Effects of Addiction on the Brain

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Academic Assignment Muhadh Ismath

THE EFFECTS OF ADDICTION ON THE BRAIN

The human brain; the maker of all we see around us today. Our brain is by far the

most complex of all the other brains that the inhabitants of this world possess,

resulting in humans being on top of the food chain. ut simply, the brain is thatorgan that controls most of the body!s acti"ities. #owe"er, the spongy mass of

tissue that only weighs about three

pounds is said to be $the most complex

li"ing structure of the uni"erse%&'() it is

the organ that regulates e"ery action

within our body keeping us ali"e;

sending instructions to our white blood

cells to *ght o+ bacteria, making sure

we ha"e the perfect amount of pressure

in our blood, controlling changes in the

heart rate to facilitate the changes that

occur in our bodies.

Opening up the Brain

The brain is laid out into distincti"e parts, the largest being the cerebrum, whichis made up of two cerebral hemispheres. This contains the most important

motor, sensory and association areas of the brain &(. The main part of the brain

that we will be di"erting our focus on is the limbic system or also commonly

recogni-ed as the reward system. This is what is known as the mesolimbic

pathway which starts at the "entral tegmental area &TA( of the midbrain and

connects all the way to the nucleus accumbens. This is the system where

addiction of any sort operates, and is said to be an ancient part of the brain,

predating the structures in"ol"ed in memory&/(, due to this the nearly all types of

acti"ities that occur in this area $takes place unconsciously% &0(. The brain

processes information by using specialised cells called neurons, which has the

ability to transmit electrical messages. #ence these are fundamental cells that

make up the brain as they particularly specialise in the wiring of it; and also form

the reward pathway. 1eurons are made out of cell body along with ner"e *bres

that are known as axons and dendrites which carry the "ital ner"ous impulses &(.

As a result, neurons play a "ital role in how one feels and react to certain stimuli,

2igure '3 Image illustrating the main

parts of the brain. &'4(


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including addiction. Through this essay, we will be focusing on how addiction

actually a+ects our brains and what result it brings.

Introduction to Addiction

Addiction; commonly associated with drugs but in reality it is related to many

di+erent acti"ities for di+erent people. It can occur in the form of excessi"e

abuse of drugs, including cocaine, heroin, or nicotine5 or as compulsi"e gambling

or o"ereating&6(. In any case it is a chronically relapsing disorder that can be

branded as the uncontrollable urge to seek and ful*l an action, resulting in the

loss of control in one!s own actions, without which a person starts to face

withdrawal symptoms. This can occasionally result in putting one through a

negati"e emotional state. It starts of as a trigger that sparks the temptation to

practice a habit. Then thoughts start to become temptations which e"entually

turn into cra"ings. Once an addict starts to cra"e, it would be extremely di7cult

not to carry out the action, once done the feelings of regret and pain o"erwhelm

the person; this "icious cycle then feels impossible to exit. Addiction is normally

achie"ed through repeated use of the drug, which brings momentary pleasure;

the pleasure is due to changes in the brain chemistry. Once this action is carried

out more fre8uently, the drug starts to cause changes in the synaptic pathways

due to enhanced use of certain neurons. The more these pathways get used, the

stronger they become. 9hat is common on all forms of addiction is the acti"ation

of the brains reward pathway, howe"er the mechanics that happen in the brain

are much more complicated and so we will try to assess them as much as

possible.

The Relationship between Our Actions and Our Brains

2or centuries it has been belie"ed by scientists that the brain stops de"eloping

by the age of around se"en&:(, although recent studies suggest that this is due to

what is known as neuroplasticity. The de*nition of neuroplasticity is simply gi"en

as $the capacity of the ner"ous system to de"elop new neuronal connections%5

the idea that the human brain is a highly dynamic system that is able to

reorganise and reshape itself throughout the entirety of our life &4(. This shows us

that addiction won!t ust ha"e chemical e+ect on the brain but rather it has the


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capability of physically changing the make5up of it. This research that has been

undertaken for the past couple of decades, ha"e made it "ery apparent to us

that addiction is based on pathological changes in brain function produced by

repeated pharmacological insult to the brain circuits, which then regulates how a

person responds and interprets stimuli&(.As there is an

increase in the same e"ents

occurring within the brain,

causing neurons to continually

*re, the e"ents become

associated with one another, and

the neuronal connections &wiring(

gets stronger. 1ow that we know

that the brain changes throughout our life, what outcome does addiction lea"e inour brain?

As we ha"e discussed before, the reward system in the brain gi"es us pleasure

when we carry out our natural needs for example eating, drinking and sexual

relations. After we drink we feel good, in other words the action of drinking at

times of thirst is pleasurable and memorable which causes us to drink whene"er

we feel thirsty. This applies for many other crucial things we need for our

sur"i"al. The system has many functions, including monitoring internal

homeostasis, learning, and memory. As well as this it also dri"es important

aspects of sexual beha"iour, feeding beha"iour and moti"ation&''(. A reward or

something linked with a reward acti"ates cells in the "entral tegmental area in

the midbrain which sends a chain reaction of acti"ation in the reward circuit that

reaches the nucleus accumbens. The way in which neurons communicate with

each other in an acti"ated neural circuit is that an impulse will be coming down

an axon branch; the impulse will then turn into a chemical called a

neurotransmitter at the synaptic knob &the end of an axon( which will be releasedinto a space in between two neurons &synaptic cleft( &(.The neurotransmitter then

2igure 3 annotated diagram showing how

neurons communicate &'


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binds onto a receptor on the following

neuron and then the impulse and so

thereby transmitting that information. As

discussed pre"iously the maor

neurotransmitter in the reward pathway of

the brain is dopamine &2igure (; which

mediates both rewards and moti"ation.

Therefore drugs and acti"ities that

increase the synaptic acti"ity in the

dopamine pathways also then increase

self5stimulation rates, in other words this

stimulation of dopamine is what causes us

to feel the pleasurable feelings or rewarding e+ects. The dopamine binds to

receptors &called dopamine receptors( and then is taken up by uptake pumps and

pre"ents them from transporting dopamine back into the neuron terminal&'(.

Most drugs increase the amount of dopamine that is released in these pathways;

this is done by them exiting the dopamine producing neurons in the TA which

results in increased extracellular dopamine concentrations throughout the limbic

system&'/(. @rugs such as cocaine act by blocking the reuptake of dopamine;

which then causes the e+ect of pleasure to last for a longer amount of time. Thisenhanced period of time where pleasure is felt is the causal of the feeling of

euphoria that is reported by cocaine abusers &'0(. Other drugs also work similarly

to cocaine5 by blocking the reuptake; causing a feeling of immense pleasure o"er

a long period of time. @rugs such as crystal meth ha"e an e"en greater e+ect5 as

well as blocking the re5uptake the drug also has the ability to trigger the rapid

release of more dopamine. As a result of mass amounts of dopamine being

trapped in the synapse for a long period of time, the neuron it is attached to is

acti"ated to "ery high le"els. This causes the brain to produce the euphoric

$rush% or $ash% that users experience&':(. The repeated usage of these drugs

then change the wiring of the brain, and so a person!s emotions, decision

making, and memory are all e+ected and changed. As a result of these changes,

an addict that has become a chronic user stops feeling the same pleasure as

when they *rst carried out their addictions, and anything other than their

addiction does not ful*l the pleasure they seek. #ence, a higher dosage of the

drug is re8uired, a+ecting the wiring of the brain further by physically and

chemically changing it.

2igure /3 Image showing the limbic

system of the brain&'>(.


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Conclusion

As the brain changes throughout our entire life, what actions we do, and the

decisions we make play a fundamental role in both our emotional state and

character. Addiction is shown as something that a+ects the entire brain;changing the natural neural pathways, and e+ecting concentrations of

neurotransmitters in certain systems. The addict *rst damages the reward

pathway in their brain, which is made up of many important parts, two of which

consist of the hypothalamus and the amygdala &2igure /(. These essential areas

are responsible for memory, emotional beha"iour and moti"ation. Thus changes

in this particular place can lead to serious conse8uences, in which the *nal

outcome resulting in the rewiring of one!s brain.

Reerences

'5 Bociety for neuroscience &CC( DErain 2acts3 A primer on the brain and

ner"ous system! Everbest Printing Company p05 Btocley, F. Oxlade, F. and 9ertheim, G. &CC'( DThe HBborne illustrated

dictionary of science3 a complete reference guide to physics, chemistry

and biology USborne Booksp/C5/C:

/5 @obbs, @. &CC4(. DA @epression Bwitch?New York Times.05 Elakeslee, B. &CC(. D#iacking the Erain Fircuits with a 1ickel Blot

Machine! New York Times.:5 2ullick, A. &CC6(. DA Eiology3 Btudents Eook! Pearson Edexcep>45 2ernande-, A. &CC6(. DThe Bharp Erains uide to Erain 2itness!nded.

S!arpBrains "ncorporatedp45>(

D1europlasticity in the mesolimbic dopamine system and cocaine

addiction! ':0&( ed. Britis! %o#rna o& P!armacoogy p/( Drinciples of Addiction Medicine! +merican

Society o& +ddiction 'edicine


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'51ational institute on drug abuse &CC

Documents

Effects of Addiction on the Brain