Physical Dependence

Physical dependence is a pharmacological condition, characterised by ‘needing’ to continue with drug use when the body or mind has become used to it. Physical dependence can be a result of following a recommended, low-dose therapeutic use of medication, such as opioids, antidepressants, benzodiazepines, and antiepileptic, as well as the recreational abuse of drugs such as opioids, benzodiazepines, and alcohol.

The higher the dosage level, the longer the use, and the earlier age a person begins to use, the greater the likelihood of physical dependency, and, consequently, withdrawal syndrome.

Symptoms of Physical Dependence

Physical dependence develops with both physical and psychological symptoms, and is a result of physiological adaptation in the brain, and the central nervous system due to chronic use of a substance. Symptoms of physical dependence can be divided into two categories:

Acute withdrawalsyndrome – This lasts for a relatively short period of time, possibly days, weeks, or, at most, months.

Protracted withdrawal syndrome – This is also known as PAWS (Post-Acute-Withdrawal Syndrome). It is a low-level continuation of some of the symptoms of acute withdrawal, and can last for months, years, or even indefinitely. Protracted withdrawal syndrome is most often caused by benzodiazepines.

Symptoms that may occur during the reduction or withdrawal from a substance include increased blood pressure and heart rate, tremors, and sweating. More severe symptoms include confusion, visual hallucinations, and seizures, in which case it is necessary to seek immediate medical care. Hypnotic drugs, such as barbiturates, benzodiazepines, and alcohol can be fatal during withdrawal, due to their propensity to induce withdrawal convulsions.

Sudden withdrawal from drugs, such as opioids, can often result in painful symptoms. For patients with general good health, and appropriate medical treatment, the risk is far lower, but in patients with weakened cardiovascular systems, there is a high risk of fatality.

Treatment for Physical Dependence

The treatment for physical dependence depends on the drug being withdrawn from. Most of the time, it involves the administration of another drug, especially one for substances that can be extremely dangerous when suddenly stopped, or when previous treatment attempts have failed. Physical dependence is usually managed by a gradual reduction in dose over an extended period of weeks, months, or sometimes longer, depending on the individual, dosage level, and drug. A physical dependence on alcohol, for instance, is often managed with a cross tolerant drug, such as benzodiazepines, to manage the withdrawal symptoms.

Opioids such as heroin, morphine, codeine, oxycodone, methadone, fentanyl, nalbuphine, and buprenorphine can all cause dependence

GABA agonists and positive allosteric modulators of both the GABA-A ionotropic receptor, and GABA-B metabotropic receptor subunits, including alcohol, barbiturates such as phenobarbital, sodium thiopental, and secobarbital are also capable of this.

There’s also benzodiazepines such as diazepam (Valium), lorazepam (Ativan), alprazolam (Xanax), and non benzodiazepines hypnotics, such as zopiclone and zolpidem.

Gamma-hydroxybutyric acid (GHB) carisoprodol and related carbamates (tybamate and meprobamate), baclofen (Lioresal) and its non-chlorinated analogue phenibut, chloral hydrate, glutethimide, clomethiazole, methaqualone, nicotine (tobacco) gabapentin (Neurontin), and pregabalin (Lyrica), as well as calcium channel modifiers that affect GABA

• Antiepileptic drugs such as valproate, lamotrigine,  tiagabine, vigabatrin, carbamazepine, oxcarbazepine, and topiramate.
• Antipsychotic drugs such as clozapine, risperidone, olanzapine, haloperidol, thioridazine, etc.
• Commonly-prescribed antidepressants such as the selective serotonin reuptake inhibitors (SSRIs), and serotonin-norepinephrine reuptake inhibitors (SNRIs)
• Blood pressure medications, including beta blockers such as propranolol and alpha-adrenergic agonists such as clonidine.

Physical Dependence and Addiction

There is a lot of confusion between the meaning of addiction and physical dependence. Are they the same? What are the differences?

The Reason for Confusion

The main reason for confusion is that there is a connection between the two concepts. Another reason for the confusion is the way they are usually used. Physical dependence is sometimes simply referred to as dependence, but this can lead to confusion because addiction is sometimes called dependence as well.

So, how do they differ, and how are they connected?

First, consider the connection.

In some substances, physical dependence can lead to addiction. Consider opioids as an example. Even when used as directed, opioids can cause physical dependence. This can also be the case for a lot of other medications that the body and brain can adjust themselves to, and come to depend on, in order to function properly. However, if misused, by using for longer than prescribed, for non-medical purposes, or taking a larger amount than prescribed, opioids can lead to addiction. So, failure to check physical dependence, and leaving it to grow uncontrolled, will result in addiction.

Now, consider the differences.

Physical dependence is different from addiction. Physical dependence occurs as a result of the brain’s adaptation to the effects of a drug, and therefore, tolerance develops as a result. To put it in different words, an individual will need to up their drug intake to achieve the initial positive effects, and will rely on continued usage of the drug to avoid painful, and uncomfortable, withdrawal symptoms. On the other hand, an addicted individual no longer takes a drug just to feel its effects, but takes it to escape withdrawal, and simply feel closer to normal. Addiction affects the parts of the brain responsible for decision-making and self-control, so a person suffering from addiction will continue to use the drug, despite the serious life consequences, such as losing their job, getting arrested, or suffering an overdose.

compulsive drug use, an inability to control drug use, and continuing to use despite doing harm to oneself or others. Uncontrollable cravings prompt the destructive behaviours associated with addiction. There is no addiction without cravings. Indeed, strong cravings are possibly the main feature of addiction, and are a result of altered brain biology. Addiction is a disease that alters, rather than maintains, normal function.

An addicted person has become dependent on a particular substance, but a person with physical dependence is not the same as an addict.

Another notable difference is the mode of treatment.

Consider the case of opioids, for example. Normally, the body is able to produce enough endogenous opioids, such as endorphins, to prevent withdrawal symptoms. However, as tolerance increases, eventually the body’s ability to maintain this equilibrium is exceeded, and the body becomes dependent on that external source. A physical dependence to opioids means that the body relies on the external source of opioids to prevent itself from experiencing withdrawal symptoms and pain. A person who is physically dependent on prescribed opioid medications, such as OxyContin or Vicodin, but is not addicted, will not experience a loss of control, strong cravings, compulsive drug use, a failure to meet work, social, or family obligations, or other negative symptoms that characterise addiction. This physical dependence is predictable, can be easily managed with medication, and is ultimately resolved with a slow taper off of the opioid. However, curing addition to a substance, opioids in this case, is much more difficult. As stated earlier, the brain has been altered, so the treatment process involves reversing, to the extent possible, these brain changes. This is accomplished through therapy and replacing the addictive behaviours with healthy alternative behaviours.

One study puts the difference between physical dependence and addiction succinctly when it compared it to insulin intake for diabetics. Diabetics are dependent on insulin, but they are not addicted to it.