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Cocaine And The Brain

I found this on google and thought this was interesting. Except the last line of this health page. It took me quite a long time to heal from this drug, things just did not seem as fun without it, but WE DO heal and i feel better than ever. Give your recovery some time and you will see all the positive changes.

Cocaine and the Brain: The Neurobiology of Addiction


Perhaps the most addictive of drugs is cocaine. Cocaine acts on the mesoaccumbens dopamine (DA) pathway of the midbrain, extending from the ventral tegumental area (VTA) to the nucleus accumbens. This pathway is also known as the reward pathway as it is the area of the brain that is activated when someone has a pleasurable experience such as eating, sex, or receiving praise. An electrode was implanted in different areas of the brains of rats and was activated when the rats voluntarily pressed a lever. Stimulation in most sites in the brain was not reinforcing (ie, the rats did not regularly activate the electrode), but one site in particular was reinforcing: the reward pathway. Because of the positive effects felt when this pathway is stimulated, such behavior is reinforced.


Cocaine binds to the dopamine reuptake transporters, thus blocking them from functioning.  As a result, dopamine levels increase in the synapse, and consequently, the receiving neuron is continuously stimulated. This constant firing of the neurons leads to a feeling of euphoria. In addicts, cocaine blocks between 60 and 77 percent of the DAT binding sites; in order to attain a "high," at least 47 percent of the binding sites must be blocked by cocaine.


Cocaine also acts on the reuptake transporters of serotonin and norepinephrine, and therefore, the levels of these neurotransmitters are also increased. Serotonin plays a role similar to dopamine in the DA pathway. Norepinephrine stimulates the "fight or flight" response of the sympathetic nervous system characterized by heightened heart rate, blood pressure, respiration rate, and body temperature as well as dilation of pupils and sweating; these phenomena produce an energizing feeling.


At a certain point, cocaine usage ceases to be a voluntary action: this is the onset of addiction. The positive reinforcement of the sensation of euphoria eventually alters the brain so that the use of cocaine is obligatory. Animal models have been used to demonstrate such positive reinforcement. Lab rats were fitted with long-term intravenous catheters and were taught how to self-administer doses of cocaine by pressing a lever. The fact that the rats continued to self-administer cocaine demonstrates the desire of the rats to be under the influence of the drug. In addition, there is a correlation between the level of the dose of cocaine and the number of infusions a rat would give itself: the lower the dosage, the smaller the gap in-between self-administrations. This indicates that the rat is aware of the level of cocaine in its system and its desire to maintain that level through subsequent injections of the drug. These experiments demonstrate the "compulsion to seek and take the drug" aspect of the definition of addiction.


Another factor in the reinforcement of cocaine use lies in the fact that after cocaine administration, dopamine levels fall significantly below normal, pre-consumption levels. The user therefore feels a "low," and the immediate response to alleviate this low is to take another hit of cocaine to again raise the level. Such behavior is referred to as a "binge," when a user continuously takes hits of cocaine to recover from ensuing lows. This demonstrates the "loss of control in limiting intake" aspect of the definition of addiction.


Over a long period of usage, the brain responds to the above-normal levels of dopamine that are present during a hit. The main manifestation is a reduction in the number of dopamine receptors on the dendrites of neurons ; if there are fewer receptors, then there will be less stimulation of the nerves in the DA pathway. This demonstrates how the brain of an addict is physically different from that of a normal person.


Because of the altered physiological state of the brain, events that previously caused stimulation of the DA pathway (pleasurable experiences other than cocaine use) no longer do; only cocaine can induce the feeling of happiness. When an addict ceases taking cocaine, he has no source of stimulation of the DA pathway and therefore experiences severe depression, irritability, and anxiety (symptoms that are opposite of the effects of the drug). (This is the "emergence of a negative emotional state when access to the drug is prevented" aspect of the definition of addiction.) Other factors also contribute to the negative behavior associated with withdrawal. For example, tests in lab animals have shown that levels of coricotropin releasing factor (CRF), which induces stress, rise while in withdrawal.


Because addicts grow to associate certain places and cues with cocaine use, exposure to such stimuli may cause a relapse once an addict has "quit" . If reminded of an event linked with cocaine use (such as passing by a place where one formerly used the drug or watching people smoke crack), a recovering addict will very likely feel a strong craving. Such a reaction to these memory-based stimuli raises the question of how long memories are able to induce a response. Recent research has shown relapses in lab rats even after four months of abstinence.


There is no well-established treatment plan for cocaine addiction, but the most effective measures are to combine a medicine with drug counseling. Drugs such as vigabatrin are being developed that seek to reduce the pleasure of a cocaine hit (this drug stops cocaine from increasing dopamine levels in the DA pathway and prevents subjects from developing place/cue associations in baboons) . Anti-depressants are often prescribed to alleviate the negative behavior of withdrawal. New research is concentrating on neutralizing cocaine in the bloodstream so that it is unable to affect the DA pathway . While medications are an important part of the recovery process, counseling also plays a seminal role as the patient must learn to resist the urge to use cocaine. Group and individual therapy sessions aid patients in coming to terms with their problem and building up self-confidence. Cocaine-specific skills training (CST) teaches patients to identify the places and cues that cause them to feel cravings; they then seek to avoid or adjust their reactions to such stimuli.


Viewing cocaine addiction as a chronically relapsing disease of the brain is a new concept for much of the public. Such scientific evidence forces people to re-evaluate their views of addicts (in particular the stereotypes associated with them) as it demonstrates that an addict must be recognized as someone with an altered brain state, just as someone with a mental illness or Alzheimerâs . Addicts cannot be cured through incarceration; instead, the process of recovery requires both counseling and medication. In fact, the lasting biological effects of cocaine addiction are so far-reaching that rehabilitators often comment that there is no way to "cure" someone of cocaine addiction - - one can only learn how to live with it.

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Start Date
May 21, 2009
by gizzy32
Last Revision
May 21, 2009
by gizzy32