Are genes coding for dopamine receptors implicated in alcoholism?

Heavy nicotine and alcohol use in alcohol dependence is associated with D2 dopamine receptor (DRD2) polymorphism

Cigarette smoking in those who are alcohol dependent is associated with higher morbidity and mortality. The A1 allele of the D2 dopamine receptor (DRD2) gene has been independently associated with alcohol and nicotine dependence. Whether this polymorphism is associated with nicotine dependence in those who are also alcohol dependent has not been investigated. Subjects were 84 (61 males; 23 females) Caucasian DSM IV diagnosed nicotine- and alcohol-dependent subjects sampled from consecutive admissions to a hospital alcohol detoxification ward. Data were obtained through standardised measures of nicotine and alcohol consumption and dependence severity. A1+ allelic (A1/A1 or A1/A2 genotype) compared to A1- allelic (A2/A2 genotype only) patients were characterised by higher levels of alcohol and cigarette consumption. A1+ allelic patients reported greater alcohol dependence severity, but not nicotine dependence severity. When the combined nicotine and alcohol dose was examined, A1+ allelic patients consumed significantly more of these drugs than their A1- allelic counterparts.

Méta-analyse des gènes candidats dans le trouble déficit attentionnel avec hyperactivité (TDAH)

Attention-deficit hyperactivity disorder (ADHD) is a common behavioral disorder observed during childhood, detected in 3% to 5% of school-age children. The disorder is characterised by marked inattention, hyperactivity, and impulsiveness. In most cases, symptoms can be treated by catecholamine-releasing drugs, such as methylphenidate. Children with ADHD are at higher risk for substance abuse and oppositional, conduct and mood disorders. Familial and adoption studies shed light on the genetic vulnerability of ADHD. Twin studies estimated the broad heritability to range between 40% and 90%. The mode of transmission is yet unknown, but is likely polygenic. Molecular genetic studies in ADHD should contribute to a greater understanding of the pathophysiology of the disorder (genetics of the vulnerability), and could help to select a more rational type of treatment (pharmacogenetic). Family-based association studies already performed are reviewed in this manuscript. Association studies, using haplotype relative risk (HRR) or transmission disequilibrium test (TDT) have focused on candidate genes which code for proteins potentially involved in the etiopathogenesis of the disorder. Genes involved in dopamine, serotonin, and noradrenalin systems have thus been assessed for their role in core features of ADHD, such as motor overactivity, inattention, and impulsiveness. According to a meta-analysis, the DAT1 gene, an obvious candidate gene in ADHD vulnerability, does not appear to be involved (OR = 1.13, p = 0.21). On the other hand, DRD4 (OR = 1.26, p = 0.01) and DRD5 (OR = 1.4, p = 0.01) are significantly associated to ADHD according to the present meta-analysis, confirming previous ones. Recent studies showed a trend for an association between one allele of the 5-HTT (considering case-control studies) and DBH (OR = 1.27, p = 0.06) genes and ADHD, but these positive findings have to be replicated. ADHD is a complex disorder with potentially many different risk factors. Genetic and phenotypic heterogeneity could explain why some association studies are positive, whereas others are negative. For instance, different developmental pathways are likely to lead to similar clinical outcomes. More clear-cut phenotypes, such as ADHD with conduct disorder, or ADHD with bipolar disorder, could be more homogenous, the genes involved being therefore more easy to detect. These phenotypes are beginning to be specifically studied in molecular genetics. In addition, the development of pharmacogenetics could help to identify predictors of clinical response for a specific type of treatment, which would be clearly helpful in clinical practice.

Alcoholism and the dopaminergic system: a review

Alcohol as well as other substances of abuse are reinforcing substances which manifest their effects through activation of the mesolimbic dopaminergic reward pathways of the brain. In animal genetic models of alcoholism, reduced dopamine levels and D2 dopamine receptor (DRD2) numbers have been found in the brains of alcohol-preferring animals. Dopamine receptor agonists reduce alcohol consumption, whereas antagonists, in general, show the opposite effect. Moreover, quantitative trait loci studies in animals suggest the DRD2 gene and the region proximate to this locus is a chromosomal "hot spot" for alcohol-related behaviors. Human studies provide additional support for connection between alcohol dependence and CNS dopaminergic function. In endocrinological studies, using dopamine receptor agonists, reduced dopaminergic activity has been found in more severe and more genetic types of alcoholics. Brain imaging studies are similarly revealing a diminished dopaminergic tone in alcoholics. Treatment of alcoholics with dopamine receptor agonists shows reduced alcohol consumption and improvements in other outcome measures. Molecular genetic studies in humans have identified an association of the Al allele of the DRD2 gene with alcoholism. Moreover, a diminished central dopaminergic function has been found in DRD2 A1 allele subjects using pharmacological, electrophysiological and neuropsychological studies. Further, treatment of alcoholics with a dopamine receptor agonist showed more salutary effects on alcoholics who carry than those who do not carry the DRD2 A1 allele. The A1 allele has also been associated with substance use disorders other than alcoholism, including and cocaine and nicotine dependence and polysubstance abuse. The emerging evidence suggests that the DRD2 is a reinforcement or reward gene. It could represent one of the most prominent single-gene determinants of susceptibility to severe substance abuse. However, the environment and other genes, when combined, still play the larger role.

D2 dopamine receptor gene in psychiatric and neurologic disorders and its phenotypes

The D2 dopamine receptor (DRD2) has been one of the most extensively investigated gene in neuropsychiatric disorders. After the first association of the TaqI A DRD2 minor (A1) allele with severe alcoholism in 1990, a large number of international studies have followed. A meta-analysis of these studies of Caucasians showed a significantly higher DRD2 A1 allelic frequency and prevalence in alcoholics when compared to controls. Variants of the DRD2 gene have also been associated with other addictive disorders including cocaine, nicotine and opioid dependence and obesity. It is hypothesized that the DRD2 is a reinforcement or reward gene. The DRD2 gene has also been implicated in schizophrenia, posttraumatic stress disorder, movement disorders and migraine. Phenotypic differences have been associated with DRD2 variants. These include reduced D2 dopamine receptor numbers and diminished glucose metabolism in brains of subjects who carry the DRD2 A1 allele. In addition, pleiotropic effects of DRD2 variants have been observed in neurophysiologic, neuropsychologic, stress response, personality and treatment outcome characteristics. The involvement of the DRD2 gene in certain neuropsychiatric disorders opens up the potential of a targeted pharmacogenomic approach to the treatment of these disorders.

Male limited association of the dopamine receptor D2 gene TaqI a polymorphism and alcohol dependence

Association studies of the TaqI A allele of the dopamine receptor D2 (DRD2) gene with alcohol dependence have produced conflicting findings. Although a wide series of clinical features have been considered in the different association studies performed, very few studies specifically analyzed the role of gender. We compared the TaqI A polymorphisms of the DRD2 gene in 120 French Caucasian alcohol-dependent inpatients (62 males and 58 females) and 107 healthy ethnically matched controls (66 males and 41 females). We observed that 55% of alcohol-dependent males have at least one A1 allele, a prevalence that is significantly above that observed in the control males (38%). On the contrary, no differences were found in females between the alcohol-dependent inpatients and controls for the A1 allele prevalence. In our sample, this male-specific association was not explained by gender specificities of alcohol dependence, such as age at onset and severity measures (mean numbers of social, somatic, and withdrawal complications). On the other hand, alcohol-dependent women with the A1 allele reported more frequently a major depressive disorder (70% vs. 40%, P = 0.03). We thus replicated the allelic association of the A1 allele of the DRD2 gene with alcohol dependence, but showed a male-limited effect of this "vulnerability allele." Recent evidence for gender difference in dopamine D2-like receptor levels and affinity may explain this discrepancy.

No association between the dopamine D3 receptor gene and Korean alcohol dependence

The genes encoding dopamine receptor (DR) subtypes have received considerable attention for the past several years as a potential candidate that may affect susceptibility to addictive disorder, including alcoholism. The many association studies that compared the frequencies of alleles of the dopamine D2 receptor (DRD2) gene between alcoholics and control groups have produced results, but some have been equivocal. Dopamine D3 receptor genes (DRD3) are in the same class as DRD2 but with different pharmacological properties. So we compared the distribution of genotypes and frequencies of BalI polymorphism of the DRD3 gene in alcoholics and controls to assess the role of the DRD3 gene in Korean alcoholism. For this study, 67 male probands from alcoholics and 67 age-matched normal male controls were engaged. No evidence for an allelic association was found between the A1 allele of DRD3 and alcoholism in a Korean population. These results suggest that any role played by this receptor may account for only part of the variation in susceptibility to alcoholism.

The genetics of addiction: alcohol-dependence and D3 dopamine receptor gene

Alcohol-dependence is a complex phenotype, with behavioral, psychological, pharmacological, medical and social dimensions. Aggregation studies, adoption and twin researches have demonstrated that the vulnerability to alcohol-dependence is at least in part linked to genetic factors, the genetic vulnerability to alcoholism being mainly not substance-specific. There are numerous candidate genes, but the D3 dopamine receptor is specifically located in the limbic area, and in particular in the nucleus accumbens, which are involved in reward and reinforcement behavior. Furthermore, a previous collaborative study showed that homozygosity for the Ball DRD3 locus was more frequently observed in opiate dependent patients with high sensation seeking scores. In this study, we analyzed the distribution of Ball DRD3 polymorphism in a new sample of 131 French male alcoholic-patients (DSM III-R criteria) and 68 healthy controls matched for sex and origins. Although we replicated the higher sensation seeking score in alcohol-dependent patients with comorbid dependence, we found no significant difference in the DRD3 gene polymorphism between controls and alcoholic patients, regardless of sensation seeking score, addictive or psychiatric comorbidity, alcoholism typology, and clinical specificities of alcoholism. There is good evidence that gene coding for the dopamine receptor D3 does not play a major role in the genetic vulnerability to alcoholism.

The DRD2 gene in psychiatric and neurological disorders and its phenotypes

The TaqIA D2 dopamine receptor (DRD2) minor (A1) allele was first associated with severe alcoholism a decade ago. Since then, studies both confirming and not confirmnning this finding were reported. However, a meta-analysis of a large number of Caucasian alcoholics (both more severe and less severe) and controls (both assessed and unassessed for substance use disorders) revealed a significantly higher frequency (p < 10(-6)) and prevalence (p < 10(-8)) of the DRD2 A1 allele in the alcoholics. Further analysis showed that the more severe alcoholics had a 3-fold higher prevalence of the DRD2 A1 allele than the assessed controls (p < 10(-10)), whereas no difference was found between the less severe alcoholics and the unassessed controls. DRD2 exonic or promoter mutations have not yet been associated with alcoholism, although two intronic variants at the TaqIB and intron 6 sites, which are in linkage disequilibrium with the TaqIA site, were associated with this disorder. Variants of the DRD2 gene have also been associated with cocaine, nicotine and opioid dependence, obesity and gambling. It is hypothesised that the DRD2 is a reinforcement or reward gene. Although less intensively studied than substance use disorders, the DRD2 gene has been implicated in Tourette's syndrome (TS), post-traumatic stress disorder (PTSD) and certain symptoms associated with affective disorders and schizophrenia. Further, DRD2 variants have been implicated in Parkinson's disease (PD) and in iatrogenically-induced movement disorders, as well as in certain migraineurs. Phenotypic differences have been associated with DRD2 variants. These include reduced D2 dopamine receptor numbers and diminished glucose metabolism in the brain of subjects who carry the DRD2 A1 allele. In addition, phenotypic differences have been found in neurocognitive and personality characteristics, and in treatment outcome of DRD2 variants. The involvement of the DRD2 gene in certain neuropsychiatric disorders opens up the potential of a targeted pharmacogenomic approach to the prevention and treatment of these disorders.

Reappraisal of the association between the DRD2 gene, alcoholism and addiction

We analysed the impact of the TaqI A1 allele of the D2 dopamine receptor gene on the risk for alcoholism, trying to depict three explanations frequently proposed to explain discrepancies in association and linkage studies: that the A1 allele may act as a marker rather than as a vulnerability factor, that stratification biases and unevaluated controls may explain positive results, and that the A1 allele is modifying the phenotype rather than increasing the risk for alcoholism. We thus tested another (dinucleotide STRP) marker within the DRD2 gene, selected a new homogenous sample of 113 alcoholic patients and 49 unaffected controls strictly matched for ethnic origins, and systematically assessed both samples with a semi-structured interview to detect (in both samples) alcohol dependence, but also such related traits as specificities of complications. The frequency of the A1 allele was not significantly different between alcoholics and controls but when comparing different subgroups of alcoholics, the A1 allele was significantly more frequent in alcoholic patients with somatic complications (OR = 3.00, CI[1.37-6.62]), social and professional complications (OR = 2. 72, CI[1.25-5.90]), or with co-morbid dependence (OR = 2.88, 95% IC [1.16-7.15]). The association for co-morbid dependence and somatic complications was also positive when taking into consideration both STRP and TaqIA polymorphisms. The A1 allele does not increase the risk for alcoholism per se in our sample, but may be involved in a related trait which is partially dependent on the diagnosis of alcoholism, through a disequilibrium with another close mutation.

Association of D2 dopamine receptor and alcohol dehydrogenase 2 genes with Polynesian alcoholics

Alleles of the D2 dopamine receptor (DRD2) and the alcohol dehydrogenase 2 (ADH2) genes were determined in 69 French Polynesian alcoholic patients and 57 controls matched for racial origin. Three racial groups were studied: pure Polynesians (PP), Polynesians mixed with Caucasian (PCA) ancestry and Polynesians mixed with Chinese (PCH) ancestry. DRD2 A1 allele frequencies in the alcoholics compared to their controls in these groups were: PP,.26 vs.32 (P =. 69); PCA,.44 vs.35 (P =.46); PCH,.40 vs 0.39 (P =.88). ADH2 1 allele frequencies in alcoholics compared to their controls groups were: PP, .56 vs.62 (P =.66); PCA,.75 vs.56 (P =.09); PCH,.78 vs.32 (P =.009). In the PCA group, the combination of the DRD2 A1 genotypes and the ADH2 1 homozygotes was strongly associated with alcoholism (P =. 0027). This preliminary study shows the importance of ascertaining racial ancestry in molecular genetic association studies. Moreover, it suggests that a combination of genes are involved in susceptibility to the development of alcoholism.

Addiction and its reward process through polymorphisms of the D2 dopamine receptor gene: a review

Since 1990, association studies have amassed strong evidence implicating the D(2) dopamine receptor (DRD2) gene in alcoholism. Specifically, the TaqI A minor (A1) allele of the DRD2 gene has been associated with alcoholism. The DRD2 gene has also been found to be involved in other substance use disorders including cocaine, nicotine and opioid dependence, and obesity. Beyond association studies, pharmacologic studies have shown reduced brain D(2) dopamine receptor numbers in A1(+) allele carriers (A1A1 and A1A2 genotypes) compared to A1(-) allele carriers (A2A2 genotype). Through a number of other approaches, different phenotypes have also been identified in subjects with the A1(+) and A1(-) alleles. These include metabolic, neurophysiological, neuropsychological, personality, stress and treatment studies. It is hypothesized that in an effort to compensate for deficiencies in the dopaminergic system, substance abusers may seek to stimulate the mesocorticolimbic circuits of the brain, long thought to be important in behavioral reward and reinforcement. In effect, one form of the DRD2 gene, the A1 allele, renders the dopaminergic system inefficient and rewards substance abuse that increases brain dopamine levels.

The DRD2 gene and the risk for alcohol dependence in bipolar patients

The high co-morbidity between bipolar disorder and alcohol dependence may have different explanations, one of them being the existence of common genetic factors for the two disorders. Several candidate genes may be involved but the genes acting in the dopaminergic pathway may be more specifically involved. We have thus tested the role of the gene encoding the D2 dopamine receptor (TaqI A1 allele) in the potentially shared vulnerability to alcohol dependence and bipolar disorder. One hundred and twenty-two French (for at least two generations) patients were recruited on the basis of hospital or outpatient files and were interviewed with the DIGS. The A1 allele frequencies were compared between four groups, namely, with bipolar patients and co-morbid alcohol dependence (N = 21), with bipolar patients without alcohol morbidity (N = 31), with alcohol dependence without mood disorder (N = 35) and unaffected controls (N = 35). The Hardy Weinberg equilibrium for the DRD2 Taq1 A1 genotypes was respected for the sample as a whole, and for each subsample. We observed that 42.9% of control subjects have at least one A1 allele, a frequency which is not significantly different from the one observed in the affected sample as a whole (39.1%), neither from patients with alcohol dependence (37.1%), patients with bipolar disorder (48.4%) nor patients with alcohol dependence and bipolar disorder (28.6%). The regression analysis based on the three variables (bipolar disorder, alcohol dependence and interaction between these two disorders) does not explain the presence of the A1 allele of the DRD2 gene. We thus found no evidence for a significant role of the A1 allele of the D2 dopamine receptor gene in the specific association between bipolar disorder and alcohol dependence in our sample.

Genome polymorphism and alcoholism

Different gene variants have been identified as risk or protective factors in alcoholism. The genes coding for dopamine receptors, serotonin transporters, and dehydrogenases represent susceptibility loci for addictive behaviour. However, alcoholism represents a complex psychiatric symptomatology which is caused by multiple factors, both genetic and environmental. Furthermore, there are probably different subtypes of alcoholism each with a distinct pathophysiology, and thus a different genetic background. Genetic research can help to identify such subtypes, which may require different therapeutic approaches. However, gene polymorphisms are not only responsible for a predisposition to alcoholism, but also for personality traits which influence the likelihood of developing addictive behaviour. Moreover, genetic polymorphisms are probably involved in the way an individual responds to treatment. Also, the severity of secondary diseases resulting from chronic alcohol uptake may depend on the genetic makeup of an individual. New treatment strategies focusing on genes contributing towards drug and alcohol dependence (such as gene therapy) are already under examination in animal models. However, further research is required before these developments will considerably change today's clinical handling of alcoholism.

Polymorphism of dopamine D2 and D4 receptor genes and Slavic-surnamed alcoholic patients

The association between alcoholism and the Taq1 "A" and "B" polymorphic alleles at the DRD2 gene and 48-bp tandem repeat in exon 3 of dopamine D4 receptor (DRD4) gene in 42 unrelated Slavic-surnamed patients and 76 normal controls was examined. The frequency of the A1 allele was higher in alcoholic patients and in alcoholic patients with a family history of alcoholism than in controls (χ²= 3.45, p < 0.001 and χ²)= 3.97, p < 0.001, respectively). Moreover, the frequency of the A1 allele was higher in alcoholics with a family history of alcoholism than in alcoholics without a family history (χ²= 3.33, p < 0.001).The results of association analysis for both the Taq1 "B" and DRD4 alleles were negative for alcoholics in general, subgroups of alcoholics and normal controls. However, the 7-repeat allele (DRD4*7R) of DRD4 gene occurred at significantly higher frequency in alcoholics with a family history of alcoholism compared with those without a family history (χ²= 3.42, p < 0.01).The results indicate that the A1 allele of the DRD2 gene is associated with susceptibility to alcoholism in general.The A1 allele, as well as the DRD4*7R allele, is significantly prevalent among alcoholics with a family history, in comparison with alcoholics without a family history, reflecting different roles of genetic factors in development of alcoholism.

D2 dopamine receptor and GABA(A) receptor beta3 subunit genes and alcoholism

As the dopaminergic and GABAergic systems have been implicated in alcohol-related behaviors, variants of the D2 dopamine receptor (DRD2) and GABA(A) receptor beta3 subunit (GABRB3) genes were determined in a population-based association study of Caucasian non-alcoholic and alcoholic subjects. In severe alcoholics, compared to non-alcoholics, a significant increase was found in the prevalence (P = 1.7 x 10(-5)) and frequency (P = 1.6 x 10(-5)) of the DRD2 minor (A1) allele. Moreover, a significant progressive increase was observed in A1 allelic prevalence (P = 3.1 x 10(-6)) and frequency (P = 2.7 x 10(-6)) in the order of non-alcoholics, less severe and severe alcoholics. In severe alcoholics, compared to non-alcoholics, a significant decrease was found in the prevalence (P = 4.5 x 10(-3)) and frequency (P = 2.7 x 10(-2)) of the GABRB3 major (G1) allele. Furthermore, a significant progressive decrease was noted in G1 allelic prevalence (P = 2.4 x 10(-3)) and frequency (P = 1.9 x 10(-2)) in non-alcoholics, less severe and severe alcoholics, respectively. In sum, in the same population of non-alcoholics and alcoholics studied, variants of both the DRD2 and GABRB3 genes independently contribute to the risk for alcoholism, with the DRD2 variants revealing a stronger effect than the GABRB3 variants. However, when the DRD2 and the GABRB3 variants are combined, the risk for alcoholism is more robust than when these variants are considered separately.

The D2 dopamine receptor gene: a review of association studies in alcoholism and phenotypes

The role of the D2 dopamine receptor (DRD2) gene in alcoholism and other substance use disorders has come under intense investigation since the minor TaqI A (A1) allele of the DRD2 gene was first reported to be associated with alcoholism. In a meta-analysis of 15 US and international studies of European (non-Hispanic) Caucasians, consisting of 1015 alcoholics (more severe and less severe) and 898 controls (unassessed and assessed for alcoholism), alcoholics had a higher prevalence (p < 10(-7)) and frequency (p < 10(-5)) of the A1 allele than controls. The prevalence of the A1 allele was 1.5-fold higher in more severe than less severe alcoholics (p < 10(-4)), whereas unassessed controls had a twofold higher prevalence of the A1 allele than assessed controls (p < 10(-4)). Whereas more severe alcoholics had a threefold higher A1 allelic prevalence than assessed controls (p < 10(-10)), A1 allelic prevalence was virtually identical in less severe alcoholics and in unassessed controls. The A1 allele has also been associated with other drug problems including cocaine, nicotine, and polysubstance abuse. Furthermore, the minor TaqI B (B1) allele of the DRD2 gene has been associated with alcoholism and psychostimulant (cocaine, amphetamine) abuse. Beyond association studies, phenotypic differences exist between genotypes containing the TaqI A minor (A1A1 and A1A2) and major (A2A2) alleles of the DRD2. These different phenotypes have been identified through a number of approaches, including pharmacological, neurophysiological, neuropsychological, stress, personality, metabolic, and treatment studies. In conclusion, the present review suggests that the type of alcoholics and the nature of controls used are among critical factors in DRD2 association studies in alcoholism. Intronic mutations in both the 3'(TaqI A) and 5'(TaqI B) regions of the DRD2 associate with alcoholism and other drug use disorders. The identification of phenotypes of DRD2 genotypes suggests that the observed intronic DRD2 mutations may have functional consequences that predispose individuals to a variety of substance use disorders.

Living situation, social network and outcome in schizophrenia: a five-year prospective follow-up study

A representative sample of 227 first-contact schizophrenic patients (according to DSM-III) was followed up for 5 years. The psychiatric teams responsible for the treatment of the patients conducted detailed standardized interviews with the patients at entry and at the end of the first, second and fifth years. Changes in patients' clinical and functional outcome were analysed according to their living situation and social network. Positive changes in clinical state and functional ability were most prominent among patients who were living with their spouse. The social and functional outcome of men living with their parents was better than that of women in the same situation, while among patients living alone or with some other person the gender difference was reversed. Family environment can be of great importance to schizophrenic patients, supporting their clinical and functional recovery from psychosis. Patients living outside families--and men in particular--are at great risk of poor outcome, perhaps because they often lose their social contacts. In the treatment of such individuals a more active strategy of out-patient and rehabilitative care is therefore needed.

Association of the D2 dopamine receptor A1 allele with alcoholism: medical severity of alcoholism and type of controls

D2 dopamine receptor (DRD2) A1 allele frequency was determined in alcoholics of varying medical severity from three different inpatient settings and in various controls. A1 frequency was .15 in 68 alcoholics in a detoxification unit (group A), .19 in 90 alcoholics in a rehabilitation unit (group B), and .31 in 43 alcoholics in a gastroenterology unit (group C). Group C had a higher A1 frequency than group B (p = .045) or group A (p = .005) alcoholics. In 46 controls (group D), A1 frequency was .18. In subsets of these controls, A1 frequency was .14 in 39 subjects with a negative family history (FH-) of alcoholism (group E), .06 in 34 subjects without previous hazardous alcohol consumption (group F), and .05 in 30 subjects with FH- and without previous hazardous alcohol consumption (group G). A1 frequency was significantly higher in group C alcoholics than group F (p = .0002) or group G (p = .0002) controls; however, no A1 frequency difference was found among group A alcoholics and any of the control groups. The severity of alcoholism and the type of controls used are important determinants of DRD2 A1 allele association with alcoholism.

Neuropsychological functioning in sons of active alcoholic, recovering alcoholic, and social drinking fathers

Sons of active alcoholic, recovering alcoholic, and social drinking fathers were administered neuropsychological tests to assess whether they differ in their cognitive functioning. Multivariate analyses of variance showed that sons of active alcoholic sons perform significantly worse on visuospatial, memory, and attentional tasks as well as general intellectual functioning than sons of social drinking fathers. The sons of recovering alcoholic fathers showed no significant difference from social drinking fathers in their cognitive functioning. These results suggest that the clinical type of the alcoholic father (i.e., inability to abstain, more severe alcoholic vs. ability to abstain, less severe alcoholic) may be an important factor that determines whether offspring of alcoholics have neuropsychological deficits.

Serotonin 5-HT3 receptor binding kinetics in the cortex of suicide victims are normal

Serotonergic abnormalities have been identified in the brain of suicide victims independent of psychiatric diagnosis. We report the first study of serotonin 5-HT3 receptors in the brain of suicide victims. There were no differences in the number (Bmax) or affinity (KD) of 5-HT3 receptors in the temporal cortex of suicide victims compared to matched controls. There was a negative correlation between brain serotonin levels and receptor number (r = -0.5, p = 0.04) in both groups. This study indicates that alterations in serotonergic function in the brain of suicide victims do not appear to directly involve the 5-HT3 receptor.

Alcohol dependence, family history, and D2 dopamine receptor function as neuroendocrinologically assessed with apomorphine

Fifteen alcohol dependent men with an alcohol dependent first degree relative (i.e. family history positive or FHP), 15 well matched alcohol dependent men without a family history for alcohol dependence (i.e. family history negative or FHN), and 15 healthy controls (CONTR) participated in this study. The three groups were compared according to their postsynaptic D2 dopamine receptor function as assessed by growth hormone release after stimulation with the dopamine receptor agonist apomorphine. Statistical evaluation was done by planned comparisons within a one-way ANOVA. Alcohol dependent subjects significantly differed from CONTRs as long as family history was not taken into account (t(42) = 2.38; P = 0.022*). When differentiating according to family history, both FHPs and FHNs maintained a blunted growth hormone response. However, the difference between FHNs and CONTRs, though present, dropped out of statistical significance (t(42) = 1.65; P = 0.105); at the same time, the difference between FHPs and CONTRs became slightly stronger (t(42) = 2.47; p = 0.017*). In conclusion, our data give neuroendocrinological support to the assumption that a reduced D2 dopamine receptor function in alcohol dependent men is not only a state marker of residual heavy drinking but also a genetically determined trait marker.

Bromocriptine in the treatment of alcoholics with the D2 dopamine receptor A1 allele

Various types of alcoholics have been described and heredity has been shown to be involved in some of these types. An important role of the mesolimbic dopamine system has been suggested in the reinforcing effects of alcohol and recent molecular genetic studies are implicating the gene for the D2 dopamine receptor (DRD2) in alcoholism. In a double-blind study, bromocriptine, a DRD2 agonist, or placebo was administered to alcoholics with either the A1 (A1/A1 and A1/A2 genotypes) or only the A2 (A2/A2 genotype) allele of the DRD2 gene. The greatest improvement in craving and anxiety occurred in the bromocriptine-treated A1 alcoholics and attrition was highest in the placebo-treated A1 alcoholics. The feasibility of a pharmacogenetic approach in treating certain types of alcoholics is suggested.