Antidepressive response to sleep deprivation in unipolar depression is not associated with dopamine D3 receptor genotype

The psychostimulant theory of antidepressive sleep deprivation (SD) proposes a contribution of dopamine D3 receptors (DRD3) in the limbic system to the antidepressant effects of SD. Neuroendocrinological studies suggest a positive correlation of clinical response to SD and cortisol secretion. We hypothesized that the clinical response to SD and amount of cortisol secretion upon SD is associated with the 1-1 genotype of the Bal1 polymorphism of DRD3 on exon 1. In this study, aiming at evaluating the feasibility of screening large patient samples, 52 inpatients (19 males/33 females) with unipolar depression and a score of 18 or more on the 21-item Hamilton Depression Rating Scale were treated with 1 night of total SD. We found that 31% of our patients responded to SD. There was no association between response to SD and the genotype of the DRD3 Bal1 polymorphism (p <0.879). There was also no association between increase in cortisol secretion after SD and DRD3 genotypes (p <1.000) in a subgroup of patients. Statistical power analysis ruled out a major effect of the DRD3 Bal1 polymorphism on clinical response to SD. These results suggest that the DRD3 Bal1 polymorphism is not a promising lead to be followed up in larger patient samples.