Elevated Kynurenine in Tourette Syndrome

Grant Type
Grant Year
Institution Location
Institution Organization Name
Birmingham University UK
Investigators Name
Handley, Sheila, PhD

This project concerns the natural body chemical, kynurenine, and its potential importance to Tourette Syndrome (TS). In a recent pilot study, we found increased kynurenine in the blood of every one of the seven patients we studied. Now, we aim to find out why kynurenine was increased and what it could mean for the causes and symptoms of TS. Kynurenine is formed from the amino-acid tryptophan which comes from the food we eat. In fact over 90% of the body’s intake of tryptophan is metabolised through the kynurenic pathway in liver and other tissues (this is why we asked our TS patients to fast overnight in our pilot study in order to stabilise their tryptophan). Kynurenine itself is metabolised to other substances, several of which are known to have effects on neurones. Kyurenine could be increased in a number of different ways. One of the most interesting is following stimulation of the immune system. This means that TS might possibly be an autoimmune disorder. Conversely, increased kynurenine might also contribute to symptoms – we have previously found that it can increase tic-like movements in a mouse model of TS. Lastly, increased kynurenine in otherwise healthy patients and their families could indicate the presence of the TS gene(s). We shall examine these possibilities by measuring tryptophan, kynurenine and its metabolite, together with other substances which will help to show whether the immune system has been activated. We shall take blood samples from TS patients, their families and from volunteers free of TS or its associated symptoms. Some patients will be followed over a period of time. In this way, we hope to make a contribution to understanding the basic nature of TS. Sheila L. Handley, BPharm, Ph.D., Prof. John A. Corbett, MBBS, FRCP, FRCPsych, MRCS, DPM Birmingham University, Birmingham, UK Mary M. Robertson, MD, MBChB, DPM, FRCPsych University College London Medical School Harlow, UK Award $15,000 Tourette Association of America Inc. – Research Grant Award 1994