Lack of association of a single-nucleotide polymorphism of the mu-opioid receptor gene with anxiety-related traits: results from a cross-sectional study of adults and a longitudinal study of children.

There is evidence from animal experiments that the mu- and delta-opioid receptors may play a role in anxiety and depression. It might therefore be expected that functional polymorphisms of these genes in humans are associated with anxiety and depression. We investigated a single-nucleotide polymorphism (Asn40Asp) of the mu-opioid receptor gene (OPRM1). This association was investigated in two samples: 1) a cross-sectional survey of 867 community-living adults aged 18-79 years who were assessed for anxiety and depression symptoms and related personality traits; and 2) a longitudinal study of childhood temperament in which 660 children were followed from infancy to the mid-teens and assessed for anxiety-related temperament and behavior problems. The data did not support a role for the Asn40Asp polymorphism in anxiety and depression, despite adequate statistical power to detect small effects.