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PLENARY – WHAT DO IMAGING STUDIES TELL US ABOUT FUNCTIONAL SYMPTOMS

Abstract

Professor Anthony David graduated in medicine from Glasgow University in 1980 and trained in neurology before entering psychiatry at the Maudsley Hospital, London. He also has a Masters degree in Cognitive Neuropsychology. He has been an honorary consultant at the Maudsley since 1990 and was awarded a personal chair from the Institute of Psychiatry, King's College London in 1996. He was appointed Vice Dean for Academic Psychiatry in 2013.

Professor David has a wide and diverse range of research interests including schizophrenia, neuropsychiatry, medically unexplained syndromes and neuroimaging – both structural and functional. He is especially interested in the concept of insight in schizophrenia and how this relates to treatment compliance. Professor David is a Fellow of the Royal College of Physicians, the Royal College of Psychiatrists and the Academy of Medical Sciences. He is a member of the Experimental Psychology Society and a founder member of both the British Neuropsychological Society and British Neuropsychiatry Association and was Chairman to the latter from 2004–7.

Understanding functional neurological or ‘conversion’ symptoms is a challenge, largely because of two persistent mysteries. The first is whether the symptoms are consciously intended and the second is how such symptoms, particularly in the motor domain, relate to cogent lived experiences and memories. Neuroimaging studies have been used to explain the first mystery by being put in the service of answering a number of explicit questions. For example, “Is there a difference in brain activation when attempting to move a paralysed limb due to conversion disorder compared with the ‘good’ limb?” Similar contrasts may be made between brain activation when a person pretends to try to move a limb or attempts to overcome hypnotically induced paralysis, or when a patient says they can't see in contrast to a person who can. To some extent the underlying implicit question is: “Is functional imaging a good lie detector?”

An alternative approach which is more aimed at the second mystery is to trace the brain events which follow the recall of a key life event or the perception of an emotion. Taking this approach leads to the surprising finding that such events are treated (by the brain) differently to other similar events, in a way that is somewhat analogous to experimentally supressed memories in laboratory studies. Further, there are patterns of connectivity which suggest, perhaps, a closer than healthy alignment between: emotional memories, perceptions and the motor system, in people with functional neurological disorders. This may come about as a cause or a consequence of the condition and there may be other neurological vulnerabilities, detectable with structural neuroimaging.

Our interpretation of neuroimaging data at this relatively early phase of scientific research, is however liable to reflect our underlying assumptions about the brain (and mind), cognition and emotion and so on, and we should acknowledge this as we move towards more precise and hypothesis testing approaches.

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