d. Additional Terms.
(1) Psychological dependence. This means that the drug has become so
central to the person's thoughts, emotions, and activities that he needs to continue
using amounts of the drug to satisfy a craving or compulsion for it. This dependence is
a mental or emotional adaptation to the effects of the drug. The abuser likes the way
the drug makes him feel, wants to re-experience those feelings, and actually believes
that he cannot function without the drug. The drug helps the abuser escape from
reality--from his problems and frustrations. The drug and its effects seem to provide the
answer to everything, including disenchantment and boredom. As long as he takes the
drug, all seems well. It is this psychological dependence which causes an abuser who
has been withdrawn from his physical dependence to return to drug abuse.
(2) Physical dependence. The body has adapted so thoroughly to the
presence of the drug that the user experiences withdrawal signs and symptoms if he
stops using the drug suddenly. With repeated use, many drugs cause physical
dependence. The body learns not only to live with the drug but also to tolerate and
require ever increasing doses of the drug. Withdrawal signs and symptoms vary with
the amount and kind of drug the abuser has used. Once the person's body adjusts to
being without the drug, withdrawal symptoms often disappear. In some cases, there are
permanent effects caused by the drug, and these effects do not disappear.
(3) Tolerance. This term refers to the fact that a person who uses some
drugs regularly finds that he must constantly increase the dose in order to get an effect
equal to that he experienced from the first dose. The body has adapted to the presence
of a foreign substance--the drug--and now requires more of the foreign substance for
unique feelings. Tolerance does not develop for all drugs or in all people, but those who
use drugs such as morphine find that tolerance builds up very quickly.
Tolerance does not develop for all the possible effects of a particular drug.
For example, tolerance develops for the euphoric-like effects (feeling of well-
being) of heroin but only slightly to the constricting effects on the pupil of the
eye. Complete tolerance to a drug's toxic (poisonous) effects may not
develop in a person. This makes it possible for a drug abuser to give himself
a fatal dose of the drug.
(4) Behavior changes. All substances which can be abused can cause
changes in a person's behavior, particularly when large amounts of the substance are
improperly used. After taking the substance or drug, the person may become
withdrawn and solitary or sociable and talkative. On the other hand, he may be easily
moved to tears or laughter. He may become very argumentative and believe that
someone is out to get him. Such changes in behavior may be harmless or a danger
both to the user and society. Much of the public concern about drug abuse comes from
the wide publicity given to changes in behavior that may accompany the use of drugs;
for example, LSD which has been particularly responsible for bizarre behavior.