Meta-analysis of the association of serotonin transporter gene polymorphism with obsessive-compulsive disorder

Genetic and epigenetic architecture of Obsessive-Compulsive Disorder: In search of possible diagnostic and prognostic biomarkers

Obsessive-Compulsive Disorder (OCD) is a prevalent and severe clinical condition whose hallmarks are excessive, unwanted thoughts (obsessions) and repetitive behaviors (compulsions). The onset of symptoms generally occurs during pre-adult life and typically affects subjects in different aspects of their life's, compromising social and professional relationships. Although robust evidence suggests a genetic component in the etiopathogenesis of OCD, the causes of the disorder are still not completely understood. It is thus of relevance to take into account how genes interact with environmental risk factors, thought to be mediated by epigenetic mechanisms. We here provide an overview of genetic and epigenetic mechanisms of OCD, focusing on the modulation of key central nervous system genes, in the attempt to suggest possible disease biomarkers.

The serotonin transporter gene polymorphism (5-HTTLPR) and affective symptoms among women diagnosed with borderline personality disorder

Gene variants of the serotonin transporter have been associated with vulnerability to affective disorders. In particular, the presence of one or two copies of the short (s) allele of the 5-HTTLPR polymorphism has been associated with reduced serotonin transporter expression and function, and vulnerability to affective disorders. To test for an association between variants of the serotonin transporter gene polymorphism (5-HTTLPR) and relevant clinical features of borderline personality disorder (BPD), a psychiatric disorder with symptoms characteristic for serotonin dysfunction, 77 women with BPD were genotyped in the 5-HTTLPR polymorphism. They rated their subjective experience of borderline-specific, depressive, anxious and obsessive-compulsive symptoms, and were interviewed about lifetime incidence of suicide attempts and self-harming acts. Carriers of two s alleles of the 5-HTTLPR reported more symptoms of borderline, depression, anxiety and obsessive-compulsive behaviours, but not of suicidal and self-injury behaviour, compared to carriers of a long (l) allele. This indicates that the 5-HTTLPR ss homozygous genotype might influence serotonin function affecting susceptibility to both borderline-specific, depressive, anxious and obsessive-compulsive symptoms in BPD, and leading to a more severe symptomatology related to these clinical features. Further, this suggests that 5-HTT gene variants may not be as influential on suicidal and self-injury behaviour in BPD.

Impact of serotonin transporter gene on rTMS augmentation of SSRIs for obsessive compulsive disorder

OBJECTIVE

Repetitive transcranial magnetic stimulation (rTMS) is beneficial for treatment-resistant patients with obsessive-compulsive disorder (OCD). The serotonin transporter gene (SLC6A4) may be associated with OCD. We aimed to determine whether SLC6A4 impacts the beneficial effects of rTMS in patients with OCD treated with selective serotonin reuptake inhibitors (SSRIs).

METHODS

Fifty-seven untreated patients with OCD were randomly assigned to receive active or sham rTMS in a 4-week double-blind study. The participants received 1-Hz rTMS over the supplementary motor area once per day, for 5 days a week, for 4 weeks. One of the widely employed SSRIs was utilized at the initiation of active or sham rTMS. Yale-Brown obsessive-compulsive scale (Y-BOCS) scores were used for assessing the symptoms. The most-researched polymorphism of SLC6A4, 5-HTTLPR (L/S), was also examined.

RESULTS

Y-BOCS scores in the active group at the completion of the treatment were significantly lower than those in the sham group. Interestingly, the improvement in Y-BOCS scores in patients with the LL genotype treated with active rTMS was significantly (p<0.05) greater than in those treated with sham rTMS. Conversely, rTMS did not produce significant improvements in S allele carriers.

CONCLUSIONS

The findings of this study suggest that rTMS can augment the beneficial effects of SSRIs in OCD patients with the LL genotype of 5-HTTLPR. Therefore, the presence of 5-HTTLPR (L/S) in SLC6A4 may be a predictable biomarker for the beneficial effects of rTMS, although more studies using larger sample sizes are warranted for confirming the results.

Association of the functional serotonin transporter haplotype with familial form of obsessive compulsive disorder in Iranian patients

OBJECTIVE

Several polymorphisms have been reported in the 5-HTTLPR of the serotonin transporter gene (SLC6A4). Family-based evidences for the association of 5-HTTLPR polymorphisms with OCD were previously reported but results were controversial. The present study investigated the possible correlation of SLC6A4 polymorphisms (5-HTTLPR, rs25532, rs25531) in Iranian OCD patients considering gender, age of onset, family history of psychiatric disorders, obsessive and compulsive subtypes and severities.

METHODS

The included OCD patients fulfilled the criteria for DSM-IV-TR whom Y-BOCS score was more than 9. Blood samples (184 cases and 192 controls) were genotyped by means of PCR-RFLP.

RESULTS

Mean of Y-BOCS scores of included patients was 20.1 ± 0.69. Rs25532 CC genotype showed significant association with OCD in men and were detected more in the patients reported positive family history of psychiatric disorders but the other single loci (5-HTTLPR and rs25531) did not associate with OCD. Haplotype analysis showed significant association of 14-A variant with OCD and revealed the association of 14-A/14-A genotype with familial form of OCD.

CONCLUSIONS

The findings of this study showed the association of SLC6A4 variants with familial form of OCD and proposed stratified analyses in the genetic studies facilitate identification of genetic risk factors for this heterogeneous disorder.

Combining genetic and epigenetic parameters of the serotonin transporter gene in obsessive-compulsive disorder

While genetic variants have been reported to be associated with obsessive-compulsive disorder (OCD), the small effect sizes suggest that epigenetic mechanisms such as DNA methylation may also be relevant. The serotonin transporter (SLC6A4) gene has been extensively investigated in relation to OCD, since serotonin reuptake inhibitors are the pharmacological treatment of choice for the disorder. The current study set three questions: Firstly, whether the high expressing loci of the SLC6A4 polymorphisms, 5-HTTLPR + rs25531, rs25532 and rs16965628 are associated with family-based (n = 164 trios) and case-control OCD (n = 186, 152, respectively). This was also examined by a meta-analysis. Secondly, whether DNA methylation and RNA levels of the SLC6A4 differ in saliva and blood of a subset of samples from pediatric and adult OCD patients and matched controls. And lastly, whether morning awakening cortisol levels correlate with the above. A meta-analysis confirmed the association of the L_A-allele with OCD (OR = 1.21, p = 0.00018), maintaining significance in the early-onset OCD subgroup (OR = 1.21, p = 0.022). There was no association between rs25532 or rs16965628 and OCD. Our preliminary data showed that SLC6A4 DNA methylation levels in an amplicon located at the beginning of the first intron were significantly higher in the saliva of pediatric OCD patients compared to controls and adult patients with OCD, but no alterations in RNA levels or in polymorphism interactions were observed. Morning awakening salivary cortisol levels positively correlated with methylation levels, and negatively correlated with RNA levels. This study further supports the involvement of the SLC6A4 gene in OCD through both genetic and epigenetic mechanisms. This finding needs to be explored further in an independent large sample.

Methylation Status of the Serotonin Transporter Promoter CpG Island Is Associated With Major Depressive Disorder in Chinese Han Population: A Case-Control Study

This study was aimed to investigate the relationship between the methylation status of serotonin transporter (5-HTT) and major depressive disorder (MDD) in Chinese Han population. A total of 96 patients with MDD and 55 healthy volunteers were recruited, and the methylation index (MtI) at six positions in the cytosine-phosphate-guanosine island of 5-HTT gene was measured for each subject using bisulfite pyrosequencing. MtIs at positions 5 and 6 were higher in patients with MDD than those in controls. According to the multivariable logistic regression analysis, MtIs at positions 4 and 5 were significantly associated with MDD. Besides, depression education was an independent risk factor, whereas higher educational levels were protective factors for MDD. In addition, positions 1 and 4 were negatively correlated with weight and diurnal variation. Therefore, 5-HTT methylation might be closely related with MDD in Chinese Han population because of the correlation with diurnal variation and weight.

Peripheral SLC6A4 Gene Expression in Obsessive-Compulsive Disorder in the Han Chinese Population

BACKGROUND

Serotonergic system dysfunction has been implicated in obsessive-compulsive disorder (OCD). This study examined peripheral SLC6A4 gene expression in OCD patients and healthy controls to explore the relationship between SLC6A4 and OCD.

METHODS

Participants included 50 first episode OCD patients and 60 age and gender-matched healthy controls. Relative SLC6A4 gene expression were examined by real-time quantitative reverse transcription polymerase chain reaction (RT-PCR) in peripheral leukocytes of all the subjects. The Yale-Brown Obsessive Compulsive Scale (Y-BOCS) was used to assess the severity and subtype of OCD.

RESULTS

SLC6A4 gene expression, normalized by glyceraldehyde-3-phosphate dehydrogenase (GAPDH), were not significantly different between the OCD patients and healthy controls(z=-0.79, p=0.428). Male OCD patients showed a tendency of low gene expression of SLC6A4 in peripheral blood (z=-1.66, p=0.096). We did not find a significant correlation between SLC6A4 expression and the severity and subtype of OCD.

CONCLUSION

There is no correlation between SLC6A4 expression levels and the severity and subtype of OCD, but male OCD patients showed a tendency of low gene expression of SLC6A4 in peripheral blood. These results suggest that gene expression of SLC6A4 in peripheral blood may not be a useful biomarker of OCD in the Han Chinese population.

A review of the role of serotonin system genes in obsessive-compulsive disorder

Obsessive-compulsive disorder (OCD) is a debilitating neuropsychiatric disorder that causes the patient to experience intrusive thoughts and/or to carry out repetitive, ritualized behaviors that are time consuming and impairing. OCD is familial and heritable. The genetic factors responsible for pathogenesis, however, remain largely unknown despite the numerous candidate gene studies conducted. Based on efficacy of serotonin reuptake inhibitors (SRIs) in treating OCD, serotonin system genes have been a dominant focus in OCD candidate gene studies. We review the most commonly studied candidate serotonin system gene variants (specifically in SLC6A4, HTR2A, HTR1B, and HTR2C) and their association with OCD. Although findings to date are mixed, serotonin transporter polymorphism 5-HTTLPR and HTR2A polymorphism rs6311 (or rs6313) are most consistently associated with OCD. Mixed findings may be the result of genetic complexity and phenotypic heterogeneity that future studies should account for. Homogenous patient subgroups reflecting OCD symptom dimensions, OCD subtypes, and sex should be used for gene discovery.

Unveiling the relative efficacy, safety and tolerability of prophylactic medications for migraine: pairwise and network-meta analysis

BACKGROUND

A large number patients struggle with migraine which is classified as a chronic disorder. The relative efficacy, safety and tolerability of prophylactic medications for migraine play a key role in managing this disease.

METHODS

We conducted an extensive literature search for popular prophylactic medications that are used for migraine patients. Pairwise meta-analysis and network meta-analysis (NMA) were carried out sequentially for determining the relative efficacy, safety and tolerability of prophylactic medications. Summary effect for migraine headache days, headache frequency, at least 50% reduction in headache attacks, all-adverse events, nausea, somnolence, dizziness, withdrawal and withdrawal due to adverse events were produced by synthesizing both direct and indirect evidence.

RESULTS

Patients with three interventions exhibited significantly less average migraine headache days compared with those treated by placebo (topiramate, propranolol, divalproex). Moreover, topiramate and valproate exhibited a significantly increased likelihood of at least 50% reduction in migraine headache attacks compared to placebo. Patients with topiramate and propranolol also exhibited significantly reduced headache frequency compared to those with placebo. On the other hand, patients with divalproex exhibited significantly higher risk of nausea compared to those with placebo, topiramate, propranolol, gabapentin and amitriptyline. Finally, divalproex was associated with an increased risk of withdrawal compared to placebo and propranolol.

CONCLUSIONS

Topiramate, propranolol and divalproex may be more efficacious than other prophylactic medications. Besides, the safety and tolerability of divalproex should be further verified by future studies.

A pilot study exploring the association of morphological changes with 5-HTTLPR polymorphism in OCD patients

BACKGROUND

Clinical and pharmacological studies of obsessive-compulsive disorder (OCD) have suggested that the serotonergic systems are involved in the pathogenesis, while structural imaging studies have found some neuroanatomical abnormalities in OCD patients. In the etiopathogenesis of OCD, few studies have performed concurrent assessment of genetic and neuroanatomical variables.

METHODS

We carried out a two-way ANOVA between a variable number of tandem repeat polymorphisms (5-HTTLPR) in the serotonin transporter gene and gray matter (GM) volumes in 40 OCD patients and 40 healthy controls (HCs).

RESULTS

We found that relative to the HCs, the OCD patients showed significant decreased GM volume in the right hippocampus, and increased GM volume in the left precentral gyrus. 5-HTTLPR polymorphism in OCD patients had a statistical tendency of stronger effects on the right frontal pole than those in HCs.

CONCLUSIONS

Our results showed that the neuroanatomical changes of specific GM regions could be endophenotypes of 5-HTTLPR polymorphism in OCD.

Genetics of anxiety: would the genome recognize the DSM?

The nosology of anxiety disorders has undergone substantial evolution over the past several decades. The modern classification of these disorders dates to the publication of Diagnostic and Statistical Manual-III (DSM-III) in 1980, but the validity of the current diagnostic categories has been the subject of controversy. Genetic research can help clarify the boundaries of diagnostic categories by examining the etiologic relationships among them. The question posed in the title of this article asks to what degree the DSM-IV definitions of the anxiety disorders are supported by the evolving body of research on the genetic basis of pathologic anxiety. With DSM-V on the horizon, there is a renewed imperative to examine the structure of these disorders. In this article, we address this issue by, first, providing a brief update about the current status of genetic research on anxiety disorders and then considering whether the evidence suggests that genetic influences conform to or transcend DSM definitions. Finally, we discuss future directions for the genetic dissection of anxiety disorders.

Serotonin transporter promoter polymorphism is associated with executive function impairments in patients with obsessive compulsive disorder

OBJECTIVE

In the present study, we investigate the association between the 5-HTTLPR polymorphism and executive functions in a sample of patients with obsessive compulsive disorder (OCD).

METHOD

A total of 98 unmedicated patients diagnosed with OCD according to DSM-IV criteria and 80 healthy controls were included in this study. The genotype frequencies of 5-HTTLPR polymorphism were compared in OCD and healthy control groups. The four subgroups of OCD and healthy control participants, determined according to having LaLa genotype (high expressing) or S- and/or Lg alleles (low expressing), were also compared using neuropsychological tests of executive functions.

RESULTS

The frequency of SLa genotype of 5-HTTLPR polymorphism was found to be higher in patients with OCD compared with healthy controls. The mean scores of conceptual level responses of the Wisconsin Card Sorting Test (WCST) were significantly lower in the OCD-high-expressing subgroup compared with the low-expressing control group. The mean scores of the number of moves of the Tower of London were found to be significantly higher in the OCD-high-expressing subgroup, compared with the high-expressing subgroup of healthy controls.

CONCLUSION

Our findings suggest that the high-expressing variant may be associated with lower performance on some abstraction and planning measures in OCD patients.

Altered inhibition-related frontolimbic connectivity in obsessive-compulsive disorder

BACKGROUND

Recent studies have shown that response inhibition is impaired in patients with obsessive-compulsive disorder and their unaffected siblings, suggesting that these deficits may be considered a cognitive endophenotype of obsessive-compulsive disorder. Structural and functional neural correlates of altered response inhibition have been identified in patients and siblings. This study aims to examine the functional integrity of the response inhibition network in patients with obsessive-compulsive disorder and their unaffected siblings.

METHODS

Forty-one unmedicated patients with obsessive-compulsive disorder, 17 of their unaffected siblings and 37 healthy controls performed a stop signal task during functional magnetic resonance imaging. Psycho-physiological interaction analysis was used to examine functional connectivity between the following regions of interest: the bilateral inferior frontal gyri, presupplementary motor area, subthalamic nuclei, inferior parietal lobes, anterior cingulate cortex, and amygdala. We then used dynamic causal modeling to investigate the directionality of the networks involved.

RESULTS

Patients, and to a lesser extent also their unaffected siblings, show altered connectivity between the inferior frontal gyrus and the amygdala during response inhibition. The follow-up dynamic causal modeling suggests a bottom-up influence of the amygdala on the inferior frontal gyrus in healthy controls, whereas processing occurs top-down in patients with obsessive-compulsive, and in both directions in siblings.

CONCLUSIONS

Our findings suggest that amygdala activation in obsessive-compulsive disorder interferes differently with the task-related recruitment of the inhibition network, underscoring the role of limbic disturbances in cognitive dysfunctions in obsessive-compulsive disorder.

Is serotonin transporter polymorphism (5-HTTLPR) allele status a predictor for obsessive-compulsive disorder? A meta-analysis

The serotonin transporter polymorphism has been implicated in obsessive-compulsive disorder (OCD). However, molecular genetic association studies have yielded inconsistent results. Variation may be due to lack of OCD subtype classification. The goal of this systematic review is to investigate the association of the S-allele of the serotonin transporter polymorphism with OCD and OCD subtypes. A total of 69 studies were initially found through a systematic search of the literature but only 13 with sufficient information to compute odds ratios were suitable for review. A total of 1991 participants with OCD and their 5-HTTLPR allele status were examined. The primary outcome measures were allele frequency and OCD diagnosis. A full meta-analysis was completed comparing the L- and S-alleles using a random effects model in RevMan 5.2.1. Further, a secondary meta-analysis stratified by sex and late-onset was conducted for S- versus L-allele frequency. In the primary meta-analysis, OCD was not associated with the S-allele of the 5-HTTLPR polymorphism (Z = 0.07, p = 0.94). Moreover, late-onset OCD was not associated with the S-allele (Z = 1.45, p = 0.15). However, when stratified by sex, there is an emerging sex-specific relationship. There was a trending association between the S-allele and OCD status in females (Z = 1.62, p = 0.10) but not in males (Z = 0.69, p = 0.49). The findings provide further support for the need of subtype classification of this heterogeneous disorder. Future studies should clearly examine sex differences and OCD age-of-onset. In particular, emphasis should be placed on the effect of female reproductive milestones on OCD onset and symptom exacerbation.

The aggression and behavioral abnormalities associated with monoamine oxidase A deficiency are rescued by acute inhibition of serotonin reuptake

The termination of serotonin (5-hydroxytryptamine, 5-HT) neurotransmission is regulated by its uptake by the 5-HT transporter (5-HTT), as well as its degradation by monoamine oxidase (MAO)-A. MAO-A deficiency results in a wide set of behavioral alterations, including perseverative behaviors and social deficits. These anomalies are likely related to 5-HTergic homeostatic imbalances; however, the role of 5-HTT in these abnormalities remains unclear. To ascertain the role of 5-HTT in the behavioral anomalies associated to MAO-A deficiency, we tested the behavioral effects of its blocker fluoxetine on perseverative, social and aggressive behaviors in transgenic animals with hypomorphic or null-allele MAO-A mutations. Acute treatment with the 5-HTT blocker fluoxetine (10 mg/kg, i.p.) reduced aggressive behavior in MAO-A knockout (KO) mice and social deficits in hypomorphic MAO-A(Neo) mice. Furthermore, this treatment also reduced perseverative responses (including marble burying and water mist-induced grooming) in both MAO-A mutant genotypes. Both MAO-A mutant lines displayed significant reductions in 5-HTT expression across the prefrontal cortex, amygdala and striatum, as quantified by immunohistochemical detection; however, the down-regulation of 5-HTT in MAO-A(Neo) mice was more pervasive and widespread than in their KO counterparts, possibly indicating a greater ability of the hypomorphic line to enact compensatory mechanisms with respect to 5-HT homeostasis. Collectively, these findings suggest that the behavioral deficits associated with low MAO-A activity may reflect developmental alterations of 5-HTT within 5-HTergic neurons. Furthermore, the translational implications of our results highlight 5-HT reuptake inhibition as an interesting approach for the control of aggressive outbursts in MAO-A deficient individuals.

Imaging genetics in obsessive-compulsive disorder: linking genetic variations to alterations in neuroimaging

Obsessive-compulsive disorder (OCD) occurs in ∼1-3% of the general population, and its often rather early onset causes major disabilities in the everyday lives of patients. Although the heritability of OCD is between 35 and 65%, many linkage, association, and genome-wide association studies have failed to identify single genes that exhibit high effect sizes. Several neuroimaging studies have revealed structural and functional alterations mainly in cortico-striato-thalamic loops. However, there is also marked heterogeneity across studies. These inconsistencies in genetic and neuroimaging studies may be due to the heterogeneous and complex phenotypes of OCD. Under the consideration that genetic variants may also influence neuroimaging in OCD, researchers have started to combine both domains in the field of imaging genetics. Here, we conducted a systematic search of PubMed and Google Scholar literature for articles that address genetic imaging in OCD and related disorders (published through March 2014). We selected 8 publications that describe the combination of imaging genetics with OCD, and extended it with 43 publications of comorbid psychiatric disorders. The most promising findings of this systematic review point to the involvement of variants in genes involved in the serotonergic (5-HTTLPR, HTR2A), dopaminergic (COMT, DAT), and glutamatergic (SLC1A1, SAPAP) systems. However, the field of imaging genetics must be further explored, best through investigations that combine multimodal imaging techniques with genetic profiling, particularly profiling techniques that employ polygenetic approaches, with much larger sample sizes than have been used up to now.

Genetics of obsessive–compulsive disorder: a research update

The genetic study of obsessive-compulsive disorder (OCD) has made significant gains in the past decade. However, etiological gene findings are still elusive. Epidemiological studies, including family and twin studies, strongly support a genetic component for OCD. In addition, complex segregation analyses suggest the presence of at least one major gene. The neurobiology of OCD also lends support to the notion that programmed CNS-based biological processes underlie OCD symptom expression, with mapping of brain circuits to fronto-subcortical circuits in a consistent manner. Genetic linkage studies of OCD, using families with multiple affected relatives, have generated several suggestive linkage peaks, regions that may harbor a gene or genes for OCD. However, the presence of multiple linkage peaks has added to the complexity of OCD genetics, suggesting that the exploration of gene-gene interactions and gene-environment interactions, in addition to the exploration of alternate phenotypes based on symptom expression, age at onset or comorbid conditions, may be key in locating etiologic genes. Finally, candidate gene studies, while promising, are not yet associated with linkage regions, except in the case of the glutamate transporter gene SLC1A1 in 9p24. While OCD appears to have a genetic component, additional innovative research is needed to unravel the genetic influences in the disorder.

How specific are inhibitory deficits to obsessive-compulsive disorder? A neurophysiological comparison with panic disorder

OBJECTIVE

Impaired inhibition may perpetuate repetitive symptoms in obsessive-compulsive disorder (OCD), however OCD-specific deficits have yet to be established. We investigated neural correlates of inhibition in OCD vs. healthy and anxious controls.

METHODS

ERPs and reaction times (RTs) were compared between participants with OCD (n=20), panic disorder (PD; n=20) and healthy controls (HCs; n=20) during an adapted Go/NoGo task, which manipulated inhibitory difficulty.

RESULTS

A classic P3 NoGo anteriorisation effect occurred across groups. Both clinical groups showed RT impairment, and similar topographical anomalies of several (P2, N2 and P3) ERP components. Notably, both clinical groups lacked the strong frontally maximal N2 component topography seen in the HCs, across stimuli. Additionally, with increasing inhibitory difficulty, N2 latency increased in HCs but not in the clinical groups.

CONCLUSIONS

Unexpectedly, ERP and behavioural anomalies during inhibition in OCD were not qualitatively different to those in PD, but were generally more severe. Common general and inhibitory deficits may underlie intrusive mental phenomena in both conditions.

SIGNIFICANCE

This first ERP response inhibition study in OCD to include anxious controls disconfirmed hypotheses regarding OCD-specific inhibitory deficits, indicating the importance of comparing OCD to other conditions, to evaluate neurobiological models.

Molecular genetics of obsessive-compulsive disorder: a comprehensive meta-analysis of genetic association studies

Twin studies indicate that obsessive-compulsive disorder (OCD) is strongly influenced by additive genetic factors. Yet, molecular genetic association studies have yielded inconsistent results, possibly because of differences across studies in statistical power. Meta-analysis can yield greater power. This study reports the first comprehensive meta-analysis of the relationship between OCD and all previously examined polymorphisms for which there was sufficient information in the source studies to compute odds ratios (ORs). A total of 230 polymorphisms from 113 genetic association studies were identified. A full meta-analysis was conducted for 20 polymorphisms that were examined in 5 or more data sets, and a secondary meta-analysis (limited to the computation of mean effect sizes) was conducted for 210 polymorphisms that were examined in fewer than 5 data sets. In the main meta-analysis, OCD was associated with serotonin-related polymorphisms (5-HTTLPR and HTR2A) and, in males only, with polymorphisms involved in catecholamine modulation (COMT and MAOA). Nonsignificant trends were identified for two dopamine-related polymorphisms (DAT1 and DRD3) and a glutamate-related polymorphism (rs3087879). The secondary meta-analysis identified another 18 polymorphisms with significant ORs that merit further investigation. This study demonstrates that OCD is associated with multiple genes, with most having a modest association with OCD. This suggests a polygenic model of OCD, consistent with twin studies, in which multiple genes make small, incremental contributions to the risk of developing the disorder. Future studies, with sufficient power to detect small effects, are needed to investigate the genetic basis of OCD subtypes, such as early vs late onset OCD.

Symptoms at postmenopause: genetic and psychosocial factors

OBJECTIVE

Menopause symptoms result from the interaction of estrogen deprivation, psychosocial influences, and genetic factors. We examined the influence of stress and of estrogen receptor-α (ER-α; PvuII and XbaI) and serotonin transporter (5-HTT) polymorphisms on symptoms at postmenopause.

METHODS

We studied 290 urban women from three cities in Mexico. General characteristics, menopause symptoms, and scores of perceived stress, effort-reward imbalance, dominance, and submission were collected. A fasting blood sample was obtained for hormone measurements and genotypification.

RESULTS

Women had a mean ± SD age of 54.4 ± 4.5 years and BMI of 29.5 ± 4.9 kg/m. The frequency of hot flashes was 75.5%; vaginal dryness, 57.8%; and diminished sexual interest, 78.7%. Follicle-stimulating hormone and estradiol levels were 59 ± 27 mIU/mL and 22 ± 29 pg/mL, respectively. Women from Torreón had higher schooling and less parity but higher scores for depression and lower submission. Hot flashes were more frequent in women from León. Genotype distribution was similar among cities. Lower scores for dominance were found in women with the pp and xx ER-α genotypes. Increased smoking habit was found for the SS genotype of 5-HTT. Factors significantly associated with symptoms were years since menopause, with hot flashes (negative), and with diminished sexual interest (positive); dominance was negatively associated with depression, perceived stress, and vaginal dryness; submission was positively associated with depression, perceived stress, anxiety, and hot flashes; and effort-reward imbalance was positively associated with anxiety, hot flashes, and perceived stress.

CONCLUSIONS

Symptoms at postmenopause were associated mainly with dominance, submission, and effort-reward imbalance. The pp genotype of ER-α showed lower scores of dominance.

A dialogue between the immune system and brain, spoken in the language of serotonin

Neuropsychiatric disorders have long been linked to both immune system activation and alterations in serotonin (5-HT) signaling. In the CNS, the contributions of 5-HT modulate a broad range of targets, most notably, hypothalamic, limbic and cortical circuits linked to the control of mood and mood disorders. In the periphery, many are aware of the production and actions of 5-HT in the gut but are unaware that the molecule and its receptors are also present in the immune system where evidence suggests they contribute to the both innate and adaptive responses. In addition, there is clear evidence that the immune system communicates to the brain via both humoral and neuronal mechanisms, and that CNS 5-HT neurons are a direct or indirect target for these actions. Following a brief primer on the immune system, we describe our current understanding of the synthesis, release, and actions of 5-HT in modulating immune function, including the expression of 5-HT biosynthetic enzymes, receptors, and transporters that are typically studied with respect to the roles in the CNS. We then orient our presentation to recent findings that pro-inflammatory cytokines can modulate CNS 5-HT signaling, leading to a conceptualization that among the many roles of 5-HT in the body is an integrated physiological and behavioral response to inflammatory events and pathogens. From this perspective, altered 5-HT/immune conversations are likely to contribute to risk for neurobehavioral disorders historically linked to compromised 5-HT function or ameliorated by 5-HT targeted medications, including depression and anxiety disorders, obsessive-compulsive disorder (OCD), and autism. Our review raises the question as to whether genetic variation impacting 5-HT signaling genes may contribute to maladaptive behavior as much through perturbed immune system modulation as through altered brain mechanisms. Conversely, targeting the immune system for therapeutic development may provide an important opportunity to treat mental illness.

Sex determines which section of the SLC6A4 gene is linked to obsessive-compulsive symptoms in normal Chinese college students

Previous case-control and family-based association studies have implicated the SLC6A4 gene in obsessive-compulsive disorder (OCD). Little research, however, has examined this gene's role in obsessive-compulsive symptoms (OCS) in community samples. The present study genotyped seven tag SNPs and two common functional tandem repeat polymorphisms (5-HTTLPR and STin2), which together cover the whole SLC6A4 gene, and investigated their associations with OCS in normal Chinese college students (N = 572). The results revealed a significant gender main effect and gender-specific genetic effects of the SLC6A4 gene on OCS. Males scored significantly higher on total OCS and its three dimensions than did females (ps < .01). The 5-HTTLPR in the promoter region showed a female-specific genetic effect, with the l/l and l/s genotypes linked to higher OCS scores than the s/s genotype (ps < .05). In contrast, a conserved haplotype polymorphism (rs1042173| rs4325622| rs3794808| rs140701| rs4583306| rs2020942) covering from intron 3 to the 3' UTR of the SLC6A4 gene showed male-specific genetic effects, with the CGAAGG/CGAAGG genotype associated with lower OCS scores than the other genotypes (ps < .05). These effects remained significant after controlling for OCS-related factors including participants' depressive and anxiety symptoms as well as stressful life events, and correction for multiple tests. These results are discussed in terms of their implications for our understanding of the sex-specific role of the different sections of the SLC6A4 gene in OCD.

Serotonin transporter gene polymorphism and psychiatric disorders: is there a link?

Though still in infancy, the field of psychiatric genetics holds great potential to contribute to the development of new diagnostic and therapeutic options to treat these disorders. Among a large number of existing neurotransmitter systems, the serotonin system dysfunction has been implicated in many psychiatric disorders and therapeutic efficacy of many drugs is also thought to be based on modulation of serotonin. Serotonin transporter gene polymorphism is one of the most extensively studied polymorphisms in psychiatric behavioral genetics. In this article, we review the status of evidence for association between the serotonin gene polymorphism and some common mental disorders like affective disorders, post-traumatic stress disorder, obsessive-compulsive disorder, suicide, autism, and other anxiety and personality disorders. Going beyond traditional association studies, gene-environment interaction, currently gaining momentum, is also discussed in the review. While the existing information of psychiatric genetics is inadequate for putting into practice genetic testing in the diagnostic work-up of the psychiatric patient, if consistent in future research attempts, such results can be of great help to improve the clinical care of a vast majority of patients suffering from such disorders.

Incomplete coverage of candidate genes: a poorly considered bias

Current genetic investigations are performed both on the basis of a rational and biologically based choice of candidate genes and through genome wide scans. Nonetheless, lack of replication is a common problem in psychiatric genetics as well as in other genetic fields. There are a number of reasons for this inconsistency, among them a well known but poorly considered issue is gene coverage. The aim of the present paper is to focus on this well known and defectively deemed bias, especially when a candidate gene approach is chosen. The rational and the technical feasibility of this proposal are discussed as well as a survey of current investigations. The known consistent methodology to fix this bias is also discussed.

SLC6 neurotransmitter transporters: structure, function, and regulation

The neurotransmitter transporters (NTTs) belonging to the solute carrier 6 (SLC6) gene family (also referred to as the neurotransmitter-sodium-symporter family or Na(+)/Cl(-)-dependent transporters) comprise a group of nine sodium- and chloride-dependent plasma membrane transporters for the monoamine neurotransmitters serotonin (5-hydroxytryptamine), dopamine, and norepinephrine, and the amino acid neurotransmitters GABA and glycine. The SLC6 NTTs are widely expressed in the mammalian brain and play an essential role in regulating neurotransmitter signaling and homeostasis by mediating uptake of released neurotransmitters from the extracellular space into neurons and glial cells. The transporters are targets for a wide range of therapeutic drugs used in treatment of psychiatric diseases, including major depression, anxiety disorders, attention deficit hyperactivity disorder and epilepsy. Furthermore, psychostimulants such as cocaine and amphetamines have the SLC6 NTTs as primary targets. Beginning with the determination of a high-resolution structure of a prokaryotic homolog of the mammalian SLC6 transporters in 2005, the understanding of the molecular structure, function, and pharmacology of these proteins has advanced rapidly. Furthermore, intensive efforts have been directed toward understanding the molecular and cellular mechanisms involved in regulation of the activity of this important class of transporters, leading to new methodological developments and important insights. This review provides an update of these advances and their implications for the current understanding of the SLC6 NTTs.

Serotonin transporter gene polymorphism implicates reduced orbito-frontal cortex in obsessive-compulsive disorder

Although a number of magnetic resonance imaging (MRI) and genetic studies have been performed on obsessive-compulsive disorder (OCD), only limited studies in which genetic and neuroanatomical variables are evaluated concurrently have been performed. Therefore, the aim of our present study is (to understand) better understanding how genetic variation in the promoter region of the 5-HTT gene (5-HTTLPR) is associated with key brain structures in OCD, orbito-frontal cortex (OFC), thalamus and anterior cingulate. 5-HTT genotypes (SS, SL, LL) were determined for 40 patients with OCD and the same number of healthy controls. MRI-derived volumes of the OFC, thalamus, and anterior cingulate were determined by reliable tracing techniques. Volumetric measurements were made with T1-weighted coronal MRI images, with 1.5-mm-thick slices, at 1.5T, and were done blindly. In comparison with controls, OCD patients demonstrated volumes reduction in OFC, increased volumes of thalamus and total white matter volumes, but no difference in total brain volume, total gray matter volumes and anterior cingulate volumes. No significant difference was observed in allelic frequencies between the patients and controls. The stronger effects of 5-HTT polymorphism on brain morphology in OCD than those in controls were determined in the both OFC and thalamus. On the other hand, for the OCD patients, ANCOVA revealed a significant main effect of genotype for both the OFC and thalamus and a significant genotype-by-side interaction for the OFC, demonstrating that the short variants had a smaller right OFC than the long variants. In conclusion, we found a significant genotype-diagnosis interaction effects on key brain structures, with a stronger effects of 5-HTT polymorphism in OFC and thalamus of OCD patients, whereas no morphological changes related to the polymorphism were found in normal individuals.

The serotonin transporter availability in untreated early-onset and late-onset patients with obsessive-compulsive disorder

The pathogenetic role of central serotonin transporters (SERT) in obsessive-compulsive disorder (OCD) has been investigated in vivo by positron emission tomography (PET) or single-photon emission computed tomography (SPECT) studies with inconsistent results. This might reflect methodological differences but possibly also the pathophysiological heterogeneity of the disorder, i.e. the age at onset of OCD. The aim of our study was to compare SERT availability in patients with OCD to healthy controls (HC) taking into account the onset type, other factors and covariates (e.g. SERT genotype, age, depression level, gender). We studied 19 drug-naive OCD patients (36±13 yr, eight females) with early onset (EO-OCD, n=6) or with late onset (LO-OCD, n=13), and 21 HC (38±8 yr, nine females) with PET and the SERT-selective radiotracer [11C]DASB. Statistical models indicated that a variety of covariates and their interaction influenced SERT availability measured by distribution volume ratios (DVR). These models revealed significant effects of onset type on DVR with lower values in LO-OCD (starting at age 18 yr) compared to EO-OCD and HC in limbic (e.g. the amygdala), paralimbic brain areas (the anterior cingulate cortex), the nucleus accumbens and striatal regions, as well as borderline significance in the thalamus and the hypothalamus. The putamen, nucleus accumbens and hypothalamus were found with significant interaction between two SERT gene polymorphisms (SERT-LPR and VNTR). These findings suggest that late but not early onset of OCD is associated with abnormally low SERT availability. In part, functional polymorphisms of the SERT gene might determine the differences.

Epigenetic changes of serotonin transporter in the patients with alcohol dependence: methylation of an serotonin transporter promoter CpG island

OBJECTIVE

Psychiatric disorders such as depression, anxiety and alcohol dependence are associated with serotonin metabolism. We assessed the methylation level of the serotonin transporter (5-HTT) promoter region in control and alcohol dependent patients.

METHODS

Twenty seven male patients who met the Diagnostic and Statistical Manual of Mental Disorder IV (DSM-IV) criteria for alcohol dependence were compared with fifteen controls. Polymerase chain reaction (PCR) assays of bisulfate-modified DNA were designed to amplify a part of the CpG island in the 5HTT gene. Pyrosequencing was performed and the methylation level at seven CpG island sites was measured.

RESULTS

We found no differences in the methylation patterns of the serotonin transporter linked promoter region (5-HTTLPR) between alcohol-dependent and control subjects.

CONCLUSION

Our negative finding may be because 5-HTT epigenetic variation may not affect the expression for 5-HTT or there may be other methylation site critical for its expression. To find out more conclusive result, repeating the study in more methylation sites with a larger number of samples in a well-controlled setting is needed.

Effects of the serotonin transporter (5-HTTLPR) and α2A-adrenoceptor (C-1291G) genotypes on substance use in children and adolescents: a longitudinal study

RATIONALE AND OBJECTIVE

Twin studies suggest that substance use initiation in children and adolescents is determined primarily by environmental influences, whereas the establishment of use patterns is strongly controlled by genetic factors. The present study analysed the effects of the serotonin transporter promoter polymorphism [5-HT transporter gene-linked polymorphic region (5-HTTLPR)] and the α(2A)-adrenoceptor C-1291G genotype (ADRA2A C-1291G) as well as their interaction effects on alcohol, tobacco and drug use from preadolescence to the late adolescence.

METHODS

Initial sample of 9-year-old children of Estonian Children Personality Behaviour and Health Study (n = 583) was recalled at ages 15 and 18. Participants reported in all waves how frequently they smoked and used alcohol and illicit drugs.

RESULTS

5-HTTLPR had age-dependent effects on alcohol, tobacco and drug use: substance use did not differ by genotype at age 9, but at age 15, the participants with the short (s)/s genotype had higher tobacco use, and at age 18, they were more active alcohol, drug and tobacco users. Effects of ADRA2A C-1291G on drug use were dependent on gender, age and 5-HTTLPR. Males (age 18) with ADRA2A CG genotype, when compared to other participants, tended to have higher drug use especially when they had s/s genotype of 5-HTTLPR.

CONCLUSIONS

Our results reveal that expression of genetic vulnerability for substance use in children and adolescents may depend on age, gender, interaction of genes, and type of substance.

Dopamine D4 receptor and serotonin transporter gene effects on the longitudinal development of infant temperament

Existing studies of the effect on infant temperament of the 48 base pair variable number of tandem repeats polymorphism in exon 3 of the dopamine D4 receptor gene, DRD4 VNTR, and the serotonin transporter-linked polymorphic region, 5-HTTLPR, have provided contradictory results, and age seems to be an important factor. The present study investigated the effect of these two polymorphisms on the stability of infant temperament between 4 and 9 months of age. Furthermore, the effect of a recently discovered single nucleotide polymorphism which modulates the 5-HTTLPR (rs25531) was investigated in relation to infant temperament. The study sample consisted of 90 infants, who were assessed by parental report at the two ages under consideration using the Revised Infant Behavior Questionnaire. It was found that infants carrying the 7-repeat allele of the DRD4 VNTR had higher levels of Negative Affect. Furthermore, there was an interaction between DRD4 VNTR and 5-HTTLPR genotype such that infants with the DRD4 VNTR 7-repeat allele and the highest expressing 5-HTTLPR genotype (L(A) L(A) ) had the highest level of Negative Affect. These effects were largely driven by scores on the Falling Reactivity scale. Genetic effects were stable across age. The results emphasize the need for developmental studies of genetic effects on temperament.

Association of SLC6A4 variants with obsessive-compulsive disorder in a large multicenter US family study

Genetic association studies of SLC6A4 (SERT) and obsessive-compulsive disorder (OCD) have been equivocal. We genotyped 1241 individuals in 278 pedigrees from the OCD Collaborative Genetics Study for 13 single-nucleotide polymorphisms, for the linked polymorphic region (LPR) indel with molecular haplotypes at rs25531, for VNTR polymorphisms in introns 2 and 7 and for a 381-bp deletion 3' to the LPR. We analyzed using the Family-Based Association Test (FBAT) under additive, dominant, recessive and genotypic models, using both OCD and sex-stratified OCD as phenotypes. Two-point FBAT analysis detected association between Int2 (P = 0.0089) and Int7 (P = 0.0187) (genotypic model). Sex-stratified two-point analysis showed strong association in females with Int2 (P<0.0002), significant after correction for linkage disequilibrium, and multiple marker and model testing (P(Adj) = 0.0069). The SLC6A4 gene is composed of two haplotype blocks (our data and the HapMap); FBAT whole-marker analysis conducted using this structure was not significant. Several noteworthy nonsignificant results have emerged. Unlike Hu et al., we found no evidence for overtransmission of the LPR L(A) allele (genotype relative risk = 1.11, 95% confidence interval: 0.77-1.60); however, rare individual haplotypes containing L(A) with P<0.05 were observed. Similarly, three individuals (two with OCD/OCPD) carried the rare I425V SLC6A4 variant, but none of them passed it on to their six OCD-affected offspring, suggesting that it is unlikely to be solely responsible for the 'OCD plus syndrome', as reported by Ozaki et al. In conclusion, we found evidence of genetic association at the SLC6A4 locus with OCD. A noteworthy lack of association at the LPR, LPR-rs25531 and rare 425V variants suggests that hypotheses about OCD risk need revision to accommodate these new findings, including a possible gender effect.

Platelet serotonin transporter function after short-term paroxetine treatment in patients with panic disorder

Dysfunctions in serotonin neurotransmission have been implicated in some psychiatric disorders, and in particular, altered serotonin transporter function has been noted in panic disorder. In this study, the authors compared platelet [(3)H]serotonin uptake parameters, including maximum velocities (V(max)) and affinity constants (K(m)), in patients with panic disorder not undergoing treatment (n=21) and in healthy subjects (n=20). V(max) and K(m) values were re-examined after 12 weeks of paroxetine treatment. Values of V(max) and K(m) were lower in panic disorder patients at baseline than in healthy subjects. After treatment, K(m) normalized in panic patients, whereas V(max) did not change. A significant inverse correlation was found between increased K(m) and changes in anxiety levels. These results support a hypothesis of serotonergic transporter abnormalities in panic disorder, and suggest that increased K(m) values of platelet serotonin transporters parallel clinical improvement after short-term pharmacotherapy in panic disorder.

Platelet serotonin transporter function and heart rate variability in patients with panic disorder

Many studies showed abnormal serotonin transporter (5-HTT) function and heart rate variability (HRV) in panic disorder patients. The present study investigated the relationship between HRV power spectral analysis findings and platelet serotonin uptake in panic disorder patients. Short-term HRV over 5 min and platelet serotonin transporter uptake parameters (V(max) and K(m)) were measured both in 45 patients with panic disorder and in 30 age-matched normal healthy control subjects. Low frequency power (LF) normalized unit (nu) and LF/high frequency power (HF) were significantly higher, whereas HF and HF nu were lower in the patient group than in the control group. V(max) and K(m) were all significantly lower (i.e., reflects decreased 5-HTT function) in patients with panic disorder than in normal controls. In the patient group, K(m) was negatively correlated with LF/HF and LF nu whereas no such correlations between them were found in the control group. By multivariate analysis based on multiple hierarchical linear regression, a low K(m) independently predicted an increased LF nu even after controlling for age, sex, and body mass index in the patient group. These results suggest that impaired 5-HTT function is closely related to dysregulation of autonomic nervous system in panic disorder.

Genetics of anxiety disorders: the complex road from DSM to DNA

Anxiety disorders are among the most common psychiatric disorders, affecting one in four individuals over a lifetime. Although our understanding of the etiology of these disorders is incomplete, familial and genetic factors are established risk factors. However, identifying the specific casual genes has been difficult. Within the past several years, advances in molecular and statistical genetic methods have made the genetic dissection of complex disorders a feasible project. Here we provide an overview of these developments, with a focus on their implications for genetic studies of anxiety disorders. Although the genetic and phenotypic complexity of the anxiety disorders present formidable challenges, advances in neuroimaging and experimental animal models of anxiety and fear offer important opportunities for discovery. Real progress in identifying the genetic basis of anxiety disorders will require integrative approaches that make use of these biologic tools as well as larger-scale genomic studies. If successful, such efforts may yield novel and more effective approaches for the prevention and treatment of these common and costly disorders.

Accurate, Large-Scale Genotyping of 5HTTLPR and Flanking Single Nucleotide Polymorphisms in an Association Study of Depression, Anxiety, and Personality Measures

BACKGROUND

The length polymorphism repeat in the promoter region of the serotonin transporter gene (5HTTLPR) is one of the most studied polymorphisms for association with a range of psychiatric and personality phenotypes. However, the original 5HTTLPR assay is prone to bias toward short allele calling.

METHODS

We designed new assays for the 5HTTLPR suitable for large-scale genotyping projects and we genotyped 13 single nucleotide polymorphisms (SNPs) in a 38-kilobase region around the 5HTTLPR, including SNP rs25531, a polymorphism of the 5HTTLPR long allele. Association analysis was conducted for major depression and/or anxiety disorder in unrelated cases (n = 1161) and control subjects (n = 1051) identified through psychiatric interviews administered to a large population sample of Australian twin families. Participants had been scored for personality traits several years earlier (n > or = 2643 unrelated individuals).

RESULTS

We identified a two-SNP haplotype proxy for 5HTTLPR; the CA haplotype of SNPs rs4251417 and rs2020934 is coupled with the short allele of 5HTTLPR (r(2) = .72). We found evidence for association (p = .0062, after accounting for multiple testing) for SLC6A4 SNPs rs6354 and rs2020936 (positioned in a different linkage disequilibrium [LD] block about 15.5 kb from 5HTTLPR) with anxiety and/or depression and neuroticism, with the strongest association for recurrent depression with onset in young adulthood (odds ratio = 1.55, 95% confidence interval = 1.16-2.06).

CONCLUSIONS

The associated SNPs are in the same LD block as the variable number of tandem repeats serotonin transporter intron 2 marker, for which association has previously been reported.

Reduced serotonin transporter binding in the insular cortex in patients with obsessive-compulsive disorder: a [11C]DASB PET study

The serotonin transporter (5-HTT) and other markers of the serotonergic system have been of interest in the pathophysiology of obsessive-compulsive disorder (OCD). Previous studies using single photon emission computed tomography (SPECT) with [(123)I]beta-CIT or positron emission tomography (PET) with [(11)C]McN5652 have not shown consistent findings about 5-HTT in OCD patients. The aim of the present study was to investigate 5-HTT binding using [(11)C]DASB, which has higher selectivity or specific binding-to-nonspecific binding ratios for 5-HTT compared to the aforementioned radioligands. Four drug-naive and 6 drug-free patients with OCD who were free of comorbid depression and 18 gender and age-matched healthy subjects underwent PET scans with [(11)C]DASB. The severity of OCD was assessed by Yale-Brown Obsessive-Compulsive Scale (Y-BOCS) (mean+/-SD: 22+/-7.6, range: 7-32). The binding potential (BP(ND)) of [(11)C]DASB was calculated using a two-parameter multilinear reference tissue model (MRTM2). The parametric images of BP(ND) were analyzed using a statistical parametric mapping system. Significant reductions of BP(ND) were observed in the right posterior and left anterior insular cortices in patients with OCD compared to controls. Region-of-interest analysis has also confirmed significant reduction of BP(ND) in the insular cortex. Although significantly reduced BP(ND) in the orbitofrontal cortex was also observed in patients with OCD compared to controls, this finding should be considered with caution because of the very low 5-HTT binding in the region. On the other hand, no significant correlation was observed between the Y-BOCS score and BP(ND). The change in [(11)C]DASB binding in the insular cortex suggests that dysfunction of the serotonergic system in the limbic area might be involved in the pathophysiology of OCD.

Recent advances in the genetics of obsessive-compulsive disorder

This article reviews recent developments in understanding the genetic etiology of obsessive-compulsive disorder (OCD). Family studies provide further support for the familial aggregation of OCD. Genome-wide linkage studies indicate that specific chromosomal regions are linked to OCD. Moreover, results from recent molecular genetic studies suggest that several candidate genes are associated with OCD. However, specific genes causing OCD have not been conclusively identified, and the molecular pathogenesis of the disorder has not been elucidated. The search for genes is complicated by the clinical and etiologic heterogeneity of OCD, as well as the possibility of gene-gene and gene-environment interactions. Despite this complexity, further refinement of the phenotype and developments in molecular and statistical genetics hold promise for further deepening our genetic understanding of OCD in the future.

Association of the serotonin transporter polymorphism and obsessive-compulsive disorder: systematic review

We investigated the association between the long (l) and short (s) alleles of the serotonin transporter polymorphism (5-HTTLPR) in the promoter region of the SLC6A4 gene and obsessive-compulsive disorder (OCD) using meta-analysis to combine all published data from case-control and family based association studies (2,283 cases). In stratified meta-analysis we investigated whether age of sample (child and adult), ethnicity (Caucasian and Asian) and study design (case-control and family-based association studies) moderated any association. In the overall meta-analysis we found no evidence of association between genetic variation at the 5-HTTLPR locus and OCD. We did find significant heterogeneity between studies. In the stratified meta-analyses, we demonstrated a significant association between the l-allele and OCD in family-based association studies and in studies involving children and Caucasians. Our meta-analysis suggests the possibility that the l-allele may be associated with OCD in specific OCD subgroups such as childhood-onset OCD and in Caucasians. Further meta-analyses based on individual patient data would be helpful in determining whether age of OCD onset, gender and the presence of comorbid illness (e.g., tics) moderates the relationship between 5-HTTLPR and OCD.

Role of serotonin in obsessive–compulsive disorder

Obsessive–compulsive disorder (OCD) is a psychiatric disorder consisting of obsessions and compulsions. Over the past two decades, it has been suggested that OCD might be related to the functioning of brain serotonin systems, mainly because of the antiobsessional efficacy of selective serotonin-reuptake inhibitors (SSRIs). Although the efficacy of SSRIs suggests a role of the serotonergic system in OCD, the exact function of serotonin is still unclear. Is the serotonergic system implicated in the pathophysiology of OCD, or is it implicated in the treatment effect in OCD? Do SSRIs compensate for a fundamental abnormality of the serotonergic system, or do SSRIs modulate an intact serotonergic system to compensate for another neurotransmitter mechanism? This review summarizes evidence supporting a role for the serotonin transporter and serotonin receptor subtypes in the pathophysiology and treatment of OCD.

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.

Decision-making impairment is related to serotonin transporter promoter polymorphism in a sample of patients with obsessive-compulsive disorder

OBJECTIVE

Decision-making impairment is an important feature of some psychiatric disorders, such as attention-deficit/hyperactivity disorder and substance-use disorders, and is associated with dysfunction of the fronto-subcortical circuit, mainly the orbitofrontal cortex (OFC). Several data reports support significant correlations between decision-making impairment and the serotonin system. Thus, this neurotransmission system may be a major step in some cognitive features, particularly in OCD because serotonin is associated with this disorder. Therefore, the serotonin transporter promoter polymorphism (5-HTTLPR) may be related to the modulation of these cognitive characteristics. In a sample of Caucasian OCD patients, we explored the link between decision-making and the 5-HTTLPR.

METHOD

We used the Iowa Gambling Task (IGT) to measure decision-making in 49 OCD patients, according to the DSM-IV criteria. All patients were submitted to Y-BOCS, BDI, BAI, the Raven Progressive Matrices, the Continuous Performance Task, and the Trail Making Test. We grouped S- and/or Lg-carriers in view of the fact that these act in a nearly dominant way.

RESULTS

On IGT, S- and/or Lg-carriers had significantly lower scores on the third, fourth, and fifth blocks. These findings were confirmed after adjusting for clinical and cognitive variables.

DISCUSSION

Inconclusive findings about the link between OCD and 5-HTTLPR may be better elucidated by studying OCD subgroups that could be more related in some genetic characteristics. Based on our study, low performance on IGT is associated with S- and/or Lg-carriers.

CONCLUSION

Our results corroborate the hypothesis that the pattern of neuropsychological functioning observed in previous studies may constitute a biological marker or heritable endophenotype of OCD.

Association study between obsessive-compulsive disorder and serotonergic candidate genes

BACKGROUND

To date, research examining the relationship between serotonergic genes and obsessive-compulsive disorder (OCD) has yielded conflicting results. The purpose of this study is to investigate the association between four serotonergic polymorphisms (STin2 VNTR and 5-HTTLPR of the SLC6A4 gene, and A-1438G (rs6311) and T102C (rs6313) of the HTR2A gene) and OCD.

METHODS

99 OCD patients, 456 non-OCD psychiatric patients, and 420 healthy controls from a homogeneous Spanish Caucasian population were genotyped using standard methods.

RESULTS

All groups showed Hardy-Weinberg equilibrium for the analyzed genetic variability. A-1438G and T102C polymorphisms were in complete linkage disequilibrium. OCD patients showed an excess of STin2.12 carriers (12/12, 12/10, and 12/9 genotypes) compared with healthy controls (chi(2) (1)=7.21, corrected p=0.021; OR=3.38, 95% CI=1.32-8.62) and non-OCD psychiatric patients (chi(2) (1)=6.70, corrected p=0.030; OR=3.24, 95% CI=1.27-8.26). However, no differences were found between non-OCD patients and healthy controls (chi(2) (1)=0.05, corrected p>1; OR=1.04, 95% CI=0.72-1.51). No significant differences were found with respect to A-1438G and 5-HTTLPR polymorphisms.

CONCLUSIONS

Our data provide supporting evidence of an association between the STin2 VNTR polymorphism of the SLC6A4 gene and OCD.

Children and adolescents with obsessive-compulsive disorder and comorbid attention-deficit/hyperactivity disorder: preliminary results of a prospective follow-up study

In the present study, we have investigated the influence of comorbid attention deficit hyperactivity disorder (ADHD) on early onset obsessive compulsive disorder (OCD). For that purpose, we compared 20 patients with "OCD with ADHD" and 20 randomly selected patients with "OCD without ADHD". "OCD with ADHD" patients tended to show an earlier age of OCD onset, a higher severity of symptoms and a higher persistence rate than OCD patients without ADHD. Both groups appear to develop different patterns of comorbid disorders.

Renner T, Wewetzer C, Warnke A. Genetische Befunde bei Zwangsstörungen im Kindes- und Jugendalter und bei Erwachsenen

Zusammenfassung: Im Kindes- und Jugendalter sind Zwangsstörungen bei einer Inzidenz von ein bis zwei Prozent keine Seltenheit und können die Betroffenen in ihrer Entwicklung deutlich beeinträchtigen. Die Erkrankung ist durch wiederkehrende und anhaltende Verhaltensweisen, Gedanken und Impulse gekennzeichnet, die als quälend erlebt werden und sich je nach Entwicklungstand gegen inneren Widerstand aufdrängen und vom Patienten als unsinnig und übertrieben wahrgenommen werden. Die Entstehung von Zwangsstörungen hängt sowohl von Umweltfaktoren, nicht genetischen hirnpathologischen als auch von genetischen Einflussfaktoren ab. Die Mehrheit der bisherigen Ergebnisse bezieht sich dabei auf Untersuchungen im Erwachsenenalter. Es wird eine aktuelle Übersicht über genetische Befunde bei Zwangsstörungen unter besonderer Berücksichtigung des Kindes- und Jugendalters gegeben. Bei jung erkrankten Patienten findet sich eine deutlichere familiäre Belastung. Befunde aus Kopplungs- und Assoziationsstudien sowie Tiermodellen werden vorgestellt und diskutiert. Die phänotypische und genetische Heterogenität von Zwangsstörungen trägt zu den unterschiedlichen Studienergebnissen bei und erfordert für künftige Untersuchungen die Differenzierung von Subtypen, z.B. die Einbeziehung des Alters bei Erkrankungsbeginn, von Symptomdimensionen, geschlechtlichen Besonderheiten und komorbider Störungen.