Association study of nicotinic-receptor variants and major depressive disorder

Background: Depressive patients are more likely to smoke than the general population and nicotine was found to reduce the incidence and severity of depressive symptoms in many studies. These findings suggest that nicotinic acetylcholine receptors (nAChRs) may be implicated in major depressive disorder. We tested the hypothesis that the allelic variant, 2 bp deletion, of the partially duplicated α7 nAChR gene confers susceptibility to major depressive disorder. Methods: We genotyped α7 nAChR in 72 patients with major depressive disorder and 103 normal controls. Results: The distribution of the partially duplicated α7 nAChR genotypes (P=0.027) and alleles (P=0.037) suggests a modest difference between depressive patients and controls. Limitations: The −2 bp allele is thought to be present only in the duplicated exon 6, and the impact of the partially duplicated α7 nAChR and its −2 bp variant remain to be determined. Conclusions: The −2 bp allele of partially duplicated α7 nAChR may have an influence on the risk for development of major depressive disorder. The levels of significance achieved are modest and the findings must be replicated in other studies.