Repetitive transcranial magnetic stimulation: Re-wiring the alcoholic human brain

Modulation of Alcohol Use Disorder by Brain Stimulation

Currently available therapeutic modalities for alcohol use disorder (AUD) produce limited effect sizes or long-term compliance. Recent methods that were developed to modulate brain activity represent potential novel treatment options. Various methods of brain stimulation, when applied repeatedly, can induce long-term neurobiological, behavioral, and cognitive modifications. Recent studies in alcoholic subjects indicate the potential of brain stimulation methods to reduce alcohol craving, consumption, and relapse. Specifically, deep brain stimulation (DBS) of the nucleus accumbens or non-surgical stimulation of the dorsolateral prefrontal cortex (PFC) or medial PFC and anterior cingulate cortex using transcranial magnetic stimulation (TMS) has shown clinical benefit. However, further preclinical and clinical research is needed to establish understanding of mechanisms and the treatment protocols of brain stimulation for AUD. While efforts to design comparable apparatus in rodents continue, preclinical studies can be used to examine targets for DBS protocols, or to administer temporal patterns of pulsus similar to those used for TMS, to more superficial targets through implanted electrodes. The clinical field will benefit from studies with larger sample sizes, higher numbers of stimulation sessions, maintenance sessions, and long follow-up periods. The effect of symptoms provocation before and during stimulation should be further studied. Larger studies may have the power to explore predictive factors for the clinical outcome and thereby to optimize patient selection and eventually even develop personalization of the stimulation parameters.

Compulsive alcohol drinking in rodents is associated with altered representations of behavioral control and seeking in dorsal medial prefrontal cortex

A key feature of compulsive alcohol drinking is continuing to drink despite negative consequences. To examine the changes in neural activity that underlie this behavior, compulsive alcohol drinking was assessed in a validated rodent model of heritable risk for excessive drinking (alcohol preferring (P) rats). Neural activity was measured in dorsal medial prefrontal cortex (dmPFC-a brain region involved in maladaptive decision-making) and assessed via change point analyses and novel principal component analyses. Neural population representations of specific decision-making variables were measured to determine how they were altered in animals that drink alcohol compulsively. Compulsive animals showed weakened representations of behavioral control signals, but strengthened representations of alcohol seeking-related signals. Finally, chemogenetic-based excitation of dmPFC prevented escalation of compulsive alcohol drinking. Collectively, these data indicate that compulsive alcohol drinking in rats is associated with alterations in dmPFC neural activity that underlie diminished behavioral control and enhanced seeking.

Alcohol Use Disorder: Neurobiology and Therapeutics

Alcohol use disorder (AUD) encompasses the dysregulation of multiple brain circuits involved in executive function leading to excessive consumption of alcohol, despite negative health and social consequences and feelings of withdrawal when access to alcohol is prevented. Ethanol exerts its toxicity through changes to multiple neurotransmitter systems, including serotonin, dopamine, gamma-aminobutyric acid, glutamate, acetylcholine, and opioid systems. These neurotransmitter imbalances result in dysregulation of brain circuits responsible for reward, motivation, decision making, affect, and the stress response. Despite serious health and psychosocial consequences, this disorder still remains one of the leading causes of death globally. Treatment options include both psychological and pharmacological interventions, which are aimed at reducing alcohol consumption and/or promoting abstinence while also addressing dysfunctional behaviours and impaired functioning. However, stigma and social barriers to accessing care continue to impact many individuals. AUD treatment should focus not only on restoring the physiological and neurological impairment directly caused by alcohol toxicity but also on addressing psychosocial factors associated with AUD that often prevent access to treatment. This review summarizes the impact of alcohol toxicity on brain neurocircuitry in the context of AUD and discusses pharmacological and non-pharmacological therapies currently available to treat this addiction disorder.

Neurobiological mechanisms of control in alcohol use disorder - moving towards mechanism-based non-invasive brain stimulation treatments

Alcohol use disorder (AUD) is characterized by excessive habitual drinking and loss of control over alcohol intake despite negative consequences. Both of these aspects foster uncontrolled drinking and high relapse rates in AUD patients. Yet, common interventions mostly focus on the phenomenological level, and prioritize the reduction of craving and withdrawal symptoms. Our review provides a mechanistic understanding of AUD and suggests alternative therapeutic approaches targeting the mechanisms underlying dysfunctional alcohol-related behaviours. Specifically, we explain how repeated drinking fosters the development of rigid drinking habits and is associated with diminished cognitive control. These behavioural and cognitive effects are then functionally related to the neurobiochemical effects of alcohol abuse. We further explain how alterations in fronto-striatal network activity may constitute the neurobiological correlates of these alcohol-related dysfunctions. Finally, we discuss limitations in current pharmacological AUD therapies and suggest non-invasive brain stimulation (like TMS and tDCS interventions) as a potential addition/alternative for modulating the activation of both cortical and subcortical areas to help re-establish the functional balance between controlled and automatic behaviour.

The hypodopaminergic state ten years after: transcranial magnetic stimulation as a tool to test the dopamine hypothesis of drug addiction

An altered dopamine transmission has been described for different types of addiction for a long time. Preclinical and clinical evidence support the hypodopaminergic hypothesis and underpin the need to increase dopamine transmission to obtain therapeutic benefit. Repetitive transcranial magnetic stimulation (rTMS) of prefrontal cortex shows efficacy in treating some forms of addiction. Recent imaging studies confirmed that the therapeutic effect of rTMS is correlated with an enhancement of dopamine transmission. Novel targets for rTMS are under evaluation to increase its effectiveness in treating addiction, and research is ongoing to find the optimal protocol to boost dopaminergic transmission in the addicted brain. TMS can thus be considered a useful tool to test the dopamine hypothesis of drug addiction and instrumental in the search for addiction therapeutics.

A sham-controlled trial of repetitive transcranial magnetic stimulation over left dorsolateral prefrontal cortex and its effects on craving in patients with alcohol dependence

AIM

The aim of this study is to study the effects of repetitive transcranial magnetic stimulation (rTMS) therapy over the left dorsolateral prefrontal cortex (DLPFC) in craving in drug-naive male inpatients of alcohol dependence syndrome.

METHODS

A single-blind randomized sham-controlled study involving sixty inpatients of alcohol dependence syndrome in a tertiary care center. Following detoxification and consent, the patients were allocated into either active or sham groups for rTMS protocol. Daily sessions of rTMS were administered over the left DLPFC at 120% of motor threshold at high-frequency (10 Hz) stimulation with 4 s train, inter-train interval of 26 s, and a total of twenty trains per session. Alcohol craving questionnaire (ACQ-NOW) was administered thrice for each patient, i.e., before rTMS, on completion of rTMS, and 02 weeks following completion of rTMS.

RESULTS

Analysis of variance of scores of ACQ NOW pre rTMS and immediately after and 2 weeks post rTMS did not show significant reduction in craving scores.

CONCLUSION

Administration of ten daily sessions of high-frequency rTMS over the left DLPFC did not have significant effect in reducing craving in patients with alcohol dependence syndrome.

Principal component regression of academic performance, substance use and sleep quality in relation to risk of anxiety and depression in young adults

Adverse lifestyle factors increase risk of anxiety and depression in young adults. Consequently, neurochemical and neuroanatomical alterations ensue, and may initiate a vicious cycle of mental distress, poor lifestyle choices and academic performance. A total of 558 students from different US colleges completed an anonymous survey on academic performance, daytime sleepiness, substance use and mental distress. Low mental distress in college students positively associated with good academic efforts and limited daytime sleepiness. Mild mental distress correlated with borderline work neglect and with a marginal negative association with Grade-point average (GPA). Severe mental distress correlated with excessive daytime sleepiness and poor academic performance. A System Dynamic model was developed to reflect the integration of these variables with mental distress and academic performance. Our results demonstrate that manageable lifestyle factors contribute to mental health in college students, which become potentially cyclic events that may impact academic performance.