Relevance of the 5-HTTLPR polymorphism and childhood abuse to increased psychiatric comorbidity in women with bulimia-spectrum disorders

Objective: Individuals with bulimia nervosa have been shown to display heterogeneous profiles of comorbid psychiatric disturbance, possibly due to varying degrees of genetic and environmental vulnerability. Using information about comorbid psychiatric disturbances, we developed an empirically based classification of individuals with bulimia-spectrum disorders, and then explored whether or not the resulting phenotypes corresponded to variations in the serotonin transporter promoter polymorphism (5-HTTLPR) and exposure to childhood abuse. Method: Eighty-nine women aged 17 to 49 years with DSM-IV bulimia-spectrum disorders completed questionnaires assessing eating and general psychopathologic symptoms, participated in interviews assessing Axis I disorders and childhood abuse, and provided blood samples for genotyping. Data on lifetime Axis I disorders were analyzed using latent class analysis, and resulting classes were compared on eating and psychopathologic symptoms, 5-HTTLPR genotype, and childhood abuse. The study was conducted from June 2002 to October 2006. Results: The analysis yielded a model with 2 classes: a first class labeled low comorbidity (N = 59, 66%), characterized by a high likelihood of major depressive disorder, and another class labeled high comorbidity (N = 30, 34%), characterized by a high likelihood of major depressive disorder, anxiety disorder, and substance-use disorders. The high-comorbidity class displayed significantly higher dieting preoccupations and conduct problems, and showed a greater likelihood of carrying the 5-HTTLPR S allele and of childhood abuse than did the low-comorbidity class. Conclusion: The present results are consistent with previous findings identifying a subgroup of individuals with bulimia characterized by high psychiatric comorbidity and suggest that the 5-HTTLPR polymorphism and childhood trauma may both be pertinent to explaining the presence of greater psychiatric comorbidity in bulimia-spectrum disorders.