Introduction
Drug addiction is a chronic disorder marked by cyclic patterns of compulsive drug-seeking behaviors and the loss of control in limiting one’s intake. Despite increasing public awareness of the negative effects that drug abuse has on one’s health and life satisfaction, substance use disorders are still one of the most significant public health problems in the world today. So, what actually happens to your body when you take drugs such as cocaine? And why do some people become addicted to narcotics so easily?
To understand this, we must first take a look at the human body’s most complex organ — the brain. The effect of drugs starts with chemical reactions in the brain that then lead to psychological and physical effects. This article will unpack the brain and its functions, then use cocaine as a case study of how a drug can affect the brain functioning to form a drug addiction.
What Does the Human Brain Comprise of?
The brain and the spinal cord
Together, the brain and the spinal cord form the central nervous system (CNS) which controls most of the body’s functions and mind including thought, speech, movements, awareness, sensations, and memory. A neuron, or nerve cell, is the basic unit of the CNS. Neurons are composed of the soma (cell body), dendrites (receives messages from other neurons), axon (nerve fiber), and terminal (connects to another neuron). The nervous system is made up of billions of tiny neurons that enable the different systems and parts of the body to communicate with one another through the brain and spinal cord. You can think of the brain like the hierarchy of a company. The brain is the top management that analyses, makes decisions, and sends information out for the various departments to execute. The line managers are the spinal cord, which transmits information to the departments.
Impulse flows
Nerve impulses are electrical signals that flow from one end of a neuron to the other and result from electrical changes across the membrane of the neuron. The impulse is carried through the axon and the synapse, the space between the axon of one neuron and the dendrites of a neighboring neuron.
The Synapse and Synaptic Neurotransmission
During synaptic transmission, a neuron communicates with another neuron across a synapse. The chemical synaptic transmission includes the release of a neurotransmitter like dopamine. Dopamine neurotransmission and modulation by endogenous opiates. Dopamine released by a neuron into the synapse binds to specialized proteins called dopamine receptors on the neighboring neuron.
The Reward Pathway and Addiction
In life, we are hardwired biologically to seek out pleasure and rewards due to evolution. Natural rewards include nurturing, water, food, and sex are natural rewards that the brain reinforces as engaging in such activities allows living things to feel pleasure.
The Reward Pathway
The mesolimbic pathway, also known as the reward pathway, is a collection of dopaminergic neurons that extends from the ventral tegmental area (VTA) to the ventral striatum which includes the nucleus accumbens and olfactory tubercle. Dopamine is contained in the neurons of the VTA and is released when the pathway is activated.
Addiction
Addiction can be defined as a psychological and physical inability to refrain one’s self from engaging in a behavior, even though it causes psychological and physical harm.
How Do These Components of the Brain Function?
Brain Regions and Neuronal Pathways
Each part of the brain is in charge of different functions. For example, the frontal lobe controls vital cognitive skills such as memory, language, problem-solving, and speech. The parietal lobe processes sensory information such as taste, touch, and temperature. Neurons in different parts of the brain are connected to each other through pathways that facilitate the sending and receiving of signals. One of the pathways central to drug addiction is the reward pathways. The reward pathway is essentially a feedback system that reinforces positive feelings and it is connected to memory and behavior. Here, neurons release a neurotransmitter, a chemical known as dopamine, that makes a person feel pleasure. When a person consumes an addictive drug, it triggers the reward pathway to reinforce this pleasurable feeling. Over time, the brain makes connections between the activity of consuming drugs and pleasure, prompting the individual to repeat the behavior. As such, drug addiction develops.
Pathways for the Sensation and Reaction to Pain
The pathway for the sensation and reaction to pain is long and flows from the brain to the spinal cord. For example, if a person falls down and injures his or her knee, the injury is sensed by the nerve endings in the knee. Sensory neurons then send signals along, axons, primary transmission lines of the nervous system, through the spinal cord, and up to the brain. In the brain, the thalamus and sensory cortex are responsible for interpreting and organizing the signals received as pain. Signals are then sent back down the spinal cord to inform the motor neurons in the knee to react to the pain.
Cocaine on the Brain
Though an addictive drug, not all cocaine users become addicted. Cocaine can be consumed through two methods: snorting or smoking. Smoking is a more common method of consuming the drug as it reaches the brain faster compared to snorting, which also means that people will feel the effects of cocaine more quickly. This is because when cocaine is snorted, it needs to flow through blood vessels in the nose and heart before it is pumped to different parts of the body. On the other hand, cocaine travels directly from the lungs to the heart and the brain if it is smoked.
The following process occurs when cocaine is ingested:
1. Localization of cocaine binding sites
Though cocaine spreads to all parts of the brain when it is smoked or snorted, it binds to specific areas such as rewards areas: the VTA and the nucleus accumbens.
2. Dopamine binding to receptors and uptake pumps in the nucleus accumbens: the action of cocaine
Usually, dopamine is released by a neuron into the synapse, where it binds to dopamine receptors on neighboring neurons. Dopamine is then recycled back into the transmitting neuron by the dopamine transporter. However, if a person has consumed cocaine, cocaine attaches to the dopamine transporters and prevents the normal recycling process from taking place. This results in a buildup of dopamine in the synapse and contributes to the pleasure that one feels when taking cocaine.
If cocaine is consumed regularly, the body will start to rely on the drug for pleasurable feelings. The person will not be able to feel pleasure or positive reinforcement through natural rewards and hence, becomes dependent on cocaine. If the person stops using cocaine, anhedonia, or the inability to feel pleasure, and depression will result. When this occurs, the person will return to using cocaine. This is why withdrawal has such a powerful impact on cocaine users, and also why relapses are common with cocaine.
Conclusion
Like cocaine, substances such as alcohol and other drugs have the potential to be misused become addictive as they trigger the reward pathway and increase dopamine transmission. Understanding these chemical processes in the brain is key to having a good understanding of drug addiction. Rehab is one of the best ways you can get clean from an addictive drug, and there are many drug rehab options within Texas that recovering addicts can seek help from.
