First of all, one has to have an understanding of the difference between dependance and addiction. The former is a state which arrises as a product of the properties of biologically active agents with each individual's agent specific, receptor regulatory properties. I am excluding the fact that people can be considered dependent upon certain agents to maintain life such as insulin.
An example is a patient hospitalized for trauma. The patient is placed on 30 mg of morphine given sub qutaneously evey 3 to 4 hours. It is inevitable that over the course of a number of days which the amount being person specific, that the patient will require a higher dose to alleviate pain. Back in the 60s, Candice Pert identified the opiode receptor. This recepotor is stimulated by endogenous endorphines. Morphine mimics endorphines and is far more potent. As a result of continued stimulation, the receptor is down regulated....thus more morpine is required.
The paint recovers and it is time to stop the morphine. All, patients if given morphine long enouigh will experience what I call pharmacological adaptation which I beleive is a more precise descriptin that dependence. As a result if the morphine is discontinued abruptly, all patients will experience withdrawal symptoms. With opiods there is a characteristic pattern....the details are not important. Suffice it to say, it is very uncomfortable. It can be minimized by weening and today, an agent for which I conducted research is available which is very helpful because it is mixed agonist-antagonist opiode, buprenorphine. It has a very high affinity for the mu receptor and when serum levels fall, some remains attached to the receptor smoothing symptoms. It was approved by the FDA I think in 1993.
After the Vietnam war, the Robins study was the first to shed light on the difference between addiction and dependence. When it was reported that 15 percent of vets were addicted to heroin, a study was conducted in which they were forced to dry out in Vietnam before returning. After one year, only 5% relapsed.
The long and short of it is that 85% of patients who are opiod naive, once haviing been exposed then detoxed in hospital, will never ever have the desire to take opiates again. That means that about 15% of these patients will have
the recurring desire to use narcotics despite the fact that they know it will cause life unmanageabilty. Furthermore, they are not taking it to treat pain. This recurring desire coupled with life unmanageability, is the sina quo non of addiction. A better definiton preposed by a collegue is that an addict cannot use mood altering drugs safely. He called this an illness. MAD disease. Personally, I have seen people who have one drink a day...yet they are alcoholic for the simple reason that it changes their mood. I am not talking about the predictable effects...their mood becomes disphoric, angry...Such people are alcoholic.
While a locus in our DNA has been found for alcoholism sesepibility, there is not test for who will become an addict after using opiods.
Opiods are an example. Many other agents can do this. Lyrica, benzodiazapines....even SSRIs.
Additionally, indiviual response cannot be predicted. The very first patient for whom I prescribed Prozac called me after a week and told me he could not get out of bed. He became very, very weak. Since then I only saw this a few times. It happens. People can have withdrawal symptoms from abrupt cessation of SSRIs.
Yes, people do have problems with abruptly stopping caffeine intake.
I would not consider people who cannot start the day without coffee addicts. Perhaps dependence...but not addiction. I have seen people who are addicted to collecting things, you name it. This sort of thing is mediated through the limbic/pleasure system. Certain behaviors stimulate endorphines. Generally or perhaps hopefully life unmanageability is not attendant with them.
What was funnty was that Dr. Dean was writing a book about GHB which we were prescribing for sleep back in the 90s. He asked me to write a Forward to it which I did. I warned him that I thought it had the potential to be addictive in the 15 to 20 percent that were suseptable. He did not think so. Unfortunately, it can be. That said, addicts can be addicted to anyting. That does not mean docs should live in fear of opiates and such. They just need to understand dependence and the difference with addiction understanding the risks and use them when they are called for. Nootropics are not known to be addictive. At least I have not run into it.