Neurophysiological findings in patients with bipolar disorder

Beauty is in the nose of the beholder: Fragrance modulates attractiveness, confidence and femininity ratings and neural responses to faces of self and others

Previous research investigated cross-modal influence of olfactory stimuli on perception and evaluation of faces. However, little is known about the neural dynamics underpinning this multisensory perception, and no research examined perception for images of oneself, and others, in presence of fragrances. This study investigated the neural mechanisms of olfactory-visual processing using electroencephalography (EEG) and subjective evaluations of self- and other-images. 22 female participants evaluated images of female actors and themselves while being exposed to the fragrance of a commercially available body wash or clean air delivered via olfactometer. Participants rated faces for attractiveness, femininity, confidence and glamorousness on visual analogue scales. EEG data was recorded and event-related potentials (ERPs) associated with onset of face stimuli were analysed to consider effects of fragrance presence on face processing, and interactions between fragrance and self-other image-type. Subjective ratings of confidence, attractiveness and femininity were increased for both image-types in pleasant fragrance relative to clean air condition. ERP components covering early-to-late stages of face processing were modulated by the presence of fragrance. Findings also revealed a cross-modal fragrance-face interaction, with pleasant fragrance particularly affecting ERPs to self-images in mid-latency ERP components. Results showed that the pleasant fragrance of the commercially available body wash impacted how participants perceived faces of self and others. Self- and other-image faces were subjectively rated as more attractive, confident and feminine in the presence of the pleasant fragrance compared to an un-fragranced control. The pleasant fragrance also modulated underlying electrophysiological activity. For the first time, an effect of pleasant fragrance on face perception was observed in the N1 component, suggesting impact within 100 ms. Pleasant fragrance also demonstrated greater impact on subsequent neural processing for self, relative to other-faces. The findings have implications for understanding multisensory integration during evaluations of oneself and others.

The Pathophysiological Underpinnings of Gamma-Band Alterations in Psychiatric Disorders

Investigating the biophysiological substrates of psychiatric illnesses is of great interest to our understanding of disorders' etiology, the identification of reliable biomarkers, and potential new therapeutic avenues. Schizophrenia represents a consolidated model of γ alterations arising from the aberrant activity of parvalbumin-positive GABAergic interneurons, whose dysfunction is associated with perineuronal net impairment and neuroinflammation. This model of pathogenesis is supported by molecular, cellular, and functional evidence. Proof for alterations of γ oscillations and their underlying mechanisms has also been reported in bipolar disorder and represents an emerging topic for major depressive disorder. Although evidence from animal models needs to be further elucidated in humans, the pathophysiology of γ-band alteration represents a common denominator for different neuropsychiatric disorders. The purpose of this narrative review is to outline a framework of converging results in psychiatric conditions characterized by γ abnormality, from neurochemical dysfunction to alterations in brain rhythms.

Methylphenidate as a treatment option for substance use disorder: a transdiagnostic perspective

A transition in viewing mental disorders from conditions defined as a set of unique characteristics to one of the quantitative variations on a collection of dimensions allows overlap between disorders. The overlap can be utilized to extend to treatment approaches. Here, we consider the overlap between attention-deficit/hyperactivity disorder and substance use disorder to probe the suitability to use methylphenidate as a treatment for substance use disorder. Both disorders are characterized by maladaptive goal-directed behavior, impaired cognitive control, hyperactive phasic dopaminergic neurotransmission in the striatum, prefrontal hypoactivation, and reduced frontal cortex gray matter volume/density. In addition, methylphenidate has been shown to improve cognitive control and normalize associated brain activation in substance use disorder patients and clinical trials have found methylphenidate to improve clinical outcomes. Despite the theoretical basis and promising, but preliminary, outcomes, many questions remain unanswered. Most prominent is whether all patients who are addicted to different substances may equally profit from methylphenidate treatment.

CCPNet136: automated detection of schizophrenia using carbon chain pattern and iterative TQWT technique with EEG signals

Objective.Schizophrenia (SZ) is a severe, chronic psychiatric-cognitive disorder. The primary objective of this work is to present a handcrafted model using state-of-the-art technique to detect SZ accurately with EEG signals.Approach.In our proposed work, the features are generated using a histogram-based generator and an iterative decomposition model. The graph-based molecular structure of the carbon chain is employed to generate low-level features. Hence, the developed feature generation model is called the carbon chain pattern (CCP). An iterative tunable q-factor wavelet transform (ITQWT) technique is implemented in the feature extraction phase to generate various sub-bands of the EEG signal. The CCP was applied to the generated sub-bands to obtain several feature vectors. The clinically significant features were selected using iterative neighborhood component analysis (INCA). The selected features were then classified using the k nearest neighbor (kNN) with a 10-fold cross-validation strategy. Finally, the iterative weighted majority method was used to obtain the results in multiple channels.Main results.The presented CCP-ITQWT and INCA-based automated model achieved an accuracy of 95.84% and 99.20% using a single channel and majority voting method, respectively with kNN classifier.Significance.Our results highlight the success of the proposed CCP-ITQWT and INCA-based model in the automated detection of SZ using EEG signals.

Managing electromyogram contamination in scalp recordings: An approach identifying reliable beta and gamma EEG features of psychoses or other disorders

OBJECTIVE

In publications on the electroencephalographic (EEG) features of psychoses and other disorders, various methods are utilized to diminish electromyogram (EMG) contamination. The extent of residual EMG contamination using these methods has not been recognized. Here, we seek to emphasize the extent of residual EMG contamination of EEG.

METHODS

We compared scalp electrical recordings after applying different EMG-pruning methods with recordings of EMG-free data from 6 fully paralyzed healthy subjects. We calculated the ratio of the power of pruned, normal scalp electrical recordings in the six subjects, to the power of unpruned recordings in the same subjects when paralyzed. We produced "contamination graphs" for different pruning methods.

RESULTS

EMG contamination exceeds EEG signals progressively more as frequencies exceed 25 Hz and with distance from the vertex. In contrast, Laplacian signals are spared in central scalp areas, even to 100 Hz.

CONCLUSION

Given probable EMG contamination of EEG in psychiatric and other studies, few findings on beta- or gamma-frequency power can be relied upon. Based on the effectiveness of current methods of EEG de-contamination, investigators should be able to reanalyze recorded data, reevaluate conclusions from high-frequency EEG data, and be aware of limitations of the methods.

Functional near-infrared spectroscopy during the verbal fluency task of English-Speaking adults with mood disorders: A preliminary study

Functional near-infrared spectroscopy (fNIRS) provides a direct and objective assessment of cerebral cortex function. It may be used to determine neurophysiological differences between psychiatric disorders with overlapping symptoms, such as major depressive disorder (MDD) and bipolar disorder (BD). Therefore, this preliminary study aimed to compare fNIRS signals during the verbal fluency task (VFT) of English-speaking healthy controls (HC), patients with MDD and patients with BD. Fifteen HCs, 15 patients with MDD and 15 patients with BD were recruited. Groups were matched for age, gender, ethnicity and education. Relative oxy-haemoglobin and deoxy-haemoglobin changes in the frontotemporal cortex was monitored with a 52-channel fNIRS system. Integral values of the frontal and temporal regions were derived as a measure cortical haemodynamic response magnitude. Both patient groups had lower frontal and temporal region integral values than HCs, and patients with MDD had lower frontal region integral value than patients with BD. Moreover, patients could be differentiated from HCs using the frontal and temporal integral values, and patient groups could be differentiated using the frontal region integral values. VFT performance, clinical history and symptom severity were not associated with integral values. These results suggest that prefrontal cortex haemodynamic dysfunction occurs in mood disorders, and it is more extensive in MDD than BD. The fNIRS-VFT paradigm may be a potential tool for differentiating MDD from BD in clinical settings, and these findings need to be verified in a larger sample of English-speaking patients with mood disorders.

Minocycline inhibits sleep deprivation-induced aberrant microglial activation and Keap1-Nrf2 expression in mouse hippocampus

Sleep deprivation (SD) is a hallmark of modern society and associated with many neuropsychiatric disorders, including depression and anxiety. However, the cellular and molecular mechanisms underlying SD-associated depression and anxiety remain elusive. Does the neuroinflammation play a role in mediating the effects of SD? In this study, we investigated SD-induced cellular and molecular alterations in the hippocampus and asked whether treatment with an anti-inflammatory drug, minocycline, could attenuate these alterations. We found that SD animals exhibit activated microglia and decreased levels of Keap1 and Nrf2 (antioxidant and anti-inflammatory factors) in the hippocampus. In vivo local field potential recordings show decreased theta and beta oscillations, but increased high gamma oscillations, as a result of SD. Behavioral analysis revealed increased immobility time in the forced swim and tail suspension tests, and decreased sucrose intake in SD mice, all indicative of depressive-like behavior. Moreover, open field test and elevated plus maze test results indicated that SD increases anxiety-like behavior. Interestingly, treatment with the microglial modulator minocycline prevented SD-induced microglial activation, restored Keap1 and Nrf2 levels, normalized neuronal oscillations, and alleviated depressive-like and anxiety-like behavior. The present study reveals that microglial activation and Keap1-Nrf2 signaling play a crucial role in SD-induced behavioral alteration, and that minocycline treatment has a protective effect on these alterations.

Functional near-infrared spectroscopy (fNIRS) as a tool to assist the diagnosis of major psychiatric disorders in a Chinese population

Advances in neuroimaging have promised the development of specific and objective biomarkers for the diagnosis and treatment of psychiatric disorders. Recently, functional near-infrared spectroscopy (fNIRS) has been used during cognitive tasks to measure cortical dysfunction associated with mental illnesses such as Schizophrenia (SCH), Major-Depressive disorder (MD) and Bipolar Disorder (BD). We investigated the ability of fNIRS as a clinically viable tool to successfully distinguish healthy individuals from those with major psychiatric disorders. 316 patients with major psychiatric disorders (198 SCH/54 MD/64 BP) and 101 healthy controls were included in this study. Changes in oxygenated-hemoglobin during a Chinese language verbal fluency test were measured using a 52-channel fNIRS machine over the bilateral temporal and frontal lobe areas. We evaluated the ability of two task-evoked features selected from prior studies the Integral and Centroid values, to identify individuals with major diagnoses. Both the integral value of frontal and centroid value of temporal showed sensitivity in classifying individuals with mental disorders from healthy controls. However, using a combined index featuring both the integral value and centroid value to differentiate psychiatric disorders from healthy controls with an AUC of 0.913, differentiate individuals with mood disorders from healthy controls showed an AUC of 0.899, while for schizophrenia the AUC was 0.737. Our data suggest that fNIRS can be used as a candidate biomarker during differential diagnosis individuals with mood or psychosis disorders and offer a step towards individualization of treatment.

Differentiating between bipolar and unipolar depression using prefrontal activation patterns: Promising results from functional near infrared spectroscopy (fNIRS) findings

BACKGROUND

Bipolar depression (BD) is a unique, severe and prevalent mental illness that shares many similarities in symptoms with unipolar depression (UD). Improving precision of their diagnoses would enhance treatment outcome and prognosis for both conditions. This study aims to provide evidence from functional Near-Infrared Spectroscopy (fNIRS) as a potential tool to differentiate UD and BD based on their differences in hemodynamic change in the prefrontal cortex during verbal fluency tasks (VFT).

METHODS

We enrolled 179 participants with clinically confirmed diagnoses, including 69 UD patients, 68 BD patients and 42 healthy controls(HC). Every participant was assessed using a 45-channel fNIRS and various clinical scales.

FINDINGS

Compared with HC, region-specific fNIR leads show UD patients had significant lower hemodynamic activation in 4 particular pre-frontal regions: 1) the left dorsolateral prefrontal cortex (DLPFC), 2) orbitofrontal cortex (OFC), 3) bilateral ventrolateral prefrontal cortex (VLPFC) and 4) left inferior frontal gyrus (IFG). In contrast, BD vs. HC comparisons showed only significant lower hemodynamic activation in the LIFG area. Furthermore, compared to BD patients, UD patients showed decreased hemodynamic activation changes in the VLPFC region.

CONCLUSION

Our results show significant frontal lobe activation pattern differences between UD and BD groups. fNIRS can be a potential tool to increase diagnostic precision for these conditions. In particular, the VLPFC area holds promise to be a useful site for such differentiation for further investigations.

Effects of Electroacupuncture Combined With Psychological Intervention on Depressive Status and Contingent Negative Variation in Patients With Internet Addiction Disorder: A Randomized Controlled Trial

Background: Depressive symptoms often accompany people with Internet addiction syndrome (IAD). Acupuncture has been found to have significant advantages in improving the severity and depressive symptoms of IAD. Contingent negative variation (CNV) is a common method to explore the mechanism of neurophysiology. Objective: The purpose of this study was to observe the efficacy of electroacupuncture (EA), psychological intervention (PI), and comprehensive intervention (CI) in the treatment of depression in Internet addiction disorder (IAD), and to observe the changes of contingent negative variation (CNV) in each group. Methods: One hundred and twenty subjects diagnosed with IAD were randomly assigned to the EA group, the PI group, or the CI group. They received EA, PI, or a combination of EA and PI for 40 days. The Internet Addiction Test (IAT), the Zung Self-rating Depression Scale (SDS), and the Hamilton Depression Scale (HAMD) were evaluated for all subjects at baseline, 20th, and 40th days of treatment, while CNV data were collected at baseline and 40th days of treatment. Results: Three treatments effectively reduced IAT, SDS, and HAMD scores, and the intergroup comparison showed that CI was superior to EA, while EA was superior to PI. CNV results indicated that the CNV amplitude increased in all three groups of IAD patients after treatment. The CNV latency of point A and A-S2' wave area of the EA group and the CI group did not change significantly after treatment. Only the A-S2' wave area of the PI group increased significantly compared with the baseline period. In addition, IAD's IAT score was positively correlated with SDS and HAMD score at baseline but negatively correlated with CNV latency. After treatment, only the change of HAMD score in the CI group was negatively correlated with amplitude. Conclusion: Our results demonstrate the efficacy of acupuncture and psychological intervention in the treatment of IAD from an electrophysiological perspective. Simultaneously, the increase in CNV amplitude might be the underlying neurophysiological mechanism by which CI improves depression and cognitive function in IAD patients. Clinical Trial Registration: ClinicalTrials.gov, identifier NCT02362698.

EEG Frontal Asymmetry and Theta Power in Unipolar and Bipolar Depression

BACKGROUND

Distinguishing between unipolar and bipolar depression is of high clinical relevance. However, there is sparse research directly comparing these groups in terms of EEG activity.

METHOD

We investigated 87 participants' left and right EEG frontal alpha-1, alpha-2, and theta activity related to happy and sad face stimuli in unipolar (UD, n=33) and bipolar (BD, n=22) depressed participants, and controls without depression (HC, n=32).

RESULTS

Post-hoc analysis of an observed hemisphere x group interaction (p< .037) showed significant differences in alpha-1 asymmetry only for the comparison of UD and HC (p< .006). Further analysis of a significant emotion x group interaction (p= .001) revealed a differential impact of stimulus valence on theta power between the groups (p< .001). The valence dependent theta power of the BD differed from that of the UD (p< .0002) and the HC (p< .004). Alpha-1 asymmetry classified HC and both depressed groups with an accuracy of .69. Valence-related theta classified BD from UD with an accuracy of .83. Leave-one-out cross validation resulted in slightly reduced accuracy.

LIMITATIONS

Important limitations were the small sample size and that subjects were not medication-free.

CONCLUSIONS

Our results demonstrate the value of simple, task related EEG activity for differentiating not only healthy individuals from those with depression, but also individuals with unipolar depression from those with bipolar depression.

Staging model in psychiatry: Review of the evolution of electroencephalography abnormalities in major psychiatric disorders

AIM

Clinical staging in psychiatry aims to classify patients according to the severity of their symptoms, from stage 0 (increased risk, asymptomatic) to stage 4 (severe illness), enabling adapted treatment at each stage of the illness. The staging model would gain specificity if one or more quantifiable biological markers could be identified. Several biomarkers reflecting possible causal mechanisms and/or consequences of the pathophysiology are candidates for integration into the clinical staging model of psychiatric illnesses.

METHODS

This review covers the evolution (from stage 0 to stage 4) of the most important brain functioning impairments as measured with electroencephalography (EEG), in psychosis spectrum and in severe mood disorders.

RESULTS

The present review of the literature demonstrates that it is currently not possible to draw any conclusion with regard to the state or trait character of any of the EEG impairments in both major depressive disorder and bipolar disorder. As for schizophrenia, the most promising markers of the stage of the illness are the pitch mismatch negativity as well as the p300 event-related potentials, as these components seem to deteriorate with increasing severity of the illness.

CONCLUSIONS

Given the complexity of major psychiatric disorders, and that not a single impairment can be observed in all patients, future research should most likely consider combinations of markers in the quest for a better identification of the stages of the psychiatric illnesses.

Current understanding of bipolar disorder: Toward integration of biological basis and treatment strategies

Biological studies of bipolar disorder initially focused on the mechanism of action for antidepressants and antipsychotic drugs, and the roles of monoamines (e.g., serotonin, dopamine) have been extensively studied. Thereafter, based on the mechanism of action of lithium, intracellular signal transduction systems, including inositol metabolism and intracellular calcium signaling, have drawn attention. Involvement of intracellular calcium signaling has been supported by genetics and cellular studies. Elucidation of the neural circuits affected by calcium signaling abnormalities is critical, and our previous study suggested a role of the paraventricular thalamic nucleus. The genetic vulnerability of mitochondria causes calcium dysregulation and results in the hyperexcitability of serotonergic neurons, which are suggested to be susceptible to oxidative stress. Efficacy of anticonvulsants, animal studies of candidate genes, and studies using induced pluripotent stem cell-derived neurons have suggested a relation between bipolar disorder and the hyperexcitability of neurons. Recent genetic findings suggest the roles of polyunsaturated acids. At the systems level, social rhythm therapy targets circadian rhythm abnormalities, and cognitive behavioral therapy may target emotion/cognition (E/C) imbalance. In the future, pharmacological and psychosocial treatments may be combined and optimized based on the biological basis of each patient, which will realize individualized treatment.

Auditory steady state response deficits are associated with symptom severity and poor functioning in patients with psychotic disorder

OBJECTIVES

Gamma oscillation is important for cortico-cortical coordination and the integration of information across neural networks. The 40 Hz auditory steady-state response (ASSR), which reflects neural synchrony in the gamma band (30-100 Hz), is abnormal in patients with schizophrenia (SZ). The present study used the ASSR at multiple frequencies to examine (1) gamma dysfunction in patients with SZ, schizoaffective (SA), and bipolar disorder (BD) compared with controls, (2) the relationship between ASSR measures and clinical symptom severity, and (3) the relationship between ASSR measures and real-life community functioning.

METHODS

EEG was recorded from 75 controls, 52 SZ, 55 SA, and 89 BD patients during 20-30-40-Hz binaural click trains. ANCOVA was used to compare ASSR measures between groups controlling for age, sex, and education. Associations between ASSR measures, symptom severity, and community functioning were examined using linear regression and Pearson partial correlations.

RESULTS

ASSR deficits at gamma frequency were observed in all patient groups. SA patients showed additional specific deficit in the 20 Hz ASSR. Severity of manic, depressive, and anxiety symptoms mediated ASSR deficits. Severity of hallucinatory symptom and community functioning, particularly independent living/meaningful activity, were significantly and independently associated with the 40 Hz ASSR.

CONCLUSIONS

SZ, SA and BD patients are likely to share the same abnormalities in neural processes that generate gamma oscillations. 40 Hz ASSR are associated with community functioning across patients and may serve as a biomarker for predicting functional outcome.

Dissociable auditory mismatch response and connectivity patterns in adolescents with schizophrenia and adolescents with bipolar disorder with psychosis: A magnetoencephalography study

BACKGROUND

There is overlap between schizophrenia and bipolar disorder regarding genetic risk as well as neuropsychological and structural brain deficits. Finding common and distinct event-response potential (ERP) responses and connectivity patterns may offer potential biomarkers to distinguish the disorders.

OBJECTIVE

To examine the neuronal auditory response elicited by a roving mismatch negativity (MMN) paradigm using magnetoencephalography (MEG).

PARTICIPANTS

15 Adolescents with schizophrenia (ASZ), 16 adolescents with bipolar disorder with psychosis (ABP), and 14 typically developing individuals (TD) METHODS: The data were analysed using time-series techniques and dynamic causal modelling (DCM).

OUTCOME MEASURES

MEG difference wave (deviant - standard) at primary auditory (~90ms), MMN (~180ms) and long latency (~300ms).

RESULTS

The amplitude of difference wave showed specific patterns at all latencies. Most notably, it was significantly reduced ABP compared to both controls and ASZ at early latencies. In contrast, the amplitude was significantly reduced in ASZ compared to both controls and ABP. The DCM analysis showed differential connectivity patterns in all three groups. Most notably, inter-hemispheric connections were strongly dominated by the right side in ASZ only.

CONCLUSIONS

Dissociable patterns of the primary auditory response and MMN response indicate possible developmentally sensitive, but separate biomarkers for schizophrenia and bipolar disorder.

Sensory prediction errors in the continuum of psychosis

Sensory prediction errors are fundamental brain responses that signal a violation of expectation in either the internal or external sensory environment, and are therefore crucial for survival and adaptive behaviour. Patients with schizophrenia show deficits in these internal and external sensory prediction errors, which can be measured using electroencephalography (EEG) components such as N1 and mismatch negativity (MMN), respectively. New evidence suggests that these deficits in sensory prediction errors are more widely distributed on a continuum of psychosis, whereas psychotic experiences exist to varying degrees throughout the general population. In this paper, we review recent findings in sensory prediction errors in the auditory domain across the continuum of psychosis, and discuss these in light of the predictive coding hypothesis.

Simultaneous functional near-infrared spectroscopy and electroencephalography for monitoring of human brain activity and oxygenation: a review

Multimodal monitoring has become particularly common in the study of human brain function. In this context, combined, synchronous measurements of functional near-infrared spectroscopy (fNIRS) and electroencephalography (EEG) are getting increased interest. Because of the absence of electro-optical interference, it is quite simple to integrate these two noninvasive recording procedures of brain activity. fNIRS and EEG are both scalp-located procedures. fNIRS estimates brain hemodynamic fluctuations relying on spectroscopic measurements, whereas EEG captures the macroscopic temporal dynamics of brain electrical activity through passive voltages evaluations. The "orthogonal" neurophysiological information provided by the two technologies and the increasing interest in the neurovascular coupling phenomenon further encourage their integration. This review provides, together with an introduction regarding the principles and future directions of the two technologies, an evaluation of major clinical and nonclinical applications of this flexible, low-cost combination of neuroimaging modalities. fNIRS-EEG systems exploit the ability of the two technologies to be conducted in an environment or experimental setting and/or on subjects that are generally not suited for other neuroimaging modalities, such as functional magnetic resonance imaging, positron emission tomography, and magnetoencephalography. fNIRS-EEG brain monitoring settles itself as a useful multimodal tool for brain electrical and hemodynamic activity investigation.

Functional Near-Infrared Spectroscopy (fNIRS) for Assessing Cerebral Cortex Function During Human Behavior in Natural/Social Situations: A Concise Review

Upon adequate stimulation, real-time maps of cortical hemodynamic responses can be obtained by functional near-infrared spectroscopy (fNIRS), which noninvasively measures changes in oxygenated and deoxygenated hemoglobin after positioning multiple sources and detectors over the human scalp. This review is aimed at giving a concise and simple overview of the basic principles of fNIRS including features, strengths, advantages, limitations, and utility for evaluating human behavior. The transportable/wireless commercially available fNIRS systems have a time resolution of 1 to 10 Hz, a depth sensitivity of about 1.5 cm, and a spatial resolution up to 1 cm. fNIRS has been found suitable for many applications on human beings, either adults or infants/children, in the field of social sciences, neuroimaging basic research, and medicine. Some examples of present and future prospects of fNIRS for assessing cerebral cortex function during human behavior in different situations (in natural and social situations) will be provided. Moreover, the most recent fNIRS studies for investigating interpersonal interactions by adopting the hyperscanning approach, which consists of the measurement of brain activity simultaneously on two or more people, will be reported.

Differentiation between major depressive disorder and bipolar disorder by auditory steady-state responses

BACKGROUND

The auditory steady-state response (ASSR) elicited by gamma band neural oscillations has received considerable interest as a biomarker of psychiatric disorders. Although recent ASSR studies have reported that patients with bipolar disorder (BD) show altered ASSRs, little is known about ASSRs in patients with major depressive disorder (MDD). The aim of this study was to evaluate whether ASSRs in MDD subjects differed from those in BD subjects or normal controls (NC).

METHOD

We analyzed ASSRs in 14 MDD patients, 19 BD patients, and 29 normal control subjects. We used whole-head 306-channel magnetoencephalography to evaluate ASSR power and phase-locking factors (PLF) elicited by 20-, 30-, 40-, and 80-Hz click trains. We determined optimal sensitivity and specificity of ASSR power and PLF for the diagnosis of MDD or BD via receiver operating characteristic (ROC) curve analysis using a nonparametric approach.

RESULTS

MDD patients exhibited no significant differences in ASSR power or PLF compared with NC subjects, while BD patients showed deficits on the ASSR measures. MDD patients showed significantly larger ASSR power and PLF for 30-, 40-, and 80-Hz stimuli compared with BD patients. The area under the curve (AUC) for the ROC analysis (MDD vs. BD) was 0.81 [95% CI=0.66-0.96, p=0.003] concerning 40-Hz ASSR power.

LIMITATIONS

We could not exclude the effect of medication and the sample size of the current study is relatively small.

CONCLUSIONS

We could differentiate between MDD and BD subjects in terms of gamma band ASSR. Our data suggest that the 40-Hz ASSR may be a potential biomarker for differentiation between MDD and BD patients.

Phonological and semantic verbal fluency: a comparative study in hearing-impaired and normal-hearing people

PURPOSE

To compare the performance of hearing-impaired and normal-hearing people on phonologic and semantic verbal fluency tests.

METHODS

A cross-sectional study was conducted with 48 hearing-impaired adults and 42 individuals (control group) with no hearing or language complaints. Sociodemographic data were collected, as well as the characteristics of hearing loss and of the electronic auditory device (hearing aids or cochlear implant), when relevant. Verbal fluency was tested in two different tasks: by semantic category (animals) and by phonology (letter F).

RESULTS

Educational level has influenced the results of fluency tests in both groups, with more evidence in the hearing-impaired subjects (p<0.001). Hearing-impaired subjects showed worse performance in verbal fluency tests when compared to normal-hearing people in groups with up to 10 years of schooling. In the comparison of performance in the two tests, both groups showed better results in the semantic fluency task.

CONCLUSION

The hearing-impaired subjects with low educational level evoked fewer words in semantic and phonologic verbal fluency tests in comparison to normal-hearing subjects. Educational level is a relevant issue to the study of verbal fluency in deaf and hearing-impaired people.

Thalamocortical abnormalities in auditory brainstem response patterns distinguish DSM-IV bipolar disorder type I from schizophrenia

BACKGROUND

Bipolar disorder type I (BP-I) belongs to a spectrum of affective disorders that are expressed in many different ways and therefore can be difficult to distinguish from other conditions, especially unipolar depression, schizoaffective disorder, schizophrenia (SZ), but also anxiety and personality disorders. Since early diagnosis and treatment have shown to improve the long-term prognosis, complementary specific biomarkers are of great value. The auditory brainstem response (ABR) has previously been applied successfully to identify specific abnormal ABR patterns in SZ and Asperger syndrome.

METHODS

The current study investigated the early auditory processing of complex sound stimuli e.g. forward masking, in BP-I compared to SZ patients. The ABR curves of BP-I patients (n=23) and SZ patients (n=20) were analyzed in terms of peak amplitudes and correlation with an ABR norm curve based on a non-psychiatric control group (n=20).

RESULTS

BP-I patients had significantly higher wave III (p=0.0062) and wave VII (p=0.0472) amplitudes compared with SZ patients. Furthermore, BP-I patients, and to a lesser extent SZ patients, showed low correlation with the norm ABR curve in the part of the curve comprising waves VI-VII.

LIMITATIONS

Sample size was relatively small and study groups were not matched for age and gender.

CONCLUSIONS

BP-I patients showed specific aberrances, specifically in the latter part of the ABR curve, implicating abnormalities in thalamocortical circuitry. The abnormal ABR wave patterns significantly separated BP-I patients from SZ patients suggesting that ABR might serve as a biomarker for BP-I.