3-16 Substance Abuse

Front 1

Objective

Discuss the effects of addictive drugs on the nucleus accumbens.

Back 1

As people become addicted to something, it dominates their attention, and the nucleus accumbens responds more strongly to it. That is, the nucleus accumbens become sensitized. Repeated use of cocaine increases the ability the drug to trigger dopamine release in the nucleus accumbens, as well as its ability to activate part of the right prefrontal cortex and to increase the individual’s tendency to seek the drug. According to one hypothesis, the prefrontal cortex ordinarily sends stimulatory input to the nucleus accumbens to support any potentially reinforcing activity. However, repeated drug use increases the background inhibition in the prefrontal cortex, so that only the strongest stimuli (i.e. the addictive substances) can get through. Everything else is filtered out.

Front 2

Objective

Describe the effects of alcohol on the brain.

Back 2

Alcohol inhibits the flow of sodium across cell membrane, expands the surface of membranes, decreases serotonin activity, facilitates response by the GABA receptor, blocks glutamate receptors, and increases dopamine activity.

Front 3

Objective

Compare Type I and Type II alcoholism.

Back 3

See study guide.

Front 4

Objective

Cite evidence that Type II alcoholism is genetic.

Back 4

Evidence for a genetic basis of Type II alcoholism includes the findings that:

1. Monozygotic twins have greater concordance for alcohol abuse than do dizygotic twins.
2. Biological children of alcoholics have an increased risk of alcoholism, even if they are adopted by non-alcoholics.

Front 5

Objective

Explain how Antabuse affects alcohol metabolism.

Back 5

After someone drinks ethyl alcohol, enzymes in the liver metabolize it to acetaldehyde, a poisonous substance. An enzyme called acetaldehyde dehydrogenase then converts acetaldehyde to acetic acid—a substance that the body can use as a source of energy.

Ethyl Alcohol → Acetaldehyde → Acetic Acid

People with a weaker gene for acetyldehyde dehydrogenase metabolize acetaldehyde more slowly. If they drink much alcohol, they accumulate acetaldehyde, which can produce unpleasant symptoms such as flushing of the face, increased heart rate, nausea, and headache. The drug Antabuse produces similar effects by blocking the action of acetaldehyde dehydrogenase.

Most studies find that Antabuse is only moderately effective. When it works, it supplements the alcoholic’s own commitment to stop drinking. By taking a daily pill and imagining the illness that could follow a drink of alcohol, the person reaffirms a decision to abstain. In that case, it does not matter whether the pill really contains Antabuse or not; someone who never drinks will not experience the threatened illness. Those who drink in spite of taking the pill become ill, but unfortunately, they are as likely to quit taking the pill as to quit drinking alcohol. Antabuse treatment is more effective if friends make sure the person takes the pill daily.

Front 6

Objective

Discuss the advantages of methadone over heroin.

Back 6

Methadone treatment for heroin addiction is based on the idea that if people cannot quit using opiates altogether, perhaps they can switch to a less harmful drug. Methadone is similar to heroin and morphine but has the advantage that it can be taken in pill form (if heroin or morphine is taken as a pill, stomach acids break down most of it). Methadone in pill form enters the bloodstream and the brain more gradually, and so its effects rise slowly, avoiding the “rush” experience associated with heroin use. Because it is metabolized slowly, methadone produces milder withdrawal symptoms than heroin. Furthermore, the user avoids the risk of an injection with an infected needle. People using methadone live longer and healthier, on average, than heroin or morphine users, and they are far more likely to hold a job. However, methadone does not end the addiction. Anyone who quits methadone will most likely experience cravings.

Front 7

Objective

Explain why naloxone is added to methadone.

Back 7

Physicians combine methadone with a small amount of the drug naloxone, which blocks its effects. If someone takes a combination of methadone and naloxone as a pill, the stomach acids break down most of the naloxone, leaving the effectiveness of methadone intact. However, if someone dissolves the pill and injects it, the stomach has no opportunity to break down the naloxone, which neutralizes the effects of the methadone.

Front 8

substance abuse

Back 8

Maladaptive pattern of substance use leading to clinically significant impairment or distress

Front 9

self-stimulation of the brain

Back 9

Behavior that is reinforced by direct electrical stimulation of a brain area

Front 10

alcohol dependence

Back 10

The inability to quit drinking or to limit intake of alcohol in spite of strong intentions to do so

Front 11

acetaldehyde

Back 11

Toxic substance produced by the metabolism of alcohol

Front 12

acetic acid

Back 12

Chemical substance that the body uses as a source of energy

Front 13

Antabuse

Back 13

A drug that helps people break an alcohol habit by impairing their ability to convert acetaldehyde to acetic acid