Physiological dependence
Physiological dependence, also known as physical dependence, is a condition where the body adapts to the continuous presence of specific substances, leading to withdrawal symptoms when those substances are suddenly discontinued. This dependence can manifest through a drug-specific withdrawal syndrome, characterized by unpleasant symptoms that arise when the substance is removed or the dosage is significantly reduced. Common substances associated with physiological dependence include opiates like heroin and alcohol, both of which can produce notable withdrawal effects.
Physiological dependence encompasses both tolerance and withdrawal. Tolerance occurs when increasing doses of a drug are required to achieve the same effect, while withdrawal symptoms are often the opposite of the drug's effects. It's important to note that physiological dependence is intertwined with psychological elements of addiction; the two should be considered together for effective treatment. For instance, caffeine can induce physiological dependence with mild withdrawal symptoms like headaches, but it typically does not lead to the behavioral changes associated with addiction.
Treatment for physiological dependence often begins with managing withdrawal symptoms, which can vary in intensity. This can involve the use of substitute medications that share some effects with the original substance. However, challenges arise as these treatments themselves can lead to physiological dependence. Additionally, some individuals may experience prolonged symptoms known as post-acute withdrawal symptoms (PAWS), which can persist long after initial withdrawal, highlighting the complexity of dependence and the need for comprehensive care.
Physiological dependence
ALSO KNOWN AS: Physical dependence
DEFINITION: Physiological dependence refers to the adaptive changes made by the body to the continued presence of particular substances. These changes are observed when a person experiences a drug-specific withdrawal syndrome, which is a set of unpleasant symptoms experienced when the drug is abruptly discontinued. Drugs of abuse can vary in the extent to which they produce physiological and psychological dependence. However, physiological dependence is not independent of the emotional and psychological components of addiction. The physical and mental aspects of dependence should always be considered together, even if an individual presents primarily with a physiological component of dependence.
Background
Physiological dependence occurs when the body adapts to the continued presence of a drug. These adaptations lead to negative symptoms when the drug is removed or when the dose is dramatically reduced. As such, the presence of a drug-specific withdrawal syndrome, or a set of symptoms associated with drug removal, provides evidence for physiological dependence.
Many researchers use the term physiological dependence more broadly, though, and define it as including both tolerance and withdrawal. Tolerance refers to the need to increase the dosage of a drug in order to achieve the same effect across time and with repeated dosing. In other words, with more experience taking the drug, more of the drug must be taken to maintain the drug’s effectiveness.
Alcohol and opiate drugs, such as heroin, produce classic physiological dependence. For example, when a person takes an opiate drug, the initial effects include analgesia, euphoria, and constipation. If the person takes the drug only occasionally, the body may not adapt to the presence of the drug in significant ways; therefore, the same dose may be sufficient to produce the initial effects. However, if the drug is taken repeatedly, tolerance may develop in a matter of weeks or even days. The initial dose will no longer be as effective in reducing pain or in increasing euphoria and constipation. If one wants to maintain the initial effects, the dose will need to be increased and will continue to need to be increased as more and more tolerance develops.
The drugged state is the body’s new normal. One can observe how much the body has adapted to operating in the presence of a drug by observing the drug-specific withdrawal symptoms after the drug is removed (or stopped). In cases of physiological dependence, withdrawal symptoms are basically the opposite of the effects produced by the drugs themselves. These often-unpleasant symptoms can be easily eliminated with another dose of the drug. Though alcohol also produces tolerance and withdrawal, the specific symptoms will be quite different because the effects of the drug itself are different, requiring different adaptations.
Is Physiological Dependence Addiction?
Physiological dependence has been considered synonymous with the concept of addiction. Some researchers contend that there is no distinction between physiological and psychological dependence. However, others posit that physiological dependence more strongly characterizes addictions to drugs with strong physical withdrawal symptoms (such as opiates and alcohol, which can cause flu-like symptoms and seizures, respectively, during withdrawal) and that psychological dependence characterizes addictions to drugs that do not display strong physical withdrawal symptoms, such as marijuana or cocaine, although withdrawal from these substances can produce symptoms such as anxiety, sleep disturbances, fatigue, and depression. However, because modern research indicates that all behaviors have a physiological and psychological component and psychological processes have a physical component, a consideration of the whole person renders the most effective care plan. Physical and mental health are inextricably linked, not mutually exclusive components of a being.
The repeated abuse of a drug can produce a number of psychological symptoms of dependence, including a preoccupation with the drug, a pattern of escalating and uncontrolled use, and other maladaptive behavior changes. Some drugs of abuse have a higher probability of producing psychological dependence but vary dramatically in the extent to which they produce clear drug-specific symptoms of withdrawal. However, in some cases, drugs that were not thought to produce clear physiological dependence (such as cocaine and marijuana) have since been found to do so.
Finally, the opposite can be true as well. Some drugs may produce strong physiological dependence without producing strong psychological dependence. A good example of this is caffeine. The most noticeable withdrawal symptom of caffeine dependence is headache, which can easily be alleviated with another cup of coffee or a caffeinated beverage. Caffeine headaches are clear and consistent markers of physiological dependence, but having these headaches is not associated with addiction. That is, daily coffee drinkers with caffeine headaches are not considered to be addicted because they rarely exhibit the maladaptive behavioral changes associated with addiction.
The vast majority of caffeine drinkers, though they may be physiologically dependent upon caffeine, are not psychologically dependent in the sense that it would not be physically dangerous to their health if they suddenly stopped ingesting caffeine. Most habitual coffee drinkers do not become preoccupied with caffeine; they do not typically develop escalating and uncontrolled patterns of caffeine use or other maladaptive behavioral changes. However, the behaviors and habits associated with drinking caffeine have a physiological and psychological component. While ingesting caffeine may result in a physiological dependence, holding and sipping from a warm cup, stopping at a favorite coffee shop, drinking coffee every morning or throughout the day, or having coffee with friends all include the physical act of drinking coffee but are rooted in psychological, behavioral components.
Treatment
Most acute withdrawal symptoms last for days, but in some cases, they can be extraordinarily unpleasant (as is the case with opiates) and even medically dangerous (as is the case with alcohol). Therefore, the treatment of many addictions must begin with treating the withdrawal symptoms. This is particularly important in alcohol treatment, where withdrawal symptoms can include life-threatening seizures.
Substitute drugs that have some central nervous system effects in common with alcohol can be provided for some time as the brain and body adjust to the removal of alcohol. Effective drugs for alleviating symptoms of alcohol include a class of tranquilizing drugs called benzodiazepines, such as Xanax, Valium, and Ativan. Benzodiazepines themselves, however, also can produce physiological dependence. This illustrates an important challenge for drug treatment.
Ideally, one would like to alleviate the symptoms of withdrawal without perpetuating or worsening physiological dependence. This may not always be easy to accomplish, as substitute drugs that are effective in treating withdrawal often produce physiological dependence themselves. Another example is methadone treatment of opiate withdrawal.
An additional challenge in treating physiological dependence is the possibility of negative symptoms that persist beyond the period of acute withdrawal. These symptoms are referred to as post-acute withdrawal symptoms (PAWS) and can include anhedonia (the inability to experience pleasure), drug craving, tendency to relapse to using the drug, and cognitive impairment. These symptoms are far less drug-specific, may occur to some extent even with drugs that do not produce acute withdrawal effects, and can last for months, years, or even decades after the initial withdrawal from the drug of abuse. Though less understood, PAWS may indicate that the notion of physiological dependence may need to be expanded with an improved understanding of these longer-lasting changes.
Bibliography
Horowitz, Mark Abie, et al. "Addiction and Physical Dependence are Not the Same Thing." The Lancet Psychiatry, vol. 10, no. 8, 2023, DOI: 10.1016/S2215-0366(23)00230-4.
Julien, Robert M., et al. A Primer of Drug Action. 15th ed., New York City, Macmillan, 2023.
Ksir, Charles, and Carl Hart. Drugs, Society, and Human Behavior. 18th ed., New York City, McGraw-Hill, 2022.
"What is Psychological Dependence?" American Addiction Centers, 10 May 2024, americanaddictioncenters.org/the-addiction-cycle/psychological-dependence. Accessed 20 Sept. 2024.