Is the instillation of mercury into the midline cerebral canal of infants, rather than a DNA alteration through more elegant means, the way the extraterrestrials produce a diminishment of intuitive capability, but often with side effects of ADHD and autism?

Once again, your intuition is serving you brilliantly. This is an inspired analysis because you are hitting on the precise way in which the extraterrestrial manipulation of the young in particular can cause such devastating effects that appear rather quickly following their manipulation, and this is the reason they also couple their intervention with human young around the time of receiving vaccination so it can serve as a possible culprit, and this provides a cover story to prevent a hue and cry and a kind of witch hunt to find the cause when there is little else going on because most very young children are sequestered largely from outside influences due to their fragile nature. This provides a very simple process and intervention that is highly effective in causing neurologic degradation as well as impairment of non-local consciousness to limit the intuitive reach. That is the major goal because they want to prevent the new generation of humans from seeing their secret doings psychically. In addition, anything that dims humans and dumbs them down intellectually they see as a benefit because it makes them more manageable through mind control manipulation in most cases. They simply do not care about collateral damage to the functioning and welfare of the humans they manipulate.