Influence of Tryptophan and Serotonin on Mood and Cognition with a Possible Role of the Gut-Brain Axis

Summary & key facts

Scientists review studies that change levels of tryptophan — the nutrient the body uses to make serotonin — to see how serotonin affects mood and thinking. Those experiments show that lower brain serotonin is linked with worse memory and lower mood. The review also says the gut and its bacteria can affect tryptophan and serotonin, so gut health might be one factor in brain problems, but this idea is still being worked out.

Key facts:

• Serotonin is a brain chemical involved in mood and thinking.
• Researchers change tryptophan levels, either lowering or raising them, to alter serotonin in the body and brain and study the effects.
• Across lab and human studies, lower brain serotonin has been linked with poorer memory and more depressed mood.
• The gut-brain axis means the brain and digestive system send signals back and forth.
• Gut bacteria can influence tryptophan and serotonin, so changes in the gut might affect mood and cognition, but this link is still being researched and is not proven as a direct cause.

Abstract

The serotonergic system forms a diffuse network within the central nervous system and plays a significant role in the regulation of mood and cognition. Manipulation of tryptophan levels, acutely or chronically, by depletion or supplementation, is an experimental procedure for modifying peripheral and central serotonin levels. These studies have allowed us to establish the role of serotonin in higher order brain function in both preclinical and clinical situations and have precipitated the finding that low brain serotonin levels are associated with poor memory and depressed mood. The gut-brain axis is a bi-directional system between the brain and gastrointestinal tract, linking emotional and cognitive centres of the brain with peripheral functioning of the digestive tract. An influence of gut microbiota on behaviour is becoming increasingly evident, as is the extension to tryptophan and serotonin, producing a possibility that alterations in the gut may be important in the pathophysiology of human central nervous system disorders. In this review we will discuss the effect of manipulating tryptophan on mood and cognition, and discuss a possible influence of the gut-brain axis.

Topics

Diet and metabolism studies Gastrointestinal motility and disorders Tryptophan and brain disorders

Categories

Health Sciences Medicine Physiology

Tags

Anxiety Central nervous system Cognition Gut flora Gut–brain axis Immunology Internal medicine Medicine Mood Mood disorders Neuroscience Psychiatry Psychology Receptor Serotonergic Serotonin

Substances

Other

Conditions & symptoms

Anxiety Depression Difficulty focusing Sadness or low mood