Neurobiology of dependence in chronic nonmalignant pain patients using opioids and possibility of screening's methods
Abstract
Chronic pain is currently a serious social and health-related problem. Pharmacotherapy is an essential therapeutic variant for the treatment of chronic pain, however, long-term opioid therapy may bring a number of complications.
The therapeutic response to opioids in chronic non-cancer pain is namely different than in cancer pain. As shown by clinical experience, exceeding mean opioid doses does not contribute to improved analgesia quality any further, but rather accentuates physical dependence and tolerance.
In some patients on opioids, dependence may become a predominant clinical problem, together with cognitive, behavioural and emotional difficulties, and it may complicate their compliance. Opioid dependence is a source of a hazard for public health related to a considerable risk of overdose, hazardous drug interactions and a number of other unfavourable social, legal and adaptive consequences related to dependence on any psychoactive substances.
Although the opioid abuse rate increased more than three times in the US population in the previous two decades, it currently remains unclear to what extent this increase is given by the difference between individuals using/not using prescribed opioids. The available statistical data provide an inaccurate differentiation of opiate addicts suffering from chronic pain from those without pain, which is a very important difference with serious clinical consequences.
In the field of chronic pain therapy, considerable concerns about dependence to opioids occur in patients with chronic non-cancer pain, sometimes even taking the form of opiate phobia (opioidphobia). For this reason, current studies of this topic, drawing from neuro-psycho-pharmacological research, seek to develop a conceptual framework of dependence development in patients suffering from chronic pain.
Addictive use of opioids is understood as a result of a cycle that starts with chronic pain and negative feelings and is reinforced by opioid-dopamine interaction leading to attention hypervigilance to pain and stimuli associated with medication, a dysfunctional connection between cognitive control networks in the brain and the allostatic dysregulation of systems that respond to stress and reward. Misuse of opioids is prominent in patients with chronic nonmalignant pain and early recognition of misuse risk could help physicians offer adequate patient care while implementing appropriate levels of monitoring to reduce aberrant drug-related behaviors.
In this article, we discuss opioid abuse and misuse issues that often arise in the treatment of patients with chronic nonmalignant pain and present an overview of assessment strategies that can be effective in improving compliance with the use of prescription opioids for pain. Many persons with chronic pain have significant medical, psychiatric and substance use comorbidities that affect treatment decisions and a comprehensive evaluation that includes a detailed history, physical, and mental health evaluation is essential.
Although there is no "gold standard" for opioid misuse risk assessment, several validated measures have been shown to be useful. Regular urine drug screens, and interventions such as multimodal psychotherapy have been shown to help improve patient compliance with opioids and to minimize aberrant drug-related behavior.
Not only the screening model of determining dependence, but also some multimodal therapeutic approaches are introduced as a potentially efficient approach to breaking the descending spiral of dependence and facilitating the treatment of chronic non-cancer pain and dependence. The aim of this article is to describe how opioids interact with cognitive, affective and psychological factors that are involved in chronic pain, and with behaviour related to dependence.
Finally, the clinical consequences of this model for psychotherapeutic treatment of patients with chronic non-cancer pain are described.