Relationships of plasma tryptophan availability to course of illness and clinical features of alcoholism: a preliminary study

The association between HTR1B gene rs13212041 polymorphism and onset of alcohol abuse

BACKGROUND

Alcohol dependence displays a wide variety of clinical phenotypes. Various typology classifications of alcoholism include age of onset of alcohol abuse as one of the major phenotypic features. Serotonergic changes have been associated with alcoholism, while serotonin receptors type 1B (5-HT1B) play an important role in regulating serotonergic neurotransmission. The rs13212041 polymorphism modulates the expression of HTR1B gene coding for 5-HT1B receptor. This study examined the association of platelet serotonin (5-HT) and HTR1B gene with the onset of alcohol abuse in alcohol-dependent subjects.

MATERIALS AND METHODS

Determination of platelet 5-HT concentration and genotyping of rs13212041 HTR1B gene polymorphism were performed in 613 alcohol-dependent patients, subdivided according to early/late onset (before/after 25 years of age) of alcohol abuse.

RESULTS

Alcohol-dependent individuals with CC genotype were more frequent in the group with early onset of alcohol abuse compared to carriers of T allele. Besides HTR1B genotype, age and gender, but not platelet 5-HT, were major variables associated with the onset of alcohol abuse. Platelet 5-HT concentration was not significantly different between patients with early and late onset of alcohol abuse, or patients carrying various HTR1B genotypes. Although we observed no influence of co-variables such as age, gender, or somatic and psychiatric comorbidities, platelet 5-HT concentration was significantly affected by smoking.

CONCLUSION

These findings support potential involvement of 5-HT1B receptors in the onset of alcohol abuse and development of alcohol dependence. Additionally, the results of our study emphasize the importance of controlling for smoking status, as one of the significant confounding factors influencing platelet 5-HT concentration.

Possible relationship between amino acids, aggression and psychopathy

OBJECTIVE

Aggressive behaviour is associated with reduced serotonin metabolism in the brain, but there is not enough knowledge on potential changes of the serotonin precursor levels among violent offenders. In this study, we aimed to evaluate the relationships among the tendency of psychopathy, anger and the basic amino acids.

METHODS

Fifty-two young adult male patients with antisocial personality disorder (APD) and 30 healthy men included the study. Serum amino acid levels were measured by HPLC method. Aggression questionnaire and Hare Psychopathology Scale were used for all participants.

RESULTS

Blood levels of phosphoserine, aspartic acid, glutamic acid, aminoadipic acid and 1-methylhistidine in group of patients with APD were significantly higher than the control group. Blood levels of TRP, asparagine, citrulline, cystine, isoleucine, tyrosine, histidine, hydroxylysine, lysine, ethanolamine and arginine in the group of patients were found lower than the control group. A significant positive correlation between anger scores and histidine, methionine and GABA was found. GABA and methionine showed a significant correlation with the indirect aggression score.

CONCLUSION

Our study showed a relationship between serum amino acid levels and the scores of aggression and psychopathy. We think that this is a productive research area for understanding the relationship among biochemical factors, aggression and psychopathy.

Comparison of alcoholism subtypes as moderators of the response to sertraline treatment

BACKGROUND

A variety of typologies have been used to categorize alcoholism's diverse manifestations. Although the most widely studied typologies are dichotomous ones based on genetic epidemiologic findings or using cluster analytic methods, recent efforts have utilized a single item or the onset of a diagnosis of alcohol dependence to subtype individuals based on the age of alcoholism onset. We compared 3 different methods to subtype alcoholics.

METHODS

This secondary analysis used data from 134 alcohol-dependent participants in a placebo-controlled trial of sertraline (Kranzler et al., 2011). We compared cluster analysis to distinguish 2 risk/severity subtypes (Babor et al., 1992) with 2 age-of-onset subtypes (i.e., based on the age of onset of problem drinking or the age at which alcohol dependence criteria were first met).

RESULTS

Each method yielded subgroups that differed significantly from one another on demographic and clinical measures. Although concordance was high between the 2 age-of-onset methods, it was poor between the age-of-onset methods and the cluster analysis-derived approach. All 3 subtyping approaches significantly moderated the effects of sertraline or placebo, but only in the L'L' genotype group, as originally reported (Kranzler et al., 2011). In all cases, sertraline treatment was superior to placebo in later-onset individuals and inferior to placebo in the earlier-onset groups.

CONCLUSIONS

Because age-of-onset subtypes can be defined retrospectively on an individual basis, they may be more clinically useful than cluster-derived subtypes, which require group data. Because the 2 age-of-onset measures we examined appear to have comparable validity, a single item is easier to use as a measure of the age of onset of problem drinking.

A double-blind, randomized trial of sertraline for alcohol dependence: moderation by age of onset [corrected] and 5-hydroxytryptamine transporter-linked promoter region genotype

Late-onset/low-vulnerability alcoholics (LOAs) appear to drink less when treated with a selective serotonin reuptake inhibitor than placebo, whereas early-onset/high-vulnerability alcoholics (EOAs) show the opposite effect. We conducted a 12-week, parallel-group, placebo-controlled trial of the efficacy of sertraline in alcohol dependence (AD). We compared the effects in LOAs versus EOAs and examined the moderating effects of a functional polymorphism in the serotonin transporter gene. Patients (N = 134, 80.6% male, 34.3% EOAs) with Diagnostic and Statistical Manual of Mental Disorders-IV AD received up to 200 mg of sertraline (n = 63) or placebo (n = 71) daily. We used urn randomization, and patients were genotyped for the tri-allelic 5-hydroxytryptamine transporter protein linked promoter region polymorphism. Planned analyses included main and interaction effects of medication group, age of onset (≤ 25 years vs >25 years), and genotype (L'/L' vs S' carriers) on drinking outcomes. Results showed that the moderating effect of age of onset on the response to sertraline was conditional on genotype. There were no main or interaction effects among S' allele carriers. However, in L' homozygotes, the effects of medication group varied by age of onset (P = 0.002). At the end of treatment, LOAs reported fewer drinking and heavy drinking days when treated with sertraline (P = 0.011), whereas EOAs had fewer drinking and heavy drinking days when treated with placebo (P < 0.001). The small cell sizes and high rate of attrition, particularly for L' homozygotes, render these findings preliminary and their replication in larger samples necessary. Because AD is common, particularly in medical settings, and selective serotonin reuptake inhibitors are widely prescribed by practitioners, these findings have potential public health significance and warrant further evaluation.

Drinking histories in alcohol-use-disordered youth: preliminary findings on relationships to platelet serotonin transporter expression with genotypes of the serotonin transporter

OBJECTIVE

The serotonin (5-HT) transporter (5-HTT) is thought to play a key role in the onset of alcohol use, with potential behavioral and biological mechanisms mediated by the level of 5-HT in the synapse and in cerebral spinal fluid. Although 5-HT dysregulation has been related to poor impulse control, the biological mechanism is unknown, although functional control of the serotonergic system has been shown to be regulated in part by differential expression of the 5-HTT. The gene responsible for encoding 5-HTT has a functional polymorphism at the 5'-regulatory promoter region, which results in two forms: long (L) and short (S). The LL genotype is hypothesized to play a key role in the early onset of alcohol use and may be related to poor impulse control. The objective of this pilot study is to determine whether adolescents with a current alcohol-use disorder (AUD) (N = 21) have platelet measures of the 5-HTT functioning that are related to 5-HTT genotype and poor impulse control. Specifically, we wanted to examine the relationships between the following: platelet 5-HTT and 5-HTT genotype; platelet 5-HTT parameters and age at onset, as well as duration of drinking; and 5-HTT genotype and impulse control.

METHOD

Adolescents with current AUD were recruited from the community to participate in a cross-section pilot study.

RESULTS

Our main findings showed significantly higher paroxetine binding (density of 5-HTT) in LL genotype versus S carriers (SS or SL genotypes); also, the LL group had a significantly earlier age at onset of drinking and longer duration of drinking, and poorer impulse control.

CONCLUSIONS

These findings provide partial support for the hypothesis that, among currently drinking adolescents with an AUD, differential expression of 5-HTT may play an important role in the onset of adolescent AUD.

Prediction of serotonergic treatment efficacy using age of onset and Type A/B typologies of alcoholism

BACKGROUND

Previously, we reported that ondansetron was efficacious at treating early-onset (< or =25-years old) but not late-onset (> or =26-years old) alcoholics in a double-blind, randomized, placebo-controlled clinical trial (n = 321 enrolled patients, 271 of them randomized). Randomized participants underwent 11 weeks of treatment with ondansetron (1, 4, or 16 microg/kg twice daily; n = 67, 77, and 71, respectively) or identical placebo (n = 56), plus weekly standardized group cognitive behavioral therapy.

METHODS

For this study, we reanalyzed the original sample to determine whether the Type A/B typological classification predicts ondansetron treatment response. In this comparative analysis, k-means clustering was applied to 19 baseline measures of drinking behavior, psychopathology, and social functioning, similar to those used by Babor in the original typological derivation. A 2-factor solution described robustly 2 groups phenomenologically consistent with Type A/B classification. Subjects were subdivided into early- and late-onset alcoholics.

RESULTS

Seventy-two percent of Type B subjects had early-onset alcoholism (EOA); 67% of Type A subjects had late-onset alcoholism (LOA). The A/B typology better discriminated 2 clusters based upon baseline severity of alcoholism. There was a significant effect (p < 0.05) for Type B alcoholics to respond to ondansetron (4 microg/kg); however, Type A alcoholics receiving ondansetron showed no beneficial effect. Early-onset vs. late-onset classification predicted ondansetron response substantially better than Type A/B classification, which did not add to the prediction of treatment outcome. Further analyses showed that ondansetron was effective in the 33% of Type A alcoholics with EOA but ineffective in the 28% of Type B alcoholics with LOA.

CONCLUSIONS

Type A/B classification best discriminates alcoholic subtypes based upon baseline severity. Early- vs. late-onset classification is, however, a better predictor of response to ondansetron treatment because it might be more closely related to fundamental neurobiological processes associated with the underlying pathophysiology of alcoholism.

The relation of free plasma tryptophan to anger, hostility, and aggression in a nonpatient sample of adult men and women

BACKGROUND

Dysregulation of central nervous system serotonergic (5-HT) activity is implicated in behavioral states and psychological traits associated with depression and aggression, with some studies suggesting possible gender-related differences.

PURPOSE

This study examined the relation of free plasma tryptophan (TRP) to aggression and depression in a sample of 138 nonsmoking adults recruited from the general community. It was hypothesized that TRP would be associated with anger, hostility, and aggression.

METHODS

To minimize effects of diurnal variation and menstrual cycle, fasting blood samples were collected in the morning, and, for women, during the follicular phase of the menstrual cycle. Participants were administered questionnaires following blood draw. Plasma TRP was determined by high performance liquid chromatography.

RESULTS

In women, but not men, higher levels of TRP were associated with trait hostility, propensity for anger, a tendency to express anger outwardly, and an antagonistic interpersonal style. For men and women, greater severity of depressive symptoms, anger, and the verbal expression of anger were associated with higher TRP. These associations were independent of age, body mass index, fasting albumin, and race and ethnicity.

CONCLUSIONS

These data suggest that in women, but not men, higher plasma levels of TRP, the precursor to 5-HT, are associated with anger-hostility-aggression and that these associations are independent of various potential confounds. Implications of these observations to studies employing acute TRP depletion studies are discussed.

Pharmacotherapy for alcohol dependence: anticraving medications for relapse prevention

Alcohol dependence is a chronic disorder that results from a variety of genetic, psychosocial, and environmental factors. Relapse prevention for alcohol dependence has traditionally involved psychosocial and psychotherapeutic interventions. Pharmacotherapy, however, in conjunction with behavioral therapy, is generating interest as another modality to prevent relapse and enhance abstinence. Naltrexone and acamprosate are at the forefront of the currently available pharmacological options. Naltrexone is an opioid receptor antagonist and is thought to reduce the rewarding effect of alcohol. Acamprosate normalizes the dysregulation of N-methyl-D- aspartate (NMDA)-mediated glutamatergic excitation that occurs in alcohol withdrawal and early abstinence. These different mechanisms of action and different target neurotransmitter systems may endow the two drugs with efficacy for different aspects of alcohol use behavior. Since not all patients seem to benefit from naltrexone and acamprosate, there are ongoing efforts to improve the treatment outcomes by examining the advantages of combined pharmacotherapy and exploring the variables that might predict the response of the medications. In addition, novel medications are being investigated to assess their efficacy in preventing relapse and increasing abstinence.

Ondansetron reduces mood disturbance among biologically predisposed, alcohol-dependent individuals

BACKGROUND

Early-onset alcoholics (EOA) differ from late-onset alcoholics (LOA) by developing problem drinking during youth, experiencing severe behavioral problems, having a familial disease history, and possessing a tendency toward subsyndromal mood disturbance, including symptoms of depression, anxiety, and hostility. Subsyndromal mood disturbance is, therefore, an important component of the early-onset syndrome and may be mediated by serotonin dysfunction. Therefore, the serotonin-3 antagonist ondansetron, which has been shown to be effective at improving drinking outcomes and promoting abstinence among EOA, presumably by ameliorating serotonin dysfunction, also may exert its beneficial effects by alleviating mood disturbance among EOA.

METHODS

After one lead-in week of single-blind placebo administration, subjects underwent 11 weeks of double-blind outpatient treatment using a 2 x 4 factorial design that examined age of onset (EOA versus LOA) and medication dose (placebo, or ondansetron 1, 4, or 16 microg/kg twice daily) combined with weekly standardized group cognitive-behavioral therapy. The placebo lead-in week was used to adjust for study entrance effects but not for excluding subjects. Assessments of mood were performed by using the overall score and subscales of the Profile of Mood States both at screening and at weekly intervals during the study.

RESULTS

Subsyndromal mood disturbance was shown to be an important component of early-onset alcoholism. Ondansetron (16 microg/kg twice daily) showed greater therapeutic efficacy at alleviating symptoms of overall mood disturbance, fatigue, vigor, confusion/bewilderment, and depression among EOA compared with LOA. EOA-associated improvements in mood disturbance seemed to be independent of drinking behavior.

CONCLUSIONS

Ondansetron has been shown to be an effective treatment for early-onset alcoholism. Ondansetron's ability to improve symptoms of depression, anxiety, and hostility among EOA may make an additional contribution to its therapeutic effect. Mechanistic studies are needed to delineate more clearly the relationship between serotonin dysfunction and pathophysiology among various subtypes of alcohol-dependent individuals.

Serotonin-3 receptors in the actions of alcohol, alcohol reinforcement, and alcoholism

This article represents the proceedings of a symposium at the 2003 annual meeting of the Research Society on Alcoholism in Fort Lauderdale, FL. The organizers and chairs were William J. McBride and David M. Lovinger. The presentations were (1) Mechanisms of alcohol potentiation of 5-HT3 receptor function, by David M. Lovinger and Tina Machu; (2) Chronic alcohol drinking alters 5-HT3 receptors regulating the mesolimbic dopamine system, by Richard J. Thielen; (3) 5-HT3 receptors in the VTA regulate alcohol drinking and the reinforcing effects of alcohol, by Zachary A. Rodd and James M. Murphy; and (4) Ondansetron as a treatment for "biological" alcoholism, by John D. Roache and Bankole A. Johnson.

Serotonergic genes and personality traits in the Korean population

Serotonergic genes have been implicated in mood disorders, alcoholism and certain personality traits. The goal of this study was to investigate the relationship between personality traits and several important genes in the serotonin system. The participants included 146 healthy adults with no history of psychiatric disorders or other physical illness during the last 6 months. All participants were tested by the Temperament and Character Inventory (TCI) and genotyped serotonin transporter, serotonin receptors (5-HT(2A) and 5-HT(6)) and tryptophan hydroxylase gene polymorphisms. Genotyping was analyzed with polymerase chain reaction. Differences in TCI dimensions and sub-scales among three groups were examined with ANOVA. Our result suggested that 5-HT(2A) receptor gene polymorphism (A-1438G) appears to be associated with self-determinism and self-transcendence (ST). Our result also indicated a significant relationship between 5-HT(6) receptor gene polymorphism (C267T) and ST. Further studies of polymorphisms of other genes and their interactions may clarify the complex relationship between personality and genes.

Genetics of alcoholism using intermediate phenotypes

This article represents the proceedings of a symposium at the 2002 meeting of the Research Society on Alcoholism in San Francisco, CA. It was organized by Mary-Anne Enoch and David Goldman and chaired by David Goldman. The presentations were (1) Two functional polymorphisms and their intermediate phenotypes in complex behaviors: COMT/executive cognition and anxiety and HTT/anxiety, by David Goldman; (2) Role of the EEG in determining genetic risk for alcoholism and anxiety disorders, by Mary-Anne Enoch; (3) The response to alcohol as an intermediate phenotype for alcoholism, by Marc A. Schuckit; and (4) Pharmacogenomic approaches to alcoholism treatment: toward a hypothesis, by Bankole A. Johnson.

Neurotransmitters, temperament and social functioning

Dimensional models can be usefully employed to describe both normal and disordered personality. Studies in molecular genetics, receptor binding, peripheral monoamines and pharmacological challenges have investigated the neurochemical basis of personality. Substantial evidence now exists to support a psychobiological model but the specificity of Cloninger's theory has not always been confirmed. Clinical studies have shown both temperament and character dimensions to improve with pharmacological treatment especially in treatment responders. Some personality changes are found to be independent of clinical effects and even to occur in normal subjects. Models of personality can help in predicting treatment outcome but individual dimensions may not be useful. It is hypothesised that social adaptation is related to the character dimensions and different sources of evidence link these to serotonergic actions. However, recent clinical studies have shown a specific effect of noradrenaline on self-perception and social motivation. Drugs with specific actions on different neurotransmitters may exert a distinctive pattern of effects on personality and social behaviour.