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1.  The role of psychiatrists in diagnosing conversion disorder: a mixed-methods analysis 
Since DSM-5 removed the requirement for a psychosocial formulation, neurologists have been able to make the diagnosis of conversion disorder without psychiatric input. We sought to examine whether neurologists and specialist psychiatrists concurred with this approach.
We used mixed methods, first surveying all the neurologists in the UK and then interviewing the neuropsychiatrists in a large UK region on the role of psychiatrists in diagnosing conversion disorder.
Of the surveyed neurologists, 76% did not think that psychiatrists were essential for the diagnosis and 71% thought that psychiatrists did not even consider conversion disorder when referred a case. The neuropsychiatrists who were interviewed held complex models of conversion disorder. They believed all cases could be explained psychosocially in theory, but the nature of the diagnostic encounter often prevented it in practice; all felt that psychosocial formulation could be very helpful and some felt that it was essential to diagnosis.
Although neurologists do not think psychiatrists are required for diagnosing conversion disorder, specialist psychiatrists disagree, at least in some cases.
PMCID: PMC4869792  PMID: 27274253
functional neurological disorders; classification; qualitative research; survey; psychiatric formulation
2.  Uncovering the etiology of conversion disorder: insights from functional neuroimaging 
Conversion disorder (CD) is a syndrome of neurological symptoms arising without organic cause, arguably in response to emotional stress, but the exact neural substrates of these symptoms and the underlying mechanisms remain poorly understood with the hunt for a biological basis afoot for centuries. In the past 15 years, novel insights have been gained with the advent of functional neuroimaging studies in patients suffering from CDs in both motor and nonmotor domains. This review summarizes recent functional neuroimaging studies including functional magnetic resonance imaging (fMRI), single photon emission computerized tomography (SPECT), and positron emission tomography (PET) to see whether they bring us closer to understanding the etiology of CD. Convergent functional neuroimaging findings suggest alterations in brain circuits that could point to different mechanisms for manifesting functional neurological symptoms, in contrast with feigning or healthy controls. Abnormalities in emotion processing and in emotion-motor processing suggest a diathesis, while differential reactions to certain stressors implicate a specific response to trauma. No comprehensive theory emerges from these clues, and all results remain preliminary, but functional neuroimaging has at least given grounds for hope that a model for CD may soon be found.
PMCID: PMC4716724  PMID: 26834476
conversion disorder; neuroimaging; functional neurology; hysteria; mechanisms
3.  White Matter Microstructural Organization Is Higher with Age in Adult Superior Cerebellar Peduncles 
Using diffusion tensor imaging, we conducted an exploratory investigation of the relationship between white matter tract microstructure and age in 200 healthy adult subjects using tract-based spatial statistics (TBSS). Though most tracts showed the slight decline in microstructural organization with age widely noted, in both superior cerebellar peduncles (SCP) it correlated positively with age, a result not previously reported. We confirmed this by using an alternative method, and by repeating our TBSS analysis in an additional sample of 133 healthy adults. In exploring this surprising result we considered the possibility that this might arise from the continual cognitive and motor refinement that is enacted in the cerebellum: we found that tract microstructure in both SCPs was also strongly correlated with IQ, again in contrast with all other tracts, and its relationship with age mediated by IQ, as a training model would predict.
PMCID: PMC4830843  PMID: 27148043
fractional anisotropy; training; intelligence; aging; diffusion tensor imaging
4.  Emotion-Motion Interactions in Conversion Disorder: An fMRI Study 
PLoS ONE  2015;10(4):e0123273.
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.
PMCID: PMC4393246  PMID: 25859660
5.  Gender Influence on White Matter Microstructure: A Tract-Based Spatial Statistics Analysis 
PLoS ONE  2014;9(3):e91109.
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.
PMCID: PMC3946347  PMID: 24603769
6.  Gender Differences in White Matter Microstructure 
PLoS ONE  2012;7(6):e38272.
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.
PMCID: PMC3368921  PMID: 22701619
7.  The function of ‘functional’: a mixed methods investigation 
The term ‘functional’ has a distinguished history, embodying a number of physiological concepts, but has increasingly come to mean ‘hysterical’. The DSM-V working group proposes to use ‘functional’ as the official diagnostic term for medically unexplained neurological symptoms (currently known as ‘conversion disorder’). This study aimed to explore the current neurological meanings of the term and to understand its resilience.
Mixed methods were used, first interviewing the neurologists in a large UK region and then surveying all neurologists in the UK on their use of the term.
The interviews revealed four dominant uses—‘not organic’, a physical disability, a brain disorder and a psychiatric problem—as well as considerable ambiguity. Although there was much dissatisfaction with the term, the ambiguity was also seen as useful when engaging with patients. The survey confirmed these findings, with a majority adhering to a strict interpretation of ‘functional’ to mean only ‘not organic’, but a minority employing it to mean different things in different contexts - and endorsing the view that ‘functional’ would one day be a neurological construct again.
‘Functional’ embodies real divisions in neurologists' conceptualisation of unexplained symptoms and, perhaps, between those of patients and neurologists: its diversity of meanings allows it to be a common term while meaning different things to different people, or at different times, and thus conceal some of the conflict in a particularly contentious area. This flexibility may help explain the term's longevity.
PMCID: PMC3277687  PMID: 22250186
8.  White Matter and Cognition in Adults Who Were Born Preterm 
PLoS ONE  2011;6(10):e24525.
Background and Purpose
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, range17–22 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.
PMCID: PMC3192037  PMID: 22022357
9.  Neurologists' understanding and management of conversion disorder 
Conversion disorder is largely managed by neurologists, for whom it presents great challenges to understanding and management. This study aimed to quantify these challenges, examining how neurologists understand conversion disorder, and what they tell their patients.
A postal survey of all consultant neurologists in the UK registered with the Association of British Neurologists.
349 of 591 practising consultant neurologists completed the survey. They saw conversion disorder commonly. While they endorsed psychological models for conversion, they diagnosed it according to features of the clinical presentation, most importantly inconsistency and abnormal illness behaviour. Most of the respondents saw feigning as entangled with conversion disorder, with a minority seeing one as a variant of the other. They were quite willing to discuss psychological factors as long as the patient was receptive but were generally unwilling to discuss feigning even though they saw it as their responsibility. Those who favoured models in terms of feigning were older, while younger, female neurologists preferred psychological models, believed conversion would one day be understood neurologically and found communicating with their conversion patients easier than it had been in the past.
Neurologists accept psychological models for conversion disorder but do not employ them in their diagnosis; they do not see conversion as clearly different from feigning. This may be changing as younger, female neurologists endorse psychological views more clearly and find it easier to discuss with their patients.
PMCID: PMC3191819  PMID: 21325661
10.  Differential effects of pre and post-payment on neurologists' response rates to a postal survey 
BMC Neurology  2010;10:100.
Monetary incentives are an effective way of increasing response rates to surveys, though they are generally less effective in physicians, and are more effective when the incentive is paid up-front rather than when made conditional on completion.
In this study we examine the effectiveness of pre- and post-completion incentives on the response rates of all the neurologists in the UK to a survey about conversion disorder, using a cluster randomised controlled design. A postal survey was sent to all practicing consultant neurologists, in two rounds, including either a book token, the promise of a book token, or nothing at all.
Three hundred and fifty-one of 591 eligible neurologists completed the survey, for a response rate of 59%. While the post-completion incentive exerted no discernible influence on response rates, a pre-completion incentive did, with an odds-ratio of 2.1 (95% confidence interval 1.5 - 3.0).
We conclude that neurologists, in the UK at least, may be influenced to respond to a postal survey by a pre-payment incentive but are unaffected by a promised reward.
PMCID: PMC2984383  PMID: 20973984
11.  In the psychiatrist's chair: how neurologists understand conversion disorder 
Brain  2009;132(10):2889-2896.
Conversion disorder (‘hysteria’) was largely considered to be a neurological problem in the 19th century, but without a neuropathological explanation it was commonly assimilated with malingering. The theories of Janet and Freud transformed hysteria into a psychiatric condition, but as such models decline in popularity and a neurobiology of conversion has yet to be found, today's neurologists once again face a disorder without an accepted model. This article explores how today's neurologists understand conversion through in-depth interviews with 22 neurology consultants. The neurologists endorsed psychological models but did not understand their patients in such terms. Rather, they distinguished conversion from other unexplained conditions clinically by its severity and inconsistency. While many did not see this as clearly distinct from feigning, they did not feel that this was their problem to resolve. They saw themselves as ‘agnostic’ regarding non-neuropathological explanations. However, since neurologists are in some ways more expert in conversion than psychiatrists, their continuing support for the deception model is important, and begs an explanation. One reason for the model's persistence may be that it is employed as a diagnostic device, used to differentiate between those unexplained symptoms that could, in principle, have a medical explanation and those that could not.
PMCID: PMC2759333  PMID: 19321463
conversion disorder; hysteria; malingering; deception; factitious disorder
12.  Limits to truth-telling: Neurologists’ communication in conversion disorder 
Patient Education and Counseling  2009;77(2):296-301.
Neurologists face a dilemma when communicating with their conversion disorder patients – whether to be frank, and risk losing the patient's trust, or to disclose less, in the hope of building a therapeutic relationship. This study reports how neurologists in the UK described dealing with this dilemma in their practice.
Practicing consultant neurologists from an NHS region were recruited by snowball sampling. Twenty-two of 35 consultants in the region were interviewed in depth, and the interviews qualitatively analysed.
The neurologists were reluctant to disclose conversion disorder as a differential diagnosis until they were certain. They were guided by the receptivity of their patients as to how psychological to make their eventual explanations, but they did not discuss their suspicions about feigning. They described their communications as much easier now than they had seen in training.
Neurologists adapt their disclosure to their patients, which facilitates communication, but imposes some limits on truth-telling. In particular, it may sometimes result in a changed diagnosis.
Practice implications
An optimum strategy for communicating diagnoses will need to balance ethical considerations with demonstrated therapeutic benefit.
PMCID: PMC2773836  PMID: 19560894
Conversion disorder; Factitious disorder; Malingering; Hysteria; Truth-telling; Deception; Neurology
13.  White matter microstructure in schizophrenia: effects of disorder, duration and medication 
The British Journal of Psychiatry  2009;194(3):236-242.
Diffusion tensor magnetic resonance imaging studies in schizophrenia to date have been largely inconsistent. This may reflect variation in methodology, and the use of small samples with differing illness duration and medication exposure.
To determine the extent and location of white matter microstructural changes in schizophrenia, using optimised diffusion tensor imaging in a large patient sample, and to consider the effects of illness duration and medication exposure.
Scans from 76 patients with schizophrenia and 76 matched controls were used to compare fractional anisotropy, a measure of white matter microstructural integrity, between the groups.
We found widespread clusters of reduced fractional anisotropy in patients, affecting most major white matter tracts. These reductions did not correlate with illness duration, and there was no difference between age-matched chronically and briefly medicated patients.
The finding of widespread fractional anisotropy reductions in our larger sample of patients with schizophrenia may explain some of the inconsistent findings of previous, smaller studies.
PMCID: PMC2802507  PMID: 19252154
14.  The Association or Otherwise of the Functional Somatic Syndromes 
Psychosomatic medicine  2007;69(9):855-859.
the Functional Somatic Syndromes (FSS) show considerable co-morbidity, leading some to suggest they may be aspects of the same disorder. This study aims to review the evidence for overlap in the phenomenology of the FSS.
a selective review of peer-reviewed articles on the co-occurrence of FSS symptoms and diagnoses.
considerable evidence of overlap was found at the level of symptoms, of diagnostic criteria, and of clinical diagnoses made.
phenomenological commonalities support a close relationship between the FSS, though differences remain in other domains. Whether the FSS may best be considered the same or different will depend on the pragmatics of diagnosis.
PMCID: PMC2575798  PMID: 18040094
diagnosis; Chronic Fatigue Syndrome; Irritable Bowel Syndrome; Fibromyalgia; phenomenology; co-morbidity

Results 1-14 (14)