Recreational Drugs and The Brain

What is a recreational drug?

Substances that alter brain function; changing mood, perception and conscious experiences. They are taken for enjoyment rather than medical reasons. They also alter the levels of neurotransmitters in the synapses between neurons in the brain.

What is meant by an ‘agonist’ drug?

An agonist is a drug that binds to receptors and activates them. E.g. heroin

What is meant by an ‘antagonist’ drug?

An antagonist drug binds and blocks receptors. E.g. cocaine

How does COCAINE work?

• It increases the amount of dopamine released

• It is an antagonist so it binds to and blocks dopamine uptake pumps leaving the synapse flooded with dopamine

• This causes a euphoric high feeling

How does PCP work?

• Is an antagonist so it binds to and blocks glutamate receptors leading to reduced neuronal activity.

• Inhibits glutamate’s excitatory activity so messages are not continued causing memory loss, anaesthesia and reduced pain.

• It also reduces the inhibiton of dopamine causing hallucinations

How does HEROIN work?

• Is an agonist so it binds to and activates opioid receptors

• This triggers the release of endorphins and hyper-polarises the post-synaptic neuron

• This causes the pain signals to not trigger the pain receptors

What are the long term effects of COCAINE?

Dopamine receptors become downregulated so fewer are active. The rest are damaged by the cocaine and the amount of dopamine released declines. This explains withdrawal, cravings for the drug and a higher dosage needed to have the same effects (tolerance).

What are the long term effects of PCP?

A tolerance for PCP is developed as Glutamate receptors become down regulated. This means higher doses of PCP are needed to have the same effect or withdrawal symptoms like pain will be experienced.

What are the long term effects of HEROIN?

Opiod receptors become down regulated so fewer opiod receptors are active and the rest are damaged so less endorphins are released. Users will now be able to experience physical pain making them crave heroin.

A strength of drugs affecting the brain.

(AO3)

I: There is supportive evidence that drugs affect the brain from Olds & Milner who found a pleasure centre in the brain of rats.

J: Rats would press a lever to receive an electric shock and when the shock was targeted at their NAC, they pressed the lever up to 2000 times in one hour. This shows that stimulants e.g. drugs or shocks can cause pleasure.

E: Subsequent research found that dopamine aids neural signalling in these regions (reward pathways), and drugs like cocaine release dopamine suggesting drugs can affect the brain.

A weakness of the idea that drugs affect the brain

(AO3)

I: Drug treatments only tackle the neurobiology of drug addiction

J: If users don't want to quit they won’t take the final step so drug treatments work best when paired with cognitive therapy to get users to rethink their priorities.

E: Isolating a single neurotransmitter as the cause of addiction is an oversimplification as humans use drugs to socialize or cope with stress. Neurobiological approaches are reductionist as they ignore all other choices and motivations that lead to drug addictions.