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

Reward Processing in Alcohol-Dependent Patients and First-Degree Relatives: Functional Brain Activity During Anticipation of Monetary Gains and Losses

BACKGROUND

According to the reward deficiency syndrome and allostatic hypotheses, hyposensitivity of mesocorticolimbic regions to non-alcohol-related stimuli predisposes to dependence or is long-lastingly enhanced by chronic substance use. To date, no study has directly compared mesocorticolimbic brain activity during non-drug reward anticipation between alcohol-dependent, at risk, and healthy subjects.

METHODS

Seventy-five abstinent alcohol-dependent human subjects (mean abstinence duration 957.66 days), 62 healthy first-degree relatives of alcohol-dependent individuals, and 76 healthy control subjects without family history of alcohol dependence performed a monetary incentive delay task. Functional magnetic resonance imaging data of the anticipation phase were analyzed, during which visual cues predicted that fast response to a target would result in monetary gain, avoidance of monetary loss, or a neutral outcome.

RESULTS

During gain anticipation, there were no significant group differences. During loss anticipation, abstinent alcohol-dependent subjects showed lower activity in the left anterior insula compared with healthy control subjects without family history of alcohol dependence only (Montreal Neurological Institute [MNI] -25 19 -5; t₂₀₆ = 4.17, familywise error corrected p = .009). However, this effect was no longer significant when age was included as a covariate. There were no group differences between abstinent alcohol-dependent subjects and healthy first-degree relatives or between healthy first-degree relatives and healthy control subjects during loss anticipation, respectively.

CONCLUSIONS

Neither the neural reward deficiency syndrome nor the allostatic hypotheses are supported by the results. Future studies should investigate whether the incentive salience hypothesis allows for more accurate predictions regarding mesocorticolimbic brain activity of subjects with alcohol dependence and healthy individuals during reward and loss anticipation and further examine the neural substrates underlying a predisposition to dependence.

Computational analysis of probabilistic reversal learning deficits in male subjects with alcohol use disorder

BACKGROUND

Alcohol use disorder is characterized by perseverative alcohol use despite negative consequences. This hallmark feature of addiction potentially relates to impairments in behavioral flexibility, which can be measured by probabilistic reversal learning (PRL) paradigms. We here aimed to examine the cognitive mechanisms underlying impaired PRL task performance in patients with alcohol use disorder (AUDP) using computational models of reinforcement learning.

METHODS

Twenty-eight early abstinent AUDP and 27 healthy controls (HC) performed an extensive PRL paradigm. We compared conventional behavioral variables of choices (perseveration; correct responses) between groups. Moreover, we fitted Bayesian computational models to the task data to compare differences in latent cognitive variables including reward and punishment learning and choice consistency between groups.

RESULTS

AUDP and HC did not significantly differ with regard to direct perseveration rates after reversals. However, AUDP made overall less correct responses and specifically showed decreased win-stay behavior compared to HC. Interestingly, AUDP showed premature switching after no or little negative feedback but elevated proneness to stay when accumulation of negative feedback would make switching a more optimal option. Computational modeling revealed that AUDP compared to HC showed enhanced learning from punishment, a tendency to learn less from positive feedback and lower choice consistency.

CONCLUSION

Our data do not support the assumption that AUDP are characterized by increased perseveration behavior. Instead our findings provide evidence that enhanced negative reinforcement and decreased non-drug-related reward learning as well as diminished choice consistency underlie dysfunctional choice behavior in AUDP.

Neurochemical mechanisms of alcohol withdrawal

Alcohol dependence encompasses a serious medical and societal problem that constitutes a major public health concern. A serious consequence of dependence is the emergence of symptoms associated with the alcohol withdrawal syndrome when drinking is abruptly terminated or substantially reduced. Clinical features of alcohol withdrawal include signs of central nervous system hyperexcitability, heightened autonomic nervous system activation, and a constellation of symptoms contributing to psychologic discomfort and negative affect. The development of alcohol dependence is a complex and dynamic process that ultimately reflects a maladaptive neurophysiologic state. Perturbations in a wide range of neurochemical systems, including glutamate, γ-aminobutyric acid, monoamines, a host of neuropeptide systems, and various ion channels produced by the chronic presence of alcohol ultimately compromise the functional integrity of the brain. These neuroadaptations not only underlie the emergence and expression of many alcohol withdrawal symptoms, but also contribute to enhanced relapse vulnerability as well as perpetuation of uncontrolled excessive drinking. This chapter highlights the hallmark features of the alcohol withdrawal syndrome, and describes neuroadaptations in a wide array of neurotransmitter and neuromodulator systems (amino acid and monoamine neurotransmitter, neuropeptide systems, and various ion channels) as they relate to the expression of various signs and symptoms of alcohol withdrawal, as well as their relationship to the significant clinical problem of relapse and uncontrolled dangerous drinking.

Wege aus der Abhängigkeit

Hintergrund: Alkohol-assoziierte Reize lösen bei alkoholabhängigen Patienten konditionierte Reaktionen aus, die zu einer erhöhten Motivation der Alkoholeinnahme führen können. Klassische Konditionierungsprozesse scheinen demnach sowohl zur Aufrechterhaltung der Abhängigkeit als auch zum Rückfallgeschehen nach Entzug beizutragen. Bildgebende Studien weisen darauf hin, dass das dopaminerge Neurotransmittersystem an assoziativen Lernvorgängen beteiligt ist und Veränderungen innerhalb dieses Systems bei entgifteten alkoholabhängigen Patienten zum Rückfall beitragen könnten. Die genauen Mechanismen in diesem Zusammenhang sind bisher jedoch ungeklärt. Zielsetzung: Ziel dieser Arbeit ist die Darstellung von motivationalen Veränderungen und deren (neuroadaptiven) Grundlagen bei Alkoholabhängigkeit. Ein genaueres Verständnis davon, welche neuronalen und motivationalen Prozesse im Rahmen des Rückfallgeschehens eine Rolle spielen, könnte sowohl pharmakologische als auch therapeutische Implikationen für die Behandlung der Alkoholabhängigkeit liefern. Methodik: Diese Arbeit umfasst eine Literaturanalyse über neuroadaptive Veränderungen bei Alkoholabhängigkeit mit besonderem Fokus auf Lernprozesse und deren Rolle beim Rückfallgeschehen. Die Literaturrecherche basiert auf Recherchen der Forschergruppe 1617 der Deutschen Forschungsgesellschaft (DFG; Learning and Habitization in Alcohol Dependence, LeAD). Schlussfolgerung: Bisher existieren keine Untersuchungen, in denen neuroadaptive Veränderungen der Alkoholabhängigkeit mit spezifischen Lerndefiziten in Zusammenhang gebracht werden. Die DFG Forschergruppe LeAD untersucht neuronale Korrelate von lernbezogenen Rückfallprädiktoren. Ein Ziel dieser Untersuchung ist es herauszufinden, warum alkoholabhängige Patienten nach ihrer Entgiftung oft nicht lernen, Alkohol durch alternative belohnende Reize und Situation zu ersetzen und welche neuronalen Grundlagen diesem Defizit zu Grunde liegen.

Acute withdrawal, protracted abstinence and negative affect in alcoholism: are they linked?

The role of withdrawal-related phenomena in the development and maintenance of alcohol addiction remains under debate. A 'self-medication' framework postulates that emotional changes are induced by a history of alcohol use, persist into abstinence, and are a major factor in maintaining alcoholism. This view initially focused on negative emotional states during early withdrawal: these are pronounced, occur in the vast majority of alcohol-dependent patients, and are characterized by depressed mood and elevated anxiety. This concept lost popularity with the realization that in most patients, these symptoms abate over 3-6 weeks of abstinence, while relapse risk persists long beyond this period. More recently, animal data have established that a prolonged history of alcohol dependence induces more subtle neuroadaptations. These confer altered emotional processing that persists long into protracted abstinence. The resulting behavioral phenotype is characterized by excessive voluntary alcohol intake and increased behavioral sensitivity to stress. Emerging human data support the clinical relevance of negative emotionality for protracted abstinence and relapse. These developments prompt a series of research questions: (1) are processes observed during acute withdrawal, while transient in nature, mechanistically related to those that remain during protracted abstinence?; (2) is susceptibility to negative emotionality in acute withdrawal in part due to heritable factors, similar to what animal models have indicated for susceptibility to physical aspects of withdrawal?; and (3) to what extent is susceptibility to negative affect that persists into protracted abstinence heritable?

Sleep disturbance as a universal risk factor for relapse in addictions to psychoactive substances

Relapse to uncontrolled use of a psychoactive substance is arguably the single most defining characteristic of an addiction. Relapse following addiction treatment is very common with serious consequences to individuals, families, and the public system of care, making predictors of relapse a highly significant area of study. Before the turn of the century, most of the addiction treatment outcome literature focused on psychosocial predictors of relapse. More recently, investigating biological predictors of relapse specifically and treatment outcome broadly has gained momentum. This line of research has linked sleep disturbances to the risk of relapse among persons who are recovering from an alcohol addiction. Given common neurobiological and psychosocial processes in sleep and addictive behaviors, we hypothesize that the link between sleep disturbance and relapse risk observed among alcohol addiction generalizes to all other types of psychoactive substances. This hypothesis has the potential for helping develop more effective and targeted treatment approaches for persons with addiction. As initial support for the hypothesis, this paper reviews evidence on common neurobiological processes among various types of psychoactive substances that suggests sleep is a universal risk factor for relapse. A conceptual framework is also presented to articulate causal mechanisms. The paper concludes with implications for research and practice.

The dopamine agonist apomorphine differentially affects cognitive performance in alcohol dependent patients and healthy controls

BACKGROUND

Reduced metabolic activity in frontal brain regions, and reduced striatal dopamine receptor densities have been shown in alcohol dependent patients. Little is known on functional changes in the fronto-striatal-thalamic dopaminergic neurocircuitry in these patients. The objective of this study was to assess sensitivity of prefrontal dopamine receptors in alcohol dependent patients.

EXPERIMENTAL PROCEDURES

Male alcohol dependent patients (N=40) and healthy controls (N=39) performed an AX-continuous performance test before and after administration of the DA agonist apomorphine (0.005 mg/kg).

RESULTS

At baseline alcohol dependent patients were slower and less accurate compared to healthy controls. After administration of apomorphine, performance improved in alcohol dependent patients and deteriorated in healthy controls.

CONCLUSIONS

Reduced cognitive performance in alcohol dependent patients compared with healthy controls may indicate dopamine dysfunctioning at the prefrontal level. Improvement of cognitive performance in alcohol dependent patients after administration of apomorphine and deterioration in healthy controls provides evidence for an inverted U-shape relation between dopaminergic functioning and cognitive performance.

Elevated prolactin serum levels and history of alcohol withdrawal seizures

BACKGROUND

Prolactin has been discussed to be useful for differential diagnosis in epilepsia. Aim of the present study was to investigate the association between prolactin serum levels and previous alcohol withdrawal seizures.

METHODS

We assessed 118 male patients admitted for detoxification treatment. Previous withdrawal seizures were recorded and prolactin serum levels were measured using an enzymatic immunoassay.

RESULTS

Patients with a history of alcohol withdrawal seizures had significantly higher prolactin levels (17.8 ng/ml, SD=12.1) than patients without previous seizures (13.0 ng/ml, SD=8.1, p<0.05). Logistic regression revealed significant predictive qualities for prolactin serum levels (B=0.05, Wald=5.30, p=0.021, OR=1.06, 95%CI=1.01-1.11).

CONCLUSIONS

The present findings show an association between elevated prolactin serum levels and a history of withdrawal seizures. Hence, the results suggest that prolactin elevation at admission may be a clinical marker for an increased risk of withdrawal seizures.

A Double-Blind, Placebo-Controlled Study of Olanzapine in the Treatment of Alcohol-Dependence Disorder

BACKGROUND

A 12-week, double-blind, randomized, parallel-group clinical trial, comparing olanzapine and placebo treatment together with cognitive-behavioral psychotherapy, was carried out to determine the efficacy, safety, and tolerability of olanzapine in the treatment of alcoholism.

METHODS

A total of 60 alcohol-dependent patients were assigned to 12 weeks' treatment with either olanzapine or placebo. The primary variable relapse to heavy drinking rate was evaluated by means of intention-to-treat analyses. Alcohol consumption, craving, adverse events, and changes in the biochemical markers of heavy drinking and possible toxicity were also evaluated.

RESULTS

We did not find significant differences in the survival analysis between placebo and olanzapine-treated patients (Kaplan-Meier log rank = 0.46, df = 1, p = 0.50). Eleven (37.9%) patients treated with olanzapine relapsed compared with 9 (29%) of those receiving placebo (chi = 0.53, df = 1, p = 0.5). Although some adverse events (weight gain, increased appetite, drowsiness, constipation, and dry mouth) were found more frequently in the olanzapine group, differences did not reach statistical significance in comparison with the placebo group.

CONCLUSIONS

Olanzapine was well tolerated, as the rate of adverse events was low, and it was safe, because it did not interfere with the normalization of biochemical markers of heavy drinking or alter liver function markers. Alcohol-dependent patients showed good adherence and compliance with the treatment protocol, but we found no differences in relapse rate or other drinking variables when comparing olanzapine with placebo-treated patients.

Prevalence and distinct correlates of anxiety, substance, and combined comorbidity in a multi-site public sector sample with bipolar disorder

BACKGROUND

Recent data indicate high prevalence of both anxiety and substance comorbidity in bipolar disorder. However, few studies have utilized public sector samples, and only one has attempted to separate contributions of each type of comorbidity.

METHODS

328 inpatient veterans with bipolar disorder across 11 sites were assessed using selected Structured Clinical Interview for DSM-IV modules and self-reports.

RESULTS

Comorbidity was common (current: 57.3%; lifetime: 78.4%), with multiple current comorbidities in 29.8%. Substance comorbidity rate was comparable to rates typically reported in non-veteran inpatient samples (33.8% current, 72.3% lifetime). Selected anxiety comorbidity rates exceeded those in other inpatient samples and appeared more chronic than episodic/recurrent (38.3% current, 43.3% lifetime). 49% of PTSD was due to non-combat stressors. Major correlates of current substance comorbidity alone were younger age, worse marital status, and higher current employability. Correlates of current anxiety comorbidity alone were early age of onset, greater number of prior-year depressive episodes, higher rates of disability pension receipt, and lower self-reported mental and physical function. Combined comorbidity resembled anxiety comorbidity.

LIMITATIONS

This is a cross-sectional analysis of acutely hospitalized veterans.

CONCLUSIONS

Distinct patterns of substance and anxiety comorbidity are striking, and may be subserved by distinct neurobiologic mechanisms. The prevalence, chronicity and functional impact of anxiety disorders indicate the need for improved recognition and treatment of this other dual diagnosis group is warranted. Clinical and research interventions should recognize these divergent comorbidity patterns and provide individualized treatment built "from the patient out."

Pharmacology of drugs of abuse

The pharmacology of most addictive substances is being studied extensively, not just for their acute effects but also the mechanisms that lead to drug seeking and addiction. The understanding of how these drugs alter their effects at the molecular level with continuing use gives promise toward investigation of novel substances that may be used for treatment. Genetic predisposition and gender differences are also some of the areas where more research is needed. Women who are addicted are likely to continue drug use during pregnancy, which can have an impact on the next generation. Prevention measures at the population level are as important. Programs need to address risks, social issues, and environmental factors that promote drug use and addiction.

Outcome predictors in substance use disorders

Given the heterogeneous nature of substance abuse, it is notable that several predictors of response are independent of the primary drug of abuse or the treatment setting [208]. Although the strength of the relationship of predictor to outcome varies, the following factors have been identified consistently: severity of dependence or withdrawal; psychiatric comorbidity; substance-related problems; motivation (abstinence commitment); length of treatment; negative affective states; cognitive factors; personality traits and disorders; coping skills; multiple substance abuse; contingency contracting or coercion; genetic factors; sleep architecture; urges and craving; self-efficacy; and economic and social factors. Although it is well known that severity of dependence (including polysubstance abuse), serious psychiatric comorbidity, and social problems are associated with poor treatment response, only recently has research examined the efficacy of intervention strategies that specifically address these problems. Adequate treatment of psychiatric comorbidity and improvement in social, economic, and family functioning lead to better treatment outcomes. The development of specific techniques to enhance self-efficacy, motivation, coping skills, and functioning in the community are concrete examples of how the identification of factors associated with positive outcomes has led to the development of new treatments. Despite significant accomplishments, the field is left with many unanswered questions. Although several biologic markers, such as neuroendocrine response and sleep architecture, show promise as outcome predictors, it is not known whether these are critical factors in the initiation of substance use or its progression to dependence. Determining whether biologic markers are epiphenomena reflecting the amount and duration of substance abuse or are fundamental to the pathophysiology of dependence is a matter of urgent concern. With some exceptions, identification of biologic predictors has not led to innovative therapies. One of these exceptions is the development of naltrexone for the treatment of alcoholism, which was based in a solid theoretical rationale and followed by hypothesis-driven experiments. Similar opportunities should emerge from current basic science and clinical research. The application of pharmacogenetic techniques to the field of addiction also holds great promise. As future studies are undertaken, researchers and clinicians must be mindful that differences in outcome predictors across drugs of abuse and treatments may emerge as subgroups of individuals with addictive disorders and new therapies are identified. There is already evidence that early onset alcoholism is associated with poor response under some circumstances, yet may be a predictor of response to targeted pharmacotherapy with ondansetron [64, 112]. As the ability to subtype disorders based on meaningful biologic differences grows, it is anticipated that several relevant outcome predictors that are specific for pharmacotherapy will emerge.

Behavioral neurobiology of alcohol addiction: recent advances and challenges

Addictive behavior associated with alcoholism is characterized by compulsive preoccupation with obtaining alcohol, loss of control over consumption, and development of tolerance and dependence, as well as impaired social and occupational functioning. Like other addictive disorders, alcoholism is characterized by chronic vulnerability to relapse after cessation of drinking. To understand the factors that compel some individuals to drink excessively, alcohol research has focused on the identification of brain mechanisms that support the reinforcing actions of alcohol and the progression of changes in neural function induced by chronic ethanol consumption that lead to the development of dependence. More recently, increasing attention has been directed toward the understanding of neurobiological and environmental factors in susceptibility to relapse.

Dopaminergic dysfunction in alcoholism and schizophrenia--psychopathological and behavioral correlates

Dysfunction of central dopaminergic neurotransmission has been implicated in the pathogenesis of schizophrenia as well as drug and alcohol dependence. Different drugs of abuse stimulate dopamine release in the ventral striatum and thus reinforce drug consumption. Increased subcortical dopamine release has also been associated with the pathogenesis of positive symptoms in schizophrenia and may be driven by a prefrontal dopaminergic dysfunction. These seemingly heterogeneous findings may be explained by recent research in non-human primates. According to these studies, reward anticipation but not anticipated reward consumption is accompanied by a phasic dopamine release in the striatum and prefrontal cortex. In the striatum, phasic dopamine release primarily affects motivation, psychomotor activation and reward craving, while in the prefrontal cortex, dopaminergic stimulation is involved in the activation of working memory and reward anticipation. In alcoholism, previously neutral stimuli that have been associated with alcohol intake can become conditioned cues which activate phasic dopamine release and reward craving. In schizophrenia, stress-induced or chaotic activation of dopamine release may attribute incentive salience to otherwise irrelevant stimuli and thus be involved in the pathogenesis of delusional mood and other positive symptoms. Studies in humans and non-human primates emphasize the role of dopaminergic neurotransmission in reward anticipation and its dysfunction in different neuropsychiatric diseases.

Dopamine and alcohol relapse: D1 and D2 antagonists increase relapse rates in animal studies and in clinical trials

A considerable number of animal studies on the effects of dopaminergic agents on alcohol intake behavior have been performed. Acute alcohol administration in rats induces dopamine release in the caudate nucleus and in the nucleus accumbens, an effect related among others to reinforcement. It has been repeatedly suggested that D1 and D2 receptor activation mediates reward. As alcohol consumption and dopaminergic transmission seem to have a close relationship, all kinds of dopaminergic agents may be regarded as putative therapeutics for preventing relapse. In a prospective European double-blind multicenter clinical trial, comparing the D1, D2, D3 antagonist flupenthixol and placebo in 281 chronic alcohol-dependent patients (27.4% women), the application of the Lesch typology made an outcome differentiation possible. It could be shown in which patients flupenthixol administration was followed by a significantly higher relapse rate and in which patient groups no differences were found when compared to placebo.

Genotype effects on neurodegeneration and neuroadaptation in monoaminergic neurotransmitter systems

Neuroadaptation and neurodegeneration in central dopaminergic and serotonergic systems are central to vulnerability, process and consequences of addictive behavior. Serotonergic dysfunction has been associated with behavior disinhibition and negative mood states that may predispose to excessive alcohol intake, while alcohol-induced stimulation of dopaminergic neurotransmission may encode the reinforcing properties of alcohol consumption. Chronic alcohol intake induces neuroadaptive reductions in striatal dopamine transporter (DAT) and D2 receptor availability, which were reversible during early abstinence. A polymorphism of the DAT gene (SLC6A3) was associated with the in vivo transporter availability in the putamen of abstinent alcoholics and control subjects. The same genotype was associated with severity of alcohol withdrawal symptoms, hypothetically due to interactions of genotype and alcohol-induced neuroadaptation. Reduction in raphe serotonin transporter (5-HTT) availability was observed in abstinent male alcoholics and it may be the result of neurodegeneration rather than reversible neuroadaptation. Neurotoxic reduction in 5-HTT protein expression seems to be limited to homozygous carriers of a long, more transcriptionally active allele of a promoter repeat polymorphism of the 5-HTT gene (SCL6A4). This genotype was also associated with a low level of acute unpleasant effects of alcohol consumption, a factor predisposing to excessive alcohol intake. The time course of neuroadaptation and recovery of monoaminergic neurotransmission in alcohol intake and withdrawal imply that monoamine transporter genotype could profoundly influence alcohol-induced reinforcement and, perhaps, contribute to neurochemical changes which are long lasting or permanent.

Severity of depression in abstinent alcoholics is associated with monoamine metabolites and dehydroepiandrosterone-sulfate concentrations

Depressed mood increases the relapse risk of abstinent alcoholics; its neurobiological correlates may include reduced serotonin and norepinephrine turnover rates and increased cortisol concentrations during detoxification stress. Neurosteroids such as dehydroepiandrosterone and its sulfate (DHEA and DHEA-S) may antagonize cortisol action and may have mood-elevating effects on their own. We measured severity of depression with Beck's Depression Inventory (BDI) and Hamilton's Depression Rating Scale (HDRS), plasma concentrations of cortisol, DHEA and DHEA-S, and CSF concentrations of the serotonin metabolite 5-hydroxyindoleacetic acid (5-HIAA), the norepinephrine metabolite 3-methoxy-4-hydroxyphenylglycol (MHPG) and the dopamine metabolite homovanillic acid (HVA) in 21 abstinent alcoholics after 4 weeks of abstinence and in 11 age-matched healthy control subjects. Only CSF MHPG concentrations were reduced in alcoholics compared to control subjects (41.4 +/- 6.6 vs. 53.3 +/- 8.6 pmol/ml). Self-rated depression was significantly correlated with CSF MHPG (Spearman's R = +0.57, P < 0.01), CSF 5-HIAA (R = +0.51, P < 0.05) and plasma cortisol concentrations (R = +0.50, P < 0.05). Negative correlations were found between DHEA-S concentrations and both self-rated depression (R = -0.45, P < 0.05) and observer-rated depression (R = -0.55, P < 0.05). The ratio of DHEA-S to cortisol serum concentrations was also negatively correlated with depression (BDI: R = -0.55, P < 0.01; HDRS: R = -0.63, P < 0.005). Anxiety (Spielberger's State Anxiety Scale) was only associated with CSF MHPG concentrations (R = +0.58, P < 0.01). Our findings point to the importance of noradrenergic dysfunction in the pathogenesis of depression among abstinent alcoholics and indicate that their mood states may also be modulated by a low DHEA-S to cortisol ratio, hypothetically indicative of low stress protection capacities.

Effects of nimodipine on extracellular dopamine levels in the rat nucleus accumbens in ethanol withdrawal

Withdrawal from chronic ethanol intoxication is associated with a reduction of dopamine neurotransmission. However, the mechanisms of dopamine depletion, a putative neurochemical correlate of the dysphoric symptomatology, are not yet understood. To assess the role of L-type calcium channels in the inhibition of the dopaminergic system in the withdrawal state, the effects of the dihydropyridine calcium channel antagonist nimodipine on the extracellular levels of dopamine were studied in the nucleus accumbens shell of awake rats 10 h after withdrawal from chronic ethanol intoxication. In control, chronic sucrose-withdrawn rats, nimodipine did not change extracellular dopamine levels. However, in ethanol-withdrawn rats nimodipine (5 or 10 mg/kg s.c.) increased extracellular dopamine to 136 +/- 16 and 305 +/- 19% of pre-administration values, respectively, the latter dose elevating levels above those of controls. The elevations of extracellular DA by nimodipine (10 mg/kg) were associated with a significant reduction (-17%) of the overall behavioural score of the withdrawal symptomatology, as evaluated for 11 behavioural items. Significant reductions of the score for convulsions (-47%) and, to a lesser extent, for catatonia (-30%) and tremors (-15%) contributed to the overall effect. It is suggested that overactivity of L-type calcium channels is involved in the mechanisms of dopamine depletion as well as in certain behavioural/neurological signs associated with ethanol withdrawal. By restoring depleted dopamine levels, dihydropyridines might ameliorate the dysphoric symptoms of ethanol abstinence.

Alcohol, slow wave sleep, and the somatotropic axis

When alcohol is a large proportion of daily nutrient energy, the network of signals for energy homeostasis appears to adapt with abnormal patterns of sleep and growth hormone (GH) release along with gradual acquisition of an addictive physical dependency on alcohol. Early relapse during treatment of alcoholism is associated with a lower GH response to challenge, perhaps reflecting an altered balance of somatostatin (SS) to somatropin releasing hormone (GHRH) that also affects slow wave sleep (SWS) in dependent patients. Normal patterns of sleep have progressively shorter SWS episodes and longer rapid eye movement (REM) episodes during the overall sleep period, but the early sleep cycles of alcoholics have truncated or non-existent SWS episodes, and the longer REM episodes occur in early cycles. During SWS delta wave activity, the hypothalamus releases GHRH, which causes the pituitary to release GH. Alcohol-dependent patients have lower levels of SWS power and GH release than normal subjects, and efforts to understand the molecular basis for this maladaptation and its relation to continued alcohol dependence merit encouragement. More needs to be learned about the possibility of decreasing alcohol dependency by increasing SWS or enhancing GHRH action.

Buspirone treatment of alcoholism: age of onset, and cerebrospinal fluid 5-hydroxyindolacetic acid and homovanillic acid concentrations, but not medication treatment, predict return to drinking

Disturbances in central nervous system serotonin (5-HT) have been implicated in the pathophysiology of alcoholism. To test the hypothesis that increasing 5-HT function could promote treatment compliance, we randomized patients who had completed a 5-week inpatient treatment program for alcoholism to receive either buspirone or placebo for 1 year. Ten of the 49 patients remained in the study for the entire year. The days to relapse did not differ significantly between patients receiving buspirone or placebo. Regardless of the medication, late-onset alcoholics had a longer time to relapse than early-onset alcoholics. Cerebrospinal fluid showed that patients with high concentrations of both the 5-HT metabolite, 5-hydroxyindoleacetic acid, and the dopamine metabolite, homovanillic acid, were more likely to relapse, compared with patients with low concentrations of cerebrospinal fluid 5-hydroxyindoleacetic acid and homovanillic acid.

Lack of allelic association of dopamine D1 and D2 (TaqIA) receptor gene polymorphisms with reduced dopaminergic sensitivity to alcoholism

Our study tested the hypothesis of whether the sensitivity of central dopamine receptors corresponds to the genotypic constitution of DNA-polymorphisms of the dopamine D1 and D2 receptor (DRD1, DRD2) genes and is associated with poor treatment outcome. Therefore, 97 alcohol-dependent patients were assessed according to their sensitivity of central dopamine receptors (apomorphine-induced secretion of growth hormone), clinical outcome during a 6-month observation period, and genotypic constitution of the TaqIA restriction fragment length polymorphism (RFLP) at the DRD2 locus and of the Bsp1286I RFLP at the DRD1 locus. On the 1st day of detoxification, dopamine receptor hyposensitivity was found in treatment nonresponders, but not in responders. Apomorphine-induced growth hormone release did not differ significantly in alcoholics with different genotypes of the DRD1 and DRD2 RFLPs. Neither did we find a significant allelic association with treatment response. Thus, we did not find evidence for a genetic determination of dopamine receptor hyposensitivity in alcoholics with poor treatment outcome.