Structure and function in neurology and psychiatry

The natural history of terms describing functional (neurological) disorders in the medical literature of the last 60 years

BACKGROUND

Functional neurological disorders (FND), a subtype of functional disorders (FD), are a frequent motive for neurology referrals. The various presentations and the unknown physiopathology of FD have led to the multiplication of terms describing these disorders over the years.

METHODS

We examined the FD-related articles published from 1960 to 2020 in PubMed and PsycINFO databases. We searched for: psychogenic, somatization, somatoform, medically unexplained symptoms, hysteria, conversion disorder, dissociative, functional neurological disorder, and functional disorder. Use rates in the title, abstract, keyword, or MeSH fields were collected over successive 5-year periods. After correcting for off-topic results, we examined proportional distribution over time, term associations, and disciplinary fields (neurology and psychiatry). Term impact was estimated via H-index and number of citations.

RESULTS

We found that none of the terms is prevailing in the recent medical literature. We observed three trends in the use rates: stability, increase, and decrease of use over time. While most of the terms were present in a stable proportion of the publications, hysteria and psychogenic lost popularity over time. We found a differential preference for terminology between disciplines. Functional neurological disorder showed the highest citation impact, yielding 10% of highly cited publications.

CONCLUSION

We found a dynamic and evolving use of the different terms describing FD in the last 60 years. Despite the tendency to use the term functional in the recent highly cited publications, its low prevalence and coexistence with several other terms suggest that a precise, explanatory and non-offensive term remains yet to be found.

Epilepsy and Neuroscience: Evolution and Interaction

Neuroscience is a relatively new and fashionable word that emerged in the 1950s in several countries, including the UK, to describe a multidisciplinary clinical and laboratory approach to the study of the brain, mind, and neuropsychiatric disorders. However collaborative study of neurological and psychiatric disorders can be traced to the 17th century with roots in antiquity. I describe the evolution of our understanding of epilepsy beginning with the first detailed clinical descriptions, associated with supernatural theories, in Babylonian medicine in the second millennium BC. Interest in natural causation arose in the Greco-Roman period when it was first suggested that "the sacred disease" was a disorder of the brain. However, this theory did not take root until the 17th and 18th centuries AD when epilepsy began to be separated from other "convulsive" diseases, including hysteria. In the 19th century developments in neuropathology and our understanding of cortical localization led to the much-debated separation of idiopathic from symptomatic epilepsy which continues to influence international classifications of seizures and epilepsies. Also in the 19th century, the concept of seizures as electrical discharges in the brain evolved, reinforced in the 20th century by the discovery of the electroencephalogram. For many reasons, people with epilepsy have experienced a high incidence of cognitive and psychosocial disorders. Epilepsy, which is a global problem, has, therefore, remained a bridge between neurology and psychiatry. Furthermore, the study of epilepsy continues to shed light on brain function and other neuropsychiatric disorders.

What is the functional/organic distinction actually doing in psychiatry and neurology?

The functional-organic distinction aims to distinguish symptoms, signs, and syndromes that can be explained by diagnosable biological changes, from those that cannot. The distinction is central to clinical practice and is a key organising principle in diagnostic systems. Following a pragmatist approach that examines meaning through use, we examine how the functional-organic distinction is deployed and conceptualised in psychiatry and neurology. We note that the conceptual scope of the terms 'functional' and 'organic' varies considerably by context. Techniques for differentially diagnosing 'functional' and 'organic' diverge in the strength of evidence they produce as a necessary function of the syndrome in question. Clinicians do not agree on the meaning of the terms and report using them strategically. The distinction often relies on an implied model of 'zero sum' causality and encourages classification of syndromes into discrete 'functional' and 'organic' versions. Although this clearly applies in some instances, this is often in contrast to our best scientific understanding of neuropsychiatric disorders as arising from a dynamic interaction between personal, social and neuropathological factors. We also note 'functional' and 'organic' have loaded social meanings, creating the potential for social disempowerment. Given this, we argue for a better understanding of how strategic simplification and complex scientific reality limit each other in neuropsychiatric thinking. We also note that the contribution of people who experience the interaction between 'functional' and 'organic' factors has rarely informed the validity of this distinction and the dilemmas arising from it, and we highlight this as a research priority.

Psychiatric manifestations of neurologic diseases: Etiology, phenomenology, and treatment

Understanding the etiology and meaning of behavioral symptomatology in the context of neurologic disease, and choosing the most effective intervention is a vexing task. This introduction summarizes the history of our understanding of the relationship between behavioral symptoms and primary neurologic conditions, and considers the ways in which both psychiatric and neurologic disorders occurring simultaneously may inform both knowledge of etiology and treatment decisions.

Social neuroscience: undoing the schism between neurology and psychiatry

Multiple disorders once jointly conceived as "nervous diseases" became segregated by the distinct institutional traditions forged in neurology and psychiatry. As a result, each field specialized in the study and treatment of a subset of such conditions. Here we propose new avenues for interdisciplinary interaction through a triangulation of both fields with social neuroscience. To this end, we review evidence from five relevant domains (facial emotion recognition, empathy, theory of mind, moral cognition, and social context assessment), highlighting their common disturbances across neurological and psychiatric conditions and discussing their multiple pathophysiological mechanisms. Our proposal is anchored in multidimensional evidence, including behavioral, neurocognitive, and genetic findings. From a clinical perspective, this work paves the way for dimensional and transdiagnostic approaches, new pharmacological treatments, and educational innovations rooted in a combined neuropsychiatric training. Research-wise, it fosters new models of the social brain and a novel platform to explore the interplay of cognitive and social functions. Finally, we identify new challenges for this synergistic framework.

Hysteria, conversion and functional disorders: a neurological contribution to classification issues

Proposals by psychiatrists to reclassify conversion disorder in DSM-5 and ICD-11 are proving difficult and controversial. Patients with conversion disorder usually present initially to neurologists, who often use different concepts and terminology. History and clinical practice suggest that the way forward is to seek agreed principles and a common understanding between the two disciplines, preferably in a single universal classification.

The function of 'functional': a mixed methods investigation

OBJECTIVE

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.

DESIGN

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.

RESULTS

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.

CONCLUSIONS

'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.

A critique of 'organic' and its proposed alternatives

OBJECTIVE

A critical examination of the term 'organic' in psychiatry and its proposed alternatives.

METHOD

An examination of the published literature on the concepts of 'organicity' in mental syndromes, and of the mind-brain problem.

RESULTS

The term 'organic' presents a number of problems, some of which can be described as those of historical schism, duality, method, practice, scholasticism and semantics. The currently available alternatives are not without their difficulties, and examples are provided.

CONCLUSION

Whether the term 'organic' is retained or replaced, we are condemned to an unsatisfactory position while we await a radically new paradigm to understand the role of neurobiological and psychosocial factors in psychiatric disorders.

The semantic status of diagnostic criteria for organic mental syndromes and disorders in DSM-III and DSM-III-R

After a general introduction referring to the contemporary debate about psychiatric classification, the nature of so-called "diagnostic criteria" in psychiatry is discussed with special reference to DSM-III(-R) and to organic mental syndromes and disorders. A set of diagnostic criteria for a disease category can be intended alternatively (i) as stating logically necessary and/or sufficient conditions for the diagnostic concept in question, or (ii) as providing contingent (probabilistic) indicators of the disease. In one possible interpretation, a main aim of DSM-III and DSM-III-R has been to formulate type (i), logical criteria, which amounts to an attempt to strictly identify syndromes or disorders with complex (polythetic) sets of easily observable symptoms and signs. It is shown that a logical interpretation would lead to such unwanted consequences for clinical and scientific practice that it could not possibly have been intended by the authors of DSM-III and DSM-III-R. But neither can the alternative interpretation in terms of type (ii), contingent or probabilistic indicators be consistently upheld. The conclusion of the essay is that the semantic status of the diagnostic criteria in DSM-III and DSM-III-R is fundamentally blurred. This unclarity may very well lead to divergent interpretations of the concepts and to corresponding uncertainties in their clinical and scientific application.

Organic mental disorders as hypothetical pathogenetic processes

A new diagnostic system for organic psychiatry is presented. We first define "organic psychiatry", and then give the theoretical basis for conceiving organic-psychiatric disorders in terms of hypothetical psychopathogenetic processes, HPP:s. Such hypothetical disorders are not strictly identical to the clusters of symptoms in which they typically manifest themselves, since the symptoms may be concealed or modified by intervening factors in non-typical circumstances and/or in the simultaneous presence of several disorders. The six basic disorders in our system are Astheno-Emotional Disorder (AED), Somnolence-Sopor-Coma Disorder (SSCD), Hallucination-Coenestopathy-Depersonalisation Disorder (HCDD), Confusional Disorder (CD), Emotional-Motivational Blunting Disorder (EMD) and Korsakoff's Amnestic Disorder (KAD). We describe their usual etiologies, their typical symptoms and course, and some forms of interaction between them.

Some excitatory and inhibitory factors involved in the epileptic state

Many factors are involved in the determination of the epileptic threshold and the precipitation of epileptic seizures. The balance between the underlying excitatory and inhibitory mechanisms are often imperfectly understood. However, some of these factors must be fully considered if the management of those with epilepsy is to be effective. This applies especially to children. Certain types of epilepsy are genetically determined, and others are age-related. Development of the brain plays a crucial role in the changing liability to epilepsy. If these processes are disturbed by various lesions and diseases, such as metabolic and toxic disorders, protective mechanisms may suffer. Kindling and mirror foci, the role of the cerebellum, and reflex epilepsy will be discussed. There are some seizure-inducing factors which are susceptible to change, and can be as important as anti-epileptic drugs in controlling seizures. The use and limitations of these measures, and of drugs, will be considered.

The psychogeriatrician's view: management of chronic disability in the community

Psychiatric services for elderly people are based on principles which are relevant to the management of chronic disorders such as Parkinson's disease. Psychological and biological factors are closely intertwined in dementia, as they are in PD. Although medical diagnosis is important the emphasis is on continuing support. The aim is to provide services within the community where they are needed, and to acknowledge the importance of carers and family for assessment and management.

Against pathology. The new psychiatry and its critics

The notion of 'pathology' presumes an experiential and socially embedded frame of reference which is at variance with some recent attempts to understand the procedures and subject matter of psychiatry. Psychiatric theories remain bound by individual and historical contingencies whose compelling urgency obfuscates the inter-relationship of phenomenon, social context, response, and explanatory model.