Drugs and the Brain

How does the brain react to drugs?

Your brain is the most complex organ in your body, it is everything you do, see, touch, and smell, without it you would be nothing. It also regulates common functions like blinking and breathing.

The brain is often compared to a computer because of it’s complexity and intricacy but instead of electrical circuits on silicon chips, the brain has billions of cells, called neurons, that are designated into different networks and circuits. The neurons act as a switch that controls the information to send to the rest of your body.

Your brain is made up with many parts with circuits that work together as a team, different brain circuits perform different tasks. The networks send signals to each other and to different parts of the body such as your spinal cord and nerves (the peripheral nervous system).

For your brain to send these messages it releases a neurotransmitter into the gap (or synapse) between it and another cell. The neurotransmitter crosses the gap and attaches receptors on the receiving neuron, this causes the receiving cell to change. There are also transporter molecules that recycle neurotransmitters, this gets rid of the signal between neurons.
Drugs mess with how the neurons send and receive signals from the neurotransmitters. Drugs like marijuana and heroin mimic the chemical structure of a neurotransmitter therefore can activate neurons in the brain but, they dont activate the neurons in the same way which means they lead to strange messages being sent through the network.
Drugs like amphetamines or cocaine, cause the neurons to release large amounts of natural neurotransmitters that prevent the normal recycling of these chemicals because they interfere with transporter, it also disrupts the natural communication between neurons.

Our brains are wired to make us want to repeat pleasurable activities. The neurotransmitter dopamine is central to this. Pleasurable experiences activate the reward circuit and a burst of dopamine signals that something memorable is happening. The dopamine signal also causes changes in the neural connectivity which makes it easier to repeat, leading to the formation of habits.

Drugs produce much larger surges of dopamine, reinforcing the connection between consumption of the drug, the pleasure afterwards, and the external events linked to the experience. Large surges of dopamine make your brain seek drugs at the expense of other goals and activities.


Using drugs often enough can cause the brain to produce fewer neurotransmitters making it more difficult to have natural rewards in the brain. This is often why when people misuse drugs they begin to feel flat and lifeless over time. Not only that but, in order to get the rewarding feeling they must continue taking the drugs. It’s like a vicious cycle. Also, to get the same “high” they had before they have to take more of the drug which again only makes the problem worse.

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