Guy with pictures of himself.Can DNA actually influence personality and emotional reactions? A Texas A&M Health Science Center expert says genetics could be responsible for fluctuating emotional highs and lows, and how we perceive our quality of life.

When we admire a person’s hair or eye color it’s normal to associate their traits with “good genes.” To be scientifically correct, a person receives genetic variants from their parents – known as alleles – that determine their unique traits. Genes are composed of different alleles that may also have a large impact on emotional responses.

Keith A. Young, Ph.D., professor of psychiatry and behavioral science at Texas A&M College of Medicine and Central Texas Veterans Health Care System, has spent the last 20 years studying a genetic variant that plays a major role in emotional behavior.

Young’s research focuses on 5HTTLPR – a specific genetic variant of the serotonin transmitter gene (serotonin is a brain chemical that moderates mood, appetite and desire). A person will inherit two copies of this gene with two variants of 5HTTLPR: A short allele and a long allele.

Previous research linked the short allele with overactive negative emotions and found people who inherited it were more likely to develop depression and anxiety. In a recent study, Young and team looked at how the short allele affects combat veterans deployed to war zones.

“We found the short allele was over-represented in veterans who returned from combat zones with post traumatic stress disorder. Our working hypothesis is that veterans who were deployed to war zones will have a harder time recovering back to normal if they possess the short allele,” Young said.

Additionally, quality of life is another mental health outcome where the short allele may come into play.

“There is now evidence that 5HTTLPR-short allele carriers perceive and report their quality of life more negatively,” Young said. “In our study of veterans, for instance, 5HTTLPR-short allele carriers reported a reduced quality of life.”

Along the lines of Young’s research, other studies suggested short allele carriers sensed changes in perception because of the allele’s effect on non-conscious bias to threat, danger or fear.

“5HTTLPR-short allele carriers might just perceive or think they had a reduced quality of life because they were focusing on all the negative things around them,” Young said. “However, in many studies, there was no test for a non-conscious bias to happy or other positive stimuli, so I think additional work needs to be done.”

“In the case of our study of veterans, we believe that 5HTTLPR-short allele carriers did not just perceive they had a lower quality of life, their PTSD and depression symptoms led to reductions in positive social interactions and other measurable changes that resulted in a lower quality of life compared to their peers not suffering from PTSD,” he said.

While Young’s research on the 5HTTLPR short allele can be interpreted in light of the alleles “negative” influences, new research found this genetic variant is more complex than it’s original reputation.

According to this new research, people with the short allele laugh and smile more than those with the long allele. The study concluded the short allele amplified emotions – emphasizing both negative and positive emotions – and inheriting it may not mean that you will end up looking on the dark side of life.

“The short allele is now thought of less as in black and white, or normal and defective, and is being pursued more quantitatively,” Young said. “It seems to heighten emotional experiences and impact a person’s emotional highs and lows. Those with the long allele do not experience these highs and lows.”

The new results align nicely with Young’s research on brain anatomy.

“Our study measured the enlargement of a certain area in the brain’s thalamus that processes emotional stimuli,” Young said. “Since the brain regions responsible for emotional processing may actually be bigger in these individuals, it makes complete sense that people who possess the short allele have an increase in both positive and negative emotional thinking.”

According to Young, there are still many questions to be answered about emotionality. “I believe more research needs to be done to clearly answer the questions of how serotonin genetic variation influences our emotions and sudden shifts in moods,” he said.

The shift in thinking about the 5HTTLPR-short allele shows researchers may be headed away from black and white outcomes in relation to emotions and genetics. Whether you dissolve into a fit of giggles or keep a more stoic demeanor, the interactions between genes and emotionality are likely to keep scientists invested for years to come.

— Lauren Thompson

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