Don't worry about the difference between dependence and addiction. It's for academics to worry about1 2. For our purposes we're talking about the same thing: losing control of when you start drinking, and losing control of stopping drinking once you've started.
You can be a dependent drinker without drinking every day. We can think about two broad types of drinker here - the every day drinker, and the binge drinker.
Daily drinkers will usually have a similar drinking pattern every day. Your tolerance to alcohol is raised - you may not even get drunk any more, but just need drink to feel normal. You may experience withdrawal symptoms when you stop drinking: most commonly shaking, sweating and retching. Read more about this 'physical dependence' below.
A lot of dependent drinkers have been drinking all day, or most of the day, for years. Others can manage without a drink in the day but drink heavily from late afternoon or evening. Other people may have days or weeks without a drink, but when they do drink it tends to be in 'binges'. They may well suffer days of awful withdrawal after each binge.
However, if you're relying on drink, and you have uncontrollable urges to drink, then whether you get withdrawal symptoms or not you're addicted, or dependent.
Alcohol dependence is primarily a psychological phenomena. It's when you can't manage to control your cravings for drink. The most important work you'll need to do to live a life without alcohol is to manage and change how you think, how you feel, and how you respond to what's going on both inside you and around you.
This is a useful checklist of the different psychological facets of dependence3:
What makes things tricky, though, is that there are powerful biological processes at work alongside the psychological ones - and they'll need to be addressed if they've developed enough strength.
Physical dependence is a consequence of repeated heavy drinking. If your central nervous system gets accustomed to the constant presence of alcohol, it learns to work harder to counteract the depressant effects of drink. As a very rough guide, this takes about 2 years of drinking 10-15 units or more a day - although this varies from individual to individual. Heavy binge drinkers can develop these withdrawal symptoms with regular drinking bouts.
Once the alcohol isn't there - for example, first thing in the morning, or if you try to stop drinking - your central nervous system is still working too hard. Without anything to push against, you get all sorts of symptoms related to this over-stimulation. These include:
There's also a chance of having a seizure (an epileptic fit), or Delirium Tremens - the infamous 'DTs’ or ‘the horrors’. The symptoms are confusion, disorientation, agitation, fever, racing heart rate and hallucinations.
Withdrawal seizures & Delirium Tremens are serious and possibly life threatening.
Detoxification is a way of managing these symptoms medically, so that it's safe to stop drinking.
1 “Dependence is not implicitly problematic. Dependence which becomes troublesome and conflicted we call addiction. Addiction is a state of conflict where powerful and immediate rewards from the drug of choice drive continued drug use, despite the obvious disadvantages of this behaviour” Tober, G. (1992) What is dependence and why is it important?, Clinical Psychology Forum, 41, pp 14-16.
3 Adapted slightly from Raistrick, R., Bradshaw, J., Tober, G., Weiner, J., Allison, J. & Healy, C (1994) Development of the Leeds Dependence Questionairre (LDQ): a questionairre to measure alcohol and opiate dependence in the context of a treatment evaluation package Addiction 98, 563-572