Neural correlates of somatoform disorders from a meta-analytic perspective on neuroimaging studies

Resolving heterogeneity of early-onset major depressive disorder through individual differential structural covariance network analysis

BACKGROUND

Early-onset major depressive disorder (EO-MDD) is characterized by its significant heterogeneity, hindering progress in research. Traditional case-control studies, like group-level structural covariance network, struggle to capture individual heterogeneity among EO-MDD patients.

METHODS

In this study, T1-weighted structural magnetic resonance imaging was obtained from 185 participants, including 103 EO-MDD patients and 82 healthy controls. A subject-level individual differential structural covariance network (IDSCN) was constructed for each patient based on the concept of normative model. Semi-supervised clustering algorithms were then employed to classify EO-MDD subtypes, followed by validation analyses to assess clustering stability.

RESULTS

Our study identified two neuroanatomical subtypes. The low-covariance subtype is characterized by significant neural maturation gaps across the whole brain and more pronounced anxiety somatization symptoms. Conversely, the high-covariance subtype demonstrates simultaneous mature of brain structures.

CONCLUSION

Our findings provide valuable insights into the neuroanatomical heterogeneity of EO-MDD patients, highlighting the importance of considering individual symptom profiles in subtype classification. These findings have substantial clinical implications for personalized treatment and precision medicine, offering more effective treatment choices and accurate diagnoses.

Living with functional movement disorders: a tale of three battles. An interpretative phenomenological analysis

OBJECTIVES

Functional movement disorders (FMD) have poor prognosis and high physical and psychological co-morbidity. Their pathogenesis remains unclear, clinicians often find them difficult to treat, and lack of agreement between healthcare providers and patients is common. This study aimed to explore the experiences of living with FMD to improve understanding of its impact and patients' needs.

METHODS

Ten participants across the UK were recruited online through a charity's social media platforms. Semi structured interviews were conducted via video calls and were audio recorded and verbatim transcripts were analysed using interpretative phenomenological analysis.

RESULTS

Three superordinate themes were generated from the data, representing the three battles fought by the participants: (1) intrapersonal: the tug of war with the secret agent within- the power struggle with symptoms; (2) interpersonal: navigating stigma and self-preservation; (3) systemic: pursuing hope and treatments against helplessness and passivity.

CONCLUSIONS

Loss of control, feelings of powerlessness and oppression by symptoms is often mirrored in participants' experiences of seeking healthcare and navigating societal stigma. Active efforts to regain influence, improve quality of life and maintain hope can be jeopardised by others' dismissive attitudes and lack of knowledge. Antonovsky's model of salutogenesis is proposed as a useful framework for facilitating empowerment in FMD service provision.

Frontal alpha asymmetry is associated with chronic stress and depression, but not with somatoform disorders

Cardinal characteristics of somatoform disorders (SFDs) are worry of illness, and impaired affective processing. We used relative frontal alpha asymmetry (FAA), a method to measure functional lateralization of affective processing, to investigate psychobiological correlates of SFDs. With alpha activity being inversely related to cortical network activity, relative FAA refers to alpha activity on the right frontal lobe minus alpha activity on the left frontal lobe. Less relative left frontal activity, reflected by negative FAA scores, is associated with lower positive and greater negative affectivity, such as observed in depression. Due to its negative affective component (illness anxiety), we expected to find less relative left frontal activity pattern in SFDs, and positive associations with self-reported chronic stress and depression symptoms. We recorded resting-state EEG activity with 64 electrodes, placed in a 10-10 system in 26 patients with a primary SFD, 23 patients with a major depressive disorder and 25 healthy control participants. The groups did not differ in FAA. Nevertheless, across all participants, less relative left frontal activity was associated with chronic stress and depression symptoms. We concluded that FAA may not serve as an indicator of SFDs. As the relationship of FAA and depressive symptoms was fully mediated by chronic stress, future studies have to clarify whether the association between FAA and chronic stress may represent a shared underlying factor for the manifestation of mental health complaints, such as depression.

Affective dysfunction mediates the link between neuroimmune markers and the default mode network functional connectivity, and the somatic symptoms in somatic symptom disorder

OBJECTIVE

Somatic symptom disorder (SSD) is characterized by physical symptoms and associated functional impairments that are often comorbid with depression and anxiety disorders. In this study, we explored relationships between affective symptoms and the functional connectivity of the default mode network (DMN) in SSD patients, as well as the impact of peripheral inflammation. We employed mediation analyses to investigate the potential pathways between these factors.

METHODS

We recruited a total of 119 individuals (74 unmedicated SSD patients and 45 healthy controls), who were subjected to comprehensive psychiatric and clinical evaluations, blood tests, and resting-state functional magnetic resonance imaging scanning. We assessed neuroimmune markers (interleukin-6 (IL-6), high-sensitivity C-reactive protein (hs-CRP), tumor necrosis factor-α (TNF-α), tryptophan, serotonin, and 5-hydroxyindoleacetic acid (5-HIAA)), clinical indicators of somatic symptoms, depression, anxiety, anger, alexithymia, and functional connectivity (FC) within the DMN regions. Data were analyzed using correlation and mediation analysis, with a focus on exploring potential relations between clinical symptoms, blood indices, and DMN FCs.

RESULTS

Patients with SSD had higher clinical scores as well as IL-6 and TNF-α levels compared with those in the control group (P < 0.05). The SSD group exhibited lower FC strength between the left inferior parietal lobule and left prefrontal cortex (Pfalse discovery rate (FDR) < 0.05). Exploratory correlation analysis revealed that somatic symptom scores were positively correlated with affective symptom scores, negatively correlated with the FC strength between the intra prefrontal cortex regions, and correlated with levels of IL-6, TNF- α, and tryptophan (uncorrected P < 0.01). Mediation analysis showed that levels of anxiety and trait anger significantly mediated the relations between DMN FC strength and somatic symptoms. In addition, the DMN FC mediated the level of trait anger with respect to somatic symptoms (all PFDR < 0.05). The levels of depression and trait anger exhibited significant mediating effects as suppressors of the relations between the level of 5-HIAA and somatic symptom score (all PFDR < 0.05). Further, the level of 5-HIAA had a mediating effect as a suppressor on the relation between DMN FC and state anger. Meanwhile, the levels of hs-CRP and IL-6 had full mediating effects as suppressors when explaining the relations of DMN FC strengths with the level of depression (all PFDR < 0.05). The patterns of valid mediation pathways were different in the control group.

CONCLUSIONS

Affective symptoms may indirectly mediate the associations between DMN connectivity, somatic symptoms, and neuroimmune markers. Inflammatory markers may also mediate the impact of DMN connectivity on affective symptoms. These results emphasize the importance of affective dysregulation in understanding the mechanisms of SSD and have potential implications for the development of tailored therapeutic approaches for SSD patients with affective symptoms. Furthermore, in SSD research using DMN FC or neuroimmune markers, considering and incorporating such mediating effects of affective symptoms suggests the possibility of more accurate prediction and explanation.

PET/CT/MRI in Clinical Trials of Alzheimer's Disease

With the advent of PET imaging in 1976, 2-deoxy-2-[18F]fluoro-D-glucose (FDG)-PET became the preferred method for in vivo investigation of cerebral processes, including regional hypometabolism in Alzheimer's disease. With the emergence of amyloid-PET tracers, [11C]Pittsburgh Compound-B in 2004 and later [18F]florbetapir, [18F]florbetaben, and [18F]flumetamol, amyloid-PET has replaced FDG-PET in Alzheimer's disease anti-amyloid clinical trial treatments to ensure "amyloid positivity" as an entry criterion, and to measure treatment-related decline in cerebral amyloid deposits. MRI has been used to rule out other brain diseases and screen for 'amyloid-related imaging abnormalities' (ARIAs) of two kinds, ARIA-E and ARIA-H, characterized by edema and micro-hemorrhage, respectively, and, to a lesser extent, to measure changes in cerebral volumes. While early immunotherapy trials of Alzheimer's disease showed no clinical effects, newer monoclonal antibody trials reported decreases of 27% to 85% in the cerebral amyloid-PET signal, interpreted by the Food and Drug Administration as amyloid removal expected to result in a reduction in clinical decline. However, due to the lack of diagnostic specificity of amyloid-PET tracers, amyloid positivity cannot prevent the inclusion of non-Alzheimer's patients and even healthy subjects in these clinical trials. Moreover, the "decreasing amyloid accumulation" assessed by amyloid-PET imaging has questionable quantitative value in the presence of treatment-related brain damage (ARIAs). Therefore, future Alzheimer's clinical trials should disregard amyloid-PET imaging and focus instead on assessment of regional brain function by FDG-PET and MRI monitoring of ARIAs and brain volume loss in all trial patients.

The central role of the Thalamus in psychosis, lessons from neurodegenerative diseases and psychedelics

The PD-DLB psychosis complex found in Parkinson's disease (PD) and Dementia with Lewy Bodies (DLB) includes hallucinations, Somatic Symptom/Functional Disorders, and delusions. These disorders exhibit similar presentation patterns and progression. Mechanisms at the root of these symptoms also share similarities with processes promoting altered states of consciousness found in Rapid Eye Movement sleep, psychiatric disorders, or the intake of psychedelic compounds. We propose that these mechanisms find a crucial driver and trigger in the dysregulated activity of high-order thalamic nuclei set in motion by ThalamoCortical Dysrhythmia (TCD). TCD generates the loss of finely tuned cortico-cortical modulations promoted by the thalamus and unleashes the aberrant activity of the Default Mode Network (DMN). TCD moves in parallel with altered thalamic filtering of external and internal information. The process produces an input overload to the cortex, thereby exacerbating DMN decoupling from task-positive networks. These phenomena alter the brain metastability, creating dreamlike, dissociative, or altered states of consciousness. In support of this hypothesis, mind-altering psychedelic drugs also modulate thalamic-cortical pathways. Understanding the pathophysiological background of these conditions provides a conceptual bridge between neurology and psychiatry, thereby helping to generate a promising and converging area of investigation and therapeutic efforts.

Microstructural Differences of the Cerebellum-Thalamus-Basal Ganglia-Limbic Cortex in Patients with Somatic Symptom Disorders: a Diffusion Kurtosis Imaging Study

Somatic symp tom disorders (SSDs) are a group of psychiatric disorders characterized by persistent disproportionate concern and obsessive behaviors regarding physical conditions. Currently, SSDs lack effective treatments and their pathophysiology is unclear. In this paper, we aimed to examine microstructural abnormalities in the brains of patients with SSD using diffusion kurtosis imaging (DKI) and to investigate the correlation between these abnormalities and clinical indicators. Diffusion kurtosis images were acquired from 30 patients with SSD and 30 healthy controls (HCs). Whole-brain maps of multiple diffusion measures, including fractional anisotropy (FA), axial diffusivity (AD), radial diffusivity (RD), mean diffusivity (MD), mean kurtosis (MK), radial kurtosis (RK), and axial kurtosis (AK), were calculated. To analyze differences between the two groups, nonparametric permutation testing with 10,000 randomized permutations and threshold-free cluster enhancement was used with family-wise error-corrected p values < 0.05 as the threshold for statistical significance. Then, the correlations between significant changes in these diffusion measures and clinical factors were examined. Compared to HCs, patients with SSD had significantly higher FA, MK, and RK and significantly lower MD and RD in the cerebellum, thalamus, basal ganglia, and limbic cortex. The FA in the left caudate and the pontine crossing tract were negatively correlated with disease duration; the MD and the RD in the genu of the corpus callosum were positively correlated with disease duration. Our findings highlight the role of the cerebellum-thalamus-basal ganglia-limbic cortex pathway, especially the cerebellum, in SSDs and enhance our understanding of the pathogenesis of SSDs.

Physical symptoms and brain morphology: a population neuroimaging study in 12,286 pre-adolescents

Physical symptoms, also known as somatic symptoms, are those for which medical examinations do not reveal a sufficient underlying root cause (e.g., pain and fatigue). The extant literature of the neurobiological underpinnings of physical symptoms is largely inconsistent and primarily comprises of (clinical) case-control studies with small sample sizes. In this cross-sectional study, we studied the association between dimensionally measured physical symptoms and brain morphology in pre-adolescents from two population-based cohorts; the Generation R Study (n = 2649, 10.1 ± 0.6 years old) and ABCD Study (n = 9637, 9.9 ± 0.6 years old). Physical symptoms were evaluated using continuous scores from the somatic complaints syndrome scale from the parent-reported Child Behavior Checklist (CBCL). High-resolution structural magnetic resonance imaging (MRI) was collected using 3-Tesla MRI systems. Linear regression models were fitted for global brain metrics (cortical and subcortical grey matter and total white matter volume) and surface-based vertex-wise measures (surface area and cortical thickness). Results were meta-analysed. Symptoms of anxiety/depression were studied as a contrasting comorbidity. In the meta-analyses across cohorts, we found negative associations between physical symptoms and surface area in the (i) left hemisphere; in the lateral orbitofrontal cortex and pars triangularis and (ii) right hemisphere; in the pars triangularis, the pars orbitalis, insula, middle temporal gyrus and caudal anterior cingulate cortex. However, only a subset of regions (left lateral orbitofrontal cortex and right pars triangularis) were specifically associated with physical symptoms, while others were also related to symptoms of anxiety/depression. No significant associations were observed for cortical thickness. This study in preadolescents, the most representative and well-powered to date, showed that more physical symptoms are modestly related to less surface area of the prefrontal cortex mostly. While these effects are subtle, future prospective research is warranted to understand the longitudinal relationship of physical symptoms and brain changes over time. Particularly, to elucidate whether physical symptoms are a potential cause or consequence of distinct neurodevelopmental trajectories.

The Amplification of Symptoms in the Medically Ill

The mechanism of symptom amplification, developed in the study of somatization, may be helpful in caring for patients with symptoms that, while they have a demonstrable medical basis, are nonetheless disproportionately severe and distressing. Amplified medical symptoms are marked by disproportionate physical suffering, unduly negative thoughts and concerns about them, and elevated levels of health-related anxiety. They are accompanied by extensive and sustained illness behaviors, disproportionate difficulty compartmentalizing them and circumscribing their impact, and consequent problems and dissatisfaction with their medical care. A distinction has long been made between "medically explained" and "medically unexplained" symptoms. However, a more comprehensive view of symptom phenomenology undermines this distinction and places all symptoms along a smooth continuum regardless of cause: Recent findings in cognitive neuroscience suggest that all symptoms-regardless of origin-are processed through convergent pathways. The complete conscious experience of both medically "explained" and "unexplained" symptoms is an amalgam of a viscerosomatic sensation fused with its ascribed salience and the patient's ideas, expectations, and concerns about the sensation. This emerging empirical evidence furnishes a basis for viewing persistent, disproportionately distressing symptoms of demonstrable disease along a continuum with medically unexplained symptoms. Thus, therapeutic modalities developed for somatization and medically unexplained symptoms can be helpful in the care of seriously ill medical patients with amplified symptoms. These interventions include educational groups for coping with chronic illness, cognitive therapies for dysfunctional thoughts, behavioral strategies for maladaptive illness behaviors, psychotherapy for associated emotional distress, and consultation with mental health professionals to assist the primary care physician with difficulties in medical management.

Altered Medial Prefrontal Connectivity in Parkinson's Disease Patients with Somatic Symptoms

BACKGROUND

The high co-occurrence of somatic symptom disorder (SSD) in Parkinson's disease (PD) patients suggests overlapping pathophysiology. However, little is known about the neural correlates of SSD and their possible interactions with PD. Existing studies have shown that SSD is associated with reduced task-evoked activity in the medial prefrontal cortex (mPFC), a central node of the default-mode network (DMN). SSD is also associated with abnormal γ-aminobutyric acid (GABA) content, a marker of local inhibitory tone and regional hypoactivity, in the same area when SSD co-occurs with PD.

OBJECTIVES

To disentangle the individual and shared effects of SSD and PD on mPFC neurotransmission and connectivity patterns and help disclose the neural mechanisms of comorbidity in the PD population.

METHODS

The study cohort included 18 PD patients with SSD (PD + SSD), 18 PD patients, 13 SSD patients who did not exhibit neurologic disorders, and 17 healthy subjects (HC). Proton magnetic resonance (MR) spectroscopy evaluated GABA levels within a volume of interest centered on the mPFC. Resting-state functional MR imaging investigated the region's functional connectivity patterns.

RESULTS

Compared to HC or PD groups, the mPFC of SSD subjects exhibited higher GABA levels and connectivity. Higher mPFC connectivity involved DMN regions in SSD patients without PD and regions of the executive and attentional networks (EAN) in patients with PD comorbidity.

CONCLUSIONS

Aberrant reconfigurations of connectivity patterns between the mPFC and the EAN are distinct features of the PD + SSD comorbidity. © 2022 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Fluoxetine reverses hyperactivity of anterior cingulate cortex and attenuates chronic stress-induced hyperalgesia

Somatic symptom disorder (SSD), which occurs in about 5-7 percent of the adult population, involves heightened physical and emotional sensitivity to pain. However, its neural mechanism remains elusive and thus hinders effective clinical intervention. In this study, we employed chronic restraint stress (CRS)-induced hyperalgesia as a mouse model to investigate the neural mechanism underlying SSD and its pharmacological treatment. We found that CRS induced hyperactivity of anterior cingulate cortex (ACC), whereas chemogenetic inhibition of such hyperactivity could prevent CRS-induced hyperalgesia. Systematic application and ACC local infusion of fluoxetine alleviated CRS-induced hyperalgesia. Moreover, we found that fluoxetine exerted its anti-hyperalgesic effects through inhibiting the hyperactivity of ACC and upregulating 5-HT1A receptors. Our study thus uncovers the functional role of 5-HT signaling in modulating pain sensation and provides a neural basis for developing precise clinical intervention for SSD.

Cortical mechanisms of visual hypersensitivity in women at risk for chronic pelvic pain

ABSTRACT

Increased sensory sensitivity across non-nociceptive modalities is a common symptom of chronic pain conditions and is associated with chronic pain development. Providing a better understanding of the brain-behavior relationships that underlie multimodal hypersensitivity (MMH) may clarify the role of MMH in the development of chronic pain. We studied sensory hypersensitivity in a cohort of women (n = 147) who had diary confirmation of menstrual status and were enriched with risk factors for chronic pelvic pain, such as dysmenorrhea and increased bladder sensitivity. We administered 2 experimental tasks to evaluate the cross-modal relationship between visual and visceral sensitivity. Visual sensitivity was probed by presenting participants with a periodic pattern-reversal checkerboard stimulus presented across 5 brightness intensities during electroencephalography recording. Self-reported visual unpleasantness ratings for each brightness intensity were simultaneously assessed. Visceral sensitivity was evaluated with an experimental bladder-filling task associated with early clinical symptoms of chronic pelvic pain. Visually evoked cortical activity increased with brightness intensity across the entire scalp, especially at occipital electrode sites. Visual stimulation-induced unpleasantness was associated with provoked bladder pain and evoked primary visual cortex activity. However, the relationship between unpleasantness and cortical activity was moderated by provoked bladder pain. These results demonstrate that activity in the primary visual cortex is not greater in individuals with greater visceral sensitivity. We hypothesize that downstream interpretation or integration of this signal is amplified in individuals with visceral hypersensitivity. Future studies aimed at reducing MMH in chronic pain conditions should prioritize targeting of cortical mechanisms responsible for aberrant downstream sensory integration.

Nature and Extent of Physical Comorbidities Among Korean Patients With Mental Illnesses: Pairwise and Network Analysis Based on Health Insurance Claims Data

OBJECTIVE

The nature of physical comorbidities in patients with mental illness may differ according to diagnosis and personal characteristics. We investigated this complexity by conventional logistic regression and network analysis.

METHODS

A health insurance claims data in Korea was analyzed. For every combination of psychiatric and physical diagnoses, odds ratios were calculated adjusting age and sex. From the patient-diagnosis data, a network of diagnoses was constructed using Jaccard coefficient as the index of comorbidity.

RESULTS

In 1,017,024 individuals, 77,447 (7.6%) were diagnosed with mental illnesses. The number of physical diagnoses among them was 11.2, which was 1.6 times higher than non-psychiatric groups. The most noticeable associations were 1) neurotic illnesses with gastrointestinal/pain disorders and 2) dementia with fracture, Parkinson's disease, and cerebrovascular accidents. Unexpectedly, the diagnosis of metabolic syndrome was only scarcely found in patients with severe mental illnesses (SMIs). However, implicit associations between metabolic syndrome and SMIs were suggested in comorbidity networks.

CONCLUSION

Physical comorbidities in patients with mental illnesses were more extensive than those with other disease categories. However, the result raised questions as to whether the medical resources were being diverted to less serious conditions than more urgent conditions in patients with SMIs.

Neuromodulation for the treatment of functional neurological disorder and somatic symptom disorder: a systematic review

Functional neurological disorder and somatic symptom disorder are complex neuropsychiatric conditions that have been linked to circuit-based dysfunction of brain networks. Neuromodulation is a novel therapeutic strategy capable of modulating relevant brain networks, making it a promising potential candidate for the treatment of these patient populations. We conducted a systematic review of Medline, Embase and PsycINFO up to 4 March 2021. Trials investigating neuromodulation devices for the treatment of functional neurological disorder or somatic symptom disorder were selected. Extracted variables included study design, demographic and clinical characteristics, psychiatric comorbidity, neurostimulation protocols, clinical outcome measures and results. 404 studies were identified with 12 meeting inclusion criteria. 221 patients were treated in the included studies with mean study sample size of 18 (4-70). Five studies were randomised clinical trials. Functional motor symptoms (six weakness, four movement disorders) were the most studied subpopulations. Transcranial magnetic stimulation (TMS) was the most frequently used device (10 studies), followed by electroconvulsive therapy (one study) and direct-current stimulation (one study). Treatment protocols varied in intended therapeutic mechanism(s): eight studies aimed to modulate underlying network dysfunction, five aimed to demonstrate movement (one also leveraged the former) and three boosted their primary mechanism with enhanced suggestion/expectation. All but one study reported positive results; however, methodological/outcome heterogeneity, mixed study quality and small sample sizes precluded quantitative meta-analysis. Neuromodulation, particularly TMS for the treatment of functional motor symptoms, shows preliminary promise in a growing line of research. Larger, sham-controlled studies are needed to further establish efficacy and better understand therapeutic mechanisms.

Functional seizures are associated with cerebrovascular disease and functional stroke is more common in patients with functional seizures than epileptic seizures

PURPOSE

To characterize the relationship between functional seizures (FSe), cerebrovascular disease (CVD), and functional stroke.

METHOD

A retrospective case-control study of 189 patients at a single large tertiary medical center. We performed a manual chart review of medical records of patients with FSe or epileptic seizures (ES), who also had ICD code evidence of CVD. The clinical characteristics of FSe, ES, CVD, and functional stroke were recorded. Logistic regression and Welch's t-tests were used to evaluate the differences between the FSe and ES groups.

RESULTS

Cerebrovascular disease was confirmed in 58.7% and 87.6% of patients with FSe or ES through manual chart review. Stroke was significantly more common in patients with ES (76.29%) than FSe (43.48%) (p = 4.07 × 10^-6). However, compared to nonepileptic controls FSe was associated with both CVD (p < 0.0019) and stroke (p < 6.62 × 10^-10). Functional stroke was significantly more common in patients with FSe (39.13%) than patients with ES (4.12%) (p = 4.47 × 10^-9). Compared to patients with ES, patients with FSe were younger (p = 0.00022), more likely to be female (p = 0.00040), and more likely to have comorbid mental health needs including anxiety (p = 1.06 × 10^-6), PTSD or history of trauma (e.g., sexual abuse) (p = 1.06 × 10^-13), and bipolar disorder (p = 0.0011).

CONCLUSION

Our results confirm the initial observation of increased CVD in patients with FSe and further suggest that patients with FSe may be predisposed to developing another functional neurological disorder (FND) (i.e., functional stroke). We speculate that this may be due to shared risk factors and pathophysiological processes that are common to various manifestations of FND.

Validity and utility of Hierarchical Taxonomy of Psychopathology (HiTOP): III. Emotional dysfunction superspectrum

The Hierarchical Taxonomy of Psychopathology (HiTOP) is a quantitative nosological system that addresses shortcomings of traditional mental disorder diagnoses, including arbitrary boundaries between psychopathology and normality, frequent disorder co-occurrence, substantial heterogeneity within disorders, and diagnostic unreliability over time and across clinicians. This paper reviews evidence on the validity and utility of the internalizing and somatoform spectra of HiTOP, which together provide support for an emotional dysfunction superspectrum. These spectra are composed of homogeneous symptom and maladaptive trait dimensions currently subsumed within multiple diagnostic classes, including depressive, anxiety, trauma-related, eating, bipolar, and somatic symptom disorders, as well as sexual dysfunction and aspects of personality disorders. Dimensions falling within the emotional dysfunction superspectrum are broadly linked to individual differences in negative affect/neuroticism. Extensive evidence establishes that dimensions falling within the superspectrum share genetic diatheses, environmental risk factors, cognitive and affective difficulties, neural substrates and biomarkers, childhood temperamental antecedents, and treatment response. The structure of these validators mirrors the quantitative structure of the superspectrum, with some correlates more specific to internalizing or somatoform conditions, and others common to both, thereby underlining the hierarchical structure of the domain. Compared to traditional diagnoses, the internalizing and somatoform spectra demonstrated substantially improved utility: greater reliability, larger explanatory and predictive power, and greater clinical applicability. Validated measures are currently available to implement the HiTOP system in practice, which can make diagnostic classification more useful, both in research and in the clinic.

A Longitudinal Study on Attenuated Structural Covariance in Patients With Somatic Symptom Disorder

OBJECTIVE

This study was performed to investigate altered regional gray matter volume (rGMV) and structural covariance related to somatic symptom disorder (SSD) and longitudinal changes after treatment. Additionally, this study examined the relationships of structural alteration with its phenotypic subtypes.

METHODS

Forty-three unmedicated patients with SSD and thirty normal controls completed psychological questionnaires and neurocognitive tests, as well as brain magnetic resonance imaging. Voxel-based morphometry and structural covariances were compared between groups and between subgroups within the SSD group. After 6 months of treatment, SSD patients were followed up for assessments.

RESULTS

Patients with SSD exhibited attenuated structural covariances in the pallidal-cerebellar circuit (FDR < 0.05-0.1), as well as regions in the default mode and sensorimotor network (FDR < 0.2), compared to normal controls. The cerebellar rGMVs were negatively correlated with the severity of somatic symptoms. In subgroup analyses, patients with somatic pain showed denser structural covariances between the bilateral superior temporal pole and left angular gyrus, the left middle temporal pole and left angular gyrus, and the left amygdala and right inferior orbitofrontal gyrus, while patients with headache and dizziness had greater structural covariance between the right inferior temporal gyrus and right cerebellum (FDR < 0.1-0.2). After 6 months of treatment, patients showed improved symptoms, however there was no significant structural alteration.

CONCLUSION

The findings suggest that attenuated structural covariance may link to dysfunctional brain network and vulnerability to SSD; they also suggested that specific brain regions and networks may contribute to different subtypes of SSD.

Functional neurological disorder and somatic symptom disorder in Parkinson's disease

The occurrence of Functional Neurological Disorder (FND) and Somatic Symptom Disorder (SSD) in PD was not commonly accepted until recently, despite some evidence that emerged in the pre and early L-Dopa era. More recently, the recognition of FND and SSD were noted to be relevant for the management of PD. FND and SSD appear early in the course of PD, often preceding motor symptoms, may interfere with treatment outcomes, often acquire psychotic features during progression, and are mixed with and often concealed by the progressive cognitive decline. We review the related features from the range of the available reports and discuss theoretical models conceived to explain the potential pathophysiological background of these disorders. Finally, we suggest that FND and SSD should be included among the non-motor symptoms of PD and be considered a prodromal feature in a subset of patients. This article is part of the Special Issue "Parkinsonism across the spectrum of movement disorders and beyond" edited by Joseph Jankovic, Daniel D. Truong and Matteo Bologna.

Decline of anterior cingulate functional network efficiency in first-episode, medication-naïve somatic symptom disorder and its relationship with catastrophizing

The high prevalence of somatic symptom disorder (SSD) led to cumulative burdens to the medical system. However, the pathogenesis of this disease still remains unclear. Graph theoretical analysis discovered altered network topology across various psychiatric disorders, yet alteration in the topological structure of brain functional network in SSD patients is still unexplored. Catastrophizing is a common cognitive distortion in SSD. We hypothesize that the network topological metrics of SSD should be altered, and should correlate with catastrophizing scales. 32 medication-naïve, first-episode SSD patients and 30 age, gender matched HCs were recruited. The 17-item Hamilton Depression Rating Scale (HAMD-17), Hamilton Anxiety Rating Scale (HAMA) and Cognitive Emotion Regulation Questionnaire (CERQ) were accessed. Functional MRI were scanned and brain functional networks were constructed based on 166 anatomically cerebrum regions from the automated anatomical labeling 3 (AAL3) template. Network topological metrics were calculated and compared between the two groups. Correlation between these metrics and clinical scales were also calculated. Network global efficiency of SSD was significantly lower than that of HC. Nodal global efficiency of the left subgenual anterior cingulate cortex (sgACC) of SSD was significantly lower than that of HC. FCs between the left sgACC and other 21 seed nodes were significantly declined in SSD in comparison with HC. In SSD group, HAMD total score was significantly negatively correlated with the connection between the left medial superior frontal gyrus and the left sgACC. CERQ catastrophizing score was significantly negatively correlated with nodal global efficiency of left sgACC and with the FCs between the left sgACC and other 13 seed nodes. Catastrophizing could reflect the specific sgACC-centered dysfunction of brain network global efficiency of SSD. The left sgACC may be a future treatment target of dealing with catastrophizing, which is a core cognitive distortion of SSD.

Is new daily persistent headache a fallout of somatization? An observational study

OBJECTIVE

New daily persistent headache (NDPH) is characterized by daily, persistent headache with clearly remembered onset, preceding events or triggers and treatment refractoriness of headache. The pathophysiology of NDPH is still unresolved. NDPH has been associated with somatoform disorder (DSM 4 TR). Somatization is characterized by vivid memory, disproportionate and persistent thought about symptoms that may explain many characteristics of NDPH. However, tendency towards somatization has not been studied in NDPH patients.

METHODS

In this cross-sectional study, we evaluated somatization in NDPH, chronic migraine (CM), and chronic tension type headache (CTTH) by comparing the prevalence of somatic symptom disorder (SSD, DSM-5). We evaluated the past tendencies to somatization by comparing various characteristics of past somatic symptoms (number, duration, type, clearly remembered onset, etc.) between NDPH, CM, and CTTH.

RESULTS

Forty-seven patients each of NDPH and CTTH and 46 patients of CM were evaluated. Criteria for SSD was fulfilled by 85.1% of NDPH and CTTH patients and only 45.7% of CM. Past history of somatic symptoms was seen in 70% patients with NDPH, 15.2% CM, and 23.4% CTTH (p<0.001). Median number of past somatic symptoms was higher in NDPH. All NDPH patients clearly remembered the onset of at least one past somatic symptom. None of CM and CTTH patients remembered the onset of past somatic symptoms.

CONCLUSION

NDPH patients displayed significant past history of somatization. Continuation of past tendencies to manifest as NDPH suggests that NDPH may be an epiphenomenon of somatization.

Associations between Antiretroviral Drugs on Depressive Symptomatology in Homogenous Subgroups of Women with HIV

Antiretroviral therapy (ART) is inconsistently associated with depression. These associations may depend on factors such as biological sex, age, and health status. Identifying such factors may help optimize treatment of HIV and depression. We implemented a novel approach to examine interindividual variability in the association between ART agents and depressive symptoms. 3434 women living with HIV (WLWH) from the Women's Interagency HIV Study (WIHS) were computationally divided into subgroups based on sociodemographic (e.g., age) and longitudinal (from 1995 to 2016) behavioral and clinical profiles (e.g., substance use, HIV RNA, CD4 counts). Five subgroups (n's ranged from 482 to 802) were identified and characterized as those with: controlled HIV/vascular comorbidities; profound HIV legacy effects; younger women [<45 years of age] with hepatitis C; primarily 35-55 year olds; and poorly controlled HIV/substance use. Within each subgroup, we examined associations between ART agents used over the past 6 months and item-level depressive symptoms on the Center for Epidemiologic Studies Depression Scale. Tenofovir (4 of 5 subgroups) followed by efavirenz, emtricitabine, stavudine, lopinavir, etravirine, nelfinavir, ritonavir, and maraviroc were the most common agents associated with depressive symptoms, although the pattern and directionality varied by subgroup. For example, lopinavir was associated with fewer symptoms among the subgroup with a legacy HIV effect but more symptoms among the subgroup with well-controlled HIV/vascular comorbidities. Unexpectedly, dolutegravir and raltegravir were not associated with depressive symptoms among any subgroup. Findings underscore marked interindividual variability in ART agents on depression in WLWH. Sociodemographic, clinical, and behavioral factors are important determinants of the relationship between ART agents and depressive symptoms in WLWH. Graphical Abstract Are antiretroviral agents a risk factor for depressive symptoms in women with HIV? We examined associations between ART-agents and depressive symptoms among similar subgroups of women with HIV from the Women's Interagency HIV Study. The patterns of associations depended on sociodemographic, clinical, and behavioral characteristics of women.

The relationship of cortical activity induced by pain stimulation with clinical and cognitive features of somatic symptom disorder: A controlled functional near infrared spectroscopy study

OBJECTIVE

The neurobiological correlates of Somatic Symptom Disorder (SSD) introduced in the DSM-5 has been the focus of a limited investigation. We aimed to examine the cortical response to painful stimuli and its relationship to symptom severity as well as cognitive and psychological characteristics in proposed models of somatoform disorders.

METHODS

We measured hemodynamic responses by 52-channel functional near-infrared spectroscopy. We compared the cortical response to painful stimuli in index patients with SSD (N = 21) versus age, and gender matched healthy control subjects (N = 21). We used brush stimulation as the control condition. We analyzed the relationship of cortical activity with SSD symptom severity as well as somatosensory amplification (SSA), alexithymia, dysfunctional illness behaviour, worry, and neuroticism.

RESULTS

Patients with SSD had higher somatic symptom severity, SSA, alexithymia, neuroticism, illness-related worry, and behaviour. Somatic symptom severity was predicted by a model including SSA and subjective feeling of pain in the index patients. Activity in the left-angular and right-middle temporal gyri was higher in the SSD subjects than the controls during pain stimulation. Positive correlations were detected between mean pain threshold levels and left middle occipital gyrus activity, as well as between SSA-scores and right-angular gyrus activity during pain condition in the index patients with SSD.

CONCLUSION

We present the first evidence that representation of pain in terms of cortical activity is different in subjects with SSD than healthy controls. SSA has functional neuroanatomic correlates and predicts symptom severity in SSD and therefore is involved as a valid intermediate phenotype in SSD pathophysiology.

Differential sensory and clinical phenotypes of patients with chronic widespread and regional musculoskeletal pain

The differentiation of chronic primary pain syndromes into those with widespread vs regional musculoskeletal pain has been characterized by controversial discussions about common or distinct mechanisms and core clinical and sensory criteria. For example, the recent revision of fibromyalgia criteria has discarded sensory characteristics such as number of "tender points." This study examined empirical evidence related to this diagnostic shift and aimed to identify basic sensory-clinical pain phenotypes in patients with chronic local primary pain (chronic primary back pain [CBP]) and patients with chronic widespread primary pain (fibromyalgia syndrome). Combined sensory-clinical pain phenotypes of 185 patients with previous CBP and fibromyalgia syndrome diagnoses were derived by a stepwise data reduction through descriptive statistical, correlational, principal components and latent class analyses. Clusters were cross-validated by linear discriminant analysis. Four clusters of patients were identified, requiring 4 pressure pain sensitivity markers (number of sensitive tender and control points, pain intensity, and pressure pain threshold at the trapezius) and 2 clinical pain characteristics (pain regions and present pain intensity). Subsequent discriminant analysis revealed that 3 discriminant functions of pressure sensitivity markers sufficed to differentiate the clusters. These sensory-clinical phenotypes differed also in somatic symptoms and impairment but neither in psychopathology nor in psychosocial cofactors. The results highlight the relevance of sensory testing in combination with clinical pain assessment in chronic primary pain syndromes.

Changes in brain glucose metabolism and connectivity in somatoform disorders: an 18F-FDG PET study

Somatoform disorders (SFD) are defined as a syndrome characterized by somatic symptoms which cannot be explained by organic reasons. Chronic or recurrent forms of somatization lead to heavy emotional and financial burden to the patients and their families. However, the underlying etiology of SFD is largely unknown. The purpose of this study is to investigate the changed brain glucose metabolic pattern in SFD. In this study, 18 SFD patients and 21 matched healthy controls were enrolled and underwent an ¹⁸F-FDG PET scan. First, we explored the altered brain glucose metabolism in SFD. Then, we calculated the mean ¹⁸F-FDG uptake values for 90 AAL regions, and detected the changed brain metabolic connectivity between the most significantly changed regions and all other regions. In addition, the Pearson coefficients between the neuropsychological scores and regional brain ¹⁸F-FDG uptake values were computed for SFD patients. We found that SFD patients showed extensive hypometabolism in bilateral superolateral prefrontal cortex, insula, and regions in bilateral temporal gyrus, right angular gyrus, left gyrus rectus, right fusiform gyrus, right rolandic operculum and bilateral occipital gyrus. The metabolic connectivity between right insula and prefrontal areas, as well as within prefrontal areas was enhanced in SFD. And several brain regions were associated with the somatic symptoms, including insula, putamen, middle temporal gyrus, superior parietal gyrus and orbital part of inferior frontal gyrus. Our study revealed widespread alterations of the brain glucose metabolic pattern in SFD patients. Those findings might elucidate the neuronal mechanisms with glucose metabolism and shed light on the pathology of SFD.

Ceftriaxone inhibits stress-induced bladder hyperalgesia and alters cerebral micturition and nociceptive circuits in the rat: A multidisciplinary approach to the study of urologic chronic pelvic pain syndrome research network study

AIMS

Emotional stress plays a role in the exacerbation and development of interstitial cystitis/bladder pain syndrome (IC/BPS). Given the significant overlap of brain circuits involved in stress, anxiety, and micturition, and the documented role of glutamate in their regulation, we examined the effects of an increase in glutamate transport on central amplification of stress-induced bladder hyperalgesia, a core feature of IC/BPS.

METHODS

Wistar-Kyoto rats were exposed to water avoidance stress (WAS, 1 hour/day x 10 days) or sham stress, with subgroups receiving daily administration of ceftriaxone (CTX), an activator of glutamate transport. Thereafter, cystometrograms were obtained during bladder infusion with visceromotor responses (VMR) recorded simultaneously. Cerebral blood flow (CBF) mapping was performed by intravenous injection of [¹⁴ C]-iodoantipyrine during passive bladder distension. Regional CBF was quantified in autoradiographs of brain slices and analyzed in three dimensional reconstructed brains with statistical parametric mapping.

RESULTS

WAS elicited visceral hypersensitivity during bladder filling as demonstrated by a decreased pressure threshold and VMR threshold triggering the voiding phase. Brain maps revealed stress effects in regions noted to be responsive to bladder filling. CTX diminished visceral hypersensitivity and attenuated many stress-related cerebral activations within the supraspinal micturition circuit and in overlapping limbic and nociceptive regions, including the posterior midline cortex (posterior cingulate/anterior retrosplenium), somatosensory cortex, and anterior thalamus.

CONCLUSIONS

CTX diminished bladder hyspersensitivity and attenuated regions of the brain that contribute to nociceptive and micturition circuits, show stress effects, and have been reported to demonstrated altered functionality in patients with IC/BPS. Glutamatergic pharmacologic strategies modulating stress-related bladder dysfunction may be a novel approach to the treatment of IC/BPS.

Chronic unexplained nausea in adults: Prevalence, impact on quality of life, and underlying organic diseases in a cohort of 5096 subjects comprehensively investigated

We evaluated to define the clinically significant chronic nausea in general population and to assess the prevalence of chronic unexplained nausea after exclusion of organic causes through the meticulous medical examination. Two phase studies were conducted. In phase 1, telephone survey was conducted to define the clinically significant nausea in 5000 representative subjects for a general population. Clinically significant nausea was identified by lowered quality of life if the frequency was 'more than one day per week'. Its prevalence was 1.6% (1.4-1.8%) and about 90% of nausea was not accompanied with vomiting. In phase 2, 5096 participants in a comprehensive health-screening cohort were enrolled. We investigated demographics, gastrointestinal symptoms, somatization symptoms and health related quality of life using validated questionnaire. All participants underwent meticulous medical examinations including endoscopy, abdominal ultrasound, thyroid function test, and blood testing. Among a total of 5096 subjects (men 51.8%, mean age 47.5 ± 10.0 years), organic diseases associated with chronic nausea were reflux esophagitis, duodenal ulcer and hyperthyroidism. The prevalence of chronic unexplained nausea was 0.6% (95% CI 0.4-0.8%) and there were significant overlap with functional dyspepsia and irritable bowel syndrome. HRQoL is significantly lower in people with nausea occurring 'more than one day per week' in a general population. Most chronic nausea was not accompanied with vomiting. Chronic unexplained nausea is uncommon affecting only 0.6% of the population but are more likely to report functional dyspepsia and irritable bowel syndrome.

Multisensory mechanisms of body perception in somatoform disorders

OBJECTIVE

According to one of the hypotheses, somatoform disorders (SD) are related to disturbed perception of bodily signals. We suspect that the disturbances and abnormalities of multisensory integration dynamics may be an additional SD mechanism. The objective of the research was to investigate multisensory bodily illusion dynamics in SD patients.

METHODS

A clinical group of SD patients (n = 16) and a control group (n = 17) participated in experiments aimed at eliciting a visual-tactile rubber hand illusion (RHI) and a visual-kinesthetic virtual hand illusion (VHI).

RESULTS

For both illusions studied, the illusion dynamics in SD patients differed from those of healthy subjects. The visual-tactile illusion on the subjective level appeared to be less strong in SD patients, and no proprioceptive drift (PD) was detected. The subjective dynamics of the visual-kinesthetic illusion in patients were similar to those of the control group, but the PD dynamics were different: after the termination of stimuli from the artificial limb, the proprioceptive system did not return to its initial state; on the contrary, PD continued to increase.

CONCLUSION

In comparison with the norm, patients with somatoform disorders display differences in multisensory mechanisms underlying the development of body perception. The results suggest that the disturbance of visual-tactile integration of the stimuli represents one of the mechanisms of body perception distortion in somatoform disorders. It may be assumed that one of the reasons for persistent symptom perception in SD patients is the rigidity of multisensory stimuli perception, at least in the visual-motor domain.

Distinct Neuroanatomical Correlates of Neuropsychiatric Symptoms in the Three Main Forms of Genetic Frontotemporal Dementia in the GENFI Cohort

Background:

The overlap between frontotemporal dementia (FTD) and primary psychiatric disorders has been brought to light by reports of prominent neuropsychiatric symptoms (NPS) in FTD-related genetic mutations, particularly among C9orf72 and GRN carriers. It has been recently demonstrated that early neuroanatomical changes in genetic FTD may be different across the major disease-causing mutations.

Objective:

We aimed to identify whether NPS could be driven by distinct structural correlates.

Methods:

One hundred and sixty-seven mutation carriers (75 GRN, 60 C9orf72, and 32 MAPT) were included from the Genetic FTD Initiative (GENFI) study, a large international cohort of genetic FTD. Neuropsychiatric symptoms including delusions, hallucinations (visual, auditory, and tactile), depression, and anxiety were investigated using a structured interview. Voxel-based morphometry was performed to identify neuroanatomical correlates of NPS.

Results:

Psychotic symptoms correlated mainly with grey matter (GM) atrophy in the anterior insula, left thalamus, cerebellum, and cortical regions including frontal, parietal, and occipital lobes in GRN mutations carriers. GM atrophy in posterior structures of the default-mode network was associated with anxiety in the GRN group. Delusions in C9orf72 expansion carriers were mainly associated with left frontal cortical atrophy. Cerebellar atrophy was found to be correlated only with anxiety in C9orf72 carriers. NPS in the MAPT group were mainly associated with volume loss in the temporal lobe.

Conclusion:

Neuroanatomical correlates of NPS appear to be distinct across the main forms of genetic FTD. Overall, our findings support overlapping brain structural changes between FTD and primary psychiatric disorders.

Associations between subclinical depressive symptoms and reduced brain volume in middle-aged to older adults

OBJECTIVES

The associations between subclinical depressive symptoms, as well specific symptom subscales, on brain structure in aging are not completely elucidated. This study investigated the extent to which depressive symptoms were related to brain volumes in fronto-limbic structures in a sample of middle-aged to older adults.

METHOD

Eighty participants underwent structural neuroimaging and completed the Beck Depression Inventory, 2nd Edition (BDI-II), which comprises separate affective, cognitive, and somatic subscales. Gray matter volumes were extracted from the caudal and rostral anterior cingulate, posterior cingulate, hippocampus, and amygdala. Hierarchical regression models examined the relationship between brain volumes and (i) total depressive symptoms and (ii) BDI-II subscales were conducted.

RESULTS

After adjusting for total intracranial volume, race, and age, higher total depressive symptoms were associated with smaller hippocampal volume (p = 0.005). For the symptom subscales, after controlling for the abovementioned covariates and the influence of the other symptom subscales, more somatic symptoms were related to smaller posterior cingulate (p = 0.025) and hippocampal (p < 0.001) volumes. In contrast, the affective and cognitive subscales were not associated with brain volumes in any regions of interest.

CONCLUSION

Our data showed that greater symptomatology was associated with smaller volume in limbic brain regions. These findings provide evidence for preclinical biological markers of major depression and specifically advance knowledge of the relationship between subclinical depressive symptoms and brain volume. Importantly, we observed variations by specific depressive symptom subscales, suggesting a symptom-differential relationship between subclinical depression and brain volume alterations in middle-aged and older individuals.

Voxel-based global-brain functional connectivity alterations in first-episode drug-naive patients with somatization disorder

BACKGROUND

Altered functional connectivity (FC) is associated with the pathophysiology of patients with somatization disorder (SD). However, inconsistent results were obtained due to different selections of regions of interest (ROIs) in previous researches. This study aims to examine voxel-wise brain-wide FC alterations in patients with first-episode, drug-naive SD in an unbiased way.

METHODS

A total of 25 patients with SD and 28 age-, sex-, and education-matched healthy controls underwent resting-state functional magnetic resonance imaging. Global-brain FC (GFC) was applied to analyze the images. Receiver operating characteristic curves and support vector machine were used to differentiate the patients from the controls.

RESULTS

Compared with healthy controls, patients with SD exhibited increased GFC in the right inferior temporal gyrus (t-value = 4.0663, p < 0.001) and left superior occipital gyrus (t-value = 3.8197, p < 0.001). Decreased GFC in the right insula (t-value = ‒4.1667, p < 0.001) was observed in the patients relative to the controls. The GFC values in the right insula of the patients were positively correlated to their scores of the sleep subscale of the Hamilton Depression Scale (r = 0.455, p = 0.022) and the lie subscale of the Eysenck Personality Questionnaire (r = 0.436, p = 0.029). A combination of GFC values in the right insula and left superior occipital gyrus can be applied to discriminate the patients from the controls with optimal sensitivity, specificity, and accuracy of 88.00%, 85.71%, and 86.79%, respectively.

CONCLUSIONS

Our study indicates that patients with SD show abnormal GFC in the brain areas of insula-centered sensorimotor network, and thus providing a new perspective for understanding the pathological changes of FC in SD. Furthermore, a combination of the GFC values in the right insula and left superior occipital gyrus may be used as a potential biomarker to identify the patients from the controls.

Structural alterations in functional neurological disorder and related conditions: a software and hardware problem?

Functional neurological (conversion) disorder (FND) is a condition at the interface of neurology and psychiatry. A "software" vs. "hardware" analogy describes abnormal neurobiological mechanisms occurring in the context of intact macroscopic brain structure. While useful for explanatory and treatment models, this framework may require more nuanced considerations in the context of quantitative structural neuroimaging findings in FND. Moreover, high co-occurrence of FND and somatic symptom disorders (SSD) as defined in DSM-IV (somatization disorder, somatoform pain disorder, and undifferentiated somatoform disorder; referred to as SSD for brevity in this article) raises the possibility of a partially overlapping pathophysiology. In this systematic review, we use a transdiagnostic approach to review and appraise the structural neuroimaging literature in FND and SSD. While larger sample size studies are needed for definitive characterization, this article highlights that individuals with FND and SSD may exhibit sensorimotor, prefrontal, striatal-thalamic, paralimbic, and limbic structural alterations. The structural neuroimaging literature is contextualized within the neurobiology of stress-related neuroplasticity, gender differences, psychiatric comorbidities, and the greater spectrum of functional somatic disorders. Future directions that could accelerate the characterization of the pathophysiology of FND and DSM-5 SSD are outlined, including "disease staging" discussions to contextualize subgroups with or without structural changes. Emerging neuroimaging evidence suggests that some individuals with FND and SSD may have a "software" and "hardware" problem, although if structural alterations are present the neural mechanisms of functional disorders remain distinct from lesional neurological conditions. Furthermore, it remains unclear whether structural alterations relate to predisposing vulnerabilities or consequences of the disorder.

Altered regional homogeneity in patients with somatic depression: A resting-state fMRI study

BACKGROUND

Somatic symptoms are common among patients with major depressive disorder (MDD), and are known to negatively impact the course and severity of the disease. Although previous studies have attempted to explore the neuropathology of MDD, little is known regarding the neural basis of somatic symptoms in MDD.

METHODS

Resting-state functional magnetic resonance images of 28 MDD patients with somatic symptoms (somatic depression, SD), 30 patients without somatic symptoms (non-somatic depression, NSD) and 30 healthy controls (HC) were obtained. We investigated the neural basis of MDD with somatic symptoms based on the measure of regional homogeneity (ReHo). We also investigated whether the altered regional homogeneity may be correlated to any clinical features of depression. These comparison were also carried out in female and male subjects respectively.

RESULTS

The SD exhibited higher ReHo in the bilateral parahippocampus and left lingual gyrus than HC, as well as lower ReHo in the right frontal gyrus. Relative to NSD, the SD exhibited lower ReHo in the right middle frontal gyrus and left precentral gyrus. Furthermore, in the SD, ReHo in the left precentral gyrus was positively correlated with cognitive factor scores of the HAMD-17. In female subjects, SD exhibited increased ReHo in the right STG and decreased ReHo in the right MFG, relative to women of the NSD group.

CONCLUSIONS

Our preliminary findings indicated that abnormal ReHo in the frontal and temporal regions may play an important role in the neural basis of somatic depression.

Individual differences in corticolimbic structural profiles linked to insecure attachment and coping styles in motor functional neurological disorders

BACKGROUND

Insecure attachment and maladaptive coping are important predisposing vulnerabilities for Functional Neurological Disorders (FND)/Conversion Disorder, yet no prior structural neuroimaging studies have investigated biomarkers associated with these risk factors in FND populations. This magnetic resonance imaging study examined cortical thickness and subcortical volumes associated with self-reported attachment and coping styles in patients with FND. We hypothesized that insecure attachment and maladaptive coping would relate to limbic-paralimbic structural alterations.

METHODS

FreeSurfer cortical thickness and subcortical volumetric analyses were performed in 26 patients with motor FND (21 women; 5 men) and 27 healthy controls (22 women; 5 men). For between-group comparisons, patients with FND were stratified by Relationship Scales Questionnaire, Ways of Coping Scale-Revised, and Connor-Davidson Resilience Scale scores. Within-group analyses were also performed in patients with FND. All analyses were performed in the complete cohort and separately in women only to evaluate for gender-specific effects. Cortical thickness analyses were whole-brain corrected at the cluster-wise level; subcortical analyses were Bonferroni corrected.

RESULTS

In women with FND, dismissing attachment correlated with reduced left parahippocampal cortical thickness. Confrontive coping was associated with reduced right hippocampal volume, while accepting responsibility positively correlated with right precentral gyrus cortical thickness. These findings held adjusting for anti-depressant use. All FND-related findings were within the normal range when compared to healthy women.

CONCLUSION

These observations connect individual-differences in limbic-paralimbic and premotor structures to attachment and coping styles in FND. The relationship between parahippocampal thickness and dismissing attachment may indicate aberrant social-emotional and contextual appraisal in women with FND.

Corticolimbic structural alterations linked to health status and trait anxiety in functional neurological disorder

OBJECTIVE

Affective symptoms influence health status (health-related quality of life) in functional neurological disorder (FND), and the salience network is implicated in the pathophysiology of FND and mood/anxiety disorders. We hypothesised that self-reported health status and affective symptoms would map onto salience network regions and that patients with FND would show decreased insular volumes compared with controls.

METHODS

This voxel-based morphometry study investigated volumetric differences in 26 patients with FND (21 women, 5 men; mean age=40.3±11.5) compared with 27 healthy controls (22 women, 5 men; mean age=40.5±10.8). Post hoc analyses stratified patients with FND by mental and physical health scores (Short Form Health Survey-36). Within-group analyses investigated associations with mental health, physical health, trait anxiety and depression in patients with FND.

RESULTS

There were no volumetric differences between the complete FND cohort and controls. In stratified analyses, however, patients with FND reporting the most severe physical health impairments showed reduced left anterior insular volume compared with controls. In within-group analyses, impaired mental health and elevated trait anxiety were associated with increased right amygdalar volumes in patients with FND. The relationship between amygdalar volume and mental health, driven by emotional well-being deficits and role limitations due to emotional problems, was independent of sensorimotor functional neurological symptom severity and motor FND subtype. In secondary within-group analyses, increased periaqueductal grey volume was associated with role limitations due to emotional problems. Impaired physical functioning correlated with decreased left anterior insular volumes.

CONCLUSIONS

These findings support roles for several regions of the salience network in the pathophysiology of FND.

Centrality of prefrontal and motor preparation cortices to Tourette Syndrome revealed by meta-analysis of task-based neuroimaging studies

Tourette Syndrome (TS) is a neurodevelopmental condition characterized by chronic multiple tics, which are experienced as compulsive and 'unwilled'. Patients with TS can differ markedly in the frequency, severity, and bodily distribution of tics. Moreover, there are high comorbidity rates with attention deficit hyperactivity disorder (ADHD), obsessive compulsive disorder (OCD), anxiety disorders, and depression. This complex clinical profile may account for apparent variability of findings across neuroimaging studies that connect neural function to cognitive and motor behavior in TS. Here we crystalized information from neuroimaging regarding the functional circuitry of TS, and furthermore, tested specifically for neural determinants of tic severity, by applying activation likelihood estimation (ALE) meta-analyses to neuroimaging (activation) studies of TS. Fourteen task-based studies (13 fMRI and one H2O-PET) met rigorous inclusion criteria. These studies, encompassing 25 experiments and 651 participants, tested for differences between TS participants and healthy controls across cognitive, motor, perceptual and somatosensory domains. Relative to controls, TS participants showed distributed differences in the activation of prefrontal (inferior, middle, and superior frontal gyri), anterior cingulate, and motor preparation cortices (lateral premotor cortex and supplementary motor area; SMA). Differences also extended into sensory (somatosensory cortex and the lingual gyrus; V4); and temporo-parietal association cortices (posterior superior temporal sulcus, supramarginal gyrus, and retrosplenial cortex). Within TS participants, tic severity (reported using the Yale Global Tic Severity Scale; YGTSS) selectively correlated with engagement of SMA, precentral gyrus, and middle frontal gyrus across tasks. The dispersed involvement of multiple cortical regions with differences in functional reactivity may account for heterogeneity in the symptomatic expression of TS and its comorbidities. More specifically for tics and tic severity, the findings reinforce previously proposed contributions of premotor and lateral prefrontal cortices to tic expression.

5-HT2A Agonists: A Novel Therapy for Functional Neurological Disorders?

Functional neurological disorders are frequently encountered in clinical practice. They have a poor prognosis and treatment options are limited. Their etiology is unknown, but leading theories propose a disturbance of somatic self-representation: the mind perceives dysfunction of a body region despite intact motor and sensory pathways. Central to this model is the concept of an abnormal top-down cognitive influence upon sensorimotor function. There is growing interest in the use of 5-HT2A agonists in the management of neuropsychiatric conditions. Recent studies have shown that these agents induce changes in neural activity that disrupt hierarchical brain dynamics and modulate networks subserving self-related processing. Converging evidence suggests they may hold unique therapeutic potential in functional neurological disorders. This is of importance given the considerable personal and societal burden of this condition and we argue a clinical trial to test this hypothesis is warranted.

The Role and Treatment Implications of Peripheral and Central Processing of Pain, Pruritus, and Nausea in Heightened Somatic Awareness: A Review

Pain, pruritus, and nausea are complex sensory and emotional physiological symptoms that can vary widely between people and even within an individual, depending on the context and meaning of the symptom and the psychological state of the person. This article reviews the acute neural transmission of pain, pruritus, and nausea symptoms, which can begin in the periphery and/or viscera. The subsequent multiple pathways in the central nervous system that become involved in the processing of these symptoms are also discussed. The authors describe human brain imaging studies that have revealed consistent cortical and subcortical networks activated by these symptoms, including sensory, limbic, and associative regions. In particular, the authors discuss information revealed by the studies regarding the primary somatosensory cortex, secondary somatosensory cortex, anterior cingulate cortex, insula, prefrontal cortex and thalamus, are the brain areas most commonly activated by noxious stimuli. Finally, the authors describe treatment options for chronic presentations of these symptoms, which are, in part, based on central nervous processing of these sensations.

Neural correlates of conversion disorder: overview and meta-analysis of neuroimaging studies on motor conversion disorder

BACKGROUND

Conversion Disorders (CD) are prevalent functional disorders. Although the pathogenesis is still not completely understood, an interaction of genetic, neurobiological, and psychosocial factors is quite likely. The aim of this study is to provide a systematic overview on imaging studies on CDs and investigate neuronal areas involved in Motor Conversion Disorders (MCD).

METHODS

A systematic literature search was conducted on CD. Subsequently a meta-analysis of functional neuroimaging studies on MCD was implemented using an Activation Likelihood Estimation (ALE). We calculated differences between patients and healthy controls as well as between affected versus unaffected sides in addition to an overall analysis in order to identify neuronal areas related to MCD.

RESULTS

Patients with MCD differ from healthy controls in the amygdala, superior temporal lobe, retrosplenial area, primary motor cortex, insula, red nucleus, thalamus, anterior as well as dorsolateral prefrontal and frontal cortex. When comparing affected versus unaffected sides, temporal cortex, dorsal anterior cingulate cortex, supramarginal gyrus, dorsal temporal lobe, anterior insula, primary somatosensory cortex, superior frontal gyrus and anterior prefrontal as well as frontal cortex show significant differences.

CONCLUSIONS

Neuronal areas seem to be involved in the pathogenesis, maintenance or as a result of MCD. Areas that are important for motor-planning, motor-selection or autonomic response seem to be especially relevant. Our results support the emotional unawareness theory but also underline the need of more support by conduction imaging studies on both CD and MCD.