title: Cluster analysis of obsessive-compulsive symptomatology: identifying obsessive-compulsive disorder subtypes.
abstract: BACKGROUND
  There is increasing evidence that obsessive-compulsive disorder (OCD) is a heterogeneous disorder. Different clinical subtypes may be characterized by differing pathophysiological mechanisms and treatment outcomes.
  
  
  METHODS
  A cluster analysis was performed on 45 items of the Yale-Brown Obsessive-Compulsive Symptoms Checklist (YBOCS-CL) for 261 patients with OCD. Cluster solutions emerging at different linkage distance levels, and the associations of identified clusters with demographic, clinical and relevant genetic variables, were investigated.
  
  
  RESULTS
  A 6-cluster solution emerged at a linkage distance level of 1.5, and a 3-cluster solution emerged at a linkage distance level of 2.1. The 3 clusters in the latter solution were labeled I) Contamination / washing, II) Hoarding / symmetry / ordering, and III) Obsessional / checking. Increased Cluster III scores were associated with earlier age of OCD onset and the Met/Met (L/L) genotype of the COMT Val158Met polymorphism.
  
  
  CONCLUSIONS
  The data here are consistent with previous work delineating the different symptom subtypes of OCD, also with previous work suggesting that the Met/Met (L/L) genotype of the COMT Val158Met polymorphism may be associated with anxiety symptoms, as well as with previous work suggesting that dopaminergic genes may be particularly important in early-onset OCD.
authors.affiliation: MRC Unit on Anxiety and Stress Disorders, Department of Psychiatry, University of Stellenbosch, South Africa. cl2@sum.ac.za
authors.forename: Christine
authors.initials: C
authors.lastname: Lochner
authors.forename: Sian M J
authors.initials: SM
authors.lastname: Hemmings
authors.forename: Craig J
authors.initials: CJ
authors.lastname: Kinnear
authors.forename: Daan
authors.initials: D
authors.lastname: Nel
authors.forename: Sian M J
authors.initials: SM
authors.lastname: Hemmings
authors.forename: Soraya
authors.initials: S
authors.lastname: Seedat
authors.forename: Johanna C
authors.initials: JC
authors.lastname: Moolman-Smook
authors.forename: Dan J
authors.initials: DJ
authors.lastname: Stein
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000704:Analysis of Variance; D002394:Catechol O-Methyltransferase / Q000235:genetics*; D016000:Cluster Analysis; D005260:Female; D005838:Genotype; D006801:Humans; D008297:Male; D008875:Middle Aged; D009771:Obsessive-Compulsive Disorder / Q000145:classification* / Q000175:diagnosis / Q000235:genetics / Q000523:psychology*; D016133:Polymerase Chain Reaction; D011110:Polymorphism, Genetic; D020641:Polymorphism, Single Nucleotide; D055815:Young Adult
chemical_list: D002394:Catechol O-Methyltransferase