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85 result(s) for "Kanaan, Richard A. A."
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Emotion-Motion Interactions in Conversion Disorder: An fMRI Study
To evaluate the neural correlates of implicit processing of negative emotions in motor conversion disorder (CD) patients. An event related fMRI task was completed by 12 motor CD patients and 14 matched healthy controls using standardised stimuli of faces with fearful and sad emotional expressions in comparison to faces with neutral expressions. Temporal changes in the sensitivity to stimuli were also modelled and tested in the two groups. We found increased amygdala activation to negative emotions in CD compared to healthy controls in region of interest analyses, which persisted over time consistent with previous findings using emotional paradigms. Furthermore during whole brain analyses we found significantly increased activation in CD patients in areas involved in the 'freeze response' to fear (periaqueductal grey matter), and areas involved in self-awareness and motor control (cingulate gyrus and supplementary motor area). In contrast to healthy controls, CD patients exhibited increased response amplitude to fearful stimuli over time, suggesting abnormal emotional regulation (failure of habituation / sensitization). Patients with CD also activated midbrain and frontal structures that could reflect an abnormal behavioral-motor response to negative including threatening stimuli. This suggests a mechanism linking emotions to motor dysfunction in CD.
White Matter and Cognition in Adults Who Were Born Preterm
Individuals born very preterm (before 33 weeks of gestation, VPT) are at risk of damage to developing white matter, which may affect later cognition and behaviour. We used diffusion tensor MRI (DT-MRI) to assess white matter microstructure (fractional anisotropy; FA) in 80 VPT and 41 term-born individuals (mean age 19.1 years, range 17-22, and 18.5 years, range 17-22 years, respectively). VPT individuals were part of a 1982-1984 birth cohort which had been followed up since birth; term individuals were recruited by local press advertisement. General intellectual function, executive function and memory were assessed. The VPT group had reduced FA in four clusters, and increased FA in four clusters relative to the Term group, involving several association tracts of both hemispheres. Clusters of increased FA were associated with more severe neonatal brain injury in the VPT group. Clusters of reduced FA were associated with lower birth weight and perinatal hypoxia, and with reduced adult cognitive performance in the VPT group only. Alterations of white matter microstructure persist into adulthood in VPT individuals and are associated with cognitive function.
Gender Differences in White Matter Microstructure
Sexual dimorphism in human brain structure is well recognised, but little is known about gender differences in white matter microstructure. We used diffusion tensor imaging to explore differences in fractional anisotropy (FA), an index of microstructural integrity. A whole brain analysis of 135 matched subjects (90 men and 45 women) using a 1.5 T scanner. A region of interest (ROI) analysis was used to confirm those results where proximity to CSF raised the possibility of partial-volume artefact. Men had higher fractional anisotropy (FA) in cerebellar white matter and in the left superior longitudinal fasciculus; women had higher FA in the corpus callosum, confirmed by ROI. The size of the differences was substantial--of the same order as that attributed to some pathology--suggesting gender may be a potentially significant confound in unbalanced clinical studies. There are several previous reports of difference in the corpus callosum, though they disagree on the direction of difference; our findings in the cerebellum and the superior longitudinal fasciculus have not previously been noted. The higher FA in women may reflect greater efficiency of a smaller corpus callosum. The relatively increased superior longitudinal fasciculus and cerebellar FA in men may reflect their increased language lateralisation and enhanced motor development, respectively.
Gender Influence on White Matter Microstructure: A Tract-Based Spatial Statistics Analysis
Sexual dimorphism in human brain structure is well recognised, but less is known about gender differences in white matter microstructure. We used diffusion tensor imaging to explore gender differences in fractional anisotropy (FA), an index of microstructural integrity. We previously found increased FA in the corpus callosum in women, and increased FA in the cerebellum and left superior longitudinal fasciculus (SLF) in men, using a whole-brain voxel-based analysis. A whole-brain tract-based spatial statistics analysis of 120 matched subjects from the previous analysis, and 134 new subjects (147 men and 107 women in total) using a 1.5T scanner, with division into tract-based regions of interest. Men had higher FA in the superior cerebellar peduncles and women had higher FA in corpus callosum in both the first and second samples. The higher SLF FA in men was not found in either sample. We confirmed our previous, controversial finding of increased FA in the corpus callosum in women, and increased cerebellar FA in men. The corpus callosum FA difference offers some explanation for the otherwise puzzling advantage in inter-callosal transfer time shown in women; the cerebellar FA difference may be associated with the developmental motor advantage shown in men.
A growing understanding of the role of muscarinic receptors in the molecular pathology and treatment of schizophrenia
Pre-clinical models, postmortem and neuroimaging studies all support a role for muscarinic receptors in the molecular pathology of schizophrenia. From these data it was proposed that activation of the muscarinic M1 and/or M4 receptor would reduce the severity of the symptoms of schizophrenia. This hypothesis is now supported by results from two clinical trials which indicate that activating central muscarinic M1 and M4 receptors can reduce the severity of positive, negative and cognitive symptoms of the disorder. This review will provide an update on a growing body of evidence that argues the muscarinic M1 and M4 receptors have critical roles in CNS functions that are dysregulated by the pathophysiology of schizophrenia. This realization has been made possible, in part, by the growing ability to visualize and quantify muscarinic M1 and M4 receptors in the human CNS using molecular neuroimaging. We will discuss how these advances have provided evidence to support the notion that there is a sub-group of patients within the syndrome of schizophrenia that have a unique molecular pathology driven by a marked loss of muscarinic M1 receptors. This review is timely, as drugs targeting muscarinic receptors approach clinical use for the treatment of schizophrenia and here we outline the background biology that supported development of such drugs to treat the disorder.
Systematic review of psychotherapy for adults with functional neurological disorder
Functional neurological disorder (FND) is a common and disabling disorder that is often considered difficult to treat, particularly in adults. Psychological therapies are often recommended for FND. Outcome research on psychological therapies for FND has grown in recent years but has not been systematically evaluated since 2005. This study aims to build on that by systematically reviewing the evidence-base for individual outpatient cognitive behavioural and psychodynamic psychotherapies for FND. Medical databases were systematically searched for prospective studies of individual outpatient psychotherapy for FND with at least five adult participants. Studies were assessed for methodological quality using a standardised assessment tool. Results were synthesised, and effect sizes calculated for illustrative purposes. The search strategy identified 131 relevant studies, of which 19 were eligible for inclusion: 12 examining cognitive behavioural therapy (CBT) and 7 investigating psychodynamic therapy (PDT). Eleven were pre–post studies and eight were randomised controlled trials. Most studies recruited a single symptom-based subtype rather than all presentations of FND. Effect sizes, where calculable, showed generally medium-sized benefits for physical symptoms, mental health, well-being, function and resource use for both CBT and PDT. Outcomes were broadly comparable across the two therapy types, although a lack of high-quality controlled trials of PDT is a significant limitation, as is the lack of long-term follow-up data in the majority of identified CBT trials. In conclusion, both CBT and PDT appear to potentially offer some benefit for FND, although better quality studies are needed.
Self‐Reported Motor and Non‐Motor Symptoms in People With Functional Gait Disorder: A Cross‐Sectional Study
Background Functional gait disorder is a common presentation of functional neurological disorder. Altered gait is the defining feature, along with a range of associated motor and nonmotor symptoms. The aim of this study was to explore the prevalence and impact of these symptoms in people with functional gait disorder. Methods A total of 156 people with functional gait disorder completed an online survey that included demographic information, self‐reported symptoms, and standardized questionnaires. Results Weakness (85.9%) and reduced balance (80.1%) were the most prevalent motor symptoms, while fatigue (85.9%), somatosensory (69.9%), and cognitive (69.9%) symptoms were the most prevalent nonmotor symptoms. Logistic regression indicated that dependent ambulation had the greatest association with fear of falling and functional seizures (X2 (11, n = 128) = 40.68, p < 0.001). Stepwise regression indicated that functional seizures, muscle rigidity, depression, fear of falling, pain, and speech symptoms were associated with reduced participation in work and social function (adjusted R2 = 0.39, F (6, 120) = 14.31, p < 0.001). Stepwise regression revealed that lower physical quality of life was associated with pain, bradykinesia, fatigue, and dystonia (adjusted R2 = 0.32, F (4, 122) = 15.92, p < 0.001) while depression, anxiety, and functional seizures were associated with reduced mental quality of life (adjusted R2 = 0.46, F (3, 123) = 36.89, p < 0.001). Conclusions Motor and nonmotor symptoms are highly prevalent in people with functional gait disorder and are associated with high levels of disability, reduced participation in work and social function, and reduced quality of life.
Functional neurological disorder and other unexplained syndromes
Functional neurological disorder is probably no exception to this rule, and the recent improvement in its status can perhaps be attributed to the extent that it has come to be considered organic: it is now named a neurological disorder, with distinctive findings on neurological examination and abnormal brain scans, as Hallett and colleagues discuss. The biopsychosocial model of functional neurological disorder that Hallett and colleagues propose is fundamentally generic to unexplained syndromes.6 Likewise, abnormalities on neuroimaging per se can be found in all unexplained syndromes, whenever they are sought.7 Even the positive signs that Hallett and colleagues consider characteristic are found in other unexplained syndromes.8 If functional neurological disorder were lumped in with the other unexplained syndromes its future could become determined by them. The acceptance of a biopsychosocial model in functional neurological disorder has given hope for broader acceptance of such models in medicine, perhaps even to the extent that functional neurological disorder would no longer be considered unexplained.9 However, by contrast, other unexplained syndromes (eg, chronic fatigue syndrome) offer a warning: their biopsychosocial model has been rejected by patient groups with such ferocity that it has become dangerous to endorse it.10 I have received grants from the Wellcome Trust, the UK Medical Research Council, the National Health and Medical Research Council, and the Medical Research Future Fund for research into functional neurological disorder and other unexplained syndromes.
A multi-centre, double-blind, 12-week, randomized, placebo-controlled trial to assess the efficacy of adjunctive N-Acetylcysteine for treatment-resistant PTSD: a study protocol
Background Most patients with Posttraumatic Stress Disorder (PTSD) suffer residual symptoms following first-line treatment. Oxidative stress has been implicated in the pathophysiology of PTSD. N-acetylcysteine (NAC) is a precursor of the brain’s primary antioxidant, glutathione, and may diminish oxidative cellular damage. An 8-week pilot study of NAC in veterans with PTSD found that symptoms were significantly reduced in the NAC group compared to placebo. This study aims to confirm these findings with a larger sample in a double-blind, placebo-controlled trial to further explore the efficacy of NAC as an adjunctive therapy in treatment-resistant PTSD. Methods A multicentre, randomised, double-blind, placebo-controlled trial for adult patients who still meet criteria for PTSD following first-line treatment. The intervention comprises either NAC as a fixed dose regime of 2.7 g/day (900 mg three times daily) administered orally for 12 weeks, or placebo. Standard care for PTSD will continue in addition, including other pharmacotherapies. Detailed clinical data will be collected at randomisation and weeks 4, 8, 12, 16, and 64 post-randomisation, with self-report measures completed weekly from baseline to 16 weeks and at 64 weeks post-randomisation. Blood-based biomarkers will be collected at baseline and 12 weeks to assess the mechanism of effect. The primary outcome measure will be change in Clinician-Administered PTSD Scale for DSM-5 at 12 weeks compared with baseline. Secondary outcomes will be change in quality of life, depression, anxiety, substance use and craving, and somatic symptoms. With 126 completed participants (63 per arm), the study is powered at 80% to detect a true difference in the primary outcome measure using a two-tailed analysis with alpha = 0.05, beta = 0.2. Discussion This is the first multicentre, double blind, randomised, placebo-controlled trial of adjunctive NAC for treatment-resistant PTSD. NAC has an established safety profile, is readily available and easy to administer, and has a favourable tolerability profile, therefore making it an attractive adjunctive therapy. Inclusion of blood analyses to assess potential target engagement biomarkers of oxidative stress and neuroinflammation may help gauge the biological mechanisms of effect of NAC. Trial registration ACTRN12618001784202, retrospectively registered 31/10/2018, URL: http://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=376004 .