Prefrontal cortex in addiction: The Executive Brain
Prefrontal cortex in addiction-Effect of Right and Left PFC
Studies around problems in the brains prefrontal cortex have been associated with Impulsive action; a trait of addictive behavior.
The prefrontal cortex in addiction (PFC) is that portion of the brain located in the very front of the brain, just behind the forehead. It’s in charge of abstract thinking and thought analysis it is also responsible for regulating behavior. This includes mediating conflicting thoughts, making choices between right and wrong, and predicting the possible outcomes of actions or events. This brain area also governs social control, such as suppressing emotional or sexual urges. Since the prefrontal cortex is the brain center responsible for taking in data through the body’s senses and deciding on actions, it is most strongly implicated in human qualities like consciousness, general intelligence, and personality
Prefrontal cortex in addiction-Function
This vital region of the brain regulates thought in terms of both short-term and long-term decision making. It allows humans to plan ahead and create strategies, and also to adjust actions or reactions in changing situations. Additionally, the PFC helps to focus thoughts, which enables people to pay attention, learn, and concentrate on goals. This area is also the part of the brain that allows humans to consider several different yet related lines of thinking when learning or evaluating complex concepts or tasks. The prefrontal cortex in addiction also houses active, working memory.
The Prefrontal Cortex in Addiction
Chemical addiction is classified as a mental illness, such that addiction changes the brain in fundamental ways. An addiction disturbs a person’s normal hierarchy of needs and desires and substitutes new priorities connected with using drugs or alcohol. The resulting compulsive behaviors that override the ability to control impulses despite the consequences are similar to hallmarks of other mental illnesses.
Prefrontal cortex in addiction-Signs of Prefrontal Cortex Damage
- Studies around problems in the brains prefrontal cortex have been associated with Impulsive action; a trait of addictive behavior.
- Lack of dopamine in the prefrontal cortex is also associated with Attention Deficit Disorder (ADD).
- Lack of serotonin is a common problem with juveniles who lash out.
Some believe that impulsive behavior says more about an addicts approach to their addiction rather than the addiction itself. If one asked, “Why would anyone use drugs knowing that they lead to suffering?” The impulsiveness argument is a good answer, because it suggests that the thinking person is not in control, which reinforces the argument that the addict is powerless.
Prefrontal cortex in addiction-Signs of Addictive Behavior
- Addicts differ in their capacity to exercise judgment and inhibit impulses.
- The brain’s prefrontal cortex helps to determine the adaptive value of pleasure recorded by the nucleus accumbens and checks the urge to take the drug when it would be unwise.
- If the prefrontal cortex is not functioning properly, an addictive drug has more power to monopolize the reward circuit.
Prefrontal cortex in addiction-Depression
Though depression involves an overall reduction in brain activity, some parts of the brain are more affected than others. In brain-imaging studies using PET scans, depressed people display abnormally low activity in the prefrontal cortex in addiction, and more specifically in its lateral, orbitofrontal, and ventromedial regions. And the severity of the depression often correlates with the extent of the decline in activity in the prefrontal cortex.
- Orbitofrontal cortex
- Lateral prefrontal cortex
- Ventromedial cortex
- Limbic system
The prefrontal cortex in addiction is known not only to be involved in emotional responses, but also to have numerous connections with other parts of the brain that are responsible for controlling dopamine, norepinephrine, and serotonin, three neurotransmitters that are important in mood regulation. More specifically, the lateral prefrontal cortex seems to help us choose a course of behavior by letting us assess the various alternatives mentally. The orbitofrontal cortex seems to let us defer certain immediate gratifications and suppress certain emotions in order to obtain greater long-term benefits. And the ventromedial cortex is thought to be one of the sites in the brain where we experience emotions and the meanings of things.
The two halves of the prefrontal cortex in addiction also seem to have specialized functions, with the left half being involved in establishing positive feelings and the right half in establishing negative ones. And indeed, in depressed people, it is the left prefrontal cortex that shows the greatest signs of weakness. In other words, when people are depressed, they find it very hard not only to set goals in order to obtain rewards, but also to believe that such goals can be achieved.
In healthy people, the left prefrontal cortex might also help to inhibit the negative emotions generated by limbic structures such as the amygdalae, which show abnormally high activity in depressed patients. In patients who respond positively to antidepressants, this over activity is reduced. And when the amygdalae remain highly hyperactive despite antidepressant treatment, the likelihood of a patient’s relapsing into depression is high.
It is also interesting to note that when someone’s left prefrontal cortex is operating at full capacity, the levels of glucocorticoids in their blood are generally very low. This follows logically, considering the harmful effects that high levels of glucocorticoids have on mood.
Brain-imaging studies have also shown that in patients with severe depression, the volume of the two hippocampi is reduced. This atrophy may be due to a loss of neurons that is also induced by the toxic effects of the high levels of glucocorticoids associated with recurrent episodes of depression. The extent of atrophy in the hippocampus even seems to be proportional to the sum of the durations of the episodes of depression, and depressions that are treated rapidly do not seem to lead to this reduction in hippocampal volume
Prefrontal cortex in addiction-Effect of Right and Left PFC
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