aggression, and a mutation in the gene that codes for the 5-HT2A receptor may double the risk of suicide for those with that genotype. Serotonin in the brain is not usually degraded after use, but is collected by serotonergic neurons by serotonin transporters on their cell surfaces. Studies have revealed nearly 10% of total variance in anxiety-related personality depends on variations in the description of where, when and how many serotonin transporters the neurons should deploy. Psychological influences Serotonin has been implicated in cognition, mood, anxiety and psychosis, but strong clarity has not been achieved. Autism spectrum disorder (ASD) In regards to research for neurotransmitters and effects on patients with Autism Spectrum Disorder (ASD), 5-HT has been studied the most in terms of research efforts and investigations. As noted, 5-HT signaling does facilitate many neural processes including that of neurogenesis, cell migration and survival, synaptogenesis, and synaptic plasticity. It was noted that 45% of tested ASD subjects contained high levels of 5-HT in their blood. In addition, investigations performed on ASD-like animal models reported that hyperserotonemia significantly reduced the motivation for social interest through inhibition of separation distress, which could be related in the ASD patients that have social impairments. Outside the nervous system In the digestive tract (emetic) Serotonin regulates gastrointestinal function. The gut is surrounded by enterochromaffin cells, which release serotonin in response to food in the lumen. This makes the gut contract around the food. Platelets in the veins draining the gut collect excess serotonin. There are often serotonin abnormalities in gastrointestinal disorders such as constipation and irritable bowel syndrome. If irritants are present in the food, the enterochromaffin cells release more serotonin to make the gut move faster, i.e., to cause diarrhea, so the gut is emptied of the noxious substance. If serotonin is released in the blood faster than the platelets can absorb it, the level of free serotonin in the blood is increased. This activates 5-HT3 receptors in the chemoreceptor trigger zone that stimulate vomiting. Thus, drugs and toxins stimulate serotonin release from enterochromaffin cells in the gut wall. The enterochromaffin cells not only react to bad food but are also very sensitive to irradiation and cancer chemotherapy. Drugs that block 5HT3 are very effective in controlling the nausea and vomiting produced by cancer treatment, and are considered the gold standard for this purpose. Bone metabolism In mice and humans, alterations in serotonin levels