This study was conducted on healthy volunteers, but who had low levels of serotonin.
People with low levels of this chemical in the brain have rated different couples as less intimate, compared to volunteers with normal levels of serotonin.
The study consisted of the administration of drinks containing amino-acid to two groups of volunteers, in order to manipulate the levels of tryptophan in the blood – a vital ingredient in the synthesis of serotonin.
One group received drinks containing tryptophan, while the other group received beverages that did not contain this amino-acid. All volunteers were asked to evaluate pictures of different couples.
The differences in judgments of the two groups reflected the changes in serotonin in the body. Volunteers who received drinks without tryptophan have consistently rated the couples as less intimate and romantic than participants who received the drinks with amino-acids.
The findings reminded that our relations are influenced by processes beyond our consciousness. Understanding the influence of serotonin is important for strengthening relations, which are known to protect people from mental illness and speed recovery in psychiatric illnesses. Also, the opposite is true, as dysfunctional relationships trigger mental illnesses.
“Although this is only a small study, the same patterns may well extend to the way we perceive our own relationships,” said Professor Robert Rogers of Oxford University.
“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, “says Dr. John Krystal, editor of Biological Psychiatry.
More research is needed before a medicine is released to help increase the feeling of intimacy.