Treatment of Addiction

Breaking the Cycle of Addiction
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Recovery involves learning new coping mechanisms to replace drug use Source: Sunshine Coast

Current treatments for addiction include both behavioural and pharmacological approaches, targeting learning and memory processes as well as physiological and psychological dependence. Although progress is being made, treatment efficacy is still limited and many who seek treatment will relapse. Successful recovery often requires the incorporation of multiple methods to create a holistic treatment plan that considers the highly complex nature of addiction. This paper will explore the neurological impact of behavioural methods of treatment[1], as well as the development and future of medications used to inhibit withdrawal symptoms and increase treatment effects. Finally, brain stimulation will be looked at as a way to modify cortical excitability and reduce cravings in recovering addicts, which could help to reduce relapse rates[2].

1. Behavioural Treatments

Behavioural treatments use psychological models of learning and memory to eliminate maladaptive behaviours, such as drug use, and reinforce the benefits of sobriety. These methods of treatment do not involve medications and can be delivered in many treatment settings. They are often used in residential programs, which allow individuals to escape their regular routine and re-evaluate their behaviour and goals.

1.1 Contingency Management

Contingency management is a method of treatment that uses the operant conditioning model of learning to reinforce abstinence while in a recovery program[3]. Positive reinforcements, such as money or privileges are given to clients after testing negative for drug use. This activates reward regions in the brain and provides incentive for the individual to continue with the recovery program and abstain from using drugs or alcohol[4]. Less often, punishments are used after a positive drug test to discourage future drug use. Punishments may involve assigning additional chores or duties within the program, or the removal of privileges such as internet time or outings in the case of residential treatment. Overall, this simple method of reinforcement causes the individual to associate rewarding experiences with sobriety, and has significant positive outcomes in clinical settings[4].

1.2 Extinction Therapy

The development of addiction is psychologically complex, often involving learning and memory processes. Individuals undergo classical conditioning of stimuli related to their drug use, such as certain locations or paraphernalia, because they are associated with the unconditioned stimulus (drugs) and the unconditioned response of drug use[3]. This classical conditioning of stimuli is threatening to recovery, as encountering the stimuli can produce strong cravings for the drug and predicts relapse. In fact, exposure to drug paraphernalia or drug-taking environments in the absence of drug use will still activate themesolimbic dopaminergic system, the same system primarily activated when anticipating drug use and experiencing craving[1]. In order to reduce this type of craving and decrease the likelihood of relapse, extinction therapy was developed. This therapy aims to decrease the addict's response to conditioned stimuli by repeated exposure to triggers in a sober state, sometimes referred to as cue exposure treatment[1]. After repeated exposure to stimuli without the reinforcing drugs, the link between the two weakens and results in the reduction of the mesolimbic dopaminergic response to drug related cues[4].

1.3 Mindfulness

Mindfulness therapy was derived from Buddhist practices and incorporated into the treatment of addictions based on its ability to regulate stress responses[3]. Mindfulness often involves meditation and becoming aware of one's current state, while ignoring thoughts of the past or the future. It allows the individual to slow down and mentally check in with themselves and their emotions, in order to gain knowledge about their current stressors or needs. This type of therapy has been shown to induce white matter changes in the regions of the brain responsible for emotion regulation[3]. Meditation has also been shown to produce white matter changes in the corona radiata and increase the connection between the anterior cingulate cortex and other brain regions[5].

2. Withdrawal Management

The extreme withdrawal symptoms associated with opioid addiction are often powerful enough to prevent individuals from becoming sober. The unpleasant effects of opioid withdrawal include vomiting, diarrhea, excessive sweating, chills, abdominal cramping and muscle pain. In order to help addicts detox, pharmacological treatments have been developed to manage these severe symptoms[6].

2.1 Methadone

Methadone is an opioid agonist that targets the mu-opioid receptor, the same receptor to which opiates bind[6]. Low doses of methadone are administered daily by a health care professional, which block cravings and withdrawal symptoms but do not produce the euphoric effects associated with opiate use[6]. The methadone dose is slowly decreased by the individual's doctor until they are no longer reliant on the drug. Unfortunately, many individuals continue to use illicit opiates while on a methadone maintenance program, which is a common cause of overdose and death[7].

2.2 Suboxone

Suboxone is a combination pill containing buprenorphine and naloxone. Buprenorphine is considered a partial agonist at the mu-opioid receptor and an antagonist at the delta- and kappa-opioid receptors[6]. As it is a partial agonist with high affinity, buprenorphine relieves withdrawal but will not produce analgesic effects in opioid-dependant individuals[6]. As a result of its antagonist activity, users report they are unable to feel the subjective effects of other opiates while taking buprenorphine, which decreases the amount of illicit opiate use while on suboxone[3]. Naloxone, a high affinity mu-opioid receptor antagonist, was combined with buprenorphine to reduce the potential for abuse[8]. Naloxone, while inactive when administered orally, will produce full withdrawal symptoms if injected and block any other opioid activity[8]. This prevents addicts from crushing and injecting suboxone pills to obtain a high and decreases risk of overdose.

3. Cognitive Enhancers

Dopamine Transporter Recovery
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Abstinence from Methamphetamine allows the brain to regain a normal dopaminergic system Source: DrugAbuse.gov

Chronic drug use can cause considerable cognitive impairments, particularly in processes of the prefrontal cortex such as working memory and attention[9]. These processes are necessary to learning and are required to retain knowledge and skills acquired in treatment. To improve treatment outcomes, cognitive enhancers have been used to compensate for the cognitive deficits some addicts show when entering recovery.

3.1 Modafinil

Modafinil is used to increase attention, working memory, and verbal memory in methamphetamine dependant individuals[9]. It has multiple effects on GABA, glutamate, and orexin, and was originally developed to promote wakefulness in individuals with sleep disorders[9]. Modafinil has been shown to increase activity in the ventrolateral PFC and ACC, confirming its enhancing effects on executive functioning[9].

3.2 D-cycloserine

D-cycloserine (DCS) acts as a partial agonist on NMDA glutamate receptors and increases glutamate transmission[10]. NMDA receptors have been identified as important mediators of learning and memory, especially in regards to cocaine-cue associations. In a study on cocaine cue extinction, it was shown that DCS in combination with extinction therapy was more effective in reducing the response to cues than either therapy alone[10]. This provides promising evidence for DCS as a potential component of addiction treatment and reducing risk of relapse.

4. Future Treatments

4.1 Transcranial Magnetic Stimulation (TMS)

TMS is a brain stimulation procedure in which an electric current produces a magnetic pulse and penetrates the skull[2]. This pulse creates an electric field and can disrupt neural activity[2]. These pulses can be delivered in different patterns, and when delivered repeatedly it is referred to as rTMS. rTMS has recently been examined as a way to treat addictions. rTMS to the PFC has been shown to alter cortical excitability and modulate the dopaminergic system, resulting in increased dopamine release in the mesolimbic and mesostriatal pathways[2]. Its effects include reduced drug craving, drug-seeking, and relapse, suggesting its value in addiction treatment.

4.2 Transcranial Direct Current Stimulation (tDCS)

tDCS is a way of altering cortical excitability. It involves delivering a weak current via two electrodes placed on the patient's head. The current flows through the cortex and changes neuronal resting membrane potentials, resulting in the modulation of brain activity[2]. After tDCS to the dorsolateral PFC in recovering alcoholics, cravings were significantly reduced compared and DLPFC activity did not increase in the presence of alcohol cues[2]. This suggests tDCS may be a helpful future method of treatment for individuals who chronically relapse.

4.3 Naltrexone Implants

Naltrexone is a competitive mu-opioid antagonist which almost completely blocks the receptor[11]. This high affinity results in the blocking of opiate effects for up to 36 hours. It has been clinically tested and proven to prevent relapse and overdose, as addicts do not use their drug of abuse when the effects are blocked[11]. In addition, patients do not develop any tolerance or withdrawal symptoms. The seemingly effective pill was not used to its full potential, however, as many dropped out of treatment when they had strong cravings for a high. To increase compliance, researchers in Australia have developed a naltrexone implant[11]. This implant is inserted subcutaneously and delivers a consistent low dose of naltrexone for up to 6 months. At the end of 6 months, the implant is removed and clients have the option of terminating treatment or receiving another 6 month implant. This long-term naltrexone delivery prevents the addict for making impulsive decisions to quit the program when they are under stress or experiencing strong cravings. In addition to its use in opiate addicts, naltrexone has also been shown to reduce the brain reactivity to visual and olfactory cues that would normally induce cravings in recovering alcoholics[12]. For these reasons, naltrexone is a strong candidate for future treatment.

Bibliography
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9. Sofuoglu, M., DeVito, E., Waters, A.J., & Carroll, K.M. Cognitive Enhancement as a Treatment for Drug Addictions. Neuropharm.64, 452-463 (2013).
10. Otto, M.W. et al. D-cycloserine deters reaquisition of cocaine self-administration by augmenting extinction learning. Neuropsychopharm. 35, 357-367 (2010).
11. Krupitsky, E. et al. Randomized Trial of Long-Acting Sustained-Release Naltrexone Implant vs Oral Naltrexone or Placebo for Preventing Relapse to Opioid Dependence. Arch Gen Psychiatry. 69, 973-981 (2012).
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