The Addictive Brain as taught by Professor Thad A. Polk Part IV

Fourth in my series of the review of The Addictive Brain. Please see part one dated 12/5/2016 then part two dated 12/20/2015 and yesterdays’s post if you haven’t read them yet. These 2 lectures cover the “hard” drugs, stimulants and opiates.

Lecture 9: Stimulants – From Cocaine to Ritalin

Cocaine was the first stimulant isolated from the coca plant. Originally used in Coca Cola.

Coca leaves have been chewed for the effect for hundreds of years. Isolated and used in high concentrations in the mid 1800s. Cocaine powder is a salt. More properly called cocaine hydrochloride. In the mid 1970s people began to separate the salt and started using free basing. Crack cocaine is also the free base. You can smoke the free base but not the hydrochloride salt form. This causes a very intense high with a high likelihood of abuse.

Amphetamine and methamphetamine are derived from the Ephedra plant. In the late 1800s chemists isolated and learned to synthesize amphetamine from the plant. Methamphetamine was synthesized a little later and found to me more effective as a psychostimulant. These meds were commonly used by the military in the 40s and later widely used as diet pills.

The most widely used psychostimulants now are Ritalin and Adderal. Both are used for treatment of Attention Deficit Disorder and Attention Deficit Hyperactivity Disorder. ADD and ADHD respectively, Low doses of these medication can help increase focus for these disorders. Doses are lower than those needed for a euphoric high. Methamphetamine is the most commonly abused illegal form of amphetamine.

Main positive effects of psychostimulants are increased alertness, decreased fatigue and euphoria. Adverse effects can be disastrous. Young people have had strokes and heart attacks and even sudden death from these drugs. Chronic stimulant use can lead to psychosis and paranoia. They can repeatedly pick or scratch at insects they imagine are crawling under their skin. “Meth Mouth” can occur with multiple cavities, loss of teeth and gum inflammation. Felt to be due to decreased salivation during meth use, stimulant effects leave to teeth grinding, also meth addicts often stop seeing dentists and have poor oral hygiene.

How do psychostimulants effect the brain? All psychostimulants directly increase the amounts of dopamine in the brain. Dopamine release is associated with all addictive drugs and the stimulants are very effective at this. Dopamine also stimulates the brain reward center. Stimulants also increase the levels of norepinephrine. This is what causes increased blood pressure and inability to sleep. The stimulants are some of the most addictive drugs known. Often these drugs are used in binging patterns. Unable to stop until the drugs are gone or you collapse from exhaustion. Addicted people can have intense cravings and associations with triggers.

Treatments are behavioral in nature. Cognitive behavioral therapy is helpful. Community based support programs or meetings are helpful. High relapse rates for stimulant addiction. No pharmacological treatments approved at this time.

Lecture 10: The Science of Poppies, Pleasure and Pain

The opiates are derived from the Poppy plant. Opium is derived from latex. In botanical terms a latex is a secretion produced from a plant that has an injury to it. The latex can cover the wound and protect against insects that try to eat the injured plant. Opium can be modified to form many different drugs called opioids. Opioids include morphine, codeine and heroin. There are many others. Opioids are characterized as being able to produce a dreamlike euphoria in their users.

Opium has been used since ancient times. Sumerians used it and called it Joy Plant. Ancient Egyptians used it. In the 17 and 1800s a mixture of opium and alcohol called laudanum was very popular. Used as a pain reliever and sleep aid. In 1804 morphine was isolated from opium. Named after Morpheus, the Greek god of dreams. Morphine became an invaluable tool in medicine for pain relief. It was used liberally in the Civil War and many Civil War veterans became addicted. It was called “Soldiers Disease”. In 1898 Bayer started marketing a drug they said was 2.5 times stronger than morphine. It was said to be non addictive and used for pain and cough suppression. The name of this drug – heroin.

Many opioids are marketed currently. Vicodin, Percocet, Methadone, Codeine, Oxycontin etc. Very effective for pain but also very addictive. They cause a dreamlike euphoria that rewards the user. Also can cause nausea and constipation. Opioids that don’t effect the brain are used as cough suppressants and anti diarrheal agents. Most dangerous side effect is suppression of breathing. Overdoses cause people to die because they stop treating.

The brain has several opioid receptors but the one that seems to cause the effects that lead to its uses and abuses are the mu receptors. Mu receptors are found in high concentration in areas of the brain associated with pain perception and with the reward circuits especially in the nucleus accumbens. The endogenous chemicals for the opioid receptors were eventually found. 3 types of chemicals were found, the dinorphins, enkephalins and endorphins. Endorphins are found in the brain. The name itself is a shortening of endogenous morphine. Endorphins are released in response to pain to help coping with the pain but can also be released with exercise – hence the term “runners high”.

How do opioids work? They mainly work by inhibiting the transmission of neural signals. The body has an elaborate system of pain receptors and nerve fibers to conduct those signals. Opioids work by inhibiting those transmissions. They work in the spinal cord and centrally. The placebo effect is also felt to be related to the release of endogenous opioids. Placebo effect can be blocked by naltrexone, an opioid antagonist. The high of opioids is from stimulation of the reward centers in the brain.

The health effects of opioid addiction are not due to the toxicity of the drug itself, like in alcohol. The health consequences are due to the behavioral changes associated with the addiction. Addicts often neglect personal hygiene and nutrition as their lives get consumed by pursuing the addiction. They use dirty needles to use the drugs. There is a narrow gap between a euphoric high and an overdose, so overdose is common.

Recent survey reports over 5 million americans have used, illegally, opioids in the past month. This includes prescription abuse of opioids. Over 92 thousand ER visits in a single year from opioid overdose. About 45 people a day die from prescription opioids. More than heroin and cocaine overdoses combined.

Opioids cause addiction much like other drugs. They overstimulate the reward centers and cause a large release of dopamine. Opioids inhibit the neurons that inhibit the VTA so they have a strong addiction potential.

Treatment for overdose is naloxone. A drug that has a high affinity for opioid receptors but doesn’t activate them. Thus other opioids don’t bind to the receptors and activate them.

To treat the addict first you must detox them. The withdrawal is very unpleasant. Methadone maintenance can be helpful. Naltrexone is an opioid antagonist that can be taken orally or in time release injection form. It blocks the opioid receptors so if someone in treatment relapses and takes an opioid it doesn’t result in getting high. Suboxone is a partial agonist, antagonist that can ameliorate withdrawal. Cognitive behavioral techniques and community meetings and support help.

The last 2 lectures in this series covers the behavioral addictions, food, gambling etc.

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