CORRESPONDENCE

I was pleased to read Dr Crowley’s Kraepelinian dichotomy Castle, D. J.,Wessely, S., van Os, J., et aletal (19 9 8) in-depth understanding of the complexity Subtypes of . In in the Inner City: The Camberwell First Episode Study,pp.37^49.Hove:, pp. 37^49.Hove: and value of the altered state of Craddock & Owen (2005) attribute the Psychology Press. consciousness. Thankfully, there are clini- proposed demise of the Kraepelinian Craddock, N. & Owen, M. J. (2005) The beginning of cians such as Dr Crowley with the con- dichotomy to advances in genetic epidemio- the end of the Kraepelinian dichotomy. British Journal of fidence not to dismiss the non-ordinary logy, and rightly emphasise the need to PsychiatryPsychiatry,, 186186, 364^366. state of consciousness as mere ‘acute confu- integrate data across multiple domains in Murray,V., McKee, I., Miller, P. M., et aletal (2005)(2005) sion’, but to believe that psychedelics, and large numbers of people. However, it may Dimensions and classes of psychosis in a population non-drug non-ordinary states of conscious- also be important to use a population-based cohort: a four class, four dimension model of ness, can inform and enlighten us with new approach. This involves extra effort but schizophrenia and affective psychoses. Psychological MedicineMedicine,, 3535,499^510. approaches to understanding the mechan- avoids being misled by convenience samples isms (and associated pathologies) of the which may not be representative of the V. Mu r r a yyV.Mu Scottish Centre for Autism, Royal brain. Since the earliest human societies population. This is illustrated by Fig. 1 in Hospital for Sick Children,GlasgowChildren, Glasgow G3 8SJ, UK. we have sought knowledge and healing the editorial of Craddock & Owen which E-mail:Val.MurrayE-mail: Val.Murray@@yorkhill.scot.nhs.uk from these states – perhaps now this tech- suggests that prototypical schizophrenia nique can be utilised in a scientific and and prototypical are rela- evidence-based approach to relieve the bur- tively rare in clinical populations. Work in den of anxiety disorders for today’s patients. population-based samples suggests that Authors’ reply: We are in full agreement I am most grateful to Dr Sandison for there is an early, insidious-onset psychosis with Dr Murray regarding the utility of his kind and supportive words – and thank with a poor outcome affecting predomi- large-scale, population-based studies. These him for the correction regarding the date of nantly men – a ‘neurodevelopmental’ form are highly desirable and will, we hope, be the American Psychiatric Association con- of schizophrenia which is very close to facilitated by the recent establishment of ference in 1955. I share his astonishment (Castle et aletal, 1998). This the Mental Health Research Network at the medical profession’s inability or prototypical form of schizophrenia together (http://www.mhrn.info) under the auspices unwillingness to embrace the therapeutic with protoypical bipolar disorder accounts of the UK Clinical Research Collaboration potential of psychedelic substances. This for 50% of people with psychosis in a (http://www.ukcrc.org). We also agree that shortcoming is augmented by the fact that treated prevalence sample, demonstrating longitudinal variables such as course, out- the hiatus in research over the past 40 years the utility of Kraepelin’s division. In our come and treatment response might be appears to have been for socio-political experience affective and non-affective key to classification, as Kraepelin supposed. rather than scientific reasons – and it is psychoses can be accounted for by these However, although we have not under- those pioneering psychiatrists like Dr prototypical forms and a further two latent taken relevant population studies ourselves, Sandison who are right to feel disheartened. classes which appear to be valid (Murray we are not convinced that Kraepelinian I am enthusiastic, however, at the et aletal, 2005). Whether such empirically dichotomous categories are any more useful current re-emergence of interest in this derived classes might provide better pheno- in population-based samples than in clinical field. There are increasing numbers of types for genetic studies is as yet samples. We find the studies of Van Os and randomised controlled trials of psychedelics undetermined. colleagues (e.g. Krabbendam et aletal, 2004),2004) (largely from the USA) and these may yield Until biological markers are identified persuasive that dimensional measures are results that guide future therapeutic there is perhaps only one way to improve useful in describing psychosis-related applications (http://www.maps.org; http:// our classification. Large-scale, empirical, morbidity in the general population and, www.heffter.org). There is also increasing population-based studies of psychiatric contrary to the proposition of Dr Murray, interest in using psychedelics in conscious- symptoms, demography, course, treatment we would expect dimensions to be moremore ness research in the UK (http://www. response and outcomes are suggested to useful than categories in populations beckleyfoundation.org). reclassify these disorders from first princi- unselected for severe illness. I do hope that my article, and a forth- ples and provide an atheoretical framework Finally, we would like to restate and coming meeting to be held at the College which may capture underlying patho- further emphasise our optimism about the (contact me at drbensessa@@hotmail.com physiological substrates. Such studies likely rate of progress in identifying bio- for further details), can help raise aware- should, as described by Craddock & Owen, logical markers that can validate psychi- ness of this subject. I also agree with Dr integrate both dimensional and categorical atric diagnoses. Markers (in the form of Sandison in his plea for continued support approaches but also require a develop- genetic polymorphisms) have already been from the College to bring this subject to mental perspective across the life span. identified that challenge current nosology. the attention of doctors in the UK. The debate about the Kraepelinian dichot- For example, using the Bipolar Affective omy illustrates the lack of evidence-based Disorder Dimension Scale (which rates Grof, S. (1990) The Holotropic Mind.NewYork:Harper diagnostic classification in psychiatry as a affective and psychotic dimensions; Collins. discipline. It would be fitting if psychiatric CraddockCraddock et aletal, 2004) in a study of over Masters, R. E. L. & Houston, J. (1973) The Varieties of genetics, which has been severely impeded 600 cases each of schizophrenia and bipolar Psychedelic Experience (2nd edn). London: Turnstone Books.Books. by the lack of a robust nosology, focused disorder, we have demonstrated that a risk the collective will of practitioners to variant within the Neuregulin 1 gene,gene, B. Sessa TheParkHospital,OldRoad,The Park Hospital,Old Road, establish the evidence base required for a which has been associated with risk of Headington,Oxford OX3 7LQ,UK. E-mail: psychiatric classification which at last schizophrenia in several samples (reviewed drbensessa@@hotmail.com reflects nature. in Craddock et aletal, 2005), may confer

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