Blood Chemistry Influences How We Judge IntimacyNew research led by an Oxford neuropsychologist finds that the judgments we make about the intimacy of other couples’ relationships appear to be influenced by the brain chemical serotonin.

The role of serotonin as a contributing factor for depression and other psychiatric activity led researchers to investigate if levels of serotonin contribute to changes in the way individuals perceive personal relationships, or even in their ability to maintain positive personal relationships.

“Serotonin is important in social behavior, and also plays a significant role in psychological disorders such as depression,” explained Robert Rogers, Ph.D., of Oxford University, who led the research. “We wanted to see whether serotonin activity influences the judgments we make about peoples’ close personal relationships.”

The study results are consistent to what we already know about serotonin — that a drop in serotonin levels is associated with depression. Depression is a condition that often results in compromised intimacy.

The study involved giving amino acid drinks to two groups of volunteers in order to manipulate blood concentrations of the amino acid tryptophan, which is a vital ingredient in the synthesis of serotonin.

One group received drinks that contained tryptophan. The other group received drinks that did not contain tryptophan. They were then asked to make judgments about sets of photographs of couples.

Differences in the judgments made by the two groups reflected changes in their serotonin activity.

The volunteers who received the drink without tryptophan consistently rated the couples in the photos as being less “intimate” and “romantic” than the participants who received the control drink.

Understanding the powerful influence of these chemicals is important as supportive close relationships are known to protect against the development of mental illnesses and to promote recovery in those affected by psychiatric conditions. The opposite is also true: Dysfunctional relationships can be triggers for those at risk of these conditions.

The results raise the possibility that lower serotonin activity in people with depression and other psychiatric conditions could contribute to changes in the way they perceive personal relationships, or even in their ability to maintain positive personal relationships.

“Although this is only a small study, the same patterns may well extend to the way we perceive our own relationships,” said Rogers.

The study is found in the journal Biological Psychiatry.

“The ability to chemically influence the capacity for intimacy could be very important. Reduced capacity for intimacy can be a vexing symptom of many psychiatric disorders and an important target for treatment,” noted Dr. John Krystal, editor of the journal.

“Drugs that ameliorate the impact of serotonin deficits might play a role in the treatment of this symptom.”

Source: Elsevier