There can be a great deal of confusion surrounding the words addiction, physical dependence, and tolerance. People will use these words as if they are referring to the exact thing, but there is a significant difference between them. Misunderstandings about these terms can not only be confusing for the general public but also many in the medical profession. One of the main culprits blamed for this confusion is the fact that the Diagnostic and Statistical Manual of Mental Disorders has chosen to use the word dependency instead of the word addiction and people assume this to mean physical dependency.
Tolerance refers to a physiological state where the effectiveness of a drug has decreased due to chronic administration. This means that more of the drug will be required to achieve the same effect in the future. One of the reasons for why this occurs is that any organism can build up a resistance against the effects of some drugs.
There are said to be two mechanisms involved in tolerance: pharmacokinetic tolerance and pharmacodynamic tolerance. With pharmacokinetic tolerance there is a decreased quantity of the substance reaching the target area. There are different reasons for why this can occur but a common example is that there has been an increase in enzymes that lead to degradation of the drug. Pharmacodynamic tolerance occurs because there is a decreased response to the drug by the cellular mechanism. A common way that this happens is that there has been a reduction in the number of receptors.
Some people will assume that increased tolerance means that over time those individuals who are regularly using a drug will need more of it to get the same effect. This is not necessarily the case. In the case of opiates there are four main effects to this drug – pain reduction, sedation, nausea, and constipation. Tolerance only really develops in relation to sedation and nausea – the effects of pain and constipation remain roughly the same for most people. This means that there is no often no need to increase the dosage of the medication over time because pain remains well controlled. The reason for why opiate abusers do need more of the drug to get the same effect is that they are chasing the euphoric effects – the brain develops a tolerance to this quickly.
Physical dependence refers to how the body experiences physiological adaptation in response to chronic use of a drug. Humans adapt so well to having these substances in their system that they suffer negative consequences if the drug is stopped abruptly – these are referred to as withdrawal symptoms. These withdrawal symptoms do not only occur with recreational drugs – they can also occur with other medications such as antidepressants. Those who develop a physical dependence will often usually develop tolerance to the drug as well. It differs from addiction because it is a physiological state and not a dysfunctional behavioral syndrome. It would be correct to say that most addicts will have developed a physical dependence on their drug.
Addiction can be defined as the compulsive use of drugs for non-medical reasons. The individual is likely to have developed physical as well as psychological dependence on the symptoms. This means that as well as feeling physically unwell when they stop the substance they will also feel psychologically unable to cope without the substance. In most instances the individual will have developed a tolerance to the euphoric effects of the drug so they will need to keep on taking more and more of it. Tolerance and physical dependence are physiological changes while addiction is a type of behavior.
As well as tolerance and physical and psychological dependence the symptoms of addiction can also include:
* The individual regularly uses more of the drug than they intended.
* They find it difficult to cut down on their intake of the drug.
* They become anxious when they are unsure about having access to the substance.
* They continue to use the drug even when it is obviously causing problems in their life.
* They feel the need to hide their substance abuse.
* The individual feels guilty about their substance abuse.
* They have lost interest in activities they once enjoyed.
* They have developed financial difficulties as a result of their drug intake.
* The substance abuse is starting to interfere with their ability to meet work, family, or social responsibilities.
* The individual engages in inappropriate behavior such as lying or acting secretively
Those individuals who have been prescribed opiate pain medication may worry about developing an addiction. This is an understandable concern give the amount of media attention given to the subject. So long as the individual is only using these drugs to treat their pain they are unlikely to develop an addiction. As already mentioned it is not usual for chronic use of opiate medication to lead to an increased tolerance to the pain relief affects of the medication. If the individual does need to have their dosage increased it will usually be because they are experiencing increased levels of pain. It needs to be noted that addiction is extremely rare in those people who are taking opiate medication purely for treatment of their pain.
Some individuals may be more at risk of abusing prescribed medications, such as opiates, than others. This will include people who:
* Have a personal history of substance abuse and addiction
* Have a history of addiction in their family – this means that the individual may be genetically predisposed to becoming an addict
* Those people who have grown up in a dysfunctional family where substance abuse is considered the norm.
* If people have experienced physical or mental trauma in their life they may be more at risk of abusing prescribed medications.