Dominique JF de Quervain and colleagues provide an elegant example of how genetic differences can relate to complex traits such as the ability to recall emotionally laden experiences. In their recent Nature Neuroscience paper, they looked at a deletion of 3 glutamic acid residues (301–303) in the third intracellular loop of the alpha-2-adrenergic receptor and its relation to emotional memory. Since emotion-laden experience (fight-or-flight) is often accompanied by surges in noradrenaline, it makes sense that adrenergic receptors might facilitate such memories. In this case, the deletion genetic variant encodes a slightly less effective receptor whose carriers show enhanced recall of positive and negatively charged images – a memory effect that is similarly achieved when the receptor is blocked using the antagonist yohimbine.
Such genetic findings can lend themselves quickly to practical applications. One first step to begin to understand how the ADRA2B genetic influence might be used to help alleviate the sometimes debilitating effects of persistent emotional memory was an examination of individuals who fled from the Rwandan civil war and were living in the Nakivale refugee camp in Uganda at the time of investigation. Individuals who carry the deletion genetic variant were more likely to re-experience symptoms of traumatic events although, this particular variant is present at relatively low frequencies (about 1 in 8 individuals are carriers).