Diana Limoncelli

Altered NMDA glutamate receptor antagonist response in recovering ethanol-dependent patients.

Ethanol is an antagonist of the N-methyl-D-aspartate (NMDA) glutamate receptor. Ethanol dependence upregulates NMDA receptors and contributes to crosstolerance with selective NMDA receptor antagonists in animals. This study evaluated whether recovering ethanol-dependent patients show evidence of a reduced level of response to the effects of the NMDA receptor antagonist, ketamine. In this double-blind study, 34 recently detoxified alcohol-dependent patients and 26 healthy comparison subjects completed 3 test days involving a 40-min infusion of saline, ketamine 0.1 mg/kg, or ketamine 0.5 mg/kg in a randomized order. Recovering ethanol-dependent patients showed reduced perceptual alterations, dysphoric mood, and impairments in executive cognitive functions during ketamine infusion relative to the healthy comparison group. No attenuation of ketamine-induced amnestic effects, euphoria, or activation was observed. The alterations in NMDA receptor function observed in recovering ethanol-dependent patients may have important implications for ethanol tolerance, ethanol dependence, and the treatment of alcoholism.

Characterization of the Interactive Effects of Glycine and D -Cycloserine in Men: Further Evidence for Enhanced NMDA Receptor Function Associated with Human Alcohol Dependence

Reduced responses to N-methyl-D-aspartate (NMDA) glutamate receptor antagonists in alcohol-dependent animals and humans provided evidence that chronic alcohol consumption increased NMDA receptor function. To further probe alterations in NMDA glutamate receptor function associated with human alcohol dependence, this study examined the interactive effects of agents acting at the glycineB coagonist site of the NMDA receptor. In doing so, it tested the hypothesis that raising brain glycine concentrations would accentuate the antagonist-like effects of the glycineB partial agonist, D-cycloserine (DCS). Twenty-two alcohol-dependent men and 22 healthy individuals completed 4 test days, during which glycine 0.3 g/kg or saline were administered intravenously and DCS 1000 mg or placebo were administered orally. The study was conducted under double-blind conditions with randomized test day assignment. In this study, DCS produced alcohol-like effects in healthy subjects that were deemed similar to a single standard alcohol drink. The alcohol-like effects of DCS were blunted in alcohol-dependent patients, providing additional evidence of increased NMDA receptor function in this group. Although glycine administration reduced DCS plasma levels, glycine accentuated DCS effects previously associated with the NMDA receptor antagonists, ketamine and ethanol. Thus, this study provided evidence that raising glycine levels accentuated the NMDA receptor antagonist-like effects of DCS and that alcohol-dependent patients showed tolerance to these DCS effects.Reduced responses to N-methyl-D-aspartate (NMDA) glutamate receptor antagonists in alcohol-dependent animals and humans provided evidence that chronic alcohol consumption increased NMDA receptor function. To further probe alterations in NMDA glutamate receptor function associated with human alcohol dependence, this study examined the interactive effects of agents acting at the glycine(B) coagonist site of the NMDA receptor. In doing so, it tested the hypothesis that raising brain glycine concentrations would accentuate the antagonist-like effects of the glycine(B) partial agonist, D-cycloserine (DCS). Twenty-two alcohol-dependent men and 22 healthy individuals completed 4 test days, during which glycine 0.3 g/kg or saline were administered intravenously and DCS 1000 mg or placebo were administered orally. The study was conducted under double-blind conditions with randomized test day assignment. In this study, DCS produced alcohol-like effects in healthy subjects that were deemed similar to a single standard alcohol drink. The alcohol-like effects of DCS were blunted in alcohol-dependent patients, providing additional evidence of increased NMDA receptor function in this group. Although glycine administration reduced DCS plasma levels, glycine accentuated DCS effects previously associated with the NMDA receptor antagonists, ketamine and ethanol. Thus, this study provided evidence that raising glycine levels accentuated the NMDA receptor antagonist-like effects of DCS and that alcohol-dependent patients showed tolerance to these DCS effects.

The Impact of Personality Disorders on Alcohol‐Use Outcomes in a Pharmacotherapy Trial for Alcohol Dependence and Comorbid Axis I Disorders

Although antisocial and borderline personality disorders frequently co-occur with alcohol dependence and other Axis I disorders, their effect on alcohol use outcomes in context of pharmacotherapy remains unclear. Patients with Major Axis I disorders, including alcohol dependence, and diagnosis of antisocial (ASPD) or borderline personality disorder (BPD) were enrolled in a 12-week medication trial for treatment of their alcohol dependence. Everyone was randomized to one of four cells: naltrexone alone, placebo alone, open label disulfiram and naltrexone, or open label disulfiram and placebo. Outcome measures included scales for alcohol use and craving. Data were analyzed comparing patients with ASPD vs. those without, and patients with BPD vs. those without. Diagnosis of personality disorder did not adversely affect alcohol outcomes, and patients with ASPD or BPD did not have a poorer response to medication than patients without diagnosis of ASPD or BPD. The findings suggest that naltrexone and disulfiram can be safely and effectively used with patients who have comorbid diagnoses of Axis I and Axis II disorders.

Preliminary analysis of positive and negative syndrome scale in ketamine-associated psychosis in comparison with schizophrenia.

OBJECTIVE Studies of the effects of the N-methyl-d-aspartate (NMDA) glutamate receptor antagonist, ketamine, have suggested similarities to the symptoms of schizophrenia. Our primary goal was to evaluate the dimensions of the Positive and Negative Syndrome Scale (PANSS) in ketamine users (acute and chronic) compared to schizophrenia patients (early and chronic stages). METHOD We conducted exploratory factor analysis for the PANSS from four groups: 135 healthy subject administrated ketamine or saline, 187 inpatients of ketamine abuse; 154 inpatients of early course schizophrenia and 522 inpatients of chronic schizophrenia. Principal component factor analyses were conducted to identify the factor structure of the PANSS. RESULTS Factor analysis yielded five factors for each group: positive, negative, cognitive, depressed, excitement or dissociation symptoms. The symptom dimensions in two schizophrenia groups were consistent with the established five-factor model (Wallwork et al., 2012). The factor structures across four groups were similar, with 19 of 30 symptoms loading on the same factor in at least 3 of 4 groups. The factors in the chronic ketamine group were more similar to the factors in the two schizophrenia groups rather than to the factors in the acute ketamine group. Symptom severities were significantly different across the groups (Kruskal-Wallis χ(2)(4) = 540.6, p < 0.0001). Symptoms in the two ketamine groups were milder than in the two schizophrenia groups (Cohens d = 0.7). CONCLUSION Our results provide the evidence of similarity in symptom dimensions between ketamine psychosis and schizophrenia psychosis. The interpretations should be cautious because of potential confounding factors.

Ethanol-like effects of thiopental and ketamine in healthy humans

The γ-aminobutyric acid-A (GABAA) and N-methyl-D-aspartate (NMDA) receptors mediate aspects of the behavioural effects of alcohol. Prior studies reported drugs that block NMDA receptors or facilitate GABAA receptor function produce ethanol-like effects in humans. The purpose of this study was to compare the ethanol-related effects of two pharmacological agents with known NMDA and GABAA receptor activity. As part of an ongoing, larger study, 28 subjects (age, 21—30) with no personal or family histories of alcoholism were administered subanesthetic doses of the GABAA receptor agonist thiopental, the NMDA receptor antagonist, ketamine and placebo on three separate test days. Various ethanol-related measures were administered. At doses of thiopental and ketamine that produced similar levels of sedation and cognitive effects, both agents produced significant ethanol-like effects and subjective intoxication. However, the intensity of the ethanol-like effects of ketamine was greater than that of thiopental. In addition, ketamine produced alterations in perception that were not produced by thiopental. These data provide further support for a model where GABAA receptor facilitation may contribute significantly to ethanol effects associated with social drinking, whereas NMDA receptor antagonism may contribute to relatively greater extent to features of ethanol ‘intoxication’.

Relationships between impulsivity and subjective response in an IV ethanol paradigm.

RationaleImpulsivity and individual differences in subjective response to alcohol are risk factors for alcohol problems and possibly endophenotypes for alcohol dependence. Few prior studies have addressed relationships between the two constructs.ObjectivesTo predict subjective responses to ethanol, we tested self-reported impulsiveness, ethanol dose condition (high dose, low dose, or placebo), and time (seven time points) along with interactions among these variables.MethodsThe present study is a secondary analysis of data from a within-subject, placebo-controlled, dose-ranging ethanol administration study using IV infusion with a clamping technique to maintain steady-state breath alcohol concentration. The sample consisted of healthy, non-alcohol dependent social alcohol drinkers between the ages of 21 and 30 (N = 105). Participants at varying levels of impulsivity were compared with regard to stimulant and subjective responses to three ethanol dose conditions over time.ResultsIndividuals with higher impulsivity reported elavated stimulant and dampened sedative response to alcohol, particularly at the higher dose. Higher impulsivity was associated with a steeper increase in stimulant effects during the first half of clamped ethanol infusion with the higher dose.ConclusionsThese results suggest that impulsive individuals may experience enhanced reinforcing, stimulant effects, and relatively muted aversive sedative effects from alcohol. These subjective responses may relate to enhanced risk of alcohol problems among more impulsive individuals.

Analgesic effects of ethanol are influenced by family history of alcoholism and neuroticism.

BACKGROUND Although personality factors and family history of substance abuse influence how individuals experience pain and respond to analgesics, the combined effects of those factors have not been extensively studied. The objective of this study was to consider the possible role of personality trait of neuroticism and family history of alcoholism on the experience of pain and their role in the analgesic response to an ethanol challenge. METHODS Forty-eight healthy subjects participated in this study; thirty-one had a positive family history of alcoholism (FHP), seventeen had a negative family history of alcoholism (FHN). They were also categorized based on their neuroticism (N) scores (low N = 28, and high N = 20). This was a double-blind, placebo-controlled, randomized, within-subject design study of intravenous administration of three doses of ethanol. The testing consisted of 3 separate test days scheduled at least 3 days apart. Test days included a placebo day (saline solution), low-exposure ethanol day (targeted breathalyzer = 0.040 g/dl), and high-exposure ethanol day (targeted breathalyzer = 0.100 g/dl). Noxious electrical stimulation and pain assessments were performed prior to start of infusion and at the 60-minute infusion mark. RESULTS The analgesic effect of ethanol was mediated by an interaction between the personality trait of neuroticism and family history. Individuals with family history of alcoholism and high N scores reported significantly more analgesia on low dose of ethanol than those with low N scores. There was no difference in the analgesic response to ethanol among FHNs with low and high N scores. CONCLUSION These findings support the conclusion that neuroticism and family history of alcoholism both influence the analgesic response of alcohol. Individuals with high N scores and FHP have the strongest response to ethanol analgesia particularly on the low exposure to alcohol.

Subjective Effects of Thiopental in Young Adults with and without a Family History of Alcoholism

BACKGROUND The development of alcohol use disorders is genetically influenced, and may be mediated through differences in the subjective response to alcohol. There is some evidence to suggest that response differences to alcohol could be conveyed by heritable differences in GABAA receptors. The purpose of this study was to investigate whether individuals with a family history positive (FHP) for alcohol dependence would experience alterations in response to the GABAA receptor agonist thiopental, in comparison to family history negative (FHN) subjects. METHODS 73 subjects (24 FHP and 49 FHN) between the ages of 21 and 30 years were administered sub-anesthetic doses of the GABAA receptor agonist thiopental and placebo on two separate test days. Various alcohol-related measures were administered, including those examining subjective effects, coordination, and cognition. RESULTS Sub-anesthetic doses of thiopental produced alcohol-like subjective effects, as well as alcohol-like impaired coordination and cognition in healthy subjects. While there were no significant main effects in subjective, coordination, or cognitive effects between FHP and FHN individuals, analysis of peak effects suggested FHP had blunted sedative, but not stimulant effects compared to FHN. CONCLUSION Thiopental produced alcohol-like effects and perceived similarities to alcohol in healthy individuals. Subtle differences in sedative effects are consistent with reports of blunted FHP response to the negative but not stimulant effects of alcohol. Future studies are needed to better understand how this insight informs our understanding of the heritable risk for alcoholism and the treatment of alcohol use disorders.