Neuroscience and addiction

Posted by on October 23, 2014 in Uncategorized | 0 comments

Neuroscience and addiction

I like to consider myself well versed on drugs and recovery. My knowledge of both of these contradicting topics comes from self-discovery and exploration. I know drugs from doing them and I know recovery through the study and participation in the 12-step recovery programs along with more recent study of other people’s recovery paths through my work as a recovery coach. But what is neuroscience and what can it explain about addiction? This is an area I have never explored.

Neuroscience is the study of the nervous system which is the brain, the spinal cord, and the sensory path throughout the body that regulates and reports on the senses and movements. In other words the peripheral nervous system which is made up of the motor and sensory systems. Although drugs effect the entire nervous system, the part of the brain that is effected the most, and results in changes in brain function, is the electrochemical messaging between the neurons.

Neurons are the functional cells of the nervous system. They transmit messages that control our movements, emotions, and thoughts. Electrical messages go down the fingerlike dendrites to the cell body then down the axon out to the synaptic terminals. Neurons do not touch, there is a cleft between the synaptic terminal of one neuron and the dendrite of the second neuron. Messages travel through this cleft by the release of neurotransmitters which are chemicals that travel to the corresponding neuron creating the electric message that continues its travel through the next neuron. (National Institute of Drug Abuse, 2010)

There are 50 know neurotransmitters. Two that are often associated with illicit drug use are serotonin and dopamine. Healthy serotonin levels are often associated with calmness and happiness. Low serotonin can result in depression, insomnia, and aggressive behavior. Dopamine release is related to sensations of pleasure. Endorphins are natural opioids that produce elation and reduction of pain, as do artificial chemicals such as opium and heroin. (Farabee, 2010)

Drug use effects the normal brain function. Cocaine blocks the reabsorption of dopamine by the axon terminal causing overstimulation. Hence the intense overwhelming good rush feeling from the coke. Over time the receptors on the post synaptic neuron may decrease from the overstimulation causing the need for more of drug. Amphetamines cause excess dopamine to be released also causing overstimulation and heightened energy. Heroin is a derivative of morphine, which in turn is obtained from opium. Heroin binds to receptors in the brain and repeated use causes a physical addiction. Eventually euphoria is no longer felt only delay of withdrawal symptoms. Anyone who does these drugs will feel their effect yet some people continue to do these drugs to the point of tolerance and addiction and others choose to put the drugs down. I believe this difference may be caused by many forces including environmental and physical. But that is a discussion for another paper. What we are focusing on in this paper is the disease aspect of addiction.

The first studies that revealed how the pleasure centers of the brain can effect behavior were in 1954. James Olds and Peter Milner of McGill University published a seminal paper in which they report evidence for the existence of a reward center in the brain. They experimented on rats and found that the rats would press a level for stimulation to a particular area of the brain, the septal area, a region in the middle of the brain. Olds and Milner then concluded that this area of the brain was responsible for reward and pleasure. A similar effect is produced when the Nucleus Accumbens is stimulated. This is the region where the neurotransmitter dopamine is released. (Lipton, 2013)

Olds and Milner went further with this experimentation on the reward center of the brain and behavior. They set up an experiment where a mouse would choose to cross an electrified grid in order to push a lever that would stimulate the pleasure center of the brain. Crossing this grid would cause a sharp painful electrification. These same mice would choose not to cross this grid for food and would starve to death. Robert Heath did similar experimentation on humans proving the same results as Olds and Milner.

The implications of this experimentation to the behavior of addicts is meaningful. Once the brain has changed to expect more dopamine the addict will behave in ways unacceptable to society’s norms and even unacceptable to themselves in order to once again feel the pleasure cause for the excess dopamine released in drug use.

Thanks to imaging technology we can now see the disease in a heart compared to a normal heart by a difference in color in the pictures. When normal brains are compared with brains of people who have addiction to cocaine we can also see the difference in color, point being, disease changes organs and addiction is a disease. Another aspect of the brain in addiction is memory connections that are strengthened. In other words, motivational pathways get hijacked. Addicts become motivated to seek the pleasurable reward of drugs over the rewards of other survival behaviors like food and sex. (Redonna K. Chandler, 2012)

Natural survival rewards of food and sex elevate dopamine. This motivates us to pursue and participate in survival behaviors. We strategize, plan, and create situations where we can participate in the survival behaviors and feel the pleasure of the increased dopamine. Drugs of abuse act on these same pathways, oftentimes even more efficiently and intensely than the natural release of dopamine. The natural release of dopamine includes reuptake of the dopamine back into the releasing neuron for future use. Drugs can inhibit this reuptake causing excess dopamine to be absorbed by the receiving neuron. Over time, the brain will change because if this. Fewer D2 receptors will receive dopamine. This is brain damage.

Why do addicts relapse? Studies have found that dopamine release can be induced in addicts with images of drug use. Imaging technology can see the change in the brain and addicts have reported cravings. When erotic videos were shown to non-addict test subjects, brain scans could see that the subjects were stimulated by the videos. Addicts, however, were not as stimulated. This is proof that the brain had changed in the addicts. The addict’s brain expects a much higher release of dopamine than the normal survival behaviors can produce.

According to the movie Pleasure Unwoven, three things can contribute to relapse. 1. Drugs 2. Drug cues (including cravings) 3. Stress. Balance in the brain, like temperature, regulates. With addiction the hedonic set point is set unnaturally high. Normal dopamine for normal pleasure no longer registers. What does register is drugs which cause the excess of dopamine that the addicted brain had come to expect. Often relapse is on the way without the addict even realizing it. (McCauley, 2010)

Judgment and choice are found in the frontal cortex area of the brain. This goes wrong in addiction and brain scans show abnormal brain activity. Prior commitments, love of family… becomes unstable when the frontal cortex fails. Denial and personality changes characterize end stage addiction. The brain attaches the drug to survival. Craving is an intense emotional suffering. There is no choice when it comes to craving. Therefore craving is the evidence against the argument that addiction is a choice.

Recovery is possible! The addicted person can learn to cope with stress, cravings, and cues. Normal pleasure once again becomes pleasurable and, over time, the brain can heal. Addicts are equal to all other patients. Addiction is a disease- disease parity in treatment is the goal!

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