Cerebrospinal fluid glutamate changes in functional movement disorders

Glutamatergic dysfunction, neuroplasticity, and redox status in the peripheral blood of patients with motor conversion disorders (functional movement disorders): a first step towards potential biomarkers discovery

Functional movement disorders (FMD) are characterized by the presence of neurological symptoms that cannot be explained by typical neurological diseases or other medical conditions. First evidence showed that, compared to healthy controls (CTR), FMD patients presented increased levels of glutamate+glutamine in the anterior cingulate cortex/medial prefrontal cortex, and decreased levels of glutamate in the cerebrospinal fluid, suggesting that a glutamatergic dysfunction might play a role in FMD pathophysiology. In this study, 12 FMD patients and 20 CTR were recruited and underwent venous blood sampling and urine collection: levels of glutamate, BDNF, dopamine, oxidative stress, creatinine, neopterin, and uric acid were analyzed. Participants also underwent a psychometric assessment investigating depression, anxiety, and alexithymia. We found that levels of glutamate, BDNF, and dopamine were significantly lower in the blood of FMD patients than CTR. Glutamate and dopamine levels were positively associated with levels of alexithymia. Our findings give further evidence that glutamatergic dysfunction might be involved in the pathophysiology of FMD, possibly representing a biomarker of disease; moreover, since glutamatergic and dopaminergic systems are closely interconnected, our results might have a relevance in terms of treatment options for FMD patients.

Socio-demographic characteristics and psychopathological assessment in a sample of 13 paediatric patients with functional neurological disorders: A preliminary report

This observational study aims to characterize, from a socio-demographic and psychopathological perspective, a sample of children with Functional Neurological Disorders (FND). Thirteen paediatric patients (below 18 years old) with FND and their parents completed a battery of anamnestic and neuropsychological tests, assessing socio-demographic status, cognitive level, behavioural and emotional issues, depression, anxiety, alexithymic traits and dissociative symptoms. Five patients presented movement disorders (tremor, myoclonus and gait disorder), three patients psychogenic non-epileptic seizures and five patients sensitivity disturbances (pain, anaesthesia and paraesthesia). Cognitive profile was normal in 11 patients; academic performance was good in nine patients, but three had a diagnosis of Specific Learning Difficulty or Attention Deficit Hyperactivity Disorder. Precipitating events occurred in 11 patients. At the self-report questionnaires, mean scores close to the clinical cut off were documented with respect to affective and somatic problems. At the parent-report questionnaires, clinically significant mean scores were observed in the subscales assessing anxious-depressive symptoms and somatic complaints. We speculate that paediatric FND patients, although acknowledging the relevance of somatic symptoms, have difficulties in recognizing internal emotional states (that, instead, are easily recognized by their parents). The case of one FND patient was described. These preliminary data might help identifying different clinical phenotypes of paediatric FND.

Altered Brain Activity in Depression of Parkinson’s Disease: A Meta-Analysis and Validation Study

Background

The pathophysiology of depression in Parkinson’s disease (PD) is not fully understood. Studies based upon functional MRI (fMRI) showed the alterations in the blood-oxygen-level-dependent (BOLD) fluctuations in multiple brain regions pertaining to depression in PD. However, large variance was observed across previous studies. Therefore, we conducted a meta-analysis to quantitatively evaluate the results in previous publications and completed an independent regions-of-interests (ROIs)-based analysis using our own data to validate the results of the meta-analysis.

Methods

We searched PubMed, Embase, and Web of Science to identify fMRI studies in PD patients with depression. Using signed differential mapping (SDM) method, we performed a voxel-based meta-analysis. Then, a validation study by using multiscale entropy (MSE) in 28 PD patients with depression and 25 PD patients without depression was conducted. The fMRI scan was completed in anti-depression-medication-off state. The ROIs of the MSE analysis were the regions identified by the meta-analysis.

Results

A total of 126 PD patients with depression and 153 PD patients without depression were included in meta-analysis. It was observed that the resting-state activities within the posterior cingulate gyrus, supplementary motor area (SMA), and cerebellum were altered in depressed patients. Then, in the validation study, these regions were used as ROIs. PD patients with depression had significantly lower MSE of the BOLD fluctuations in these regions (posterior cingulate gyrus: F = 0.856, p = 0.049; SMA: F = 0.914, p = 0.039; cerebellum: F = 0.227, p = 0.043).

Conclusion

Our study revealed that the altered BOLD activity in cingulate, SMA, and cerebellum of the brain were pertaining to depression in PD.

Functional neuroimaging in Irritable Bowel Syndrome: a systematic review highlights common brain alterations with Functional Movement Disorders

Irritable bowel syndrome (IBS) is a chronic functional gastrointestinal disorder characterized by recurring abdominal pain and altered bowel habits without detectable organic causes. This study aims to provide a comprehensive overview of the literature on functional neuroimaging in IBS and to highlight brain alterations similarities with other functional disorders - functional movement disorders in particular. We conducted the bibliographic search via PubMed in August 2020 and included 50 studies following Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines for systematic reviews. Overall, our findings showed an aberrant activation and functional connectivity of the insular, cingulate, sensorimotor and frontal cortices, the amygdala and the hippocampus, suggesting an altered activity of the homeostatic and salience network and of the autonomous nervous system. Moreover, glutamatergic dysfunction in the anterior insula and hypothalamic pituitary axis dysregulation were often reported. These alterations seem to be very similar to those observed in patients with functional movement disorders. Hence, we speculate that different functional disturbances might share a common pathophysiology and we discussed our findings in the light of a Bayesian model framework.

Remission of functional motor symptoms following esketamine administration in a patient with treatment-resistant depression: a single-case report

Functional movement disorders (FMD) involve a broad range of abnormal involuntary movements not consistent with neurological diseases. These conditions often occur in combination with mood and anxiety disorders and are associated with poor clinical outcomes. We report the case of a 57-year-old woman diagnosed with treatment-resistant depression (TRD) and comorbid FMD treated with weekly intranasal administrations of esketamine over a six-month follow-up period. A comprehensive clinical and psychometric assessment was carried out at different time points. After 2 months of treatment, a complete remission of motor and axial functional disturbances (athetosis, trunk torsion and genuflections) was detectable, along with a progressive improvement in depressive symptoms during follow-up until full remission. According to novel lines of evidence, glutamatergic transmission might play a role in the pathophysiology of FMD through aberrant limbic-motor interactions. We report that treatment with esketamine, a noncompetitive N-methyl-d-aspartate glutamatergic receptor antagonist, was associated with remission of FMD symptoms in a patient with TRD. Pharmacological compounds modulating brain glutamatergic activity may be of potential benefit in the clinical management of FMD.