This test detects a genetic variation, known as the “grouchy” gene, which affects serotonin levels and increases the risk of anxiety and depression.
What is serotonin?
Serotonin is a neurotransmitter in the brain that gives us feelings of pleasure and well-being. When serotonin is released from cells in the brain or neurons it sends out signals to be happy and content. The role of the 5-HTT serotonin transporter is to move serotonin from the synaptic cleft to the presynaptic neuron, allowing serotonin recycling in a sodium-dependent manner. The 5-HTT serotonin transporter is also important to maintain functional neural circuits connecting the amygdala and the cingulate regions of the brain. The 5-HTT serotonin transporter is encoded by the SLC6A4 gene, and it is within the 5-HTTLPR region of this gene that the “grouchy” variation occurs.
The “grouchy” gene
Individuals with the “grouchy” gene have the short version of the 5-HTTLPR region of SLC6A4. These individuals produce lower levels of the serotonin transporter, and have smaller amygdala and cingulate regions – two brain regions involved in emotional responses. This results in an increased risk of:
- Grumpy or sad feelings
- Anxiety related behaviour and stress response
- Antisocial behaviour
- Attention deficit disorder
- Psychological disorders such as autism, depression, bipolar disorder
- Addictive behaviour
- Sudden infant death syndrome
- Response to antidepressants