So - for some people, what began with casual drug abuse can develop into drug dependence. This can happen quickly - over a period of weeks, or slowly - over a period of many years.
You'll note that a person who abuses drugs occasionally doesn't intend to go on to become dependent on them. This is not a voluntary process. There seems to be a line somewhere in any individual's personality and drug use, that once the line is crossed it's too late - that person is very likely to be powerless to reduce or stop his or her drug intake by their own efforts.
We're not just talking about desperate heroin addicts or alcoholics on park benches here. There's a whole range of drug dependence and it can affect anyone. This could be:
Someone who needs a drink or drug to feel confident when they socialise with other people.
Someone who needs to take a drink or drug every day to avoid withdrawal symptoms.
Someone who needs to use drink or drugs to forget personal problems.
Someone who needs to take a drink or drug to cope with the stress of day-to-day living.
Anyone who feels they need to keep using a drink or drug in order to feel "better".
The compulsive drink is no different to the heroin injection. The intensity of desire may be very similar.