Evidence for prolonged recovery of dopaminergic transmission after detoxification in alcoholics with poor treatment outcome

Summary It has been hypothesized that dysfunction of dopaminergic neurotransmission is involved in the pathogenesis of alcohol addiction. Therefore, peripheral dopamine levels, sensitivity of central dopamine receptors (apomorphine-induced Growth Hormone (GH) secretion), and the inhibitory efficacy of G-proteins on adenylyl cyclase activity (as an indicator for dopamine D2-receptor coupled second messenger mechanisms) were measured in 45 alcohol-dependent patients before and after detoxification and in 10 healthy controls. The time needed to adjust to abstinence conditions differed between patients with good and poor treatment outcome. In subsequent abstainers, effects of alcohol withdrawal were already found during the first 24 hours of abstinence (normalisation of GH response, increases in dopamine levels and the inhibitory efficacy of G-proteins). During the next 7 days of abstinence, no more significant changes were observed in the assessed variables. In subsequent relapsers, no significant effect of acute ethanol withdrawal on the same measures was found. However, at day 8 of abstinence, increases in apomorphine-induced GH secretion (towards normalisation), in dopamine plasma levels, and in the inhibitory efficacy of G-proteins (towards above-normal levels) were observed. This retarded adjustment of dopaminergic signal transduction seems to reflect the relapse risk of treatment non-responders.     

Pharmacogenetics of naltrexone in asian americans: a randomized placebo-controlled laboratory study

Recent clinical and laboratory studies have shown that the effects of naltrexone for alcoholism may be moderated by the Asn40Asp single-nucleotide polymorphism (SNP) of the μ-opioid receptor gene (OPRM1). Allele frequencies for this polymorphism, however, have been shown to vary substantially as a function of ethnic background, such that individuals of Asian descent are more likely to carry the minor (Asp40) allele. The objective of this study is to test the naltrexone pharmacogenetic effects of the Asn40Asp SNP in a sample of Asian Americans. This study consists of a double-blinded, randomized, placebo-controlled laboratory trial of naltrexone. Participants (n=35, 10 females; 13 Asn40Asn and 22 Asp40 carriers) were non-treatment-seeking heavy drinkers recruited from the community. After taking naltrexone or placebo, participants completed an intravenous alcohol administration session. The primary outcome measures were subjective intoxication and alcohol craving. Results suggested that Asp40 carriers experienced greater alcohol-induced sedation, subjective intoxication, and lower alcohol craving on naltrexone, as compared to placebo, and to Asn40 homozygotes. There results were maintained when controlling for ALDH2 (rs671) and ADH1B (rs1229984) markers and when examining the three levels of OPRM1 genotype, thereby supporting an OPRM1 gene dose response. These findings provide a much-needed extension of previous studies of naltrexone pharmacogenetics to individuals of Asian descent, an ethnic group more likely to express the minor allele putatively associated with improved biobehavioral and clinical response to this medication. These findings help further delineate the biobehavioral mechanisms of naltrexone and its pharmacogenetics.     

Dopamine transporters increase in human brain after alcohol withdrawal

Dopaminergic transmission has been suggested to be a main mechanism mediating reinforcement, withdrawal and craving associated with alcohol addiction. We measured here striatal dopamine (DA) transporter binding from 27 alcoholics within 4 days after cessation of prolonged heavy drinking and after a 4-week period of abstinence with single photon emission computed tomography (SPECT) using a cocaine analogue, iodine-123-beta-CIT. Controls were 29 healthy volunteers. Blind quantitative analyses of the SPECT data revealed markedly lower DA transporter binding in alcoholics on admission for detoxification than in the non-alcoholic controls. After a 4-week period of abstinence DA transporter binding increased significantly in the alcoholics (P<0.0001) reaching the levels of the healthy controls. The most substantial recovery in DA transporter binding occurred during the first 4 days of abstinence. The data indicate that prolonged heavy drinking decreases DA transporter binding and disturbs synaptic dopamine transport. This may sensitize alcoholics to dopaminergic transmission, which may lead to early relapse after ethanol withdrawal.     

Genetic variation of the human mu-opioid receptor and susceptibility to idiopathic absence epilepsy

Pharmacological and autoradiological studies suggest that mu-opioid receptor (OPRM) mediated neurotransmission is involved in the generation of absence seizures. Mutation screening of the human OPRM gene identified a common amino acid substitution polymorphism (Asn40Asp) that differentially modulates the binding affinity of beta-endorphin and signal transduction of the receptor. The present association study tested the candidate gene hypothesis that the Asn40Asp substitution polymorphism in the N-terminal OPRM domain confers genetic susceptibility to idiopathic absence epilepsy (IAE). The genotypes of the Asn40Asp polymorphism were assessed by allele-specific polymerase chain reaction in 72 German IAE patients and in 340 ethnically matched control subjects. The frequency of the Asp40 allele was significantly increased in the IAE patients [f(Asp40) = 0.139] compared to the controls [f(Asp40) = 0.078; chi2 = 5.467, df = 1, P = 0.019; OR = 2.03; 95%-CI: 1.12-3.68]. This allelic association suggests that the functional Asp40 variant of OPRM modulates neuronal excitability underlying the epileptogenesis of IAE.     

Endocrinological studies in alcoholics during withdrawal and after abstinence

Several endocrine parameters were assessed in 35 alcoholic inpatients after admission to hospital, and 17 of the 35 were retested after several weeks of sobriety. No difference was found in clonidine-stimulated growth hormone (GH) secretion between male alcoholics and male healthy controls, but significant positive correlations of GH secretion and alcohol content in expired breath on admission and gamma-GT values after abstinence were observed. Nonsuppression in the dexamethasone suppression test was found in 17% of the patients on admission, which seemed to be due to alcohol withdrawal. Postdexamethasone cortisol levels were significantly positively correlated with the "apathic syndrome" (r = 0.40; p less than or equal to 0.05). About one-third of the patients showed a blunted response in the TRH-test both on admission and after abstinence. No significant influence of alcohol intake, withdrawal or familial disposition on prolactin values could be detected. The results of the TRH test and the DST point to similar endocrinological patterns in alcoholics as in depressive patients and thus support the hypothesis of a link between alcoholism and depression.     

Levodopa treatment does not affect low-dose apomorphine test in patients with Parkinson's disease.

Challenge with low-dose apomorphine causes a significant rise in growth hormone (GH) in patients with Parkinson's disease (PD) compared to controls and patients with multiple system atrophy (MSA) who have not previously received dopaminergic treatment. To date, it has not been demonstrated whether an apomorphine-induced rise in GH can still be detected in PD patients who are currently treated with levodopa. We investigated whether an ongoing treatment with levodopa influences the GH response to subcutaneously applied low-dose apomorphine in PD patients. We studied 44 patients with idiopathic PD using the low-dose apomorphine test. Twenty-three patients were under treatment with levodopa and 21 patients were without any dopaminergic therapy. GH and cortisol levels were analyzed at time of injection and 45 minutes and 60 minutes after subcutaneous apomorphine injection. Forty-five minutes after apomorphine injection, there was no significant difference between the mean rise in plasma GH in untreated PD patients compared with levodopa-treated patients (P = 0.235). There was no increase of cortisol levels in each treatment group. Age, sex, duration, and severity of the disease did not show a covariate effect with GH levels. A small group of PD patients (n = 8) treated with dopamine agonists and a small group of patients with MSA (n = 5) as well as patients with vascular parkinsonism (n = 5) did not show any increase of GH. Our data suggest that the apomorphine-induced rise in GH does not depend on previous levodopa treatment in PD patients but, as expected, is blocked by dopamine agonists and is not present in patients with other than idiopathic parkinsonian syndrome. Thus, the low-dose apomorphine test may also be a useful biological marker in the early differential diagnosis of PD patients who have already received levodopa treatment.     

Severity of alcohol withdrawal symptoms and the T1128c polymorphism of the neuropeptide Y gene

Summary. Neuropeptide Y (NPY) modulates ethanol drinking in rodents. The C-allele of the T1128C polymorphism of the human NPY gene has been previously associated with elevated alcohol consumption in a Finn population study. The present study tested the hypothesis that the T1128C polymorphism is associated with the diagnosis of alcoholism or with severe forms of alcohol withdrawal and with the daily consumption of alcohol in alcoholic patients. After PCR-RFLP genotyping, two groups of alcoholics with severe withdrawal symptoms (delirium tremens, n = 83; withdrawal seizures, n = 65) were compared to alcoholics with mild withdrawal symptoms (n = 97). An elevated frequency of the C-allele in the individuals with severe withdrawal symptoms was found, however not reaching statistical significance. Further a group of healthy controls (n = 102) was compared to all included alcoholics (n = 216) revealing no significant result. Alcoholics carrying the C-allele reported a non significantly elevated daily consumption of alcohol compared to alcoholics with the TT genotype. All alcohol dependent subjects with severe withdrawal symptoms revealed a significantly elevated daily consumption of alcohol compared to alcoholics with only mild withdrawal symptoms. More studies on different ethnic groups are needed to further elucidate the influence of the NPY gene on alcoholism. Received January 7, 2002; accepted April 17, 2002 Published online June 28, 2002 Acknowledgements This study was financially supported by the “fortuene-fund” (project 490) of Tuebingen University, Germany. We are grateful to all individuals participating in the study. Authors' address: Dr. M. D. Koehnke, University Hospital of Psychiatry, Osianderstrasse 24, D-72076 Tuebingen, Federal Republic of Germany, e-mail: michael.koehnke@med.uni-tuebingen.de     

DBH*444G/A polymorphism of the dopamine-β-hydroxylase gene is associated with alcoholism but not with severe alcohol withdrawal symptoms

Summary. As the enzyme dopamine-β-hydroxylase (DβH) converts dopamine to norepinephrine and both transmitters seem to be involved in the pathology of alcoholism and severe alcohol withdrawal symptoms, the gene encoding DβH (DBH) was applied to explore the genetic background of alcoholism and severe withdrawal symptoms. 102 healthy control subjects and 208 alcoholics, including 97 patients with a history of mild withdrawal symptoms, 57 with a history of alcohol withdrawal seizure (AWS) and 82 with a history of delirium tremens (DT) were genotyped for the DBH^*444G/A polymorphism revealing a significantly elevated frequency of genotypes carrying the A-allele (p = 0.02; after Bonferroni adjustment for multiple tests) in alcoholics compared to healthy controls. Frequencies of alleles and genotypes of individuals with mild withdrawal symptoms did not differ significantly from those of patients with DT or AWS.     

Family history of alcoholism and cognitive recovery in subacute withdrawal

Abstract  A family history of alcoholism has been demonstrated to be an important factor affecting cognitive function. However, no studies have yet been conducted to compare cognitive recovery of family history-positive (FH+) and family history-negative (FH–) alcoholics in the subacute withdrawal period. To tackle this problem, a neuropsychological test battery consisting of six computerized tests was administered to 19 FH+ and 20 FH– alcoholics at 2 and 7 weeks after abstinence. At 2 weeks after abstinence, overall performance of both FH+ and FH– groups was significantly poorer than that of healthy controls. At 7 weeks, these performances tended to recover, but in Trail Making A and Figure Position, performances of FH+ alcoholics remained worse than those of controls, while those of FH– alcoholics did not. Thus cognitive recovery during the subacute withdrawal period was worse among FH+ alcoholics than FH– alcoholics, and this finding should be considered when planning alcohol rehabilitation programs.     

Association of mu-opioid receptor gene polymorphism A118G with alcohol dependence in a Japanese population

Ethanol is considered to activate the brain reward system by increasing the release of an endogenous opioid receptor ligand, beta-endorphin. The polymorphism A118G in the micro-opioid receptor gene (OPRM1) causes the amino acid change Asn40Asp and has been reported to affect the affinity of the ligand for the receptor. The association of this polymorphism with the vulnerability to alcohol dependence has been studied in many populations, but not yet in Japanese people. In the present study, we compared the frequencies of the polymorphism OPRM1 A118G between patients with alcohol dependence and healthy control subjects living in a Japanese provincial prefecture. We also genotyped a polymorphism, G1510A, in the acetaldehyde dehydrogenase 2 gene (ALDH2), in which the A allele causes poor metabolism of acetaldehyde, a major metabolite of alcohol. Both OPRM1 118G and ALDH2 1510G were significantly associated with alcohol dependence. These results suggest that OPRM1 118G in addition to ALDH2 1510G might be one of the risk factors for alcohol dependence in Japanese people.     

Alcohol withdrawal and dopamine receptor sensitivtty after prolonged abstinence

• 1.1. Forty-four male inpatients suffering from moderate to severe alcohol dependence (DSMIII-R and ICD-10) as well as 14 healthy controls entered this study. Individuals were classified according to the severity of their withdrawal symptoms during Detoxification I. e. group 1) no withdrawal, group 2) autonomie hyperactivity, group 3) withdrawal delirium and group 4) controls.
• 2.2. During the 6th week of treatment, that is, when all patients were recovered, controlled abstinent, and several weeks away from the end of their withdrawal syndrome, dopamine receptor sensitivity was neuroendocrinologically assessed by stimulating human growth hormone (HGH) with apomorphine (APO).
• 3.3. In a repeated measures model ANOVA, the four groups differed significantly in their HGH release. However, when excluding the controls from the analysis and focusing on alcoholics only (group 1 – 3), the significant difference disappeared. Covariates such as age, weight, quantity of drinking and duration of dependence were not related to the dependent variable.
• 4.4. In conclusion, the first significant result (with controls) reflects a blunted HGH response in alcoholics. It confirms earlier reports. The second, non significant result with the alcohol dependents only, suggests that the severity of withdrawal is not reflected by the amount of HGH released. Therefore, in alcoholics, a reduced dopamine receptor function after six weeks of abstinence, as neuro-endocrinologicaliy assessed with apomorphine, seems to be related to alcohol dependence rather than to the severity of alcohol withdrawal.

     

Alcohol and central serotonin metabolism in man.

Animal studies and some of thephenomena associated with alcoholism in humans suggest that some central effects of alcohol may involve serotonergic systems. The CSF metabolites of serotonin and dopamine, 5-hydroxyindoleacetic acid (5HIAA), and homovanillic acid (HVA) were studied in hospitalized alcoholics. There were no significant differences in HVA levels between groups. The level of 5HIAA of alcoholics in the abstinence phase, 28 to 63 days after their last drink, was significantly lower (21.8 +/- 1.9 ng/mL) than both a nonalcoholic comparison group (31.7 +/- 2.0 ng/mL) and alcoholics in the immediate postintoxication phase, within one to two days after their last drink (32.3 +/- 2.9 ng/mL).     

Craving for alcohol and dopamine receptor sensitivity in alcohol-dependent men and control subjects

Summary. Detoxified alcohol-dependent men and control subjects were repetitively exposed by sight and smell to either a neutral cue (tea) or an alcohol-related cue (their favourite alcoholic beverage) to provoke a maximum craving response. Additionally, their dopamine receptor sensitivity was evaluated by measuring growth hormone (HGH) response to stimulation with the dopamine receptor agonist apomorphine (APO). It was hypothesized that the subjects' desire to drink (craving) is related to their dopaminergic activity. In both groups, craving increased in the presence of the alcohol stimulus with significantly higher craving scores in alcoholics than in controls. However, in none of the groups and at no cue exposure did the craving response correlate with the individuals' dopaminergic activity as reflected by HGH release. Therefore, this study cannot add support to the hypothesis that craving for alcohol is associated with dopamine receptor sensitivity in abstinent alcoholics or healthy control subjects. Received June 16, 1999; accepted January 4, 2000     

Event-related potentials in chronic alcoholics during withdrawal and abstinence

Twenty-one chronic alcoholics were submitted to an "oddball" auditory event-related potentials (ERP) paradigm and to the Wechsler Memory Scale (WMS) after four weeks' abstinence. Eight of these patients were also submitted to the same ERP procedure and to two WMS items (digit span and associations) during a minor withdrawal state in the first days of hospitalization. Alcoholics showed reduced N1-P3 and N2-P3 amplitudes as compared to control subjects. Three alcoholics showed a P3 latency that exceeded the age-corrected control range (2 SE). There was no correlation between neuropsychological performances and electrophysiological measures, but the three subjects with abnormal P3 latencies had lower WMS scores. During withdrawal, greater N1-P2 amplitudes and shorter P3 latencies were observed as well as poorer performances on the two WMS items. The results are discussed in view of the possible contributions of ERPs in the understanding of the effects of chronic alcohol intake and alcohol withdrawal on CNS functions.     

Effect of oral acamprosate on abstinence in patients with alcohol dependence in a double-blind, placebo-controlled trial: the role of patient motivation

This is the first US study to evaluate the clinical efficacy of acamprosate (Campral), a newly FDA-approved medication for maintaining abstinence in patients with alcohol dependence following alcohol withdrawal. We compared effects of the standard 2 g dose (n=258) and an exploratory 3 g dose of acamprosate (n=83) versus placebo (n=260), and evaluated drug safety in a double-blind, placebo-controlled 6-month trial conducted in 21 outpatient clinics across the US. Participants were 601 volunteers with current alcohol dependence recruited primarily by advertisement. All patients concomitantly received eight sessions of brief manual-guided counseling (www.alcoholfree.info). The main outcome measure was the percentage of alcohol-free days over the 6-month study. Self-report was validated by breath alcohol concentration, gamma-glutamyltransferase (GGT) and collateral informant interviews. The percentage of abstinent days did not differ significantly across groups in a priori analysis (54.3% for placebo, 56.1% for 2 g, 60.7% for 3 g). Post-hoc analysis controlling for baseline variables and treatment exposure found acamprosate was associated with a significantly higher percentage of abstinent days than placebo (52.3% for placebo, 58.2% for 2 g, 62.7% for 3 g; P=0.01), with an even greater effect in the subgroup of 241 patients having a baseline goal of abstinence (58.1% for placebo, 70.0% for 2 g, 72.5% for 3 g; P=0.02). There were no deaths or serious drug-related adverse events. The US study findings suggest that acamprosate is safe and well tolerated in a broadly inclusive sample of alcoholics and appears effective in populations of patients motivated to have a treatment goal of abstinence.     

Association of a functional polymorphism in the mu-opioid receptor gene with alcohol response and consumption in male rhesus macaques

CONTEXT: Innate differences in opioid neurotransmission are hypothesized to influence abuse liability of alcohol. In humans, a variant of the mu-opioid receptor gene (OPRM1A118G) increases receptor affinity, alcohol-induced euphoria, and risk for alcohol use disorders. OBJECTIVE: To determine whether a variant in the mu-opioid receptor gene (OPRM1C77G) that increases affinity of the receptor is associated with alcohol response and consumption in macaques. DESIGN: Young adult rhesus macaques (Macaca mulatta) were intravenously administered 2.0 to 2.1 g of ethanol per kilogram of body weight and assessed for alcohol response. Animals were later given simultaneous access to an aspartame-sweetened 8.4% (vol/vol) ethanol solution and a vehicle for 1 hour per day, 5 days a week, for a period of 6 weeks. Animals (N = 82) were genotyped for the OPRM1C77G polymorphism; the effects of the genotype on alcohol response and consumption were determined by analysis of variance, with sex included as a nominal independent variable. MAIN OUTCOME MEASURES: Alcohol response (ataxia, stimulation, and sedation), average alcohol consumption, the percentage of days during which an animal consumed alcohol at a level sufficient to produce intoxication (> or =0.67 g of alcohol per kilogram of body weight), and alcohol preference (calculated as 100 x {alcoholic solution/[alcoholic solution + nonalcoholic solution]}). RESULTS: Increased alcohol-induced stimulation was observed among male macaques carrying the OPRM1C77G allele. OPRM1C77G allele carriers consumed more ethanol and exhibited increased ethanol preference. Male carriers of the OPRM1C77G allele exhibited higher alcohol preference and consumption, and drank to intoxication more frequently than did C/C males. CONCLUSIONS: These findings demonstrate that the rhesus macaques' equivalent of the OPRM1A118G variant is associated with increased alcohol response, consumption, and preference. Our results reveal effects of the OPRM1C77G genotype to be male-restricted or more marked among male macaques. This is of interest, given the fact that early-onset type II alcoholism is more common among men and that, among addicted individuals, men are more responsive to mu-opioid receptor blockade.     

TRH (protirelin) in depressed alcoholic men. Behavioral changes and endocrine responses.

Chronic alcoholics with secondary depression were treated with protirelin in a double-blind, placebo-controlled study. Behavioral data, collected only during the acute alcohol withdrawal state, indicated a beneficial effect of protirelin three hours after injection, but not during subsequent days. Injections caused only mild and infrequent subjective side effects and no cardiovascular effects. Endocrine data were recorded in the acute withdrawal state and after clinical remission. Findings in the acute state suggested thyroid activation and increased central dopaminergic activity, as evidenced by elevated baseline levels of growth hormone, low baseline levels of prolactin, and blunted thyroid-stimulating hormone (TSH) response to protirelin. The first two abnormalities returned to normal levels in the remission state. A blunted TSH response was observed in both the acute and the remission states. Partial persistence of this finding suggests that TSH blunting may not be solely state-dependent. In the acute withdrawal state, TSH blunting was associated with favorable behavioral responses to protirelin.     

Effects of (+/-) 3,4-methylene-dioxymethamphetamine (ecstasy) on dopamine system function in humans

Twelve (+/-) 3,4-methylenedioxymethamphetamine (MDMA) users, who did not show other drug dependencies or prolonged alcohol abuse (group A), and 12 control subjects (group B) were included in the study. Prolactin (PRL) and growth hormone (GH) responses to the dopaminergic agonist bromocriptine (BROM) and psychometric measures were evaluated 3 weeks after MDMA discontinuation. PRL decreased both in A and B subjects after BROM suppression, without any significant difference between the two groups. PRL responses to BROM in MDMA users were in the normal range. In contrast, GH responses to BROM stimulation were found significantly reduced in ecstasy users, in comparison with control subjects (P < 0.001; F = 6.26). MDMA users showed higher scores on the Novelty Seeking (NS) scale at the Three dimensional Personality Questionnaire (TPQ), on direct aggressiveness subscale at Buss Durkee Hostility Inventory (BDHI), on subscale D (depression) at Minnesota Multiphasic Personality Inventory (MMPI 2) and on Hamilton Depression Rating Scale (HDRS) than control subjects. PRL areas under the curves (AUCs) showed a significant inverse correlation with NS scores both in A and B subjects. GH AUCs directly correlated with NS scores in healthy subjects, but not in MDMA users. No other psychometric measure correlated with hormonal responses. GH AUCs were inversely correlated with the measures of MDMA exposure (r = -0.48; P < 0.01). Lower GH response to BROM in A subjects (MDMA users) could reflect reduced D2 receptor sensitivity in the hypothalamus, possibly due to increased intrasynaptic dopamine concentration. Although the hypothesis of dopaminergic changes associated with a premorbid condition cannot be completely excluded, the inverse correlation between DA receptors sensitivity and the extent of ecstasy exposure may suggest a direct pharmacological action of MDMA on brain dopamine function in humans.     

Psychopathology of alcoholics during withdrawal and early abstinence

Epidemiologic surveys show a high lifetime co-morbidity with psychiatric disorders (e.g., depression and anxiety) in alcoholics. However, alcoholics frequently complained about psychopathologic symptoms, particularly during alcohol withdrawal. There is some evidence that symptomatology decreases spontaneously with prolonged abstinence. Thus, the question arises whether high levels of psychopathology could be accounted for by withdrawal effects. This study was aimed at examining the impact of the alcohol withdrawal severity (assessed by the AWS scale) on psychopathologic symptoms. The psychopathologic profile of 110 alcoholics as measured by the Symptom Checklist-90 revised (SCL-90-R) was compared to that of 253 patients with adjustment, anxiety or depressive disorders (according to ICD-10 criteria). No relationship between the severity of alcohol withdrawal and psychopathology could be found which might hint at two different neurobiological processes underlying these phenomena. The comparison with patients suffering from depression or anxiety disorders revealed that the global symptom severity of alcoholics undergoing withdrawal was similar, but recovery was achieved more rapidly than in the other groups. On the other hand, the self-rated psychopathologic symptom profile of alcoholics was rather similar to that of patients with adjustment disorders. While about one-quarter of the alcoholics reported severe psychopathology on admission, only about 10% showed symptomatology at discharge about three weeks later, predominantly depression or anxiety. These results underline the notion that much of the psychopathology described by alcoholics decreases within 2-3 weeks after withdrawal without specific treatment.