title: Subtyping of alcohol dependence in Indian males: A cluster analytic approach.
abstract: OBJECTIVE
  Two cluster solutions for the subtyping of alcohol dependence (AD) was investigated in an Indian male population. Subtypes were compared for various personality traits and childhood externalizing disorders. They were also compared with respect to single-nucleotide polymorphisms (SNP) of various candidate genes.
  
  
  METHODS
  This was a clinic-based study conducted among 202 patients with AD. All patients were assessed with SSAGA-II for comorbid antisocial personality disorder (ASPD) and childhood conduct disorder (CD), oppositional defiant disorder (ODD), and attention deficit hyperactivity disorder (ADHD). For the assessment of personality traits, the Indian Adaptation of Sensation Seeking Scale (SSS) and Barratt's Impulsiveness Scale were administered. SNP genotyping was done using taqmann assay by real-time polymerase chain reaction.
  
  
  RESULTS
  Among those with AD, the two-cluster model which was able to produce the maximum degree of cohesion among disorders in the same cluster and separateness from the other cluster was the one with or without ASPD and CD. The quality of the cluster analysis was reduced when ODD and ADHD were included in the model along with ASPD and CD. Thus, in our index population, there are two distinct clusters of AD, one with ASPD and CD or the externalizing cluster (Cluster 2) and the other without ASPD and CD or the nonexternalizing cluster (Cluster 1). Externalizing cluster had significantly higher score in both the impulsiveness and the SSS. This cluster was also significantly associated with childhood ADHD and ODD. The genotype frequencies of all candidate genes were found to be nonsignificantly distributed among the two groups.
  
  
  CONCLUSIONS
  Our study has conferred a cross-cultural validation of the known alcoholism subtypes.
authors.affiliation: Department of Psychiatry, Postgraduate Institute of Medical Education and Research, Chandigarh, India.
authors.forename: Savita
authors.initials: S
authors.lastname: Malhotra
authors.affiliation: Department of Psychiatry, Postgraduate Institute of Medical Education and Research, Chandigarh, India.
authors.forename: Debasish
authors.initials: D
authors.lastname: Basu
authors.affiliation: Department of Psychiatry, Postgraduate Institute of Medical Education and Research, Chandigarh, India.
authors.forename: Abhishek
authors.initials: A
authors.lastname: Ghosh
authors.affiliation: Department of Experimental Medicine and Biotechnology, Postgraduate Institute of Medical Education and Research, Chandigarh, India.
authors.forename: Madhu
authors.initials: M
authors.lastname: Khullar
authors.affiliation: Department of Psychiatry, Postgraduate Institute of Medical Education and Research, Chandigarh, India.
authors.forename: Neeraj
authors.initials: N
authors.lastname: Kakkar
keywords: Alcohol dependence; cluster analysis; externalizing disorders; subtypes