Neuroscience of Addiction what is Addiction?

 Addiction is the condition of repeatedly using a particular substance or doing a particular activity, despite its damages. In some estimates, the modern-day addiction crisis in the United States started in the 1800s when patients suffering from injuries and illnesses did not have proper medications to ease their pain. Pharmaceutical industries developed painkiller drugs and convinced doctors that they were not addictive. However, after using painkiller drugs for a particular time patients started to become addicted to them. The use of opioid prescriptions started to rise and many people started to die because of overdosing. In 1914, the government banned the use of some drugs, such as opiates and cocaine, and limited the trade of others.

In 1946 President Truman signed the National Mental Health Act, which provided funds for the National Institute of Mental Health, and researchers started to develop medication and treatment for individuals with mental disorders. In 2000, the use of drugs decreased but a large number of people kept using drugs for pleasure. Today, in the United States more than 7.4 million people suffer from drug addiction, and opioid overdoses cause the death of 115 people every day. Environmental Factors which lead to Addiction Johan Hari, the author of the book “Casing the Scream”, is one of the researchers who claim that environmental factors such as social isolation, depression, and stress can increase the susceptibility to addiction while motivation and sociability disincline it. For example, during the US-Vietnam War, depression and stress led the majority of soldiers to use drugs.

Yet, 95% of the veterans were able to quit it when the war was over. However, when veterans returned to their country, they resumed their normal lives without continuing their drug habits. This shows that happiness, motivation, and a balanced lifestyle can help individuals to quit their drug habits. Stimulating activities and a friendly environment is another major factor that may disincline addiction. A laboratory experiment on rats, which was carried out by Professor Alexander, is a great illustration of this claim. In the experiment, rats were left alone in a cage and had access to both normal water and water containing heroin or cocaine. The rats preferred medicined water almost 100% of the time, ultimately resulting in their death. However, another group of rats were given access to drugged water but were put in a cage with more rats, good food, and lots of stimulating activities.

In this case, these rats almost never used drugged water. (cite) This shows that people are more likely to use drugs when they are alone, stressed, and unmotivated. The chemical structure of drugs causes sudden and gratuitous happiness which grabs the attention of people who suffer from stress, anxiety, and depression. Today 20% of Americans with depression and anxiety also experience drug addiction, which shows that there is a direct connection between depression and drug use. Effects of drugs on the brain, the most complex organ in the human body, regulate the basic functions in our body and enable us to think and feel. The brain is formed by billions of neuron cells which are organized into circuits and networks.

Neurons receive signals from other neurons in the circuit to transfer information. Each part of the brain is responsible for specific functions, but they are all interconnected with circuits and work as a team. To transfer information, the neuron releases neurotransmitters into the synapse (the space between two neurons), and neurotransmitters attach to the receptors of the receiving cell which causes a change in the neuron. Other units which are known as transporters recycle the neurotransmitters by bringing them back to the neuron which released them. Some drugs, such as heroin and marijuana, have a similar chemical structure with natural neurotransmitters and imitate certainly.

However, they activate neuron cells in a different way and cause neurons to send abnormal messages to networks. Other drugs, such as amphetamine or cocaine cause neurons to release unusual amounts of natural neurotransmitters which generate high motivation and happiness. Also, they interfere with transporters and prevent the normal recycling of neurotransmitters. Therefore, marijuana weakens memory while heroin slows breathing and heart rate. Cocaine and amphetamine may cause victims to get violent, have panic attacks, feel paranoid, or have a heart attack. Brain parts that are affected by drug use The brain are the coordinating center of sensation and the nervous system, and each part of the brain plays an essential role in regulating our body.

The basal ganglia are a group of structures in the brain which are responsible for motivation and play a role in the formation of routines and habits. The motivating activities, such as eating, playing, and sex, form the reward system. Taking drugs over-activates the reward circuit and causes gratuitous happiness and motivation. However, drugs decrease the sensitivity of the circuit. After using drugs for a certain time, the brain doesn't feel enough pleasure from other activities besides drugs. The extended amygdala, the stress system of the brain, evaluates and responds to stressful feelings, such as fear and anxiety. It plays a key role in the transition to addiction and maintains dependence even after drug use is stopped. That makes it easier for addicted people to repeat drug use over and over again without thinking about it. For this reason, most addicted people use drugs to stop cravings and to find relief rather than to get motivated.

The prefrontal cortex enables us to think, make decisions and solve problems. This is also the part that makes people more vulnerable during teenagehood. There is a balance between this circuit, extended amygdala, and the reward and stress systems of the basal ganglia. Drug use shifts the balance between these circuits and makes a person lose control and seek a drug continuously. Genetics of Addiction Genesis the units of DNA that make up the human genome. Genomes code for information that regulates the basic cellular activities of the body. On average, the DNA of most people is 99.9 percent the same and 0.1 percent different. This 0.1 percent difference contributes to visible traits such as eye color and height and invisible traits, such as increased risk to certain diseases like Huntington's disease, Cystic fibrosis, heart attack, diabetes, and addiction. The recent studies in genetics, help researchers to analyze complex diseases, such as addiction by examining persons whole genome.

To identify errors in DNA (single nucleotide polymorphism) scientists study whole genome sequencing and exome sequencing. Single Nucleotide Polymorphism analysis has proven that Circadian genes are an important factor that affects the development of addiction. Circadian genes code for proteins that make up Circadian rhythm. The circadian rhythm regulates most of the behavioral, physiological, and physical rhythms, such as mood, body temperature, hormones, metabolism, oxygen usage, and blood pressure. Circadian genes also plan our normal sleep, wake, and social schedules. Outside factors such as lightness and darkness also affect the circadian rhythm. For example, at night you feel sleepy because your brain sends a signal to your body to release melatonin which makes you feel tired. Drug use causes a disruption in daily circadian rhythm.

Drugs, such as Cocaine, Methamphetamine, Ethanol, and Morphine affect the circuit of circadian rhythms of behavior and physiology. Moreover, people who have distribution in circadian genes show more use of drugs and withdrawals. Circadian rhythm also regulates the physiological response to drug use. New clinical reports show that drug overdoses and withdrawals are circadian rhythm-dependent. The laboratory experiments show that animals use cocaine significantly more when they are treated at night rather than in the morning. After three cocaine intake in an hour, the circadian rhythm gets disturbed. Treatment Addiction is a complex and hard treated disease which affects the brain's functions. Different treatments work for different people and addicted individuals should start the treatments as soon as possible. New medications and (......) help people to manage withdrawal symptoms, prevent relapse, and treat reoccurring conditions.

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