intended. Drug abuse may lead tophysical dependenceon the drug. This occurs when
drug abusers need a drug to feel well physically. If they stop using the drug, they may
experience symptoms like vomiting, diarrhea, or depression. This is calledwithdrawal.
Drug abuse may also lead topsychological dependence. This occurs when drug abusers
need a drug to feel well emotionally and mentally.
For some drug abusers, a drug takes over their life. Their thoughts and activities revolve
around getting and using the drug. No matter what the consequences, they keep using the
drug. Even if they want to stop using the drug, they can’t. When drug abuse reaches this
state, it’s calleddrug addiction. Alcohol, nicotine, and cocaine are all highly addictive
drugs.
People that are addicted to a drug may need to take more of the drug to feel the same effects
as when they first started using the drug. This is calledtolerance. People that develop
tolerance are at risk of adrug overdose. A drug overdose occurs when someone takes so
much of a drug that it causes serious illness or death.
Keeping the Nervous System Healthy
There are many choices you can make to keep your nervous system healthy. One obvious
choice is to avoid using alcohol or other drugs. Not only will you avoid the injury that drugs
themselves can cause. You will also be less likely to get involved in other risky behaviors
that could harm your nervous system.
Another way to keep the nervous system healthy is to eat a variety of healthy foods. The
mineralscalciumandpotassiumandvitaminsB 1 andB 12 areimportantforahealthynervous
system. Some foods that are good sources for these minerals and vitamins are shownFigure
20.39.
Figure 20.39: These foods are sources of nutrients needed for a healthy nervous system. ( 22 )
Daily physical activity is also important for nervous system health. Regular exercise makes
your heart more efficient at pumping blood to your brain. As a result, your brain gets more