Nervous System and drug addiction

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Based on Time, May 5, 1997

Slide 22

Cocaine blocks the normal absorption of dopamine. As a result, dopamine accumulates in the synapse, where is stimulates the receiver cell.

Amphetamines stimulate excess release of dopamine, overwhelming the processes of reuptake and enzyme breakdown.

Nicotine stimulates the release of dopamine, while another substance in cigarette smoke blocks the action of MAO.

How Drug Affect Dopamine Levels

Based on Time, May 5, 1997

Slide 23

Physiology of Addiction

Drug enhances amount of dopamine in the synapses

Increased dopamine results in increased feelings of pleasure

Nervous system responds by reducing the number of dopamine receptor sites

Addict must take more drug to produce the same “high”

“So while addicts begin by taking drugs to feel high, they end up taking them in order not to feel low.”

Slide 24

Withdrawal

Physiological response to lack of drug effects, especially the drug’s substitution for naturally produced neurotransmitter

Withdrawal effects can be intense at first, especially if the drug addict quits abruptly

Eventually the body’s physiology returns to normal, and the person will stop craving the drug

Slide 25

Treatment for Heroin Addicts

Heroin addicts are put on methadone to wean them off of heroin

Methadone replaces the heroin without giving the “rush”

If the addict tries to take heroin, the methadone blocks the euphoric effects of it

Eventually the addict’s neurotransmitter production returns to normal if they can avoid taking heroin

Slide 26

So how has the scientific view of the cause of drug addiction and treatment changed?

Slide 27

Changing View of Drug Addiction

Drug addiction has been viewed as a failure of character and combated with criminal laws and imprisonment

Now some scientists feel drug addiction may be a disorder of the brain no different from other forms of mental illness

May be caused by deficiency in neurotransmitters

May be genetically based