Family-based study of the association of the dopamine D2 receptor gene (DRD2) with habitual smoking

A recent study showed an association between the dopamine D2 receptor gene (DRD2) and smoking. The purpose of this study was to determine if the familial transmission of smoking is linked to variation at the DRD2 locus in a genetically informative sample. Subjects were identified in alcohol treatment centers and their relatives were recruited for study. All subjects were interviewed to assess alcohol dependence, smoking habits, and psychiatric disorders. Two polymorphisms within the DRD2 gene were analyzed, including the TaqIA polymorphism. The sample consisted of 138 nuclear families with at least one offspring with habitual smoking, and analysis was by the transmission disequilibrium test (TDT), which avoids problems due to population stratification. There was no significant difference in the frequency between DRD2 alleles transmitted and not transmitted to habitual smokers. There also was no evidence for unequal transmission of DRD2 alleles for the phenotypes "ever smoker" or comorbid alcohol dependence and habitual smoking. This study does not support linkage of the DRD2 with smoking.

A latent class analysis of antisocial personality disorder symptom data from a multi-centre family study of alcoholism

AIMS

To determine if there are subtypes of Antisocial Personality Disorder (ASPD), as manifested by distinctive symptom profiles or by associations with alcohol, other drug dependence or other psychiatric disorders.

METHODS

Data on 38 symptoms of ASPD (including childhood conduct disorder) obtained from probands, their relatives and controls (2834 females and 3488 males) recruited for the Collaborative Study on the Genetics of Alcoholism (COGA) were analyzed using latent class analysis. Associations of the resulting latent classes with alcohol dependence (AD) and other psychiatric disorders were examined.

FINDINGS

Among women, a 4-class solution was obtained in which conduct disorder and ASPD were found almost exclusively in the most severely affected class with two additional classes with mild and moderate behavior problems also identified. A strong linear trend (p < 0.001) for AD was observed, with each successive class manifesting a higher prevalence than the previous class. Milestones of drinking careers and dependence on other drugs also showed a strong association with class severity. Among men, a 5-class solution was obtained and, like women, the highest prevalence of ASPD (74.6%) was found in the most severely affected class. Somewhat unexpected was the observation that prevalence of AD was equivalent in the two most severe classes. The data for men indicated a class with a milder spectrum of childhood misbehaviors but with an adult ASPD profile--as well as other psychiatric co-morbidity--that was comparable to the most severe class.

CONCLUSIONS

Overall, findings from both men and women did not support the existence of subtypes of ASPD, but rather indicated a disorder distributed on a severity spectrum.

Clinical correlates of cigarette smoking and nicotine dependence in alcohol-dependent men and women. The Collaborative Study Group on the Genetics of Alcoholism

This paper examines the clinical characteristics associated with tobacco use and nicotine dependence in a large sample of alcohol-dependent subjects. The goal was to determine if the characteristics of the alcohol use history were associated with the smoking status, even after controlling for additional characteristics, such as the antisocial personality disorder, other drug dependence and gender. As part of the Collaborative Study on the Genetics of Alcoholism, a semi-structured interview, including a detailed history of alcohol and tobacco use, was administered to 1005 alcohol-dependent men and women, made up of 658 (65.5%) current smokers, 167 (16.6%) former smokers, and 180 (17.9%) non-smokers. Among former smokers, 50.3%, and among current smokers, 72.8% had ever been nicotine-dependent (DSM-III-R). Current smokers and nicotine-dependent subjects had a greater severity of alcohol dependence, even as evaluated through logistic regression analyses in which gender and associated diagnoses were considered. The data also enabled us to study the relationships among depression, nicotine dependence, and alcohol dependence, with most of the correlation occurring for substance-induced, not independent, mood disorders.

Family-based study of the association of the dopamine D2 receptor gene (DRD2) with habitual smoking

A recent study showed an association between the dopamine D2 receptor gene (DRD2) and smoking. The purpose of this study was to determine if the familial transmission of smoking is linked to variation at the DRD2 locus in a genetically informative sample. Subjects were identified in alcohol treatment centers and their relatives were recruited for study. All subjects were interviewed to assess alcohol dependence, smoking habits, and psychiatric disorders. Two polymorphisms within the DRD2 gene were analyzed, including the TaqIA polymorphism. The sample consisted of 138 nuclear families with at least one offspring with habitual smoking, and analysis was by the transmission disequilibrium test (TDT), which avoids problems due to population stratification. There was no significant difference in the frequency between DRD2 alleles transmitted and not transmitted to habitual smokers. There also was no evidence for unequal transmission of DRD2 alleles for the phenotypes "ever smoker" or comorbid alcohol dependence and habitual smoking. This study does not support linkage of the DRD2 with smoking.

Co-occurring risk factors for alcohol dependence and habitual smoking

Smoking and alcohol dependence frequently occur together, and both behaviors are determined in part by genetic influences. The Collaborative Study on the Genetics of Alcoholism (COGA), which is investigating the genetic factors contributing to alcohol dependence, also allows for analyses of the genetic factors determining smoking. Using a sample comprised of alcoholics and their closest (i.e., first-degree) relatives as well as a community-based control sample, COGA investigators found that both alcohol dependence and habitual smoking were transmitted within families. This familial transmission resulted from both common and drug-specific influences, which likely include genetic factors. Further genetic studies (i.e., candidate gene studies and genomic screening approaches) have identified several DNA regions that may contain genes that confer a susceptibility for alcoholism. Some of those genes also may contribute to the risk for habitual smoking.

Impact of a stimulant-focused enhanced program on the outcome of alcohol- and/or stimulant-dependent men

BACKGROUND

The approaches to the treatment of most forms of substance dependence are similar. It is not clear whether specific treatment components need to be added to address specific substances. This study asks two questions: What is the impact of a more intense drug treatment program, and do different substance problems require different treatment interventions?

METHODS

The 383 veterans included in this study represent two groups of consecutive inpatient male admissions with current alcohol dependence and/or dependence on amphetamines or cocaine at the inpatient Alcohol and Drug Treatment Program of the Veterans Affairs San Diego Healthcare System. All were interviewed at intake by trained interviewers using a standardized semistructured assessment instrument, and a resource person interview also was conducted with 85% of them. The first group of men received the Standard Treatment Program (STP), whereas the second group received the Enhanced Treatment Program (ETP). The latter included an addition of 10 hr per week of intense treatment aimed at stimulants, including two newly developed manual-driven groups (Relapse Prevention and Interpersonal Counseling), each of which met twice a week.

RESULTS

The patient follow-up was 92% at 3 months and 83% at 12 months. Abstinence from substances of abuse for ETP and STP were 63% vs. 49% at 3 months and 43% vs. 24% at 12 months. Logistic regressions demonstrated that treatment type continued to predict outcome even in the context of other potentially predictive variables.

CONCLUSIONS

Despite the ETP emphasis on stimulants, both alcohol- and stimulant-dependent men appeared to benefit, suggesting a generic improvement in substance use.

Evaluation of the self-rating of the effects of alcohol form in Asian Americans with aldehyde dehydrogenase polymorphisms

OBJECTIVE

In order to easily assess individual differences in response to alcohol, the Self-Rating of the Effects of Alcohol (SRE) form was recently developed and its psychometric properties tested in primarily white subjects. This study aimed to further evaluate the SRE in a population known to have genetically mediated variability in response to alcohol and risk for alcoholism, Asian Americans with ALDH2 polymorphisms.

METHOD

Men and women of Chinese, Japanese or Korean heritage between the ages of 21 and 26 years (N = 156) completed the SRE and a blood sample was drawn for genotyping at the ALDH2 locus.

RESULTS

SRE results were available from 137 (78 female) subjects. With the effects of gender, body weight, frequency of recent drinking and quantity of recent drinking controlled, ALDH2 genotype still accounted for a significant amount of variability in SRE score in this Asian-American sample. Evaluation of SRE scores 4.5 or higher indicated that a low response to alcohol was associated with ALDH2*1/2*1 genotype, male gender and Korean heritage, all factors associated with increased risk for alcoholism.

CONCLUSIONS

These results provide additional support for the SRE as a valid instrument for assessing individual variability in response to alcohol and as a useful measure for identifying individuals at relatively increased or decreased risk for alcoholism based on level of reaction to alcohol.

Clinical characteristics of alcoholism in alcohol-dependent subjects with and without a history of alcohol treatment

BACKGROUND

Most clinical alcohol research is carried out on alcoholics who are in treatment, usually inpatients. However, most alcohol-dependent men and women never enter treatment, and even fewer ever receive inpatient care. Thus, some generally accepted data on the clinical course of alcoholism, derived from treatment samples, might not generalize to the entire population of alcohol-dependent individuals. This article characterizes the clinical characteristics of alcohol dependence in three groups of alcoholics, based on their histories of treatment for alcohol problems: those without prior rehabilitation; those with only outpatient approaches or Alcoholics Anonymous (AA); and subjects with an inpatient experience.

METHODS

Semistructured interviews were administered to 3572 DSM-III-R-defined alcohol-dependent subjects from the Collaborative Study on the Genetics of Alcoholism. The clinical patterns were compared across the three groups of alcoholics: Group 1, never-treated (n = 1582; 44%); Group 2, histories of outpatient or AA only (n = 399; 11%); and Group 3, at least one inpatient experience (n = 1591; 45%).

RESULTS

A progression was shown from Groups 1 to 3 for more general life problems (e.g., unemployment, marital instability); higher rates of additional drug dependencies and psychiatric disorders; and more alcohol-related adverse events. Logistic regression analyses revealed that those with no prior treatment were more likely to be women, Caucasian, and employed, and to report a lower rate of divorce/separation, lower levels of alcohol intake, and fewer alcohol problems. Among those who received help, inpatient care was predicted by an opposite profile.

CONCLUSIONS

These results indicate that studies using data from inpatient populations may give a skewed picture of the clinical characteristics of alcohol dependence.

How would you label your own drinking pattern overall? An evaluation of answers provided by 181 high functioning middle-aged men

The self-rating of drinking habits was compared to DSM-III-R diagnoses of alcohol abuse and dependence in 181 men with an average age (+/- SD) of 38.7 +/- 1.91 years. Results indicate that the 150 subjects without alcohol-related diagnosis (Group 1) rated themselves as 'non-problem drinker', in categories from 'non-drinker' to 'heavy drinker'. Among the 15 individuals with alcohol abuse (Group 2), none rated their drinking pattern as 'problem drinker'. Two (12.5%) subjects in the group of 16 individuals with alcohol dependence (Group 3) rated themselves as 'problem drinker', while most did not consider their drinking patterns as problematic. Within subjects who identified themselves as the same type of drinker (e.g. 'infrequent drinker', 'moderate drinker', etc ...), the quantity, frequency, and number of alcohol-related problems were higher in Groups 2 and 3, compared to Group 1. The self-rating of drinking habits using a single question failed to identify over 90% of the subjects diagnosed with alcohol use disorder (100% of those with alcohol abuse and 87.5% of those with alcohol dependence), and did not differentiate between levels of alcohol intake and number of alcohol-related problems for subjects who identified as a particular drinking type.

Characteristics of alcohol dependent subjects with very elevated levels of Gamma-Glutamyltransferase (GGT)

OBJECTIVE

This article examines characteristics of a subgroup of alcohol dependent men with very elevated serum Gamma-Glutamyltransferase (GGT) activity.

METHOD

GGT was measured in 196 men soon after admission to an inpatient alcohol and drug treatment program. Subjects were split into two groups based on the a priori GGT value of > or =150 U/L for Group 1 (n = 20), and <150 U/L for Group 2 (n = 176). Serum aspartate amino-transferase (AST), serum alanine amino-transferase (ALT) and mean corpuscular volume (MCV), as well as several aspects of the drinking history, were compared cross-sectionally between the two groups. The stability of GGT in the context of drinking was evaluated prospectively over 12 months in a subsample of 35 individuals.

RESULTS

Most measures of the drinking pattern and severity of dependence were similar between the two groups, although subjects in Group 1 demonstrated higher levels for AST (p < .01), MCV (p < .01) and ALT (p < .01). Subjects in Group 1 reported more drinking days per month (23.8 +/- 3.98 vs 17.8 +/- 8.71, t = 5.43, p < .001), and more related history of alcoholic liver disease (30.0% vs 8.5%, chi2 = 8.66, p < .01). In the presence of the variables significantly different between the two groups, AST, the number of drinking days per month and the proportion with alcoholic liver disease predicted membership to Group 1, although their influence was moderate (pseudo R between 0.16 and 0.20). The correlation between GGT at intake and follow-up in 35 individuals who returned to drinking was r = .56, p < .001, while two out of three subjects with high GGT at intake were also high at follow-up.

CONCLUSIONS

Subjects with very high GGT seem to demonstrate a more intense vulnerability to alcohol, a characteristic which appears to be stable over time.

Selective genotyping for the role of 5-HT2A, 5-HT2C, and GABA alpha 6 receptors and the serotonin transporter in the level of response to alcohol: a pilot study

BACKGROUND

The vulnerability to alcohol dependence appears to be genetically influenced through a variety of mechanisms. One potentially genetically mediated channel may be a low level of response (LR) to alcohol, which has been seen in children of alcoholics and noted to predict future alcohol abuse and dependence. This pilot study uses a case and control genetic association approach to evaluate the possible role of five genotypes in both LR and alcoholism in informative subgroups of men with high and low LR scores documented 15 years earlier.

METHODS

As part of a larger study, 41 men, about 39 years old, were selected from among the first 113, completed 15-year follow-ups in a prospective study. The 17 subjects whose LRs at age 20 were in the lower third were compared on five polymorphisms of four genes with 24 men whose reactions to alcohol had been above the median.

RESULTS

The 14 men with the LL genotype of the serotonin transporter (5-HTT) polymorphism and the seven with the Pro/Ser genotype of the GABAA alpha 6 polymorphism had demonstrated lower LR scores at about age 20, and had significantly higher proportions of alcoholics than the other genotypes for those loci. All four subjects with combined LL and Pro/Ser genotypes had developed alcoholism and demonstrated the lowest LR scores overall. There was no evidence that two polymorphisms of the 5-HT2A receptor gene and one of the 5-HT2C receptor gene were related to LR or alcoholism in this sample.

CONCLUSIONS

These results are consistent with animal and human studies suggesting a possible role for genetic variation in the GABAA alpha 6 and the serotonin transporter in the reaction to alcohol and the alcoholism risk.

Clinical implications for four drugs of the DSM-IV distinction between substance dependence with and without a physiological component

OBJECTIVE

The DSM-IV work group asked researchers and clinicians to subtype substance dependent individuals according to the presence or absence of physiological symptoms. A recent report from the Collaborative Study on the Genetics of Alcoholism demonstrated that among alcohol-dependent men and women, a history of tolerance or withdrawal was associated with a more severe clinical course, especially for individuals with histories of alcohol withdrawal. This article evaluates similar distinctions among subjects in the collaborative study who were dependent on marijuana, cocaine, amphetamines, or opiates.

METHOD

Structured interviews gathered information from 1,457 individuals with a lifetime diagnosis of marijuana dependence, 1,262 with histories of cocaine dependence, 647 with amphetamine dependence, and 368 subjects with opiate dependence. For each drug, the clinical course was compared for subjects whose dependence included a history of withdrawal (group 1), those dependent on each drug who denied withdrawal but reported tolerance (group 2), and those who denied both tolerance and withdrawal (group 3).

RESULTS

The proportion of dependent individuals who denied tolerance or withdrawal (group 3) ranged from 30% for marijuana to 4% for opiates. For each substance, individuals in groups 1 and 2 evidenced more severe substance-related problems and at least a trend for greater intensities of exposure to the drug; those reporting withdrawal (group 1) showed the greatest intensity of problems.

CONCLUSIONS

The designation of dependence in the context of tolerance or withdrawal identifies individuals with more severe clinical histories. These results support the importance of the designation of a physiological component to dependence, especially for people who have experienced a withdrawal syndrome.

Familial transmission of substance dependence: alcohol, marijuana, cocaine, and habitual smoking: a report from the Collaborative Study on the Genetics of Alcoholism

BACKGROUND

Alcoholism and substance dependence frequently co-occur. Accordingly, we evaluated the familial transmission of alcohol, marijuana, and cocaine dependence and habitual smoking in the Collaborative Study on the Genetics of Alcoholism.

METHODS

Subjects (n=1212) who met criteria for both DSM-III-R alcohol dependence and Feighner definite alcoholism and their siblings (n=2755) were recruited for study. A comparison sample was also recruited (probands, n=217; siblings, n=254). Subjects were interviewed with the Semi-Structured Assessment for the Genetics of Alcoholism. The familial aggregation of drug dependence and habitual smoking in siblings of alcohol-dependent and non-alcohol-dependent probands was measured by means of the Cox proportional hazards model.

RESULTS

Rates of alcohol, marijuana, and cocaine dependence and habitual smoking were increased in siblings of alcohol-dependent probands compared with siblings of controls. For siblings of alcohol-dependent probands, 49.3% to 50.1% of brothers and 22.4% to 25.0% of sisters were alcohol dependent (lifetime diagnosis), but this elevated risk was not further increased by comorbid substance dependence in probands. Siblings of marijuana-dependent probands had an elevated risk of developing marijuana dependence (relative risk [RR], 1.78) and siblings of cocaine-dependent probands had an elevated risk of developing cocaine dependence (RR, 1.71). There was a similar finding for habitual smoking (RR, 1.77 in siblings of habitual-smoking probands).

CONCLUSIONS

Alcohol, marijuana, and cocaine dependence and habitual smoking are all familial, and there is evidence of both common and specific addictive factors transmitted in families. This specificity suggests independent causative factors in the development of each type of substance dependence.

Alcohol dependence and mood disorders

This article explores the complex relationships between alcohol dependence and mood disorders. Although many alcoholics present with substance-induced depressions, once appropriate methodological controls are used, there does not appear to be a significant relationship between independent unipolar depression and alcohol dependence. However, the data support a small, but significant, relationship between bipolar manic-depressive disease and alcoholism. The literature does not support the relevance of self-medication as a course of alcoholism, unless one includes the use of alcohol to alleviate alcohol-induced psychological and neurochemical perturbations. The clinical importance of distinguishing between substance-induced and independent mood disorders is reviewed.

Influence of age and body mass index on gamma-glutamyltransferase activity: a 15-year follow-up evaluation in a community sample

Most clinicians and researchers view serum gamma-glutamyltransferase (GGT) activity as a measure that can be interpreted equally in patients regardless of their demography. The present study evaluates the concurrent influence of age and body mass index (BMI) on GGT in a sample of 133 high functioning young men, with detailed assessment of the pattern of alcohol use at ages 20 [time 1 (T1)], 30 [time 2 (T2)], and 35 [time 3 (T3)]. GGT increased between T1 and T2 (15.4 +/- 9.65 units/liter vs. 20.1 +/- 12.07 units/liter, t = 4.17, p < 0.001), and between T2 and T3 (20.1 +/- 12.07 units/liter vs. 27.3 +/- 24.69 units/liter, t = 4.11, p < 0.001). Controlling for drinking quantity and frequency did not change the finding. The relationship between GGT and BMI was estimated after splitting the sample into normal (BMI < or = 25 kg/m2) and overweight (BMI > 25 kg/m2) subjects. The correlation between GGT and BMI in normal weight men at T1 was r = 0.15, p = 0.09, at T2 r = 0.00, p = 0.96, and at T3 r = 0.09, p = 0.09. In overweight subjects, correlation at T1 was r = 0.40, p = 0.20, at T2 r = 0.36, p < 0.05, and at T3 r = 0.44, p < 0.001. Controlling for the effect of alcohol consumption and/or age did not alter these conclusions. Testing for the interaction of age, BMI, and alcohol consumption did not yield relevant results. We concluded that GGT is positively related to age in the 20s to late 30s and to BMI in overweight subjects; both relationships of age and BMI were independent of alcohol consumption. The interpretation of GGT should take age and BMI into account when suspecting subclinical alcohol problems in young men.

The clinical course of alcohol-related problems in alcohol dependent and nonalcohol dependent drinking women and men

OBJECTIVE

This article examines the differences in the clinical course of alcohol dependence in men and women, interpreting results in light of the gender differences in nonalcoholics and potential findings from the general population.

METHOD

As part of the Collaborative Study on the Genetics of Alcoholism (COGA) protocol, a detailed semistructured interview was administered to 1,085 alcohol dependent women and 2,120 alcohol dependent men, along with 1,936 women and 1,233 men who were drinkers but not alcoholic. Subjects were alcohol dependent probands, controls, and relatives of each.

RESULTS

The men's and women's rank orders of alcohol-related life events were similar for alcohol dependent subjects, with a rho (rho) of .95, a figure that remained constant even when only primary alcoholics were considered. In general, those items for which the two genders evidenced differences in either the mean age of occurrence or the proportion of people who experienced an event were similar to gender differences in drinking among nonalcoholics or the literature on the general population. These included for women a lower maximum number of drinks per day, a 1- to 2-year later onset of several early alcohol-related problems and fewer years between the onset of problems and seeking help. Female alcoholics also showed a lower proportion with legal, job or personal problems related to alcohol. There were also high levels of similarity (p = .76, p > .001) for 28 life events related to alcohol for 1,936 women and 1,233 men who were drinkers but not alcohol dependent.

CONCLUSIONS

Overall, the time course of alcohol-related problems for men and women were more similar than different. While there was evidence of a "telescoping" of the time between the onset of problems and treatment for women, the gender differences in ages of onset of events were relatively small. These data support the conclusion that, after considering gender differences in drinking in society, there is little evidence that the natural history of alcohol dependence in women is substantially different than in men.

Biological, psychological and environmental predictors of the alcoholism risk: a longitudinal study

OBJECTIVE

This article reviews results from an ongoing prospective study of 453 sons of alcoholics and controls, and presents new data from the 15-year follow-up.

METHOD

Drinking, but not alcohol dependent, 20-year-old sons of alcoholics and controls were evaluated for their level of response (LR) to alcohol and were subsequently followed, through personal interviews, 10 years and 15 years later.

RESULTS

The 10-year follow-up of 450 (99.3%) men and provisional analyses from the first 127 subjects at 15 years revealed that a low LR at about age 20 predicted subsequent alcoholism, even after considering the original quantity and frequency of drinking and six additional domains of influence. Regarding the latter, behavioral undercontrol and work stress appear to interact with LR, with alcohol expectancies, coping mechanisms and aspects of the drinking in the environment also appearing to add to the model, while other aspects of life stress and the social support network do not.

CONCLUSIONS

The prospective evaluation of subjects at higher risk for alcoholism is a potentially powerful tool in identifying the relationships among a broad range of moderators and mediators of the alcoholism risk. The present tentative results based on the first 127 subjects are primarily heuristic as findings might change in the full sample. These data set the stage for completion of the 15-year follow-up and for a subsequent 20-year evaluation which will focus on the same domains in the projected almost 560 sons and daughters of the original sample.

Clinical relevance of the distinction between alcohol dependence with and without a physiological component

OBJECTIVE

DSM-IV indicates that diagnoses of substance dependence should be further characterized with regard to the presence of a physiological component, defined by tolerance or withdrawal. This study evaluated the possible meaning of this distinction in alcohol-dependent men and women.

METHOD

As part of the Collaborative Study on the Genetics of Alcoholism, structured interviews were carried out with 3,395 DSM-III-R-defined alcohol-dependent individuals divided into 2,949 subjects (86.9%) with evidence of tolerance and/or withdrawal (group 1), 51.3% of whom evidenced withdrawal symptoms, and 446 subjects (13.1%) without a physiological component (group 2). Data were evaluated to determine differences between the two groups.

RESULTS

Group 1 reported greater severity of alcohol dependence as demonstrated by a larger maximum number of drinks in 24 hours, more persons reporting binges, more alcohol-related life problems, more relevant DSM-III-R criteria endorsed, more physiological complications, and more alcohol-related emotional/psychiatric symptoms such as depression and anxiety. Each of these severity indicators for problems in group 1 was significant in the presence of the others in a logistic regression, and similar items remained significant when tolerance alone, withdrawal alone, or their combination was used as the criterion for group 1 membership; however, for withdrawal a larger proportion of the variance was explained by the predictor variables. The regression results were independent of gender, proband status, and history of antisocial personality disorder.

CONCLUSIONS

The results support the clinical relevance of distinguishing between alcohol-dependent patients with and without a physiological component. The data indicate a potential advantage to limiting that definition to withdrawal only.

Genome-wide search for genes affecting the risk for alcohol dependence

Alcohol dependence is a leading cause of morbidity and premature death. Several lines of evidence suggest a substantial genetic component to the risk for alcoholism: sibs of alcoholic probands have a 3-8 fold increased risk of also developing alcoholism, and twin heritability estimates of 50-60% are reported by contemporary studies of twins. We report on the results of a six-center collaborative study to identify susceptibility loci for alcohol dependence. A genome-wide screen examined 291 markers in 987 individuals from 105 families. Two-point and multipoint nonparametric linkage analyses were performed to detect susceptibility loci for alcohol dependence. Multipoint methods provided the strongest suggestions of linkage with susceptibility loci for alcohol dependence on chromosomes 1 and 7, and more modest evidence for a locus on chromosome 2. In addition, there was suggestive evidence for a protective locus on chromosome 4 near the alcohol dehydrogenase genes, for which protective effects have been reported in Asian populations.

Platelet monoamine oxidase activity in subgroups of alcoholics and controls: results from the Collaborative Study on the Genetics of Alcoholism

OBJECTIVE

Platelet monoamine oxidase (MAO) B activity levels were evaluated to determine whether low platelet MAO activity is a marker for alcoholism, correlates of alcoholism (e.g., cigarette smoking), or a subtype of alcoholism.

METHODS

Adult women (n = 788) and men (n = 685) participating in the Collaborative Study on the Genetics of Alcoholism study were evaluated with a semistructured interview, and blood samples were obtained for determination of platelet MAO activity using tryptamine (0.1 mM) as substrate. DSM-III-R alcohol-dependent individuals were subgrouped using four currently available methods (e.g., two variations of the type 1/type 2 scheme, primary versus secondary typology, type A/type B dichotomy).

RESULTS

In the overall sample, subjects' gender, cigarette smoking status, and the Collaborative Study on the Genetics of Alcoholism site at which their platelets were prepared explained 22% of the variance in platelet MAO activity levels, and multivariate analysis showed that carrying a broad diagnosis of alcohol dependence did not uniquely explain any additional variance in platelet MAO activity levels. Furthermore, within each of the alcoholic subgrouping methods tested, there were no significant differences in platelet MAO activity for type 1 versus type 2, type A versus type B, or primary versus secondary alcoholics.

CONCLUSIONS

Cigarette smoking and male gender are associated with decreased platelet MAO activity levels. After considering these factors, a diagnosis of alcohol dependence does not predict any additional variance in MAO-B activity. Phenotypes of alcoholics (e.g., type 1 versus type 2, type A versus type B, primary versus secondary) do not differ in platelet MAO activity. The results suggest that decreased platelet MAO activity is not a trait marker of alcoholism or one of its subtypes; but, rather, is a state marker of cigarette smoking.

Quantitative trait loci analysis of human event-related brain potentials: P3 voltage

The P3 event-related brain potential (ERP) is a positive-going voltage change of scalp-recorded electroencephalographic activity that occurs between 300-500 ms after stimulus onset. It is elicited when a stimulus is perceived, memory operations are engaged, and attentional resources are allocated toward its processing. Because this ERP component reflects fundamental cognitive processing, it has found wide utility as an assessment of human mental function in basic and clinical studies. In particular, P3 attributes are heritable and have demonstrated considerable promise as a means to identify individuals at genetic risk for alcoholism. We have conducted a quantitative linkage analysis on a large sample from families with a high density of affected individuals. The analyses suggest that several regions of the human genome contain genetic loci related to the generation of the P3 component of the ERP, which are possible candidate loci underlying the functional organization of human neuroelectric activity.

Periods of abstinence following the onset of alcohol dependence in 1,853 men and women

OBJECTIVE

Data from both laboratory experiments and retrospective histories of alcoholics indicate that alternations between periods of abstinence and heavy drinking are common in the course of alcoholism. This article examines the prevalence, chronological characteristics and clinical features associated with periods of abstinence in a large sample of alcohol dependent men and women.

METHOD

As part of the Collaborative Study on the Genetics of Alcoholism (COGA), semistructured personal interviews were used to gather data on the course of alcoholism in 1,853 alcohol dependent men and women. Data were evaluated regarding the characteristics of alcoholics with and without periods of abstinence lasting 3 or more months, and the course of these periods over time were evaluated separately for subjects with one, two, three or four episodes of abstention.

RESULTS

Despite a relatively high threshold of 3 months for defining an abstinence period, 62.3% of the subjects had at least one such episode, including 55.6% of the 1,853 alcoholics for whom complete data were available. Those alcohol dependent subjects with periods of abstention had an average (+/- SD) of 1.7 +/- 0.99 such periods, and 43% of abstainers had two or more. Logistic regression analyses revealed that the predictors of history of abstention were female gender (odds ratio [OR] = 1.78), older age at interview (OR = 1.04 per year), younger age of onset of alcoholism (OR 0.93 per year), ever having been married (OR = 1.45), the number of DSM-III-R dependence items endorsed (OR = 1.03 per item) and attendance in AA (OR = 2.82). Among abstainers, a period lasting 5 or more years was predicted by older age (OR = 1.03 per year) and AA participation (OR = 3.23), but also by more years of alcoholism (OR = 1.06 per year), white racial background (OR = 1.79) and the absence of history of having been a proband (OR = 3.39).

CONCLUSIONS

Periods of abstinence of 3 or more months were commonly observed in the course of alcohol dependence. This information is important for clinicians who need to avoid inappropriate stereotypes of alcoholism and who wish to educate their alcohol dependent patients about the course of this disorder.

The life-time rates of three major mood disorders and four major anxiety disorders in alcoholics and controls

AIMS

While psychiatric symptoms are common in the general population and even more prevalent in alcoholics, their clinical implications are not clear. The goal of this study was to establish the life-time rates of several independent and concurrent mood and anxiety disorders in alcoholics, controls and their relatives.

DESIGN

Structured interviews were administered to alcoholics entering treatment, their relatives, and controls.

SETTING

The study was carried out in six different centers in the United States as part of the Collaborative Study on the Genetics of Alcoholism (COGA).

PARTICIPANTS

Data were gathered from 2713 alcohol dependent subjects (probands and their alcoholic relatives) and 919 controls.

MEASUREMENTS

The timeline-based Semi-Structured Assessment for the Genetics of Alcoholism (SSAGA) interview was administered face to face by trained, closely supervised interviewers. The life-time rates for concurrent and independent disorders were determined for three DSM-III-R major mood and four major anxiety disorders.

FINDINGS

Some form of independent mood disorder was seen during the life-time in slightly fewer alcoholics than controls (14.0% and 17.1%), but alcoholics did show higher rates of independent bipolar disorder (2.3% vs. 1.0%). The life-time rate for independent anxiety disorders was significantly higher in alcoholics than controls (9.4% vs. 3.7%), with most of the differential related to panic disorder (4.2% vs. 1.0%) and social phobia (3.2% vs. 1.4%), but no significant group differences for agoraphobia or obsessive-compulsive disorder. In general, these findings regarding mood and anxiety disorders were reflected in close relatives.

CONCLUSIONS

The large majority of alcohol-dependent men and women in this sample did not have any of the independent mood or anxiety disorders evaluated here. However, there was evidence of enhanced risks among alcoholics for independent bipolar, panic and social phobic disorders. Studies which do not distinguish carefully between independent and concurrent mood and anxiety disorders in alcoholics are likely to report much higher rates of co-morbid psychiatric disorders than those that distinguish between the two types of syndromes.