Lets consider this - A young girl spins round and round in circles and falls down giddy and sick on the floor. A moment later she jumps up and continues to spin happily. Similarly, a boy gets very nervous and awkward while asking a girl out on a first date. Nonetheless, he then immediately rushes home excitedly to tell his friends that the girl accepted.
If you have noticed these two examples, you would have understood that both these involve people doing a particular activity in a particular way and then immediately there is a change in both mood and feeling - the girl was first happy and then giddily sick; the boy, anxious at first but ecstatic later. Both these mood alterations took place in a matter of a few seconds. THIS is what drugs do to you.
Biologically, our body is conditioned to maintain homeostasis or "balance" at all times. When there is an imbalance in our chemical proportions, we get sick. Legal drugs like stimulants, depressants etc., work by either stimulating or depressing natural brain chemicals called neurotransmitters. Neurotransmitters are naturally occurring brain chemicals that are necessary in transmitting the nerve messages in the nervous system. They are responsible for the normal activity of the brain like emotions, feelings, thinking, perception and behaviour. When some foreign substance messes up their natural balance, they mess us up.
Drugs are responsible for affecting these neurotransmitters and hus have an effect on our emotonal and physical balance.
Types of drugs most commonly used are psychoactive drugs. Psychoactive drugs are chemicals, medicines which can rapid affect on peoples mood, emotions, and thinking. For example, changes in mood include stimulation, sedation and euphoria. Behaviourial changes include acceleration or retardation of movement. Changes in thinking include speeding up or slowing down of thinking processes as well as hallucinations, delusions, illusions.
Some medications like antidepressants are able to change people's mood over days. They are not considered psychoactive because they do not cause euphoric swings. These are therefore termed as mood regulators.
Thus we can see that seeing the effects that drugs have on the neurotransmitters, they can be classified and dealt with. this makes the study of drugs easier.
