusion in the large anterior circulation arteries. Thirty-six patients with steno-occlusion in the anterior circulation arteries (anterior cerebral artery, middle cerebral artery, and internal carotid artery) were included and compared to thirty-six control subjects. Patients were categorized into two groups (deteriorated vascular reserve vs. preserved vascular reserve) based on the results of Diamox single- photon emission computed tomography imaging. HbO₂ data were collected using functional near-infrared spectroscopy. The slope of ΔHbO₂ and the ipsilateral/contralateral slope ratio of ΔHbO₂ were analyzed. Among the included patients (n = 36), 25 (69.4%) had deteriorated vascular reserve. Patients with deteriorated vascular reserve had a significantly higher average slope of ΔHbO₂ on the ipsilateral side (5.01 ± 2.14) and a higher ipsilateral/contralateral ratio (1.44 ± 0.62) compared to those with preserved vascular reserve (3.17 ± 1.36, P = 0.014; 0.93 ± 0.33, P = 0.016, respectively) or the controls (3.82 ± 1.69, P = 0.019; 0.94 ± 0.29, P = 0.001). The ipsilateral/contralateral ΔHbO₂ ratio could be used as a surrogate for vascular reserve in patients with severe steno-occlusion in the anterior circulation arteries.

Exhaustion disorder and altered brain activity in frontal cortex detected with fNIRS

Patients with stress-related Exhaustion Disorder (ED) have problems with memory and executive function. These problems have been associated with deviant activity in prefrontal cortex (PFC). We investigated cognitive performance and functional activity in the PFC during prolonged mental activity in patients with ED (n = 20, 16 women) with a mean duration since diagnosis of 46 ± 23 months in comparison to healthy individuals (n = 20, 12 women). A block of six neuropsychological tests was performed in a sequence that was repeated once. The brain imaging technique, functional near infrared spectroscopy (fNIRS) was used for all tests. There were no differences between the groups in terms of changes over time, i.e. difference between first and second test block. In the Stroop-Simon test, the controls showedhigher functional activity in the frontal cortex. In the left ventrolateral PFC, we observed an increased activity in controls in the incongruent compared to the congruent trials, whereas no changes were detected in the ED patient group. During processing speed tasks, only ED patients showed higher functional activity in right dorsolateral PFC. The ED patients reported lower subjective energy level and they also performed less well on a mental control task compared to healthy individuals. In conclusion, ED patients showed altered functional activity compared to controls, indicating that ED patients process information differently in the prefrontal cortex, but the functional activity did not change during the 2½ hr procedure, as revealed by the test-retest design. Lay summary In this paper we show that patient with exhaustion disorder have a reduced functional activity in the prefrontal cortex. This functional activity was not affected by 2.5 hours mental activity.

"Braking" the Prefrontal Cortex: The Role of Glucocorticoids and Interneurons in Stress Adaptation and Pathology

The medial prefrontal cortex (mPFC) receives information regarding stimuli and appropriately orchestrates neurophysiological, autonomic, and behavioral responses to stress. The cellular and neurochemical heterogeneity of the mPFC and its projections are key to fine-tuning of stress responses and adaptation. Output of the mPFC is mediated by glutamatergic pyramidal neurons whose activity is coordinated by an intricate network of interneurons. Excitatory/inhibitory (E/I) balance in the mPFC is critical for appropriate responsiveness to stress, and E/I imbalance occurs in numerous neuropsychiatric disorders that co-occur with chronic stress. Moreover, there is mounting data suggesting that chronic stress may precipitate E/I imbalance. This review will provide information regarding the cellular and anatomical makeup of the mPFC and discuss the impact of acute and chronic stress in adulthood and early life on interneuron function, with implications for E/I balance affecting functional connectivity. Specifically, the review will highlight the importance of interneuron type, connectivity, and location (both layer- and subregion-specific). The discussion of local mPFC networks will focus on stress context, including stressor duration (acute vs. chronic) and timing (early life vs. adulthood), as these factors have significant implications for the interpretation of experiments and mPFC E/I balance. Indeed, interneurons appear to play a prominent role in prefrontal adaptation, and a better understanding of the interactions between stress and interneuron function may yield insight to the transition from adaptation to pathology. Ultimately, determining the mechanisms mediating adaptive versus pathologic plasticity will promote the development of novel treatments for neuropsychiatric disorders related to prefrontal E/I imbalance.

Age and pain differences in non-verbal fluency performance: Associations with cortical thickness and subcortical volumes

Musculoskeletal pain is a cause of disability in older individuals and is commonly associated with executive function deficits. In particular, verbal fluency deficits have been previously reported in older individuals with and without musculoskeletal pain, however, no studies have examined non-verbal fluency. The present study investigated non-verbal fluency performance in younger and older individuals and associations with clinical and experimental pain. The NEPAL study included older (n = 63) and younger (n = 28) individuals who completed demographic, and clinical pain assessments followed by a multi-modal QST battery. A subset of participants (older n = 39/63, younger n = 11/28) underwent a structural 3T MRI to extract cortical thickness and subcortical gray matter volumes. The Ruff Figural Fluency Test was administered to assess fluid/divergent thinking, ability to shift cognitive set, and planning strategies. Total Unique Designs drawn and Error Ratio assessed participants' ability to minimize repetition while maximizing unique productions. Adjusting for race and education, older participants with chronic pain had significantly lower Total Unique Designs (67.1 ± 20.3) compared to older adults without chronic pain (78.8 ± 15.9) and younger controls (93.8 ± 20.3, p < 0.001). Within the older sample, those with chronic pain had a significantly greater Error Ratio (0.22 ± 0.3) compared to those without chronic pain (0.09 ± 0.06) and younger controls (0.05 ± 0.05, p = 0.002). In older participants, greater Total Unique Design scores were significantly associated only with lower pressure pain sensitivity (r = 0.300, p = 0.031) while greater Error Ratio scores were significantly associated with greater thermal pain sensitivity (r = 0.304, p = 0.027). However, after accounting for sleep quality, clinical and experimental pain associations were eliminated. Across all participants, non-verbal fluency performance was associated with cortical thickness in frontal, parietal and temporal regions as well as several subcortical gray matter structures even after adjusting for multiple comparisons (p's < 0.001). Our findings suggest a pain-related deficit in non-verbal fluency beyond the established age-related decrements that may be dependent on sleep quality and was associated with specific patterns of gray matter structure.

The effects of perceived chronic stress on the fMRI correlates of attentional control in women managers

The aims of the current study were to examine differences in brain responses to cognitive control in stressed and non-stressed women managers. Stress complaints are highly prevalent among active workers and play an important role in women managers mental health and cognitive functioning. Psychosocial stress has been associated with differential executive functions in this population, but little is known about the neural correlates underlying such differences. We examined brain responses of a particular group of workers that has been proposed to have a different response to stress as a function of their status (i.e., managers). Stressed (n = 19) and non-stressed women managers (n = 21) were scanned using functional magnetic resonance imaging (fMRI) during the performance of a cognitively demanding task. We used the Stroop color-word task to compare neural activation associated with the suppression of a predominant response tendency (i.e., word reading) and the initiation of an appropriate behavior alternative (i.e., naming word color). Despite similar behavioral performances, stressed managers exhibited increased activation in the occipital cortex during response inhibition. No regions were more activated in the non-stressed relative to the stressed group. This finding of greater activation has been interpreted as compensatory brain response to maintain performance in front of cognitive challenge.

Amygdala and prefrontal cortex activity varies with individual differences in the emotional response to psychosocial stress

Stress elicits a variety of psychophysiological responses that show large interindividual variability. Determining the neural mechanisms that mediate individual differences in the emotional response to stress would provide new insight that would have important implications for understanding stress-related disorders. Therefore, the present study examined individual differences in the relationship between brain activity and the emotional response to stress. In the largest stress study to date, 239 participants completed the Montreal Imaging Stress Task (MIST) while heart rate, skin conductance response (SCR), cortisol, self-reported stress, and blood oxygen level dependent (BOLD) functional MRI (fMRI) signal responses were measured. The relationship between differential responses (heart rate, SCR, cortisol, and self-reported stress) and differential BOLD fMRI data was analyzed. Dorsolateral prefrontal cortex (PFC), dorsomedial PFC, ventromedial PFC, and amygdala activity varied with the behavioral response (i.e., SCR and self-reported stress). These results suggest the PFC and amygdala support processes that are important for the expression and regulation of the emotional response to stress, and that stress-related PFC and amygdala activity underlie interindividual variability in peripheral physiologic measures of the stress response. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Salivary cortisol and nitrite concentrations in school teachers: A longitudinal pilot study

OBJECTIVE

Occupational/mental stressors, which may be evaluated with measurements of salivary cortisol concentrations, affect the endothelial function and has implications on cardiovascular health. Nitric oxide (NO) is known to have an important role in cardiac function and may also be assessed in the saliva, but its participation in physiological responses to hypothalamic-pituitary-adrenal (HPA) axis stimulation is still not completely understood. The aim of the present study was to test the hypothesis that salivary NO (as nitrite) and cortisol concentrations in school teachers vary throughout the academic year.

METHODS

Saliva samples were collected from 13 teachers distributed across five secondary schools. The samples were collected at 6:30 a.m., 11:30 a.m., and 5:30 p.m. in the months of March, July, and December. Salivary cortisol levels were measured by enzyme immunoassay (EIA), and salivary NO concentration was determined by the quantification of nitrite. The area under the curve in relation to ground (AUC) was calculated to assess the cortisol and nitrite concentrations throughout the day.

RESULTS

No significant changes were observed in cortisol or nitrite concentrations across the three periods of the school year, while cortisol and nitrite levels showed a low positive and significant correlation (r=0.3455, p=0.0336).

CONCLUSION

The results suggest that changes in salivary cortisol levels are accompanied by changes in salivary nitrite levels. This is the first time that such association has been demonstrated. These results encourage further studies aimed to confirm the importance of salivary NO measurement in relation to occupational stress and cardiovascular health.

Reduced language lateralization in first episode schizophrenia: A near infrared spectroscopy study

BACKGROUND

Diminished functional lateralization in language-related areas is found in chronic schizophrenia (SZ). However, whether this reduced lateralization exists at the early stage of SZ remains unclear. The present study aimed to investigate language lateralization in first episode schizophrenia (FES) using near infrared spectroscopy (NIRS) during a letter version of verbal fluency test (VFT).

METHODS

A total of 28 FES patients and 33 healthy controls (HCs) underwent NIRS while performing a VFT. Six regions of interests (ROIs) were defined: the bilateral frontal-, inferior frontal gyrus (IFG), and temporal regions. Laterality index (LI) was calculated and compared between the two groups in ROIs. In addition, we investigated whether language lateralization was correlated with severity of clinical symptoms.

RESULTS

Across all ROIs, LI was significantly reduced in FES patients (p=0.037) compared to controls in the IFG region. In addition, LI was not found to be correlated with VFT performance, the PANSS positive, negative or general psychopathology subscales.

CONCLUSIONS

Our study demonstrated a diminution of leftward functional lateralization in the IFG during a VFT in FES patients. This is the first NIRS study to report reduced functional lateralization in patients at the early stage of schizophrenia.

Decreased prefrontal functional brain response during memory testing in women with Cushing's syndrome in remission

Neurocognitive dysfunction is an important feature of Cushing's syndrome (CS). Our hypothesis was that patients with CS in remission have decreased functional brain responses in the prefrontal cortex and hippocampus during memory testing. In this cross-sectional study we included 19 women previously treated for CS and 19 controls matched for age, gender, and education. The median remission time was 7 (IQR 6-10) years. Brain activity was studied with functional magnetic resonance imaging during episodic- and working-memory tasks. The primary regions of interest were the prefrontal cortex and the hippocampus. A voxel-wise comparison of functional brain responses in patients and controls was performed. During episodic-memory encoding, patients displayed lower functional brain responses in the left and right prefrontal gyrus (p<0.001) and in the right inferior occipital gyrus (p<0.001) compared with controls. There was a trend towards lower functional brain responses in the left posterior hippocampus in patients (p=0.05). During episodic-memory retrieval, the patients displayed lower functional brain responses in several brain areas with the most predominant difference in the right prefrontal cortex (p<0.001). During the working memory task, patients had lower response in the prefrontal cortices bilaterally (p<0.005). Patients, but not controls, had lower functional brain response during a more complex working memory task compared with a simpler one. In conclusion, women with CS in long-term remission have reduced functional brain responses during episodic and working memory testing. This observation extends previous findings showing long-term adverse effects of severe hypercortisolaemia on brain function.