Once a behaviour is manifested in the mind, it may become the basis for an addiction.
There are many models to explain the pathway of an addiction. There are biological, genetic, social, psychological reasons and of course the various combinations. Given the low success rates treating addictions, I am not so convinced that any of these modes hold a final answer and they may be missing an important point. Anyway, fom a medical standpoint, an addiction is primarily a chronic neuro-biological disorder, with genetic, environmental and psychological-social components, and compared to what we said before, this seems to be conclusive.
One key principle in developing an addiction is salience. Humans cannot pay attention to more than one or very few items simultaneously, so they are faced with the challenge of continuously integrating and prioritising different bottom-up and top-down influences. Attention is usually guided by top-down, memory-dependent, or anticipatory mechanisms, such as when looking ahead of moving objects or sideways before crossing streets. When attention deployment is driven by salient stimuli, it is considered to be bottom-up, memory-free, and reactive. It means that the nervous system overrides the more cognitive-analytical functions of the brain, in order to respond swiftly to what it deems most relevant at the time. It is a survival mechanism and a pre-programmed function, often co-opted by the substance. It is the explanation between what we have come to know as reaction, based on the information of the conditioned mind and action, based on the inherent inner wisdom of any human being.
It is interesting that this mechanism is co-opted by the mind in the case of an addiction. When exposed to the respective substance, our memory systems, reward circuits, decision-making skills and conditioning kick in. It is salience in overdrive to create an all-consuming pattern of uncontrollable craving. Some people have a genetic predisposition to addiction, but because it involves these basic brain functions, everyone will become an addict if sufficiently exposed to nicotine, drugs or alcohol.
That can go for non-chemical addictions as well. Behaviors, from gambling to shopping to sex, may start out as habits but slide into addictions. Almost anything deeply enjoyable can turn into an addiction and the question at hand is, what it is exactly, that is considered deeply enjoyable.
I am not going into the details now, but on all levels there is a strong relation between the stress network and addiction. Among higher creatures like us, stress can alter the way the brain thinks, particularly the way it contemplates the consequences of actions. When we find ourself in a stressful situation, when we are were scared, nervous or threatened, the brain tunes out everything besides whatever it is that was frightening us, it is the fight-or-flight mode that is the survival mode of our species. The part of the brain that is involved in deliberative cognition is shut down by stress. It’s supposed to be, but it’s even more inhibited in substance abusers and a less responsive prefrontal cortex sets up addicts to be more impulsive as well.
This seems to be the basic mechanism for an addiction to develop. First a behaviour is fulfilling an egoic desire – something tastes good, makes me more relaxed, helps me sleep. Next this behaviour gets anchored in the mind, until the mind takes over and wants to repeat the experience. In order to do this, the desire has to become salient and the mind co-opts the human survival mechanism to guarantee the fulfilment. This is helping us to understand, why addicts believe they cannot live without the drug and have to follow their impulse. An addiction it is driven by past experiences and future expectations. At its core, an addiction is a misguided response to a desire, a want. And every want is rooted in a need.
The close connection between stress and addiction seem to hold another insight.