There are many chemical messengers involved in human responses to eachother and abilities to learn but for this post I am going to draw attention to vasopressin because we hear so little about it. Vasopressin is a brain hormone that is released by the pituitary gland. It improves attention, concentration, memory retention, and recall (both short-term and long-term). Vasopressin facilitates more effective learning by helping to "imprint" new information in the memory centres of the brain, a function which cannot be achieved without the action of vasopressin. It is involved in pair bonding and the ability to connect with other people.
Cocaine, LSD, amphetamines, Ritalin, and Cylert (pemoline) cause a release of vasopressin. Frequent use of these drugs can deplete levels of vasopressin with a result of making you slow and dopey.
Alcohol and marijuana, however, inhibit the release of vasopressin. Adding vasopressin when using these drugs will compensate for much of the dopiness caused by them. Nicotine increases vasopressin levels which is maybe one reason there is a tendency to add it to the mix when using alcohol or marijuana.
In my opinion...it's increasingly obvious how use of various chemicals can significantly interfere with our relationships with others and how important it is to keep things on an even keel in this regard because it is so confusing to everyone involved when levels of hormones such as vasopressin are being randomly tinkered with. It make sense to adjust our brain chemistry in a more on-goingly sustainable way which i think can be done. Especially now at a time when it seems such an urge for us to collectively link up.