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Impaired Decision-making, Impulsivity, and Compulsivity: Addictions' Effect on the Cerebral Cortex

A. Tom Horvath, Ph.D., ABPP, Kaushik Misra, Ph.D., Amy K. Epner, Ph.D., and Galen Morgan Cooper, Ph.D.

The cerebral cortex is the outer most layer of the brain. The cerebral cortex is further divided into four areas. These four areas are: the frontal lobe (or frontal cortex), parietal lobes (left and right), temporal lobes (left and right), and occipital lobes (left and right). Each area is associated with certain brain functions: One area of the frontal cortex is called the prefrontal cortex. It has a vital role in higher-order functions. These functions include language, spatial learning, conscious thought, judgment, and decision-making. The process of addiction can negatively affect this area and alter its functioning.

brain and neuronsThe prefrontal cortex enables us to make rational, sound decisions. It also helps us to override impulsive urges. If acted upon, these impulses urges can cause us to act without thinking. This is usually not in our best interest. For instance, suppose I've had a bad day at work. I may have an impulsive urge to tell my boss exactly what I think of her. To act on this impulse is not in my best interest. Fortunately, my prefrontal cortex is functioning quite well. I still have my job!

Obviously, this ability to inhibit impulses is very helpful. It enables us to function well in society. It protects us from harm by allowing us to consider the consequences of our actions. However, when the pre-frontal cortex is not functioning correctly, the opposite occurs. Addiction causes changes to the prefrontal cortex. These changes account for two characteristics of addiction: impulsivity and compulsivity.

Impulsivity is the inclination to act upon sudden urges or desires without considering potential consequences. Sometimes people describe impulsivity as living in the present moment without regard to the future. Compulsivity is a behavior that an individual feels driven to perform to relieve anxiety. Once a person performs the compulsive behavior, the anxiety goes away and restores comfort. Thus, the presence of these behavioral characteristics in addicted persons indicates that changes to the prefrontal cortex have occurred. Unfortunately, these changes also make the discontinuation of drug use more difficult.

Addiction is a process that coordinates the transition from impulsive to compulsive behavior. Impulsivity occurs during the early stages of addiction. During this phase, people impulsively act on powerful urges to experience the pleasure of their addiction. Anxiety is not associated with the urges during these early stages. Instead, addiction reflects acting on impulsive desire to receive immediate pleasure from the drug or activity. People are not considering the future consequences.

As addiction progresses a shift begins to occur. At this point, the compulsive aspect of addiction takes hold. When this shift occurs, people are no longer pursuing their addiction solely for pleasure. The compulsions compel them to participate in their addiction to relieve anxious, uncomfortable feelings. These may arise at the mere thought of stopping the addiction for any reason (supply shortages, lack of opportunity, etc.). At this later compulsive stage, "pleasure" comes in the form of relief from these anxious, uncomfortable feelings. Thus, despite the negative consequences of addiction, the addictive behavior continues in a compulsive manner.

Another way to describe the pre-frontal cortex is to think of it as a braking system. The pre-frontal cortex acts as the brain's brakes. It sends out signals to inhibit particular behaviors or actions. When addiction damages this brain area, it limits the brain's ability to control other behavioral systems as well. Imagine how difficult it would be to operate a car without brakes. At this point, we might say the brain is "high-jacked" by the addiction. The prefrontal cortex also projects to other brain regions associated with addictive problems. These include the reward system; memory and emotion; and stress regulation centers of the brain. Therefore, damage to the prefrontal cortex may further interfere with the functioning of these other brain regions as well.

Although addiction damages the brain's brakes (pre-frontal cortex) this is not to say there is a complete loss of control. We are not slaves to our biology. We have a tremendous amount of control over our actions.  This is true even when impulsive and compulsive forces are operating. This recognition is vitally important if someone wishes to recover from addiction. When a person consciously decides the costs of addiction outweigh its benefits, they become motivated and able stop. This allows them to actively counter the effects of addiction on the frontal cortex and other brain regions.

Unfortunately, people's addictions limit their ability to use rationale thought. This is due in part to the damage to the prefrontal cortex. They may incorrectly tally the costs and benefits of their addiction; over-estimating the benefits, while minimizing the costs. The addict is often told, "You're in denial." This is incorrect. When people use this phrase, they are applying it improperly. Denial refers to a psychological defense, or justification for a negative behavior. This is quite different than a loss of rational brain functioning that occurs with addiction. This is where addiction treatment professionals can be very helpful. They can guide addicted persons to make an accurate assessment of the costs and benefits. This more accurate assessment often leads to the motivation to change. Once someone decides it is time to change, they have taken the first step toward recovery.

The addiction process relies on learning and memory to drive the addiction cycle forward. Addiction chemically alters the system. However, people can learn how counteract these changes. There are specific techniques that people can learn to oppose powerful urges. As people become more skillful, the wonderfully adaptive brain makes adjustments and corrections. This in turn leads to lasting recovery from addiction. We discuss these techniques and strategies in The Psychology of Addiction and Recovery. In some cases, pharmacological intervention may also be beneficial.


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