You can read the abstract of this article at The idea of Reward Deficiency Syndrome suggests that addiction to various substances occurs because they stimulate the brains reward system so intensely that the population of dopamine D2 receptors (DD2R) decreases
Instead of just altering neurotransmitter levels, it promotes the actual formation of new synaptic connections the wiring that underlies memory, learning, and cognition
Sheriff, S., Du, H
Additionally, it has been reported that inhibition of autophagy accelerated ROS production and apoptosis induced by CP, while its activation reversed these effects (Zhao et al., 2017)
However, if a person is unaware that their supplement has expired, they may believe they are consuming more nutrients than they are
Lets take a look at each of these factors in more detail, below