“High serotonin is characteristic of autism.”

“Psychiatric drugs have striking effects on monoamines. Antipsychotics block dopamine, and antidepressants block the reuptake of serotonin. These observations have sometimes been used to support aetiological theories. One is that schizophrenia is caused by abnormal dopamine transmission. The hypothesis remains controversial, and even if it tells part of the story, it is almost certainly oversimplistic (Howes et al, 2012). Another is that depression is caused by underactivity (or imbalance) of serotonin or norepinephrine. That hypothesis has even less evidence to support it, and no one has ever demonstrated monoamine imbalances in patients who have depression (Moncrieff, 2008).”