Neuronal mechanisms underlying the role of serotonin and its genetic polymorphism on compulsive behaviours

Study code

Lead researcher
Professor Trevor W. Robbins

Study type
Participant re-contact

Institution or company
University of Cambridge

Researcher type

Speciality area
Mental Health

Recruitment Site


The purpose of this study is to investigate how the temporal lowering of tryptophan activity affects learning and decision-making. Tryptophan is a naturally occurring amino acid found in protein rich foods such as meat and dairy products. This amino acid is a main building block of a brain chemical called serotonin.

Temporarily lowering tryptophan levels is known to lead to a short-term reduction of serotonin in the brain and could affect people’s learning capacity and decision-making. Serotonin is important in a number of psychiatric disorders, including depression, anxiety and OCD.

By looking at how people learn and make decisions when serotonin is low we hope to better understand why different mental illnesses occur.

Participation: For this study we recruited 24 volunteers from the Cambridge BioResource to attend a day long session where they gave blood samples, completed computerised tasks and mood based questionnaires.

Organisation: This study is organised by Professor Trevor W Robbins at the University of Cambridge.