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Increasing Serotonin Crucial for Treating Obsessive-Compulsive Disorder: Presented at SFN

By Glynn Wilson

NEW ORLEANS, LA -- November 14, 2003 -- Increasing the serotonin levels in the brain is crucial for treating Obsessive-Compulsive Disorder (OCD), according to a study presented here November 10^th at the Society for Neuroscience 33^rd Annual Meeting.

Lower serotonin levels in the brain due to modern lifestyle practices can lead to behavioral problems such as OCD, and researchers in Canada have found further evidence that increasing the serotonin levels in the brain can treat the malady.

Alexandre E. Berney, MD, Department of Psychology, McGill University, Montreal, Quebec, Canada, presented these findings in a poster session.

Serotonin is a biochemical messenger and regulator that is synthesized from the essential amino acid L-Tryptophan. Serotonin is found primarily in the central nervous system, gastrointestinal tract and blood platelets. Serotonin mediates several important physiological functions, including neurotransmission, gastrointestinal motility, hemostasis and cardiovascular integrity.

Previous studies have shown that low serotonin levels in the brain are a common consequence of modern lifestyle and dietary practices, along with stress. This plays a role in the growing problem of obesity by causing people to crave sugar and other carbohydrates, experience bouts of depression, and to report frequent headaches, muscle aches and pain. It can also lead to other maladies such as OCD.

"Curiously, one method that allows us to lower patients' serotonin levels failed, in previous studies, to actually worsen remedied patients," Dr. Berney noted. So his team decided to replicate those studies and look at the issue in more detail.

Fourteen patients with OCD split evenly as to gender and with a mean age of 31.6, were included in the study. Gradual symptom provocation using the Behavioral Avoidance Test was performed 5 hours after patients ingested a tryptophan drink to lower the serotonin level in their brains.

Patients were subjected to stressful situations specific to their answers on a survey asking what types of situations they typically try to avoid in every day life, Dr. Berney said (i.e., using a public restroom, shaking hands -- which is against social mores in some cultures -- and touching things they would usually avoid).

Compared to the control drink, the tryptophan drink led to a significant increase in the subjective unit of distress, as well as compulsive urges and rituals.

"Anxiety and depression were significantly increased only during tryptophan depletion," said Dr. Berney.

A Repeated Measures Analysis of Variance revealed a significant Time x Condition interaction (P = .044), with significantly higher levels of distress in the Acute Tryptophan Depletion group during provocation with moderate and severe stressors.

The results of this study suggest that Acute Tryptophan Depletion may reverse the effectiveness of anti-OCD treatments, leading to a transient worsening of obsessive-compulsive symptoms, especially when patients have to face specific challenging situations they would rather avoid, Dr. Berney said.

Previous studies may not have stressed individuals sufficiently to test the patients beyond a baseline measure, Dr. Berney indicated.

These results further support the theory that a functional 5-hydroxy-thymidine (5HT) system is critical for doctors to see symptomatic improvements in OCD patients. Dr. Berney concluded that serotonin has to be prescribed in higher doses and for a longer period of time for OCD patents than for patients with simple depression.


[Study Title: Acute Tryptophan Depletion Increases Relapse Susceptibility in Remitted Obsessive Compulsive Disorder (OCD). Abstract 416.14]

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