Neurobiology of Addiction



Addiction is an extremely complex disease to treat, arguably more complex than any other because it fundamentally blurs the line between psychology and biology, and in many cases the patients own mind will be actively working against any attempts at healing.

Cerebellum Temporal Lobes Occipital Lobe Parietal Lobes Frontal Lobes Brain Stem Brain Stem Temporal Lobes Cerebellum Frontal Lobes Parietal Lobes occipital lobes

Often the line between free will and diseased thinking is hard to determine, because the mind of an addict is so hijacked by the substance that its difficult sometimes to ascertain who or what you are working with, is it the patient, the addiction, or some synthesis of the two struggling for dominance? For this reason it is important for anyone thinking about what types of treatment will be effective to have at least a cursory understanding of the human mind, and how its components and functions relate to and are affected by addiction.

The addicted brain is probably best understood as a collection of individual players fighting for control over the will. For this metaphor we would divide the brain into two primary components, the ‘higher brain’, where reasoning, consequential thinking, and critical analysis takes place, and the ‘lower brain’ where immediate gratification, self-preservation, and basic instinct drive decisions. Understanding the different regions of the brain and their relationship to the disease of addiction is essential to understanding how to go about getting help.

Frontal Lobe

The frontal lobe endows us with much of what makes us human. It is responsible for consequential thinking, reason, and conscious decision making, and therefore its role in addiction cannot be over-emphasized. When we want to speed on the freeway, it’s the frontal lobe that slows us down, and when you go on a diet, its the frontal lobe that overrides your desire for unhealthy foods, because it understands the consequences and long-term goals of the diet. Essentially, the purpose of the frontal lobe insofar as addiction is concerned is to delay gratification. The other parts of the brain are interested only in immediate pleasure and relief, but the frontal lobe is what allows us to make calculated decisions that will ultimately result in a larger payoff.

An addict in active addiction is driven by the lower parts of the brain that are interested only in instant reward, and the longer the addict stays in that state, the more the frontal lobe atrophies. Therefore it is of the utmost importance that the frontal lobe be ‘exercised’ in the process of recovery. Exercising the frontal lobe is simple, it involves doing things that you do not ‘feel like’ doing in the moment. Things like working out, going to work, eating healthy, and taking care of more mundane tasks like keeping a neat living space. Its not the tasks in and of themselves that are necessarily beneficial, but rather through the process of forcing yourself to complete them, the frontal lobe is exercised and regains the strength it lost in the depths of your addiction.

Parietal Lobe

The parietal lobe is primarily responsible for the processing of sensory information, such as sight, smell, touch and taste. It is used to process spatial information and orientation and allows you to reach out and pick things up and understand what you are seeing or hearing. All of this is great in a normal person, but in an addict, certain sights, sounds, tastes and smells become strongly associated with using their drug of choice. These external stimuli are sometimes referred to as ‘triggers’ in the recovery community, and it is pretty much universally agreed that they should be avoided or minimized to the extent possible. Being around places where the addict used, or seeing their drug of choice regularly can significantly slow down the recovery process, and most often leads very quickly to relapse.

Occipital Lobe

The occipital lobe is responsible primarily for lower-level visual processing, analyzing shapes and colors and then passing that information along to the parietal and temporal lobes for higher-level processing and analysis. This is also the region of the brain from which dreams originate. Dreams are thought by some to be a method of learning by simulation. The theory states that dreams are a way for the brain to simulate various scenarios and play out the outcomes of different decisions and actions taken and make guesses about how to best handle the situation in real life. In addiction, this process is hijacked somewhat, because the occipital lobe is not driven by the rational part of the mind, it is driven by the more primal instincts for pleasure and reward, and so often dreams will center around getting high. These are usually referred to as ‘using dreams’, and they can be extremely upsetting to a recovering addict, because they often bring up very strong feelings and desires for the substance in the dream.

Temporal Lobe

The temporal lobe operates to some extent in parallel with the parietal lobe in doing higher-level visual and auditory processing. However, where the parietal lobe has more to do with spatial relationships and orientation, the temporal lobe is more about identifying objects and developing and recalling memories associated with visual and auditory stimuli. In essence, the job of the temporal lobe is to translate visual and auditory information into ideas and abstractions that we can understand and conceptualize as symbols, rather than pixels of color and sound. Unfortunately the abstractions of an object in memory are associated with memories of past experiences with them. This can mean that an intravenous heroin user might be strongly triggered by the sight of a spoon, even if that particular spoon had never been used to cook heroin. It is very important for the recovering addict to be conscious of these environmental cues and learn how to avoid or manage them so that they do not lead to relapse.


The cerebellum is one of the older and more primitive components of the human brain, it is associated with very basic and powerful feelings like fear and pleasure, as well as handling simple aspects of reactionary motor control. It is here that what we normally think of as ‘instincts’ reside, this is the part of the brain that makes you eat when you are hungry, drink when you’re thirsty, and jump out of the way of a moving car. In order to be effective at accomplishing these tasks, the cerebellum has to operate extremely quickly, so it does very minimal, if any, processing of more complex, abstract concepts like long-term consequences.

This part of the brain becomes grossly over-emphasized in the addicted person and begins to dominate and override the higher-level reasoning regions of the brain in all aspects of behavior and decision making. This imbalance takes quite a while to re-adjust, and can be slowed down substantially by certain factors, like constant exposure to triggers and stress, which is the primary reason why inpatient rehab facilities are so strongly recommended for anyone trying to achieve lasting sobriety.

Brain Stem

The brain stem is the most primitive part of the brain, and its role is limited almost exclusively to regulating autonomic functions like heartbeat, breathing, and the sleep cycle, as well as providing an interface between the central nervous system and the spinal column. This region is essentially what keeps us alive on a moment-to-moment basis, and generally has very little to do with addiction because it has almost no bearing on conscious decision making. Its job is simply to regulate the basic functions of the human body in order for the rest of the brain to be able to carry out its functions.