Original Article

Neuropsychopharmacology (2010) 35, 1729–1733; doi:10.1038/npp.2010.38; published online 24 March 2010

A Season-of-Birth/DRD4 Interaction Predicts Maximal Body Mass Index in Women with Bulimia Nervosa

Robert D Levitan1, Allan S Kaplan1,2, Caroline Davis3, Raymond W Lam4 and James L Kennedy1,5

  1. 1Mood and Anxiety Division, Department of Psychiatry, Centre for Addiction and Mental Health, University of Toronto, Toronto, ON, Canada
  2. 2Eating Disorders Program, Toronto General Hospital, University Health Network, University of Toronto, Toronto, ON, Canada
  3. 3Department of Psychology; York University, Toronto, ON, Canada
  4. 4Department of Psychiatry, University of British Columbia, Toronto, ON, Canada
  5. 5Neurogenetics Section, Department of Psychiatry, Centre for Addiction and Mental Health, University of Toronto, Toronto, ON, Canada

Correspondence: Dr RD Levitan, Department of Psychiatry, University of Toronto, c/o CAMH, 250 College Street, room 1126, Toronto, ON, Canada M5T 1R8, Tel: +1 416 535 8501 ext. 4020, Fax: +1 416 979 6821, E-mail: robert_levitan@camh.net

Received 21 October 2009; Revised 11 February 2010; Accepted 23 February 2010; Published online 24 March 2010.



We have earlier reported that season of birth interacts with the hypofunctional 7-repeat (7R) allele of the dopamine-4 receptor gene (DRD4) to promote weight gain and obesity in women with seasonal affective disorder (SAD). This study examined whether this gene–environment interaction influences body weight regulation in women with bulimia nervosa (BN). In 188 female probands with BN, we performed an analysis of covariance predicting maximum lifetime body mass index (BMI) using season-of-birth, DRD4 genotype (7R present/absent), and past history of anorexia nervosa (yes/no) as independent variables, and age at maximum weight as the co-variate. Consistent with our SAD study, the birth-season × DRD4 interaction was a significant predictor of maximal BMI. Although in SAD, the spring-birth/7R+ group had markedly elevated maximal BMIs and high rates of obesity, in this BN sample, the fall-birth/7R+ group exhibited the highest BMI values (N=17: mean maximal BMI=28.2kg/m2 (SE 0.9) vs 25.2kg/ m2 (SE 0.3) for all other probands combined (N=171); p=0.002). The lifetime rate of obesity (BMI>30) was also higher in the fall-birth/7R+ vs ‘other’ group (29.9 vs 8.8%, respectively, p=0.008). These data offer further evidence that season of birth interacts with the 7R allele of DRD4 to influence body weight regulation in female overeating populations.


bulimia nervosa; dopamine-4 receptor gene; birth season; obesity; thrifty phenotype hypothesis; developmental plasticity

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