ADRA2B and emotional recall

Source: New Scientist
Date: 29 July 2007

Emotional recall is in your genes

Your ability to recall emotional events – such as meeting the love of your life, or the trauma of a painful car crash – is governed by a common variation in a single gene, according to a new study.

We recall emotionally charged events far more than mundane ones because they tend to be advantageous in evolutionary terms. Remembering favourable or dangerous events helps our survival far more than recalling the daily commute to work, for example.

Highly emotive incidents trigger the brain to release the hormone and neurotransmitter noradrenaline. This stimulates the amygdala – part of the brain involved with processing emotional reactions – to store memories in the hippocampus and other parts of the brain, says Dominique de Quervain, a neuroscientist at the University of Zurich in Switzerland.

Yet for some reason, recall of emotional events varies a great deal from person to person. So de Quervain wondered if common variations in a gene called ADRA2B, which codes for the noradrenaline receptor, could be responsible. Some 30 per cent of Caucasians and 12 per cent of Africans possess this variant, he says.

Traumatised survivors

To find out, he and colleagues in Germany and Uganda showed photos of strongly positive, neutral and strongly negative emotional events to two large groups of people. They later asked the group members to recall them and describe them in writing.

Positive photos included a grandfather with his grandchildren and a wedding scene. Negative ones included an accident victim with a head wound – and images of devastating pollution spills. Neutral images showed people walking in the street or talking on the phone.

One group comprised healthy Swiss citizens and the other comprised traumatised survivors of the Rwandan genocide – who were living in a refugee camp in Uganda.

Higher negative recall

The researchers found that, in both groups, people carrying the ADRA2B gene variant were "substantially more likely" to remember both positive and negative pictures than people with other forms of the gene. Neutral images were recalled to the same degree by people with and without the variant.

However, Rwandans with the variant had far higher recall of negative emotional events than the Europeans who carried it – and this was unrelated to whether or not they suffered from post traumatic stress disorder.

"The genetic variant is related to enhanced emotional memory," concludes de Quervain. "But it also appears to predispose people to stronger traumatic memories when something terrible happens."

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