Alleles of a functional serotonin transporter promoter polymorphism are associated with major depression in alcoholics

The Genetic Side of the Mood: A Scientometric Review of the Genetic Basis of Mood Disorders

Mood disorders are highly heritable psychiatric disorders. Over the years, many genetic polymorphisms have been identified to pose a higher risk for the development of mood disorders. To overview the literature on the genetics of mood disorders, a scientometric analysis was performed on a sample of 5342 documents downloaded from Scopus. The most active countries and the most impactful documents in the field were identified. Furthermore, a total of 13 main thematic clusters emerged in the literature. From the qualitative inspection of clusters, it emerged that the research interest moved from a monogenic to a polygenic risk framework. Researchers have moved from the study of single genes in the early 1990s to conducting genome-wide association studies around 2015. In this way, genetic overlaps between mood disorders and other psychiatric conditions emerged too. Furthermore, around the 2010s, the interaction between genes and environmental factors emerged as pivotal in understanding the risk for mood disorders. The inspection of thematic clusters provides a valuable insight into the past and recent trends of research in the genetics of mood disorders and sheds light onto future lines of research.

Depressive Symptoms among Middle-Aged Women-Understanding the Cause

Menopause is an important event in a woman’s life associated with hormonal changes that play a substantial role in the functioning of her body. A decline in the level of estrogens contributes to depressive symptoms and mood disorders during this period. The severity of depressive symptoms experienced by middle-aged women depends on many factors, including sociodemographic data (e.g., menopause, employment status, and marital status) and genetic variables (MAO-A and 5-HTT gene polymorphisms). In order to assess their influence on the development of depression in females, we analyzed 1453 healthy Polish women in different stages of menopause. Based on the results, we found that the l/l + l/s inheritance model for the 5-HTT gene polymorphism was more common in women without and with moderate depressive symptoms according to the Beck Depression Inventory (BDI), while the l/s model was more often observed in women with mild depression. Moreover, the overdominant 3/3 + 4/4 genotype of the MAO-A gene polymorphism was more often found in respondents without depressive symptoms, while women with depressive symptoms had more often the overdominant 3/4 genotype.

Depression and substance use disorders: Clinical comorbidity and shared neurobiology

Mood disorders, including major depressive disorder (MDD), are the most prevalent psychiatric illnesses, and pose an incredible burden to society, both in terms of disability and in terms of costs associated with medical care and lost work time. MDD has extremely high rates of comorbidity with substance use disorders (SUD) as many of the same neurobiological circuits and molecular mechanisms regulate the reward pathways disrupted in both conditions. MDD may induce SUDs, SUD may contribute to MDD development, or underlying vulnerabilities and common life experience may confer risk to developing both conditions. In this chapter we explore theories of MDD and SUD comorbidity, the neurobiological underpinnings of depression, overlapping cellular and molecular pathways for both conditions, and current treatment approaches for these comorbid conditions.

A review of 5-HT transporter linked promoter region (5-HTTLPR) polymorphism and associations with alcohol use problems and sexual risk behaviors

Alcohol use and sexual risk behaviors are multidimensional phenomena involving many genetic and environmental factors. 5-HT transporter linked promoter region (5-HTTLPR) polymorphism constitutes an important factor affecting alcohol use problems and risky sexual behaviors. This paper narratively reviews studies on 5-HTTLPR polymorphism and its associations with alcohol use problems and sexual risk behaviors. We searched the electronic databases, PubMed, Ovid, and Google Scholar for articles using MeSH terms. Relevant articles were reviewed and eligible articles were selected for the study. Many studies have reported a significant but moderate association between 5-HTTLPR polymorphism and alcohol use problems. These studies have implicated the presence of at least one S allele to be associated with significant increases in alcohol use problems. Similarly, some studies associate the S allele with increased sexual risk behaviors. Effective alcohol cessation initiatives and STI/HIV prevention programs should be modified to account for 5-HTTLPR polymorphism before planning interventions; genetic effects could moderate the intervention effect.

Multi-cultural association of the serotonin transporter gene (SLC6A4) with substance use disorder

A number of studies have reported associations between the serotonin transporter gene (SLC6A4) and alcohol, heroin, cocaine, or methamphetamine abuse. Other studies have yielded contrary results. There are a number of reasons for non-replication, including inadequate statistical power, population stratification, and poor phenotype definition. This study was to test the association using a meta-analytic approach across a variety of racial and ethnic populations. Using the genotype data of 55 studies (7999 cases, 8264 controls, and 676 families or parent-offspring trios) published in the past 15 years, we have conducted comprehensive meta-analyses to examine the associations of the 5-HTTLPR and STin2 polymorphisms with substance use disorder. The meta-analyses support the associations of 5-HTTLPR with alcohol, heroin, cocaine, and methamphetamine dependence and abuse (eg, the smallest P-values were 0.0058 with odds ratio (OR)=0.54 (0.35, 0.84); 0.0024 with OR=0.77 (0.66, 0.91); 0.018 with OR=1.38 (1.06, 1.81); and 0.028 with OR=0.46 (0.23, 0.92) for alcohol, heroin, cocaine, and methamphetamine dependence/abuse, respectively). When all the phenotypes are combined, the P-value was 0.0006 with OR=0.86 (0.78, 0.94) in the combined European, Asian, and Mexican populations and P-value was 0.0028 with OR=1.41 (1.13, 1.78) in the African populations. Evidence of significant associations was also identified in other subgroup analyses regarding differently combined substance and populations. The effect sizes of 5-HTTLPR were comparable among the European, Asian, and Mexican populations, however, the risk allele was more frequent in Asians than in Europeans and Mexicans. The opposite directions of risk allele in African population might be driven by the opposite directions of risk allele in cocaine dependence. This meta-analysis supports that the association of the SLC6A4 gene with substance use disorder varies depending on substances with different risk allele frequencies in the multi-cultural populations. Further studies using larger sample size are warranted.

A prospective assessment of reports of drinking to self-medicate mood symptoms with the incidence and persistence of alcohol dependence

IMPORTANCE

Mood disorders and alcohol dependence frequently co-occur. Etiologic theories concerning the comorbidity often focus on drinking to self-medicate or cope with affective symptoms. However, there have been few, if any, prospective studies in population-based samples of alcohol self-medication of mood symptoms with the occurrence of alcohol dependence. Furthermore, it is not known whether these associations are affected by treatment or symptom severity.

OBJECTIVE

To evaluate the hypothesis that alcohol self-medication of mood symptoms increases the probability of subsequent onset and the persistence or chronicity of alcohol dependence.

DESIGN

Prospective study using face-to-face interviews-the National Epidemiologic Survey on Alcohol and Related Conditions.

SETTING

Nationally representative survey of the US population.

PARTICIPANTS

Drinkers at risk for alcohol dependence among the 43 093 adults surveyed in 2001 and 2002 (wave 1); 34 653 of whom were reinterviewed in 2004 and 2005 (wave 2).

MAIN OUTCOMES AND MEASURES

Association of alcohol self-medication of mood symptoms with incident and persistent DSM-IV alcohol dependence using logistic regression and the propensity score method of inverse probability of treatment weighting.

RESULTS

The report of alcohol self-medication of mood symptoms was associated with an increased odds of incident alcohol dependence at follow-up (adjusted odds ratio [AOR], 3.10; 95% CI, 1.55-6.19; P = .002) and persistence of dependence (AOR, 3.45; 95% CI, 2.35-5.08; P < .001). The population-attributable fraction was 11.9% (95% CI, 6.7%-16.9%) for incident dependence and 30.6% (95% CI, 24.8%-36.0%) for persistent dependence. Stratified analyses were conducted by age, sex, race/ethnicity, mood symptom severity, and treatment history for mood symptoms.

CONCLUSIONS AND RELEVANCE

Drinking to alleviate mood symptoms is associated with the development of alcohol dependence and its persistence once dependence develops. These associations occur among individuals with subthreshold mood symptoms, with DSM-IV affective disorders, and for those who have received treatment. Drinking to self-medicate mood symptoms may be a potential target for prevention and early intervention efforts aimed at reducing the occurrence of alcohol dependence.

Girls' Tobacco and Alcohol Use During Early Adolescence: Prediction from Trajectories of Depressive Symptoms Across Two Studies

Associations between trajectories of depressive symptoms and subsequent tobacco and alcohol use were examined in two samples of girls assessed at age 11.5 (T1), 12.5 (T2), and 13.5 (T3). Two samples were examined to ascertain if there was generalizability of processes across risk levels and cultures. Study 1 comprised a United States-based sample of 100 girls in foster care; Study 2 comprised 264 girls in a United Kingdom community-based sample. Controlling for T1 aggression and T1 substance use, individual variation in intercept and slope of depressive symptoms was associated with tobacco use at T3 in both samples: greater intercept and increases in depressive symptoms increased the risk for T3 tobacco use. A similar pattern of associations was found for alcohol use in Study 1. The replicability of findings for the prediction of tobacco use from trajectories of depressive symptoms suggests potential benefit in identifying girls with elevated depressive symptoms for tobacco use prevention programs prior to the transition to secondary school.

Escitalopram, an antidepressant with an allosteric effect at the serotonin transporter--a review of current understanding of its mechanism of action

RATIONALE

Escitalopram is a widely used antidepressant for the treatment of patients with major depression. It is the pure S-enantiomer of racemic citalopram. Several clinical trials and meta-analyses indicate that escitalopram is quantitatively more efficacious than many other antidepressants with a faster onset of action.

OBJECTIVE

This paper reviews current knowledge about the mechanism of action of escitalopram.

RESULTS

The primary target for escitalopram is the serotonin transporter (SERT), which is responsible for serotonin (or 5-hydroxytryptamine [5-HT]) reuptake at the terminals and cell bodies of serotonergic neurons. Escitalopram and selective serotonin reuptake inhibitors bind with high affinity to the 5-HT binding site (orthosteric site) on the transporter. This leads to antidepressant effects by increasing extracellular 5-HT levels which enhance 5-HT neurotransmission. SERT also has one or more allosteric sites, binding to which modulates activity at the orthosteric binding site but does not directly affect 5-HT reuptake by the transporter. In vitro studies have shown that through allosteric binding, escitalopram decreases its own dissociation rate from the orthosteric site on the SERT. R-citalopram, the nontherapeutic enantiomer in citalopram, is also an allosteric modulator of SERT but can inhibit the actions of escitalopram by interfering negatively with its binding. Both nonclinical studies and some clinical investigations have demonstrated the cellular, neurochemical, neuroadaptive, and neuroplastic changes induced by escitalopram with acute and chronic administration.

CONCLUSIONS

The findings from binding, neurochemical, and neurophysiological studies may provide a mechanistic rationale for the clinical difference observed with escitalopram compared to other antidepressant therapies.

Genetic propensities to increase ethanol intake in response to stress: studies with selectively bred swim test susceptible (SUS), alcohol-preferring (P), and non-preferring (NP) lines of rats

RATIONALE

Swim test susceptible (SUS) rats selectively bred for reduced struggling in the forced swim test (FST) following stress show high voluntary ethanol intake like alcohol-preferring (P) rats selectively bred for ethanol preference. It is unknown whether stress enhances drinking in SUS rats or FST behavior in P and non-preferring (NP) rats.

OBJECTIVES

The aim of this study was to assess the response to stress in male SUS, Sprague-Dawley (SD), P, and NP rats on 10% ethanol drinking and FST behavior.

METHODS

In experiment 1, SUS and SD rats had limited access to ethanol and water following white noise, rehousing, and forced swim stress. In experiment 2, P and NP rats received footshock, white noise, restraint, or no stress prior to the FST. Rats then had continuous access to ethanol and water, and the effects of weekly exposures to stress were measured.

RESULTS

SUS rats drank more ethanol (M = 2.98 g/kg) than SD rats (M = 1.26 g/kg) at baseline. Stress produced sustained increases (~33% of baseline) in ethanol intake in SUS rats. NP rats spent twice as much time immobile as P rats in the FST. Stress did not alter FST behavior in P or NP rats. Only footshock produced an increase (~29%) in ethanol intake in P rats.

CONCLUSIONS

Selection for stress-induced depressive-like behavior in SUS rats is associated with enhanced stress-induced ethanol drinking. However, the selection for alcohol preference is not associated with stress-induced depressive-like behavior but is associated with footshock stress-induced ethanol drinking. In these experiments, relationships among stress, depressive-like behavior, and alcohol preference were not symmetrical.

Does variance in drinking motives explain the genetic overlap between personality and alcohol use disorder symptoms? A twin study of young women

BACKGROUND

Genetic risk for alcohol dependence has been shown to overlap with genetic factors contributing to variation in dimensions of personality. Although drinking motives have been posited as important mediators of the alcohol-personality relation, the extent to which the genetic covariance between alcohol use disorder (AUD) symptoms (i.e., abuse and dependence criteria) and personality is explained by genetic factors contributing to variation in drinking motives remains unclear.

METHODS

Using data from 2,904 young adult female twins, the phenotypic and genetic associations between personality dimensions (constraint [measured by the Multidimensional Personality Questionnaire; Tellegen A, 1982 unpublished data], conscientiousness, neuroticism, and agreeableness [measured by the NEO-PI; Costa and McCrae, 1985]), internal drinking motives (enhancement and coping motives [measured by the Drinking Motive Questionnaire; Cooper, 1994]), and AUD symptoms were tested.

RESULTS

Significant genetic associations were found between all personality measures and AUD symptoms. Coping motives showed significant genetic overlap with AUD symptoms and most personality measures, whereas enhancement motives were not significantly heritable. Adjusting for coping motives, genetic correlations between AUD symptoms and traits of neuroticism and agreeableness were no longer statistically significant.

CONCLUSIONS

Findings suggest that genetic variation in drinking to cope might account for a considerable proportion of the genetic covariance between specific personality dimensions and AUD symptoms.

The influence of serotonin transporter polymorphisms on cortical activity: a resting EEG study

BACKGROUND

The serotonin transporter gene (5-HTT) is a key regulator of serotonergic neurotransmission and has been linked to various psychiatric disorders. Among the genetic variants, polymorphisms in the 5-HTT gene-linked polymorphic region (5-HTTLPR) and variable-number-of-tandem-repeat in the second intron (5-HTTVNTR) have functional consequences. However, their genetic impact on cortical oscillation remains unclear. This study examined the modulatory effects of 5-HTTLPR (L-allele carriers vs. non-carriers) and 5-HTTVNTR (10-repeat allele carriers vs. non-carriers) polymorphism on regional neural activity in a young female population.

METHODS

Blood samples and resting state eyes-closed electroencephalography (EEG) signals were collected from 195 healthy women and stratified into 2 sets of comparisons of 2 groups each: L-allele carriers (N=91) vs. non-carriers for 5-HTTLPR and 10-repeat allele carriers (N=25) vs. non-carriers for 5-HTTVNTR. The mean power of 18 electrodes across theta, alpha, beta, gamma, gamma1, and gamma2 frequencies was analyzed. Between-group statistics were performed by an independent t-test, and global trends of regional power were quantified by non-parametric analyses.

RESULTS

Among 5-HTTVNTR genotypes, 10-repeat allele carriers showed significantly low regional power at gamma frequencies across the brain. We noticed a consistent global trend that carriers with low transcription efficiency of 5-HTT possessed low regional powers, regardless of frequency bands. The non-parametric analyses confirmed this observation, with P values of 3.071×10-8 and 1.459×10-12 for 5-HTTLPR and 5-HTTVNTR, respectively.

CONCLUSIONS AND LIMITATIONS

Our analyses showed that genotypes with low 5-HTT activity are associated with less local neural synchronization during relaxation. The implication with respect to genetic vulnerability of 5-HTT across a broad range of psychiatric disorders is discussed. Given the low frequency of 10-repeat allele of 5-HTTVNTR in our research sample, the possibility of false positive findings should also be considered.

Serotonin transporter polymorphism as a predictor for escitalopram treatment of major depressive disorder comorbid with alcohol dependence

The aim of this study was to determine whether the serotonin transporter gene polymorphism (5-HTTLPR) is associated with the treatment outcomes of escitalopram for patients with comorbid major depression and alcohol dependence. Eighty treatment-seeking patients were randomly assigned to either receive 20mg of escitalopram or a control of 20mg of the non-serotonergically acting memantine. Depression was measured by the Montgomery-Asberg Depression Rating Scale (MADRS) and alcoholism by the Alcohol Use Disorders Identification Test (AUDIT). Twenty-nine participants in each treatment group completed the study, and from those DNA was given by 27 in the escitalopram group and 21 in the memantine group. In the escitalopram group linear regression showed that LL genotype predicted greater decrease in MADRS scores compared with the SS/SL genotypes (p=0.04) after a 3month treatment period. Moreover, each L allele associated with MADRS score decrease by 15% (p=0.04) in the escitalopram group. In the memantine group, however, no association between LL genotype and MADRS decrease was detected. AUDIT decrease was not associated with the 5-HTTLPR genotype for either medication. This is the first study in the treatment of depression in dual diagnosis patients to report a significant association between outcomes with escitalopram and the 5-HTTLPR gene polymorphism.

The serotonin transporter gene and risk for alcohol dependence: a meta-analytic review

Previous studies have implicated a relationship between particular allelic variations of the serotonin transporter gene (5HTTLPR) and alcohol dependence. To provide a current estimate of the strength of this association, particularly in light of inconsistent results for 5HTTLPR, we conducted a meta-analytic review of the association between 5HTTLPR and a clinical diagnosis of alcohol dependence. Of 145 studies initially identified, 22 (including 8050 participants) met inclusion criteria. Results indicated that there was a significant albeit modest association between alcohol dependence diagnosis and the presence of at least 1 short allele (OR=1.15, 95% CI=1.01, 1.30, p<.05). Slightly more robust results were observed for participants who were homogeneous for the short allele (OR=1.21, 95% CI=1.02, 1.44, p<.05). These results were unrelated to sex and race/ethnicity of participants; however, the effect size was moderated by study sample size and publication year. Additionally, the fail-safe N analysis indicated potential publication bias. Therefore, although our review indicates that there is a significant association between 5HTTLPR and alcohol dependence diagnosis, this result should be interpreted with caution.

For what diagnoses are psychotropic medications being prescribed?: a nationally representative survey of physicians

BACKGROUND

Psychoactive medications, such as antidepressants, are one of the most widely prescribed categories of drugs in the US; yet few studies have comprehensively examined the conditions for which psychoactive medications are prescribed. To our knowledge, no prior study has examined the extent to which psychoactive medications are prescribed for non-psychiatric somatic illnesses or the main types of psychiatric disorders for which psychoactive medications are being used.

OBJECTIVE

To examine the diagnoses for which psychiatric medications are being prescribed in the US by analysing data from a nationally representative survey of physicians.

METHODS

The data were obtained from the 2005 National Disease and Therapeutic Index (NDTI), a continuing survey of a US office-based panel of physicians. The 2005 physician panel consisted of approximately 4000 physicians reporting quarterly, which was projected to a universe of 500,722 physicians. The study focused on the diagnoses that were given as the primary reason for prescribing the following types of psychotropic medications: antidepressants, antipsychotics and anti-anxiety medications.

RESULTS

Of the total number of antidepressant drug mentions, 92.7% were prescribed for psychiatric conditions. The most common (65.3%) were mood disorders (e.g. depression), followed by anxiety disorders (16.4%), which together comprised 81.7% of all antidepressant drug mentions. Of the total number of anti-anxiety drug mentions, 67.7% were prescribed for psychiatric conditions. The most common diagnosis was anxiety disorders (comprising 39.6% of all drug mentions), followed by mood disorders (comprising 18.9% of all drug mentions). Almost one-third of anxiety medication drug mentions were for non-psychiatric conditions or conditions of unspecified type. Of the total number of antipsychotic drug mentions, 98.9% were prescribed for psychiatric conditions. The most common diagnoses, comprising 39.0% of all drug mentions, were mood disorders such as depression and bipolar disorder. The second most common psychiatric diagnosis was schizophrenia or other psychotic disorders, comprising 34.5% of drug mentions. Approximately 7.4% of drug mentions were for delirium, dementia, amnestic or other cognitive disorders. Attention-deficit/conduct/disruptive behaviour disorders were the diagnoses indicated on 5.7% of all antipsychotic drug mentions. Anxiety disorders were indicated on 5.5% of antipsychotic drug mentions. Disorders usually diagnosed in infancy/childhood/adolescence (e.g. autism) comprised 2.3% of antipsychotic drug mentions.

CONCLUSIONS

This research provides a broad view of the nature of psychoactive medication prescribing, which may serve as a guide to future research, policy and education about these medications, their perceived benefits and risks, and their uses.

Impact of psychosocial adversity on alcohol intake in young adults: moderation by the LL genotype of the serotonin transporter polymorphism

BACKGROUND

Evidence from animal studies supports a role for serotonin transporter gene promoter polymorphism (5-HTTLPR) gene-environment interaction (G x E) in the development of excessive alcohol intake. Few studies in humans have been conducted on this topic, yielding inconsistent results. The present study aims to further explore G x E between 5-HTTLPR and exposure to psychosocial adversity on alcohol consumption in a high-risk community sample of young adults.

METHODS

Data were collected as part of the Mannheim Study of Children at Risk, an ongoing epidemiological cohort study following the outcome of early risk factors from birth into young adulthood. At age 19 years, 309 participants (142 male participants, 167 female participants) were genotyped for the biallelic and triallelic 5-HTTLPR and were administered a 45-day alcohol timeline follow-back interview, providing measures of the total number of drinks and the number of binge drinking days. Psychosocial adversity was assessed at birth (family adversity) and at age 19 (negative life events).

RESULTS

In contrast to various previous reports, a significant G x E emerged, indicating that, when exposed to high psychosocial adversity, individuals with the LL genotype of 5-HTTLPR exhibited more hazardous drinking than those carrying the S allele or those without exposure to adversity. This effect, which was confined to male participants, held both for different classifications of 5-HTTLPR and different types of adversity.

CONCLUSIONS

One explanation for the discrepant results might be heterogeneity in alcohol phenotypes. While the L allele relates more strongly to early-onset alcoholism, the S allele may be linked more closely to alcohol use associated with anxiety and depression.

Effect of the 5-HTTLPR polymorphism in the serotonin transporter gene on major depressive disorder and related comorbid disorders

OBJECTIVES

The serotonin transporter gene (5-HTT) has been proposed as a candidate gene for major depressive disorder (MDD). Association studies, however, have revealed inconsistent results. This could be because of the phenotypic heterogeneity of MDD, as it often presents with comorbid disorders such as generalized anxiety disorder (GAD), alcohol-related disorders, and dysthymia.

METHODS

In this exploratory study, we performed regression analyses with generalized estimating equations in patients with familial MDD (n=233) in order to explore whether a polymorphism in the serotonin transporter gene (5-HTTLPR) is differentially associated with MDD and a comorbid disorder compared with MDD without that particular comorbidity. As in general, GAD is more common in females and alcohol-related disorders are more common in males, the analyses were stratified for sex.

RESULTS

Comorbid dysthymia was less common in s-allele carriers with MDD (P<0.05) than in patients homozygous for the long allele. In the sex-specific analyses, an association between the 5-HTTLPR and comorbid alcohol use disorders was observed in females, with s-carriers reporting significantly less alcohol use disorders. The relationship with comorbid GAD differed by sex with male s-carriers reporting more comorbid GAD than female s-carriers.

CONCLUSION

The effect of the 5-HTTLPR polymorphism on MDD is co-dependent on the presence of comorbid disorders and sex. In this study, the s-allele of the 5-HTTLPR polymorphism was associated with significantly lower rates of particular lifetime comorbid disorders. Therefore, the presence of comorbid psychiatric disorders should be taken into account to clarify the association of the 5-HTTLPR polymorphism with MDD phenotypes.

Mood-related drinking motives mediate the familial association between major depression and alcohol dependence

BACKGROUND

Major depression and alcohol dependence co-occur within individuals and families to a higher than expected degree. This study investigated whether mood-related drinking motives mediate the association between major depression and alcohol dependence, and what the genetic and environmental bases are for this relationship.

METHODS

The sample included 5,181 individuals from the Virginia Adult Twin Study of Psychiatric and Substance Use Disorders, aged 30 and older. Participants completed a clinical interview which assessed lifetime major depression, alcohol dependence, and mood-related drinking motives.

RESULTS

Mood-related drinking motives significantly explained the depression-alcohol dependence relationship at both the phenotypic and familial levels. Results from twin analyses indicated that for both males and females, the familial factors underlying mood-related drinking motives accounted for virtually all of the familial variance that overlaps between depression and alcohol dependence.

CONCLUSIONS

The results are consistent with an indirect role for mood-related drinking motives in the etiology of depression and alcohol dependence, and suggest that mood-related drinking motives may be a useful index of vulnerability for these conditions.

Depressed mood in childhood and subsequent alcohol use through adolescence and young adulthood

CONTEXT

Despite prior evidence supporting cross-sectional associations of depression and alcohol use disorders, there is relatively little prospective data on the temporal association between depressed mood and maladaptive drinking, particularly across extended intervals.

OBJECTIVE

To assess the association between depressed mood in childhood and alcohol use during adolescence and young adulthood by mood level and sex and race/ethnicity subgroups.

DESIGN

Cohort study of individuals observed during late childhood, early adolescence, and young adulthood.

SETTING

Urban mid-Atlantic region of the United States.

PARTICIPANTS

Two successive cohorts of students from 19 elementary schools have been followed up since entry into first grade (1985, cohort I [n = 1196]; 1986, cohort II [n = 1115]). The students were roughly equally divided by sex (48% female) and were predominantly African American (70%). Between 1989 and 1994, annual assessments were performed on students remaining in the public school system, and between 2000 and 2001, approximately 75% participated in an interview at young adulthood (n = 1692).

MAIN OUTCOME MEASURES

Among participants who reported having used alcohol, Cox and multinomial regression analyses were used to assess the association of childhood mood level, as measured by a depression symptom screener, with each alcohol outcome (incident alcohol intoxication, incident alcohol-related problems, and DSM-IV alcohol abuse and dependence).

RESULTS

In adjusted regression analyses among those who drank alcohol, a high level of childhood depressed mood was associated with an earlier onset and increased risk of alcohol intoxication, alcohol-related problems during late childhood and early adolescence, and development of DSM-IV alcohol dependence in young adulthood.

CONCLUSIONS

Early manifestations associated with possible depressive conditions in childhood helped predict and account for subsequent alcohol involvement extending across life stages from childhood through young adulthood.

Population-based study of first onset and chronicity in major depressive disorder

CONTEXT

There are no studies of the natural history of major depressive disorder that lack prevalence and clinic biases.

OBJECTIVES

To estimate risk factors for first lifetime onset and parameters of chronicity following the first episode, including duration, recovery, and recurrence, and to search for predictors of each parameter.

DESIGN

Prospective population-based cohort study with 23 years of follow-up.

SETTING

East Baltimore, Maryland, an urban setting.

PARTICIPANTS

Probability sample of 3481 adult household residents in 1981, including 92 with first lifetime onset of major depressive disorder during the course of the follow-up, and 1739 other participants followed up for at least 13 years.

OUTCOME MEASURES

Diagnostic Interview Schedule and Life Chart Interview.

RESULTS

Female participants showed higher risk of onset of disorder, longer duration of episodes, and a nonsignificant tendency for higher risk of recurrence. Sex was not related to recovery. The median episode length was 12 weeks. About 15% of 92 individuals with first episodes did not have a year free of episodes, even after 23 years. About 50% of first episode participants recovered and had no future episodes. The evolution of the course was relatively stable from first to later episodes. Individuals with 1 or 2 short alleles of the serotonin transporter gene were at higher risk for an initial episode, but experienced episodes of shorter duration. There were few strong predictors of recovery or recurrence.

CONCLUSIONS

Major depressive disorder is unremitting in 15% of cases and recurrent in 35%. About half of those with a first-onset episode recover and have no further episodes.

The moderation by the serotonin transporter gene of environmental adversity in the aetiology of mental illness: review and methodological analysis

Gene-environmental interaction (G x E) between a common functional polymorphism in the promoter region of the serotonin transporter gene (5-HTT) and environmental adversity on the onset of depression in humans has been found in fifteen independent studies. It is supported by evidence from animal experiments, pharmacological challenge and neuroimaging investigations. However, negative findings have been reported in two large samples. We explore reasons for the inconsistencies and suggest means to their resolution. Sample age and gender composition emerge as important factors. While the G x E has been consistently detected in young adult samples, there are contradictory findings in adolescent boys and elderly people. The method of assessment of environmental adversity is also important with detailed interview-based approaches being associated with positive G x E findings. Unresolved issues in the definition of the genotype include the dominance of alleles and influence of other polymorphisms, both in 5-HTT and other genes. Assessment of multiple adverse outcomes, including depression, substance use and self-destructive behaviour is needed to clarify the generalisability of the G x E pathogenic mechanisms. Biological and behavioural intermediate phenotypes are yet to be exploited to understand the mechanisms underlying the G x E.

Association analyses of the serotonin transporter gene with lifetime depression and alcohol dependence in the Collaborative Study on the Genetics of Alcoholism (COGA) sample

The objective of this study was to analyze association of the serotonin transporter gene 5-HTTLPR polymorphism on lifetime depression and alcohol dependence in the Collaborative Study on the Genetics of Alcoholism sample. We conducted family-based association analyses in 1913 Caucasians genotyped for the 5-HTTLPR polymorphism. We found evidence for association of the short allele with depression, but no evidence of association with alcohol dependence. On the basis of the evidence that the effect of this polymorphism may be moderated by stressful life events, we classified individuals for the presence and/or absence of stress, as defined by unemployment, relationship problems, or poor health. The evidence for the association with lifetime depression was limited to the group of individuals who had experienced stress, paralleling the direction of effects originally reported by Caspi and colleagues. No evidence was found for the association with alcohol dependence in either the stress or the no-stress groups.

Influence of the serotonin transporter gene on comorbid disorders among alcohol-dependent individuals

OBJECTIVE

The role of the human serotonin transporter protein (5-HTT) gene in psychiatric disorders suggests that its variation may influence the comorbidity pattern and the heterogeneity of alcoholism. The aim of the present study is to verify possible associations between the 5-HTTLPR control region polymorphism with alcoholism and comorbid disorders.

METHODS

The polymorphic site was genotyped in 114 patients with alcohol dependence and 218 controls, all of them Brazilians of European descent. A comprehensive diagnostic interview identified the comorbid disorders.

RESULTS

Study participants with alcohol dependence and controls did not differ in the genotype and allele frequencies (genotypes: chi(2) = 2.52, P = 0.28; alleles: chi(2) = 0.37; P = 0.54). Patients with comorbid major depressive disorder (chi(2) = 6.14, P = 0.01), drug abuse (chi(2) = 6.82, P = 0.01) and nicotine dependence (chi(2) = 4.10, P = 0.04), however, presented a higher frequency of the S allele than patients without these comorbidities. Patients with comorbid depression and drug abuse also presented a higher frequency of the S allele than controls.

CONCLUSIONS

The present results are consistent with the importance of the 5-HTT gene in psychiatry. They suggest a role of the 5-HTTLPR polymorphism in a group of comorbid disorders among alcohol-dependent individuals, supporting a genetic influence in alcoholism heterogeneity.

Neuroticism mediates the association of the serotonin transporter gene with lifetime major depression

BACKGROUND AND OBJECTIVES

An association between a polymorphism in the serotonin transporter gene (5HTT-LPR) and the personality trait of neuroticism has been reported. We sought to address the question of whether trait neuroticism mediates the putative association between this polymorphism and lifetime major depression in adults drawn from the general population.

METHODS

Two hundred and fifty-one participants completed the Eysenck Personality Questionnaire and an adapted version of the depression section of the Structured Clinical Interview for DSM-III-R diagnosis, modified for implementation by a self-report questionnaire. A path method was applied to assess the mediator effect of neuroticism on the association between 5HTT-LPR genotype and lifetime major depression.

RESULTS

5HTT-LPR genotype was significantly associated with both neuroticism (p=0.02) and lifetime major depression (p=0.04), and neuroticism with lifetime major depression (p<0.001). Neuroticism accounted for 42.3% of the effect of 5HTT-LPR genotype on lifetime major depression, indicating possible mediation (p<0.001).

CONCLUSIONS

These results suggest that neuroticism mediates the association between 5HTT-LPR genotype and lifetime major depression, consistent with models of the aetiology of depression which suggest that anxiety-related personality traits represent a substantial risk factor for affective disorder.

Alcohol dependence and gene x environment interaction in emotion regulation: Is serotonin the link?

Alcohol dependence is characterized by frequent, compulsive and uncontrolled consumption of alcohol associated with behavior of maladaption and destruction. It is an etiologically and clinically heterogeneous syndrome, moderately to highly heritable, and caused by interaction of genes and environment. Alcohol dependence is related to other psychiatric diseases by common neurobiological pathways, including those that modulate reward, behavioral control as well as anxiety and stress response. Alcohol induces adaptive changes in brain function providing the basis for tolerance, craving, withdrawal, and emotional disturbance. The differentiation of psychobiological traits of addictive behavior reflecting neurobiological processes is therefore of particular importance for the dissection of the complex genetic susceptibility to alcohol dependence. A central serotonin (5-HT) deficit is thought to be involved in the pathogenesis of alcohol dependence by modulating motivational behavior, neuroadaptive processes, and resulting emotional disturbance. 5-HT-related impulsive, aggressive, and suicidal behavior has been linked to a primordial personality that is susceptible to alcohol dependence. Although variations in many of the genes that encode receptors, enzymes, and transporters of the 5-HT system have been tested as risk factors for alcohol dependence, genetic analyses of 5-HT signaling in alcohol dependence have mainly been focused on the 5-HT transporter (5-HTT) gene. Due to its central role in the fine-tuning serotonergic neurotransmission, a regulatory variant of the 5-HTT, which is associated with anxiety related traits, is not only a key player in the neurobiological mechanism of gene x environment interaction in the etiology of depression, but also contributes to the risk to develop alcohol dependence with antisocial behavior and suicidality. Evidence for a modulatory effect of allelic variation of 5-HTT function on limbic circuit responses to emotional stimuli suggests that genotype-endophenotype correlations may be accessible to molecular functional imaging of the brain. These new developments have broad implications for our understanding how genetic vulnerability to alcohol dependence is manifested in the brain's response to emotional stimuli.

Polymorphism in the serotonin transporter gene and response to treatment in African American cocaine and alcohol-abusing individuals

The serotonin transporter (5-HTT) regulates serotonin transmission and modulates behavioral effects of drug of abuse. A polymorphism in the promoter region of the serotonin transporter gene (5-HTTLPR) yielding a short (S) and long (L) allele has been associated with severity of substance abuse. The aims of the study were to investigate whether 5-HTTLPR genotypes differed in their response to treatment in cocaine- and alcohol-abusing patients. Polymerase chain reaction-based genotyping of a 44 base pair insertion/deletion polymorphism was performed in 141 African American cocaine-dependent patients with concurrent alcohol use who were entering a 12-week behaviorally oriented outpatient treatment program. In treatment, end of treatment and 6-month follow-up outcome measures included changes in Addiction Severity Index (ASI) scores, urine drug screens, days in treatment, individual/group sessions, dropout and completion rates. As expected, there was a reduction in substance abuse by the end of treatment and follow-up (F = 5.15, p = 0.000). However, there were no differences in the reduction in cocaine use across the LL, LS and SS genotypes. Interestingly, individuals with the S allele showed greater severity of alcohol use at admission (F = 4.84, p = 0.03), and the SS genotype showed less improvement in alcohol measures than the LL at follow-up (F = 3.68, p = 0.03), after controlling for baseline variables. While we found no association of the 5-HTTLPR variants with severity of cocaine abuse or any cocaine-related outcome measures, the data suggested that the 5-HTTLPR polymorphism may distinguish responders from non-responders to behavioral treatment in terms of alcohol use. Further investigations are required to determine the role of the 5-HTTLPR polymorphism in influencing treatment - outcome among substance abusers.

Effect of mirtazapine treatment on serotonin transporter in blood peripheral lymphocytes of major depression patients

Lymphocytes from human peripheral blood exhibit a series of markers of neurotransmitters, such as specific receptors and transporters. A reduction of serotonin transporters and an increase of them has been reported after treatment with fluoxetine in depressed patients. The aim of this study was to determine if the administration of an antidepressant with a different mechanism of action, such as mirtazapine, could produce a similar effect. Twenty eight patients (age 41.40+/-2.45) were diagnosed following the criteria for major depression by the Structured Clinical Interview for Disorders of Axis I of the American Psychiatric Association. Severity was measured by Hamilton Scale and by Beck Inventory for Depression, scores of 30.88+/-7.48 and 30.24+/-10.88, respectively, prior to treatment. Samples from control subjects were obtained alternating with patients before and after the administration of the antidepressant: twenty eight and twenty four, respectively (age 38.80+/-2.95). Mirtazapine was given in a dose of 30 mg/day for 6 weeks. Blood lymphocytes were isolated by density gradient from patients and controls before and after treatment. There was a partial response according to clinical evaluation and scores of the Scale and the Inventory. Serotonin transporters were labeled with [3H] paroxetine. Number of sites (B(max)) were 10.86+/-2.60 and 12.58+/-2.71 fmol/10(6) cells for both groups of controls. The depressed patients had a significant reduction of serotonin transporters in their lymphocytes before treatment and an increase after it, with B(max) values of 6.52+/-0.49 and 15.61+/-0.49 fmol/10(6) cells, respectively. There were no significant differences in the affinity for the ligand. Concentrations of serotonin or noradrenaline in lymphocytes were not modified before the treatment, although there was a significant decrease after taking 30 mg/day of the antidepressant for 6 weeks. Mirtazapine, not being a serotonin reuptake inhibitor, did increase the number of transporters in lymphocytes of major depression patients, indicating a complex mechanism, not only directly related to the transporter, but involved in the therapeutic response.

Association between the serotonin transporter gene and alcohol consumption in social drinkers

Relatively few studies have investigated the role of the 5HTT gene in intermediate phenotypes such as alcohol consumption in non-alcohol dependent populations. A recent study reported an association with alcohol consumption in a student population. We attempted to replicate these findings and extend on this work in a representative, ethnically homogenous, non-alcohol dependent sample of social drinkers in the United Kingdom. The short allele of the 5HTT gene was significantly associated with increased alcohol consumption (P = 0.03). There was suggestive evidence of a genotype-sex interaction (P = 0.04). Post-hoc tests indicated higher alcohol consumption in men with one or more copies of the short allele, while in women consumption was highest among heterozygotes compared to both homozygote groups. Age at time of data collection and cigarette consumption were entered as covariates. These results replicate recent previous findings and suggest a possibility that this association may differ in men and women.

Meta-analysis of the association of a functional serotonin transporter promoter polymorphism with alcohol dependence

The neurotransmitter serotonin (5-HT) has been shown to regulate alcohol consumption in both animals and humans. Since activity of the 5-HT transporter protein (5-HTT) regulates 5-HT levels, the gene encoding this protein may contribute to the risk of alcohol dependence (AD). Studies of the association to AD of a functional insertion-deletion polymorphism in the 5-HTT-linked promoter region (5-HTTLPR) have yielded inconsistent results. We conducted a meta-analysis of data from 17 published studies (including 3,489 alcoholics and 2,325 controls) investigating the association between 5-HTTLPR alleles and AD. The frequency of the short (S) allele at 5-HTTLPR was significantly associated with AD [odds ratio (OR) = 1.18, 95% CI = 1.03-1.33). Moreover, a greater association with the S allele was seen among individuals with AD complicated by either a co-morbid psychiatric condition or an early-onset or more severe AD subtype [OR = 1.34 (95% CI = 1.11-1.63)]. Allelic variation at 5-HTTLPR contributes to risk for AD, with the greatest effect observed among individuals with a co-occurring clinical feature.

Polymorphismes géniques de marqueurs sérotoninergiques et alcoolodépendance

Genetic factors have a non-specific but significant impact on the risk of alcohol-dependence. Molecular genetic analyses are now less devoted to the genes involved in the metabolism of ethanol, focusing on core concepts of addiction, such as arousal, pleasure, reward, craving, and impulsivity. Indeed, the neuro-cognitive functions, temperament traits and psycho-behavioral specificities of patients with alcohol abuse or dependence led to select new sets of candidate genes. One of them are related to serotonin transmission, as serotonin modulates dopaminergic pathways, and is also stimulated by many addictive susbtances. The genetic analyses of serotonin in alcohol-dependence are mainly focused on the serotonin transporter gene (5-HTT), as one polymorphism within the promoter has a functional impact. From the 16 case-control association studies yet performed, many are positive, and one family-based study showed a large excess of transmission of the short allele. We performed a meta-analysis of the case-control studies showing that the S allele could be a risk factor for a phenotype related to alcohol-dependence (OR=1.31), with still unknown boundaries. Other genes coding for serotonin receptors were analysed with mainly negative results, for example the 5-HT2A, 5-HT2C, 5-HT5A and 5-HT7 receptors. The 5-HT1B could be more interesting as being located in a locus linked to alcohol preference in rodents, and associated with antisocial alcoholism in two human studies. Genetics may thus provide new insights about the different mechanisms which explain why some subjects are more at risk for the development of alcohol abuse or dependence. Genes involved in the transmission, reuptake and metabolism of serotonin constitute a set of candidate genes that could be involved in core aspects of alcoholism, such as the tendency to prefer immediate reward, despite negative consequences.