Hormone serotonin, impulsivity linked in British study

WASHINGTON, June 5, 2008 (AFP) – Serotonin plays a key role in regulating emotions such as aggression and impulsivity during decision making, according to British research appearing Thursday in the United States.

Neurologists and psychiatrists have long linked serotonin, a hormone that transmits chemical messages between nerve cells, and social behavior, but its precise role is controversial.

The British study in the June 6 edition of the journal Science is among the first to show a causal link between low levels of serotonin in the brain and impulsivity.

It is also demonstrates why people can become combative on an empty stomach.

Serotonin levels naturally drop when a person hasn’t eaten, because tryptophan, an essential amino acid necessary for the body to create serotonin, can only be obtained through diet.

Scientists from the University of Cambridge took advantage of that fact, and lowered the levels of brain serotonin in study participants by manipulating their diet.

Participants were asked to participate in an activity called the “Ultimatum Game,” so researchers could observe how they reacted to situations perceived as unfair.

In the game, a player proposes dividing a sum