Addiction Brain

Long before addiction was properly understood, people at the time attributed it to individuals being weak-willed or morally deficient. It was subsequently difficult to get proper care because physicians were treating the disease for the wrong reasons.

It was in 1875 that Levinstein (one of the first scientists to study morphine addiction) identified key elements responsible for opiate addiction. Even then, his discoveries were not widely accepted until decades later.

Today, we recognise addiction as a serious disease that alters both the brain’s chemistry (function) and its structure. In this article, we discuss how addiction influences a person’s life through one of the most vital organs in the body: the brain.

How Does Addiction Affect the Brain?

The human brain is the most complex part of the body. It is responsible for the cognitive and emotional activity, as well as the voluntary and involuntary functions we perform. Our brain is the centre of activities, from driving a car to sleeping at night.

Addiction comes from the Latin word ‘enslaved’ or ‘to be bound to’. This is explanatory because anybody who is addicted often feels the condition is beyond their own control.

Substances such as alcohol can impact certain receptors in the brain and cause them to fixate on it to function. The substance often works by inducing the secretion of certain neurotransmitters (chemicals for neural communication) and exciting the pleasure pathway. When the brain learns this shortcut to pleasure, it continues to demand it until a cycle is formed, whereby the body reacts negatively in the absence of the substance in question.

Is Addiction a Brain Disease?

Yes. Addiction can be described as a brain disease. A disease is a condition that damages any part of the body and affects its ability to function optimally. With addiction, the brain chemistry is altered and simple functions such as cognition, muscle coordination, consciousness and memory are impaired.

However, addiction doesn’t just alter the brain, it indirectly affects other parts of the body such as the heart, respiratory system and the liver. It is as much a mental health condition as a physical one. Therefore, many addicts suffer from co-occurring disorders such as anxiety, depression, schizophrenia or paranoia. Treatment is therefore achieved by a combination of physical (detox) and mental (rehab therapy) procedures.

The Role of Neurotransmitters in the Cause and Treatment of Drug Dependence

Neurotransmitters are chemicals that act in the brain by relaying chemical signals to individual nerve cells, allowing them to work together and support the essential functions of the body.

Examples of neurotransmitters include dopamine, serotonin and Gamma Amino Butyric Acid (GABA). While dopamine and serotonin are responsible for pleasure and happy moods, GABA calms down brain activity. Some drugs like heroin and cannabis mimic the actions of certain neurotransmitters, thus gaining access to the receptors in the brain. They can also affect the reuptake inhibitors and cause the neurotransmitter to remain longer in the body. When this happens, it prolongs feelings of euphoria in the user.

During treatment, non-addictive medications that access the same chemical receptors are administered to suppress cravings and keep the patient calm.

The Evolution of Motivation

Why do we take drugs, even when they pose life-threatening risks? Scientists have long studied the evolutionary connection between our need for reward (motivation) and drug use.

Based on the ‘Hijack hypothesis’, drug use is the result of reward-seeking behaviour and drug addiction is the consequence we experience as the drug interferes with our natural reward pathway. In other words, the substances we take usurp the mesolimbic pathway, hence hijacking a system that was originally meant for rewards such as food or sex.

Another hypothesis surmises the paradox of drug reward as a double-edged sword with the ability to produce both aversive and rewarding consequences for the user. Therefore, in seeking reward, you ultimately become exposed to the danger of using drugs.

In both instances, the common motivation is a reward. As humans, we are often driven by the goal of pleasure, but in the case of addiction, the substance we use comes back to hurt us.

The Anatomy of Addiction

To comprehend the anatomy of addiction is to understand the brain and the centres affected by addiction. Four parts of the brain involved with drug abuse and addiction are:

We shall discuss this ‘pleasure pathway’ in detail later, but it’s important to note that the speed of addiction is related to how rapidly dopamine is secreted in the brain. All drugs of abuse – from nicotine to cocaine – trigger the release of dopamine in the nucleus accumbens. Over time, the brain becomes used to this pleasure, so it’s no longer as effective. This is known as tolerance; after which, compulsion takes over. The pleasure associated with using the drug tends to decrease, but the memory of desired pleasure feeds the addiction.

Addiction and Dopamine Receptors

Using addictive drugs sends large amounts of dopamine to the limbic part of the brain. Sometimes, it increases as much as five to ten times the usual amount. With levels this high, your brain starts to associate the drug with massive neurochemical rewards (i.e. pleasure).

Dopamine receptors in the brain are often stimulated on the first and subsequent trials. After the initial attempt, the brain is flooded with dopamine, identifying the drug being used (or a particular activity) as something rewarding. Your brain is thus conditioned to crave the drug to achieve the same reward.

Over time, constantly elevated levels of dopamine alter the brain, thus desensitising the neurons until they are less stimulated by the drug. This eventually reduces the number of receptors, until the addiction is formed. The user loses control and is left with a compulsive urge to continue using the drug.

Addiction and the Dopamine Transporter

The dopamine transporter (or dopamine active transporter, SLC6A3 or DAT) is a protein membrane that secretes dopamine from the synaptic cleft, back to the cytosol. Whilst in the cytosol, other transporters separate the neurotransmitter into vesicles to be stored and released later.

DAT is responsible for dopamine reuptake, via which the chemical is removed from the synapses. However, some psychoactive drugs prevent the transporter from draining the synapses, thus causing dopamine to be present for a longer period and continue producing pleasurable sensations.

Addiction and Glutamate

Glutamate was recently identified as a key player in addictive behaviour. Glutamate is a neurotransmitter that is responsible for regulating the release of dopamine into the nucleus accumbens.

It’s vital to note that glutamate works with another neurotransmitter – acetylcholine – to inhibit upregulation of the system and the onset of addiction. Unfortunately, some addictive drugs work by inhibiting glutamate production, thereby creating an imbalance of dopamine levels.

Without glutamate to inhibit dopamine secretion, its (dopamine) levels increase and spur addictive behaviour.

Addiction is triggered by neurons transmitting signals of motivation (to continue using the psychoactive chemical). As long as dopamine levels are high, these neurons will continue to influence drug use behaviour from the brain.

The Brain’s Reward Pathway

Earlier, we discussed the four parts of the brain responsible for addiction; the cerebral cortex, the amygdala, the hippocampus and the nucleus accumbens. These each constitute the pleasure pathway – a series of communication channels driven by pleasure chemicals that result in a neurochemical reward.

Addictive substances create a shortcut to the brain’s reward system via this pathway. They flood the nucleus accumbens with dopamine, creating a short-term feeling of euphoria. The hippocampus registers the pleasurable memory, while the amygdala forms a conditioned response to the stimuli (smoking, pill swallowing or injecting).

How the Brain Views Addiction vs. Abuse

Addiction is a physical dependence on a substance. The brain views this as being critical to its functions, whereas abuse is the behaviour that leads to this dependence. Subsequently, during the abuse stage, the brain’s chemical functions are yet to be completely re-tuned and therefore consider the substance an important component of your body to function.

However, as you keep abusing this substance, full addiction will develop. This is why it’s vital that you seek help as soon as you notice any addictive behaviour in yourself or a loved one.

Resetting the Addicted Brain

An addicted brain is often different in structure and function than a healthy one. Resetting it requires special treatment that starts with detoxification and mental rehabilitation. Before the brain can heal, the body must be purged of all remnants of the addictive substance.

During rehabilitation therapy, a counsellor attempts to uncover the origin of the addiction. After that, a reconciliation and reorientation of the mind towards drug independence is undertaken. This may involve training for positive thinking or motivational behaviour that replaces the need for drug use.

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