January 3, 2015

The Hippocampus Is Central To Many Aspects of Addictive Process

During childhood the brain will naturally produce the adequate amounts of nerve cells known as neurons which work to power the main coordination and control functions of the central nervous system. In medical terms, the process of neuron production is known as neurogenesis. During adulthood, neurogenesis essentially comes to a halt in almost all areas of the brain except for a region called the hippocampus, which plays a primary role in certain functions related to memory and learning. According to findings reported in 2011 by the National Institute on Drug Abuse, use or abuse of the illegal stimulants cocaine and methamphetamine can interfere with adult neuron growth inside the hippocampus. In turn, disruption of neuron production in this brain region can increase overall risks for the onset of a stimulant addiction.

Neurogenesis is a crucial process in the brain as it helps to populate or re-populate the brain with neurons. These neurons form the core of the communications network that makes the brain the center of all nervous system activity within the rest of the body. The primary period of neuron production occurs before birth during the process of fetal growth and development. The process of neurogenesis also continues during childhood and adolescence in a less extensive form. However, by the time an individual reaches adulthood, the production of new neurons comes to a halt except inside the hippocampus and in a region called the subventricular zone, which is located near fluid-filled chambers in the brain known as the lateral ventricles.

Getting to know hippocampus

Hippocampus belongs to a pathway called the limbic system together with other crucial structures in the brain. The hippocampus is a paired structure that assumes a resemblance of bananas. The whole of the limbic system plays a prime role in the human ability to experience rewarding or pleasurable sensations. However, as a distinct structure, the hippocampus functions largely as the brain’s center for taking in new memories, arranging those memories and creating an index that makes the newly arranged memories easy to find in the future. Other vital tasks carried out by this brain region include coordinating emotion-based responses to internal or external situations, helping the body orient itself spatially to its surroundings and providing the ability to remember and navigate the details of previously encountered physical environments.

This part of the brain plays very important roles but it can be adversely affected by the use of stimulants and other drugs of leisure. Substances such as cocaine and methamphetamine produce their primary effects inside the brain by boosting the presence of dopamine which is a neurotransmitting chemical that activates the pleasure-producing neurons contained within the limbic system. As stated above the limbic system includes the hippocampus, along with several other brain structures. According to the results of two separate studies published in 2008 in the Journal of Neuroscience and Biological Psychiatry, the presence of either cocaine or methamphetamine alters normal adult neurogenesis inside the hippocampus and damages this region’s ability replenish its neuron supply. It has been found that stimulants as well as other drugs of pleasure interfere with the basic processes of neurogenesis at an early, critical stage known as proliferation. In particular cocaine also interferes with the ability of existing immature neurons to grow into their normal mature forms.

Owing to its vital roles, the hippocampus has since become an area of particular interest, as it is central to many aspects of the addictive process, including relapse to drug taking. A recently appreciated hippocampal neuro-adaptation produced by drugs as diverse as opiates and psycho-stimulants is decreased neurogenesis in the sub-granular zone (SGZ). Stem cell Adult-generated neurons and drug-induced alterations of adult neurogenesis advance our understanding of the complex mechanisms by which opiates and psycho-stimulants affect brain function.

How drugs addiction affects Hippocampus

In a research that was done by researchers from the University of Texas Southwestern Medical Center in 2011, the results of this study that examined the addiction risks related to the disruption of normal neurogenesis inside the hippocampus indicated that cocaine abuse led to decreased production of neurons in the hippocampus. During this study, adult rat were deprived of their normal ability to produce new hippocampal neurons. These rats were then given free access to cocaine for four hours a day. When compared to adults rats not robbed of their ability to produce new neurons in the hippocampus, these neurogenesis-impaired rats consistently increased their cocaine intake by 60 percent. The neurogenesis-impaired rats also had a much greater tendency to seek out cocaine between the sanctioned periods of drug access; substance abuse specialists typically view this type of drug-seeking behavior as a critical indicator of a developing drug addiction.

Hippocampus These researchers also measured neurogenesis-impaired rats’ susceptibility to a drug relapse. During the first phase of this stage of testing, the rats were removed from the cages where drug use had taken place, blocked all drug access for a month, and let the rats go through withdrawal. At the end of the month, the rats were returned to their old cages but still received no access to cocaine. Compared to rats with normal rates of neurogenesis which also went through the same process, the neurogenesis-impaired rats showed more prominent signs of drug craving and a desire to continue drug use as often the case in relapse.

Finally, Drug abuse, addiction and independence are problems that people grapple with every day. These problems need to be treated effectively through integrative medicine. Dr. Dalal Akoury (MD) is an expert at this. Call her on (843) 213-1480 for help.

The Hippocampus Is Central To Many Aspects of Addictive Process

Prefrontal cortex in addiction: The Executive Brain

April 5, 2014

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