Stimulants increase the behaviour of the excitatory neurotransmitter Glutamate which leads to excess activation of the NMDA and AMPA receptors. This increases the action potential rate, resulting in more positively charged Calcium Ions (CA++) flooding into the axon terminals or pre-synaptic amine neurons. When this flood occurs, nerve impulse activity increases throughout the body which can result in a temporary loss of motor function control. In minor cases it's usually limited mostly to the facial muscles, hence uncontrollable tics and grinding along with jaw muscle tension. In more severe cases, motor control can be lost throughout other parts of the body as witnessed in that video.
Is tics or Stereotypes related?
en.wikipedia.org
Stereotypes is a repetitive or ritualistic movement, posture, or utterance. Stereotypies may be simple movements such as body rocking, or complex, such as self-caressing, crossing and uncrossing of legs, and marching in place. They are found especially in people with
autism spectrum disorders, but can also be found in
intellectual disabilities,
tardive dyskinesia and
stereotypic movement disorder, yet may also be encountered in neurotypical individuals as well.
Like
tics, stereotypies are patterned and periodic, and are aggravated by fatigue, stress, and anxiety. Unlike tics, stereotypies usually begin before the age of three, involve more of the body, are more rhythmic and less random, and are associated more with engrossment in another activity rather than premonitory urges. Examples of early tics are things like blinking and throat clearing, while arm flapping is a more common stereotypy. Stereotypies do not have the ever-changing, waxing and waning nature of tics, and can remain constant for years. Tics are usually suppressible for brief periods; in contrast, children rarely consciously attempt to control a stereotypy, although they can be distracted from one
- Common stereotypies - these include behaviors that are often observed such as nail biting, thumb sucking, hair twirling, biting oneself, teeth grinding, rocking, and head banging. Typically, these type of behaviors become less frequent with age.
Complex motor stereotypies - these behaviors include arm flapping, repetitive movements with the hands
