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Dissecting the Gilles de la Tourette spectrum: a factor analytic study on 639 patients
  1. Andrea E Cavanna1,2,3,
  2. Hugo D Critchley4,5,
  3. Michael Orth6,
  4. Jeremy S Stern7,
  5. Mary-Beth Young7,8,
  6. Mary M Robertson2,3,7
  1. 1Department of Neuropsychiatry, University of Birmingham and BSMHFT, Birmingham, UK
  2. 2Department of Mental Health Sciences, UCL, London, UK
  3. 3Sobell Department of Motor Neuroscience and Movement Disorders, Institute of Neurology, UCL, London, UK
  4. 4Brighton and Sussex Medical School, University of Sussex Falmer Campus, Brighton, UK
  5. 5Sussex Partnership NHS Foundation Trust, Millview Hospital, Hove, UK
  6. 6Department of Neurology and European Huntington's Disease Network, Universitätsklinikum Ulm, Ulm, Germany
  7. 7Department of Neurology, St George's Hospital and Medical School, London, UK
  8. 8Department of Psychology, UCL, London, UK
  1. Correspondence to Dr A E Cavanna, Department of Neuropsychiatry, Birmingham and Solihull Mental Health NHS Foundation Trust, University of Birmingham, Barberry Building, 25 Vincent Drive, Edgbaston, Birmingham B15 2FG, UK; a.cavanna{at}ion.ucl.ac.uk

Abstract

Background Recent studies using quantitative methods, such as principal component factor analysis, hierarchical cluster analysis and latent class analysis have suggested that Gilles de la Tourette syndrome (GTS) should no longer be considered a unitary condition as in current classification systems.

Objective To identify quantitative components of GTS symptomatology using a large, well characterised cohort of singleton individuals with GTS in order to inform future genetic studies with more homogeneous phenotypes.

Methods Principal component factor analysis with oblique rotation was used to analyse symptom data from a sample of 639 patients recruited at two tertiary referral centres using identical schedules during the period 1980–2008.

Results Three Factors were identified: (1) complex motor tics and echo-paliphenomena; (2) attention deficit and hyperactivity symptoms plus aggressive behaviours; and (3) complex vocal tics and coprophenomena. Obsessive compulsive behaviours loaded significantly on the first two factors. The three factors accounted for 48.5% of the total symptomatic variance.

Conclusions GTS is a phenotypically heterogeneous condition encompassing simple tics, specific complex tics and associated behavioural problems. The results, coupled with previous findings, identified a clinical continuum of complex tics, hyperactivity/impulsivity symptoms and semantically relevant utterances and gestures. A better characterisation of the GTS phenotypes will help to identify susceptibility genes.

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Footnotes

  • Funding Gratitude is expressed to Tourettes Action-UK for their financial support with a grant awarded to MMR specifically to undertake the study.

  • Competing interests None.

  • Ethics approval This study was conducted with the approval of COREC.

  • Provenance and peer review Not commissioned; externally peer reviewed.

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