A population-based twin study of generalized anxiety disorder in men and women

Assessment of the Genetic Characteristics of a Generation Born during a Long-Term Socioeconomic Crisis

BACKGROUND

A socioeconomic crisis in Russia lasted from 1991 to 1998 and was accompanied by a sharp drop in the birth rate. The main factor that influenced the refusal to have children during this period is thought to be prolonged social stress.

METHODS

comparing frequencies of common gene variants associated with stress-induced diseases among generations born before, after, and during this crisis may show which genes may be preferred under the pressure of natural selection during periods of increased social stress in urban populations.

RESULTS

In the "crisis" group, a statistically significant difference from the other two groups was found in rs6557168 frequency (p = 0.001); rs4522666 was not in the Hardy-Weinberg equilibrium in this group, although its frequency did not show a significant difference from the other groups (p = 0.118). Frequencies of VNTRs in SLC6A3 and MAOA as well as common variants rs17689918 in CRHR1, rs1360780 in FKBP5, rs53576 in OXTR, rs12720071 and rs806377 in CNR1, rs4311 in ACE, rs1800497 in ANKK1, and rs7412 and rs429358 in APOE did not differ among the groups.

CONCLUSIONS

a generation born during a period of prolonged destructive events may differ from the rest of the gene pool of the population in some variants associated with personality traits or stress-related disorders.

Genetic and environmental contributions to individual differences in sustainable working life-A Swedish twin cohort study

Although genetics is known to have a role in sickness absences (SA), disability pensions (DP) and in their mutual associations, the empirical knowledge is scarce on not having these interruptions, i.e., sustainable working life. Hence, we aimed to investigate how genetic and environmental factors affect individual variation in sustainable working life in short-term (two consecutive years) and in long-term (22 years of follow-up) using the classical twin modeling based on different genetic relatedness of mono- and dizygotic twins. The final sample (n = 51 071) included Swedish same-sex twins with known zygosity born between 1930 and 1990 (53% women) with complete national register data of employment, SA, DP, unemployment, old-age pension, emigration, and death. For the short-term sustainable working life, genetic factors explained 36% (95% confidence intervals (CI) 31-41%), environmental factors shared by co-twins such as family background 8% (95% CI 5-14%) and environmental factors unique to each twin individual 56% (95% CI 56-56%) on the individual differences. For the long-term sustainable working life, the largest proportions on individual differences were explained by environmental factors shared by co-twins (46%, 95% CI 44-48%) and unique to each twin individual (37% 95% CI 36-38%) whereas a small proportion was explained by genetic factors (18%, 95%CI 14-22%). To conclude, short-term sustainable working life was explained to a large extent by unique environment and to lesser extent by genetic factors whereas long-term (22 years) sustainable working life had both moderate unique and common environmental effect, and to lower extent genetic effects contributing to individual differences. These findings suggest that sustainable working life have different short- and long-term predictors.

Prevalence of Common Alleles of Some Stress Resilience Genes among Adolescents Born in Different Periods Relative to the Socioeconomic Crisis of the 1990s in Russia

Social stress is common among people and is considered one of the causes of the declining birth rate. Predisposition to stress and stress-induced disorders is largely determined genetically. We hypothesized that due to differences in stress resistance, carriers of different genetic variants of genes associated with stress resilience and stress-induced diseases may have dissimilar numbers of offspring under conditions of long-term social stress. To test this hypothesis, a comparative analysis of frequencies of seven common polymorphic regions [exon 3 variable number of tandem repeats (VNTR) of the DRD4 gene, rs4680 of COMT, STin2 VNTR and the 5-HTTLPR (rs774676466) insertion/deletion polymorphism of SLC6A4, rs4570625 of TPH2, rs6265 of BDNF, and rs258747 of NR3C1] was performed on standardized groups of randomly selected adolescents born before, during, and after severe socioeconomic deprivation (the crisis of the 1990s in Russia). There were significant differences in frequencies of "long" alleles of the DRD4 gene (p = 0.020, χ² = 5.492) and rs4680 (p = 0.022, χ² = 5.289) in the "crisis" group as compared to the combined "noncrisis" population. It is possible that the dopaminergic system had an impact on the successful adaptation of a person to social stress.

Sickness absence among young employees in private and public sectors with a history of depression and anxiety

The aim was to investigate occurrence and duration of sickness absence (SA) among young employees with previous depression/anxiety in private and public sectors. This population-based prospective study included 11,519 Swedish twin individuals of age 19-29 years that were followed regarding SA during 2006-2016. Data on previous depression/anxiety came from two screening surveys in 2005. Data on SA and employment sector were received from national registries. Descriptive statistics and logistic regression were used, also controlling for familial factors. Proportion of employees with SA was significantly higher among those with, as compared to those without, previous depression/anxiety, regardless the employment sector. Individuals with previous depression/anxiety had increased risk for future SA, in both private (OR 2.25, 95% CI 1.90-2.66) and public sectors (OR 2.10, 95% CI 1.73-2.54). Familial factors played a role in the association among employees in the private sector. A higher proportion of long-term SA was observed among employees with previous depression/anxiety in the private as compared to the public sector. To conclude, previous depression/anxiety tends to increase risk for SA among young employees in both employment sectors, whereas long-term SA seemed to be more prevalent among those in the private as compared to the public sector.

An Extended Swedish Adoption Study of Anxiety Disorder and Its Cross-Generational Familial Relationship With Major Depression

OBJECTIVE

To clarify, using an extended adoption design, the sources of parent-offspring transmission for anxiety disorder (AD) and its major subforms and their familial cross-generational relationship with major depression (MD).

METHODS

Offspring (born 1960-1992) and their parents, from six family types (intact, not-lived-with biological father or mother, lived-with step-father or step-mother, and adoptive), were ascertained from Swedish national samples. Diagnoses were obtained from national medical registers. We assessed three sources of parent-child resemblance: genes plus rearing, genes only, and rearing only. To test comorbidity effects, single diagnoses were assigned in comorbid cases based on frequency and recency.

RESULTS

For AD to AD parent-child transmission, best-estimate tetrachoric correlations for the three types of parent-offspring relationships genes plus rearing, genes only, and rearing only-equaled +0.16 (95% CI=0.16, 0.16), +0.12 (95% CI=0.10, 0.13), and +0.06 (95% CI=0.04, 0.07), respectively, with broadly similar results for MD to MD transmission. Cross-disorder cross-generation correlations were modestly lower, with genetic and rearing correlations for AD and MD estimated at +0.83 (95% CI=0.76, 0.90) and +0.83 (95% CI=0.69, 0.96), respectively. Analyses for panic disorder and generalized anxiety disorder (GAD) produced comparable findings, with the genetic correlation with MD modestly higher for generalized anxiety disorder than panic disorder. Applying a diagnostic hierarchy to comorbid cases resulted in a decline in cross-disorder cross-generation transmission with the estimated genetic correlation equaling +0.46 (95% CI=0.30, 0.62).

CONCLUSIONS AND RELEVANCE

For AD and its major subforms, cross-generational transmission includes both genetic and rearing effects. In traditional analyses, AD and MD demonstrate highly correlated genetic and rearing effects. The genetic correlation weakened when applying a diagnostic hierarchy.

Sustainable Working Life Patterns in a Swedish Twin Cohort: Age-Related Sequences of Sickness Absence, Disability Pension, Unemployment, and Premature Death during Working Life

We aimed to investigate sustainable working life via age-related sequences of sickness absence (SA), disability pension (DP), unemployment (UE), premature death, and the influence of individual characteristics, accounting for familial confounding. The sample included monozygotic (MZ) and dizygotic (DZ) same-sexed twin pairs with register data (n = 47,450) that were followed for 10 years in four age cohorts: 26-35 (n = 9892), 36-45 (n = 10,620), 46-55 (n = 12,964) and 56-65 (n = 13,974). A sequence analysis was done in a 7-element state space: 1. "Sustainable working life": SA/DP 0-30 days and UE 0-90 days; 2. "Unemployment >90 days": SA/DP 0-30 days and UE > 90 days; 3. "Moderate SA/DP": SA/DP 30-180 days; 4. "Almost full year of SA/DP": SA/DP 180-365 days; 5. "Full year of SA/DP": SA/DP ≥ 365 days; 6. Death; 7. Old-age pension. The largest cluster had a sustainable working life and never experienced states 2-6 (34-59%). Higher education and being married predicted a lower likelihood of experiencing states 2-6. The MZ twin pairs (vs. DZ) were more often in the same cluster suggesting the role of genetic factors. To conclude, the sustainable working life was the largest cluster group. Few individuals had prolonged periods of interruptions of sustainable working life meriting actions, especially in early adulthood for interventions to support workability.

Anxiety in patients treated in a temporary hospital in Belgrade, Serbia, during the first epidemic wave of COVID-19

BACKGROUND

It has been reported that COVID-19 patients in general often experience anxiety, depression and stress, but those problems in patients of temporary COVID-19 hospitals seem to have attracted less attention.

METHODS

The study included 87 SARS-Cov-2 infected subjects accommodated and treated in a temporary hospital in Belgrade, Serbia, during the first epidemic wave of COVID-19. The patients' level of anxiety was assessed on two occasions (at admission to the temporary hospital, and 2 weeks after discharge) using the Hamilton Anxiety Rating Scale (HAM-A). Demographic and clinical data were obtained through questionnairesor retrieved from patients' medical records.

RESULTS

A multiple linear regression model revealed that sex, age, the severity of COVID-19 symptoms (COVID-19_SS) and the family history of psychiatric disorder (FHPD) remain significant predictors of the level of anxiety at hospital admission (F (4, 82) = 14.916, p < 0.0001), wih an R² of 0.421. Participants' predicted level of anxiety at admission to the temporary COVID-19 hospital can be calculated as 0.931-0.708 × SEX +0.029 × AGE +0.674 × COVID-19_SS + 1.491 × FHPD, where SEX is coded as 1 for male and 0 for female, AGE is measured in years, COVID-19_SS is coded as 0 for asymptomatic, 1 for mild, 2 for moderate and 3 for severe, and FHPD as 0 for negative and 1 for positive. Comparison between individual HAM-A score at admission to the temporary hospital (median (IQR): 7.00 (2.00-11.75)) and 2 weeks after discharge (median (IQR): 0.00 (0.00-1.00)) revealed significant reduction in the level of anxiety among study participants (Z = -7.53, p < 0.001).

CONCLUSION

These data indicate that psychological changes exist in those hospitalized in temporary hospitals, but that they regress soon after they leave.

Psychosocial Working Conditions and Subsequent Sickness Absence-Effects of Pain and Common Mental Disorders in a Population-Based Swedish Twin Sample

OBJECTIVE

To investigate pain and/or common mental disorders (CMDs) in the associations between psychosocial working conditions and sickness absence (SA) while controlling familial confounding.

METHODS

Prospective Prospective twin cohort study included survey data for pain and CMD, register data for SA and psychosocial working conditions. The follow-up from 2005 to 2016 of 28,916 twin individuals for first incident SA spell measured as the main International Classification of Diseases version 10 (ICD-10) diagnosis groups (F00-F99, I00-I99, and M00-M99), or the duration. We used regression models to obtain odds ratio (OR), incidence rate ratio (IRR), or relative risk ratio (RRR) with 95% confidence intervals (CI).

RESULTS

The covariate adjusted models of 9156 SA spells indicated almost no statistically significant associations between psychosocial working conditions and SA.

CONCLUSIONS

Psychosocial working conditions were not associated with SA while familial confounding could not be ruled out.

The role of sickness absence diagnosis for the risk of future inpatient- or specialized outpatient care in a Swedish population-based twin sample

Background

Studies of consequences of sickness absence such as health and well-being have been rare whereas risk factors for sickness absence have been studied extensively. This study assumed the consequences of sickness absence would differ by diagnostic group or by patient care type. The aim was to investigate sickness absence due to various diagnosis groups as a predictor for subsequent inpatient- and specialized outpatient care while controlling for familial confounding.

Methods

We utilized the register data of 69,552 twin individuals between 16 and 80years of age (48% women). The first incident sickness absence spell, from baseline year 2005, including diagnosis of sickness absence was our primary exposure of interest and we followed them until the first incident inpatient- and specialized outpatient care episode with main diagnosis code or until 31.12.2013.

Results

A total of 7464 incident sickness absence spells took place (11%), 42% had inpatient care and 83% specialized outpatient care (mean follow-up time 3.2years, SD 3.1years). All the main sickness absence diagnosis groups were associated with increased risk of future care in comparison to no sickness absence. Controlling for confounders attenuated the associations in magnitude but with retaining direction, and we could not confirm an effect of familial factors.

Conclusions

Sickness absence predicts both inpatient- and specialized outpatient care and the association is universal across diagnosis groups. The lower survival time and incidence rates of inpatient than specialized outpatient care point towards severity of diseases assumption. This finding was also universal across sickness absence diagnosis groups.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12889-021-10942-2.

Prevalence of anxiety, depression and suicidal behaviors among Brazilian undergraduate students: A systematic review and meta-analysis

BACKGROUND

The university context can be an overwhelming background, being especially harmful to undergraduates' mental health. Considering that several studies have reported on the prevalence of psychological distress among Brazilian undergraduate students, this study aimed to conduct a systematic review and meta-analysis of the prevalence and associated factors of anxiety, depression and suicidal behavior in this population.

METHODS

Studies reporting on the prevalence of anxiety, depression and suicidal behavior and its associated factors among Brazilian undergraduate students were systematically searched in scientific electronic databases. Pooled prevalence was calculated using a random-effects meta-analysis. Individual associated factors were summarized, and study characteristics associated with outcome prevalence were tested through meta-regression analysis.

RESULTS

Forty-seven articles were included, of which 44 were meta-analyzed (37,486 undergraduates). The pooled prevalence estimates of anxiety, depression and suicidal behavior were 37.75%, 28.51%, and 9.10%, respectively. Meta-regression analysis showed that investigations with probabilistic samples presented a higher prevalence of anxiety and that studies conducted within public institutions and with samples of exclusively medical students presented higher frequencies of depression.

LIMITATIONS

Cross-sectional data do not allow the establishment of temporality and causal inference. Furthermore, the high heterogeneity of the included studies may also constitute a weakness of this review.

CONCLUSIONS

The prevalence of anxiety, depression and suicidal behavior among Brazilian undergraduates was high. These results have scientific and practical implications, the former regarding the need for the standardization of the methodology of studies and the latter regarding the need for comprehensive mental health care for Brazilian undergraduates.

Transtorno de ansiedade generalizada entre estudantes de cursos de pré-vestibular

RESUMO Objetivo Medir a prevalência de sintomatologia de transtorno de ansiedade generalizada (TAG) entre estudantes de um curso pré-vestibular do sul do Brasil e sua associação com fatores sociais, demográficos, acadêmicos e psicológicos. Métodos Este estudo teve delineamento transversal, tendo como participantes estudantes com idade igual ou superior a 18 anos de um curso pré-vestibular privado do sul do Brasil. Foi administrado um questionário autoaplicável que avaliava aspectos sociais, demográficos, acadêmicos, de ansiedade relacionada à prova e estresse percebido. O desfecho analisado foi a sintomatologia de TAG, por meio do instrumento General Anxiety Disorder-7 (GAD-7). Para análise multivariável, utilizou-se a regressão de Poisson com ajuste robusto da variância. Resultados Participaram 137 alunos (taxa de resposta de 90,7%) e a prevalência de sintomatologia de TAG foi de 41,4%. Após análise ajustada, ser do sexo feminino, ter estudado em escola privada, ter maiores escores de estresse percebido e de ansiedade relacionada à prova permaneceram como fatores de risco. Estar com 19 anos apresentou-se como fator de proteção. Conclusões A ansiedade relacionada à prova foi o fator mais fortemente associado com a sintomatologia de TAG, o que sugere que as emoções e preocupações específicas do contexto de avaliação podem predispor o indivíduo a maior risco de desenvolver esse transtorno. A partir desses resultados, sugere-se a inclusão de profissionais da saúde mental no contexto do pré-vestibular, assim como intervenções direcionadas ao desenvolvimento de uma relação saudável entre o aluno e suas demandas acadêmicas.

Pathway specific activation of ventral hippocampal cells projecting to the prelimbic cortex diminishes fear renewal

The ability to learn that a stimulus no longer signals danger is known as extinction. A major characteristic of extinction is that it is context-dependent, which means that fear reduction only occurs in the same context as extinction training. In other contexts, there is re-emergence of fear, known as contextual renewal. The ability to properly extinguish fear memories and generalize safety associations to multiple contexts provides therapeutic potential, but little is known about the specific neural pathways that mediate fear renewal and extinction generalization. The ventral hippocampus (VH) is thought to provide a contextual gating mechanism that determines whether fear or safety is expressed in particular contexts through its projections to areas of the fear circuit, including the infralimbic (IL) and prelimbic (PL) cortices. Moreover, VH principal cells fire in large, overlapping regions of the environment, a characteristic that is ideal to support generalization; yet it is unclear how different projection cells mediate this process. Using a pathway-specific (intersectional) chemogenetic approach, we demonstrate that selective activation of VH cells projecting to PL attenuates fear renewal without affecting fear expression. These results have implications for anxiety disorders since they uncover a neural pathway associated with extinction generalization.

Reduced cortical thickness and increased gyrification in generalized anxiety disorder: a 3 T MRI study

BACKGROUND

Although the study of the neuroanatomical correlates of generalized anxiety disorder (GAD) is gaining increasing interest, up to now the cortical anatomy of GAD patients has been poorly investigated and still no data on cortical gyrification are available. The aim of the present study is to quantitatively examine the cortical morphology in patients with GAD compared with healthy controls (HC) using magnetic resonance imaging (MRI). To the best of our knowledge, this is the first study analyzing the gyrification patterns in GAD.

METHODS

A total of 31 GAD patients and 31 HC underwent 3 T structural MRI. For each subject, cortical surface area (CSA), cortical thickness (CT), gray matter volume (GMV), and local gyrification index (LGI) were estimated in 19 regions of interest using the Freesurfer software. These parameters were then compared between the two groups using General Linear Model designs.

RESULTS

Compared with HC, GAD patients showed: (1) reduced CT in right caudal middle frontal gyrus (p < 0.05, Bonferroni corrected), (2) hyper-gyrification in right fusiform, inferior temporal, superior parietal and supramarginal gyri and in left supramarginal and superior frontal gyri (p < 0.05, Bonferroni corrected). No significant alterations in CSA and GMV were observed.

CONCLUSIONS

Our findings support the hypothesis of a neuroanatomical basis for GAD, highlighting a possible key role of the right hemisphere. The alterations of CT and gyrification in GAD suggest a neurodevelopmental origin of the disorder. Further studies on GAD are needed to understand the evolution of the cerebral morphology with age and during the clinical course of the illness.

Biological markers of generalized anxiety disorder

Generalized anxiety disorder (GAD) is a prevalent and highly disabling mental health condition; however, there is still much to learn with regard to pertinent biomarkers, as well as diagnosis, made more difficult by the marked and common overlap of GAD with affective and anxiety disorders. Recently, intensive research efforts have focused on GAD, applying neuroimaging, genetic, and blood-based approaches toward discovery of pathogenetic and treatment-related biomarkers. In this paper, we review the large amount of available data, and we focus in particular on evidence from neuroimaging, genetic, and neurochemical measurements in GAD in order to better understand potential biomarkers involved in its etiology and treatment. Overall, the majority of these studies have produced results that are solitary findings, sometimes inconsistent and not clearly replicable. For these reasons, they have not yet been translated into clinical practice. Therefore, further research efforts are needed to distinguish GAD from other mental disorders and to provide new biological insights into its pathogenesis and treatment.

Polymorphism in Tmem132d regulates expression and anxiety-related behavior through binding of RNA polymerase II complex

TMEM132D is a candidate gene, where risk genotypes have been associated with anxiety severity along with higher mRNA expression in the frontal cortex of panic disorder patients. Concurrently, in a high (HAB) and low (LAB) trait anxiety mouse model, Tmem132d was found to show increased expression in the anterior cingulate cortex (aCC) of HAB as compared to LAB mice. To understand the molecular underpinnings underlying the differential expression, we sequenced the gene and found two single-nucleotide polymorphisms (SNPs) in the promoter differing between both lines which could explain the observed mRNA expression profiles using gene reporter assays. In addition, there was no difference in basal DNA methylation in the CpG Island that encompasses the HAB vs. LAB Tmem132d promoter region. Furthermore, we found significantly higher binding of RNA polymerase II (POLR2A) to the proximal HAB-specific SNP (rs233264624) than the corresponding LAB locus in an oligonucleotide pull-down assay, suggesting increased transcription. Virus mediated overexpression of Tmem132d in the aCC of C57BL/6 J mice could confirm its role in mediating an anxiogenic phenotype. To model gene-environmental interactions, HAB mice exposed to enriched environment (HAB-EE) responded with decreased anxiety levels but, had enhanced Tmem132d mRNA expression as compared to standard-housed HAB (HAB-SH) mice. While LAB mice subjected to unpredictable chronic mild stress (LAB-UCMS) exhibited higher anxiety levels and had lower mRNA expression compared to standard-housed LAB (LAB-SH) mice. Chromatin immunoprecipitation revealed significantly higher binding of POLR2A to rs233264624 in HAB-EE, while LAB-UCMS had lower POLR2A binding at this locus, thus explaining the enhanced or attenuated expression of Tmem132d compared to their respective SH controls. To further investigate gene-environment interactions, DNA methylation was assessed using Illumina 450 K BeadChip in 74 panic disorder patients. Significant methylation differences were observed in two CpGs (cg26322591 and cg03283235) located in TMEM132D depending on the number of positive life events supporting the results of an influence of positive environmental cues on regulation of Tmem132d expression in mice.

African-American representation in family and twin studies of mood and anxiety disorders: A systematic review

PURPOSE

Mood and anxiety disorders are common and disabling psychiatric disorders with known heritable risk factors. But the extent to which their heritability and familial risks can be generalized across ethnic/racial groups is still largely unknown, but remains of considerable scientific and clinical interest. The main objective in this review was to evaluate African-American (AA) representation in family and twin studies of major mood and anxiety disorders.

METHOD

We conducted key word-driven computerized searches in MEDLINE and PsycINFO and manual searches from reference lists of selected articles. Search parameters included family or twin studies, mood or anxiety disorders, and familial aggregation or heritability. US-based studies published from 1980 to 2015 were included.

RESULTS

The final selection yielded 209 studies, of which 88 did not report race/ethnicity or only reported Caucasian/white race. Of the remaining 121 studies, 66% did not include AAs, 24% included 1-10% AA, 8% included greater than 10% AA and 2 studies were exclusively AA. These trends were similar across study type, disorder and time periods spanning 35 years.

LIMITATIONS

Small samples, including the large number of studies without race/ethnicity reports, limited detailed analyses of change across time by disorder and study type. Adoption studies were not included in this review.

CONCLUSIONS

Underrepresentation of AAs in family and twin studies of affective disorders is substantial and can limit generalizability of established heritability and familial risk estimates across clinical and research settings. Additional twin and family studies focusing on AAs can be of benefit in closing this gap.

Identification and validation of mixed anxiety-depression

BACKGROUND

Mixed anxiety-depression (MAD) has been under scrutiny to determine its potential place in psychiatric nosology. The current study sought to investigate its prevalence, clinical characteristics, course and potential validators.

METHOD

Restricted latent-class analyses were fit to 12-month self-reports of depression and anxiety symptom criteria in a large population-based sample of twins. Classes were examined across an array of relevant indicators (demographics, co-morbidity, adverse life events, clinical significance and twin concordance). Longitudinal analyses investigated the stability of, and transitions between, these classes for two time periods approximately 1.5 years apart.

RESULTS

In all analyses, a class exhibiting levels of MAD symptomatology distinctly above the unaffected subjects yet having low prevalence of either major depression (MD) or generalized anxiety disorder (GAD) was identified. A restricted four-class model, constraining two classes to have no prior disorder history to distinguish residual or recurrent symptoms from new onsets in the last year, provided an interpretable classification: two groups with no prior history that were unaffected or had MAD and two with prior history having relatively low or high symptom levels. Prevalence of MAD was substantial (9-11%), and subjects with MAD differed quantitatively but not qualitatively from those with lifetime MD or GAD across the clinical validators examined.

CONCLUSIONS

Our findings suggest that MAD is a commonly occurring, identifiable syndromal subtype that warrants further study and consideration for inclusion in future nosologic systems.

The impact of childhood parental loss on risk for mood, anxiety and substance use disorders in a population-based sample of male twins

Previous studies have identified the relationship between parental loss and psychopathology later in life. However, this relationship varied depending on the kind of loss, the parent involved, and the type of psychopathology. In the present study, we examined the association between parental loss (any loss, death, and separation) during childhood and lifetime risk for seven common psychiatric and substance use disorders in a sample of 2605 male twins from the Virginia population-based twin registry. Using structural equation modeling (SEM), we also examined the extent to which the influence of parental loss contributes to adult psychopathology. Parental separation was associated with a wide range of adult psychopathology, whereas parental death was specifically associated with phobia and alcohol dependence. Maternal and paternal separations were almost equally associated with most forms of psychopathology. SEM suggested that parental loss accounted for about 10% of the variance of adult psychopathology, of which parental separation had the strongest impacts on risk for depression and drug abuse/dependence (11% of the total variance). Our findings suggest that early parental separation has stronger and wider effects on adult psychopathology than parental death.

[Generalized anxiety disorder]

Generalized anxiety disorder (GAD) is a prevalent mental condition with substantial impact on psychosocial functioning and quality of life. There is also an increased risk of comorbidity with several other mental and somatic diseases. Clinical symptomatology is characterized by excessive and uncontrollable worrying about distinct issues of daily living which is frequently associated with somatic symptoms of stress and anxiety. Neurobiological and psychological research provide evidence for alterations in (para) limbic areas, a disturbed monoaminergic transmission as well as for dysfunctional learning in the pathogenesis of GAD. Therefore, second generation antidepressants, such as selective serotonin reuptake inhibitors (SSRI), selective serotonin-norepinephrine reuptake inhibitors (SSNRI), the calcium channel modulator pregabalin and cognitive behavioral therapy (CBT) are the first choice treatment options. Depending on symptom severity, patient preference and availability, both medication and CBT can be applied as monotherapy or in combination.

Serotonin transporter and BDNF polymorphisms interact to predict trait worry

BACKGROUND AND OBJECTIVES

Excessive worry is associated with a range of psychological disorders. While previous studies have examined genes associated with a range of different anxiety phenotypes, none have explored genes specifically associated with the general tendency to worry.

DESIGN

The present study tested associations between trait worry and functional polymorphisms of three candidate genes: the serotonin transporter-linked polymorphic region (5-HTTLPR) of the SLC6A4 gene, the Val66Met region of the brain-derived neurotrophic factor (BDNF) gene, and the Val158Met region of the catechol-O-methyltransferase (COMT) gene.

METHODS

A heterogeneous sample of adult participants (n=173) completed the Penn State Worry Questionnaire (PSWQ) and provided DNA samples for genotyping.

RESULTS

Results revealed a significant interaction between 5-HTTLPR and BDNF genotypes predicting levels of worry. Specifically, there was a significant positive association between 5-HTTLPR short alleles and PSWQ scores, but only in BDNF met allele carriers. COMT genotype was not significantly associated levels of worry, nor did COMT interact with 5-HTTLPR or BDNF genotypes to predict PSWQ scores.

CONCLUSIONS

These findings provide preliminary evidence about the putative genetic etiology of worrying. Key limitations of the present study and corresponding directions for future research on this topic are discussed.

Differential postpartum sensitivity to the anxiety-modulating effects of offspring contact is associated with innate anxiety and brainstem levels of dopamine beta-hydroxylase in female laboratory rats

In female mammals, the postpartum period involves dramatic shifts in many socioemotional behaviors. This includes a suppression of anxiety-related behaviors that requires recent physical contact with offspring. Factors contributing to differences among females in their susceptibility to the anxiety-modulating effect of offspring contact are unknown, but could include their innate anxiety and brain monoaminergic activity. Anxiety behavior was assessed in a large group of nulliparous female rats and the least-anxious and most-anxious tertiles were mated. Anxiety was assessed again postpartum after females were permitted or prevented from contacting their offspring 4 h before testing. Levels of dopamine β-hydroxylase (DBH, norepinephrine synthesizing enzyme) and tryptophan hydroxylase-2 (TPH2, serotonin synthesizing enzyme) were measured in the brainstem and dorsal raphe, respectively. It was found that anxiety-related behavior in the two groups did not differ when dams were permitted contact with offspring before testing. Removal of the offspring before testing, however, differentially affected anxiety based on dams' innate anxiety. Specifically, dams reverted back to their pre-mating levels of anxiety such that offspring removal slightly increased anxiety in the most-anxious females but greatly lowered anxiety in the least-anxious females. This reduction in anxiety in the least-anxious females after litter removal was associated with lower brainstem DBH. There was no relationship between females' anxiety and dorsal raphe TPH2. Thus, a primary effect of recent contact with offspring on anxiety-related behavior in postpartum rats is to shift females away from their innate anxiety to a more moderate level of responding. This effect is particularly true for females with the lowest anxiety, may be mediated by central noradrenergic systems, and has implications for their ability to attend to their offspring.

Genome-wide association study of co-occurring anxiety in major depression

OBJECTIVES

Co-morbidity between depression and anxiety disorders is common. In this study we define a quantitative measure of anxiety by summating four anxiety items from the SCAN interview in a large collection of major depression (MDD) cases to identify genes contributing to this complex phenotype.

METHODS

A total of 1522 MDD cases dichotomised according to those with at least one anxiety item scored (n = 1080) and those without anxiety (n = 442) were analysed, and also compared to 1588 healthy controls at a genome-wide level, to identify genes that may contribute to anxiety in MDD.

RESULTS

For the quantitative trait, suggestive evidence of association was detected for two SNPs, and for the dichotomous anxiety present/absent ratings for three SNPs at genome-wide level. In the genome-wide analysis of MDD cases with co-morbid anxiety and healthy controls, two SNPs attained P values of < 5 × 10⁻⁶. Analysing candidate genes, P values ≤ 0.0005 were found with three SNPs for the quantitative trait and three SNPs for the dichotomous trait.

CONCLUSIONS

This study provides an initial genome-wide assessment of possible genetic contribution to anxiety in MDD. Although suggestive evidence of association was found for several SNPs, our findings suggest that there are no common variants strongly associated with anxious depression.

Performance of polygenic scores for predicting phobic anxiety

Context

Anxiety disorders are common, with a lifetime prevalence of 20% in the U.S., and are responsible for substantial burdens of disability, missed work days and health care utilization. To date, no causal genetic variants have been identified for anxiety, anxiety disorders, or related traits.

Objective

To investigate whether a phobic anxiety symptom score was associated with 3 alternative polygenic risk scores, derived from external genome-wide association studies of anxiety, an internally estimated agnostic polygenic score, or previously identified candidate genes.

Design

Longitudinal follow-up study. Using linear and logistic regression we investigated whether phobic anxiety was associated with polygenic risk scores derived from internal, leave-one out genome-wide association studies, from 31 candidate genes, and from out-of-sample genome-wide association weights previously shown to predict depression and anxiety in another cohort.

Setting and Participants

Study participants (n = 11,127) were individuals from the Nurses' Health Study and Health Professionals Follow-up Study.

Main Outcome Measure

Anxiety symptoms were assessed via the 8-item phobic anxiety scale of the Crown Crisp Index at two time points, from which a continuous phenotype score was derived.

Results

We found no genome-wide significant associations with phobic anxiety. Phobic anxiety was also not associated with a polygenic risk score derived from the genome-wide association study beta weights using liberal p-value thresholds; with a previously published genome-wide polygenic score; or with a candidate gene risk score based on 31 genes previously hypothesized to predict anxiety.

Conclusion

There is a substantial gap between twin-study heritability estimates of anxiety disorders ranging between 20–40% and heritability explained by genome-wide association results. New approaches such as improved genome imputations, application of gene expression and biological pathways information, and incorporating social or environmental modifiers of genetic risks may be necessary to identify significant genetic predictors of anxiety.

Parenting and risk for mood, anxiety and substance use disorders: a study in population-based male twins

BACKGROUND

Previous studies consistently identified a relationship between parenting behavior and psychopathology. In this study, we extended prior analyses performed in female twins to a large sample of twins from male-male pairs.

METHODS

We used interview data on 2,609 adult male twins from a population-based twin registry. We examined the association between three retrospectively reported parenting dimensions (coldness, protectiveness, and authoritarianism) and lifetime history of seven common psychiatric and substance use disorders. Using univariate structural equation modeling, we also examined the influence of the genetic and environmental factors on parenting.

RESULTS

Examined individually, coldness was consistently associated with risk for a broad range of adult psychopathology. Averaged odds of psychiatric disorders associated with parenting were increased between 26 and 36 %. When the three parenting dimensions were examined together, coldness remained significant for major depression, phobia, and generalized anxiety disorder. Controlling for other disorders, the associations between the parenting dimensions and psychopathology were non-specific. Twin fitting model demonstrated that modest heritability accounted for parenting, whereas most variance resulted from the non-shared environment.

CONCLUSIONS

Based on our current and prior findings, there is broad similarity in the impact of parenting on adult psychopathology between men and women.

The diagnosis and treatment of generalized anxiety disorder

BACKGROUND

Generalized anxiety disorder (GAD) is a common and serious disease with a lifetime prevalence of 4.3% to 5.9%. It is underdiagnosed in primary care.

METHODS

Recommendations on the treatment of GAD are given on the basis of all available findings from pertinent randomized trials, retrieved by a selective search of the literature.

RESULTS

Among psychotherapeutic techniques, various kinds of cognitive behavioral therapy (CBT) have been found useful in controlled trials. The drugs of first choice include selective serotonin reuptake inhibitors (SSRIs), serotonin-norepinephine reuptake inhibitors (SNRIs), and the calcium-channel modulator pregabalin. Tricyclic antidepressants are also effective but have more adverse effects than SSRIs. Although benzodiazepines are effective anxiolytic agents for short-term use, they should not be given over the long term because of the danger of addiction. Buspirone, an azapirone, was found to be effective in a small number of trials, but the findings across trials are inconsistent. The response rate of GAD to CBT in published studies lies between 47% and 75%, while its response rate to drug treatment lies between 44% and 81%.

CONCLUSION

The treatment of GAD with CBT and drugs is evidence-based and has a good chance of improving the manifestations of the disorder.

Common psychiatric disorders and caffeine use, tolerance, and withdrawal: an examination of shared genetic and environmental effects

BACKGROUND

Previous studies examined caffeine use and caffeine dependence and risk for the symptoms, or diagnosis, of psychiatric disorders. The current study aimed to determine if generalized anxiety disorder (GAD), panic disorder, phobias, major depressive disorder (MDD), anorexia nervosa (AN), or bulimia nervosa (BN) shared common genetic or environmental factors with caffeine use, caffeine tolerance, or caffeine withdrawal.

METHOD

Using 2,270 women from the Virginia Adult Twin Study of Psychiatric and Substance Use Disorders, bivariate Cholesky decomposition models were used to determine if any of the psychiatric disorders shared genetic or environmental factors with caffeine use phenotypes.

RESULTS

GAD, phobias, and MDD shared genetic factors with caffeine use, with genetic correlations estimated to be 0.48, 0.25, and 0.38, respectively. Removal of the shared genetic and environmental parameter for phobias and caffeine use resulted in a significantly worse fitting model. MDD shared unique environmental factors (environmental correlation=0.23) with caffeine tolerance; the genetic correlation between AN and caffeine tolerance and BN and caffeine tolerance were 0.64 and 0.49, respectively. Removal of the genetic and environmental correlation parameters resulted in significantly worse fitting models for GAD, phobias, MDD, AN, and BN, which suggested that there was significant shared liability between each of these phenotypes and caffeine tolerance. GAD had modest genetic correlations with caffeine tolerance, 0.24, and caffeine withdrawal, 0.35.

CONCLUSIONS

There was suggestive evidence of shared genetic and environmental liability between psychiatric disorders and caffeine phenotypes. This might inform us about the etiology of the comorbidity between these phenotypes.

A Twin Study of Lifetime Generalized Anxiety Disorder (GAD) in Older Adults: Genetic and Environmental Influences Shared by Neuroticism and GAD

The nature of Generalized Anxiety Disorder (GAD) and worry across the lifespan remains incompletely understood. We investigated genetic and environmental influences on GAD and the proportion of genetic and environmental variation in GAD that is shared with neuroticism in older adult twins. Participants included 1618 monozygotic and 2291 same-sexed dizygotic twin pairs from the Swedish Twin Registry aged 55 to 74. Participants provided personality information in 1973 and also participated in a telephone screening between 1998 and 2002 that included an assessment for lifetime GAD. Univariate biometric models indicated that both GAD and neuroticism were moderately heritable (.27 and .47, respectively), while the balance of variation reflected environmental factors unique to the individual. Bivariate analyses indicated that approximately one third of the genetic influences on GAD were in common with genetic influences on neuroticism, while individual specific environmental influences were virtually unshared between GAD and neuroticism. Analyses of sex effects suggested that men and women differed in the frequency of lifetime GAD and level of neuroticism; however, no sex differences for genetic and environmental influences for either trait were identified.

Familial Clustering of Major Depression and Anxiety Disorders in Australian and Dutch Twins and Siblings

The aim of this study was to investigate familial influences and their dependence on sex for panic disorder and/or agoraphobia, social phobia, generalized anxiety disorder and major depression. Data from Australian (N= 2287) and Dutch (N= 1185) twins and siblings who were selected for a linkage study and participated in clinical interviews to obtain lifetimeDiagnostic and Statistical Manual of Mental Disorders(4th ed.; DSM-IV) diagnoses were used. In a liability model, tetrachoric correlations were estimated in sibling pairs and sex differences between sibling correlations were tested. For each diagnosis, the sibling correlations could be constrained to be equal across the Australian and Dutch samples. With the exception of panic disorder and/or agoraphobia, all sibling correlations were the same for brother, sister and opposite-sex sibling pairs and were around .20. For panic disorder and/or agoraphobia, the correlation was .23 in brother and sister pairs, but absent in opposite-sex sibling pairs. From these results it can be concluded that upper heritability estimates, based on twice the correlations in the sibling pairs, vary between 36% (major depression) and 50% (social phobia). Furthermore, different genetic risk factors appear to contribute to the vulnerability for panic disorder and/or agoraphobia in men and women. No other sex differences were found.

Contextual conditioning in rats as an animal model for generalized anxiety disorder

Animal models of psychiatric disorders are important translational tools for exploring new treatment options and gaining more insight into the disease. Thus far, there is no systematically validated animal model for generalized anxiety disorder (GAD), a severely impairing and difficult-to-treat disease. In this review, we propose contextual conditioning (CC) as an animal model for GAD. We argue that this model has sufficient face validity (there are several symptom similarities), predictive validity (it responds to clinically effective treatments), and construct validity (the underlying mechanisms are comparable). Although the refinement and validation of an animal model is a never-ending process, we want to give a concise overview of the currently available evidence. We suggest that the CC model might be a valuable preclinical tool to enhance the development of new treatment strategies and our understanding of GAD.

Genetic liability to disability pension in women and men: a prospective population-based twin study

BACKGROUND

Previous studies of risk factors for disability pension (DP) have mainly focused on psychosocial, or environmental, factors, while the relative importance of genetic effects has been less studied. Sex differences in biological mechanisms have not been investigated at all.

METHODS

The study sample included 46,454 Swedish twins, consisting of 23,227 complete twin pairs, born 1928-1958, who were followed during 1993-2008. Data on DP, including diagnoses, were obtained from the National Social Insurance Agency. Within-pair similarity in liability to DP was assessed by calculating intraclass correlations. Genetic and environmental influences on liability to DP were estimated by applying discrete-time frailty modeling.

RESULTS

During follow-up, 7,669 individuals were granted DP (18.8% women and 14.1% men). Intraclass correlations were generally higher in MZ pairs than DZ pairs, while DZ same-sexed pairs were more similar than opposite-sexed pairs. The best-fitting model indicated that genetic factors contributed 49% (95% CI: 39-59) to the variance in DP due to mental diagnoses, 35% (95% CI: 29-41) due to musculoskeletal diagnoses, and 27% (95% CI: 20-33) due to all other diagnoses. In both sexes, genetic effects common to all ages explained one-third, whereas age-specific factors almost two-thirds, of the total variance in liability to DP irrespective of diagnosis. Sex differences in liability to DP were indicated, in that partly different sets of genes were found to operate in women and men, even though the magnitude of genetic variance explained was equal for both sexes.

CONCLUSIONS

The findings of the study suggest that genetic effects are important for liability to DP due to different diagnoses. Moreover, genetic contributions to liability to DP tend to differ between women and men, even though the overall relative contribution of genetic influences does not differ by sex. Hence, the pathways leading to DP might differ between women and men.

Generalized anxiety disorder and anorexia nervosa: evidence of shared genetic variation

BACKGROUND

Previous studies have indicated a high prevalence of generalized anxiety disorder (GAD) in women with anorexia nervosa (AN). However, the shared genetic and environmental components of these disorders have not been explored. This study seeks to elucidate the shared genetic and environmental components between GAD and AN.

METHOD

Using 2,083 women from the Virginia Adult Twin Study of Psychiatric and Substance Use Disorders, structural equation modeling was used to obtain maximum likelihood estimates of the environmental genetic, shared and unique environmental components in 496 women with GAD, 47 women with AN, 43 women with GAD + AN, and 1,497 women without GAD or AN.

RESULTS

Results show that the heritability of GAD was 0.32 and AN was 0.31, and the genetic correlation between the two disorders was 0.20, indicating a modest genetic contribution to their comorbidity. Unique environment estimate was 0.68 for GAD and 0.69 for AN, with a unique environmental correlation of 0.18. All common environmental parameters were estimated at zero.

CONCLUSIONS

The modest shared genetic and unique environmental liability to both disorders may help explain the high prevalence of GAD in women with AN. This knowledge could help in the treatment and prevention of comorbid disorders.

Anxiety disorders in children with williams syndrome, their mothers, and their siblings: implications for the etiology of anxiety disorders

This study examines the prevalence of anxiety disorders in children with Williams syndrome (WS), their sibling closest in age, and their mothers as well as the predictors of anxiety in these groups. The prevalence of anxiety disorders was assessed and compared to that in the general population. Children with WS had a significantly higher prevalence of specific phobia, generalized anxiety disorder (GAD), and separation anxiety in comparison to children in the general population. While mothers had a higher prevalence of GAD than population controls, the excess was accounted for by mothers who had onset after the birth of their WS child. The siblings had rates similar to the general population. This pattern of findings suggests the presence of a gene in the WS region whose deletion predisposes to anxiety disorders. It is also worthwhile to investigate relations between genes deleted in WS and genes previously implicated in anxiety disorders.

Genetic association between BDNF gene polymorphisms and phobic disorders: a case-control study among mainland Han Chinese

INTRODUCTION

Phobic disorders are a common group of syndromes comprising persistently recurring, irrational severe anxiety of specific objects, activities, or situations with avoidance behavior of the phobic stimulus. The present study investigated the association between whole region polymorphisms, (including the Val66Met variant), in the BDNF gene and phobic disorders among Han Chinese young adults.

METHODS

We conducted a case-control study to investigate the genetic association between BDNF polymorphisms and phobic disorders among mainland Chinese. One hundred and twenty young adults with phobic disorders and 267 matched controls were recruited. Three tag SNPs of BDNF were successfully genotyped by using PCR-based ligase detection reaction (PCR-LDR).

RESULTS

We found significant differences in allele distributions of SNP rs10835210 (P<0.001) between the experimental and the control groups. In the haplotype analysis based on linkage-disequilibrium across this gene locus, we demonstrated significant association between phobic disorders and BDNF haplotype CAC (P=0.004). Association was significant after 10(4) permutation tests (P<0.001).

CONCLUSION

To the best of our knowledge, this is the first study showing that the BDNF gene may play a significant role in the etiology of phobic disorders in the Han Chinese population.

Genomics for disease treatment and prevention

The enormous advances in genetics and genomics of the past decade have the potential to revolutionize health care, including mental health care, and bring about a system predominantly characterized by the practice of genomic and personalized medicine. This article briefly reviews the history of genetics and genomics and assesses the extent to which the results of genetic and genomic studies are currently being leveraged clinically for disease treatment and prevention. Relevant social, economic, and policy issues relevant to genomic medicine are also reviewed, and priority research areas in which further work is needed are identified.

The neurobiology of anxiety disorders: brain imaging, genetics, and psychoneuroendocrinology

Anxiety disorders are highly comorbid with each other and with major depressive disorder. As syndromes, anxiety and mood disorders share many symptoms, and several treatments are effective for both. Despite this overlap, there exist many distinguishing features that support the continued classification of individual anxiety disorders that are distinct from each other and from major depression. The goal of this article is to describe the key biological similarities and differences between anxiety disorders.

Psychiatric 'diseases' versus behavioral disorders and degree of genetic influence

BACKGROUND

Psychiatric conditions in which symptoms arise involuntarily ('diseases') might be assumed to be more heritable than those in which choices are essential (behavioral disorders). We sought to determine whether psychiatric 'diseases' (Alzheimer's disease, schizophrenia, and mood and anxiety disorders) are more heritable than behavioral disorders (substance use disorders and anorexia nervosa).

METHOD

We reviewed the literature for recent quantitative summaries of heritabilities. When these were unavailable, we calculated weighted mean heritabilities from twin studies meeting modern methological standards.

RESULTS

Heritability summary estimates were as follows: bipolar disorder (85%), schizophrenia (81%), Alzheimer's disease (75%), cocaine use disorder (72%), anorexia nervosa (60%), alcohol dependence (56%), sedative use disorder (51%), cannabis use disorder (48%), panic disorder (43%), stimulant use disorder (40%), major depressive disorder (37%), and generalized anxiety disorder (28%).

CONCLUSIONS

No systematic relationship exists between the disease-like character of a psychiatric disorder and its heritability; many behavioral disorders seem to be more heritable than conditions commonly construed as diseases. These results suggest an error in 'common-sense' assumptions about the etiology of psychiatric disorders. That is, among psychiatric disorders, there is no close relationship between the strength of genetic influences and the etiologic importance of volitional processes.

Association study of CREB1 with Major Depressive Disorder and related phenotypes

Cyclic AMP response element binding protein (CREB) has been implicated in behavioral models of anxiety and depression, antidepressant response in humans, and suicide. One group reported a female-specific association of the CREB1 gene in early-onset Major Depressive Disorder (MDD), while another found no evidence of association with this phenotype. In this study, we sought to examine the evidence for association of the CREB1 gene to MDD and related phenotypes. We used multivariate structural equation modeling to identify and select twin pairs that scored at the extremes of a latent genetic risk factor shared by MDD, neuroticism, and several anxiety disorders from the Virginia Twin Registry. Using one member from each of these pairs, the resulting sample of 589 cases (including 473 subjects with lifetime MDD) and 539 controls were entered into a 2-stage association study in which genetic markers were screened in stage 1, the positive results of which were tested for replication in stage 2. Eight SNP markers selected to capture the major allelic variation across the haplotype block containing CREB1 were analyzed for differences between cases and controls. Several markers showed criterion differences between cases and controls in the stage 1 sample with some evidence of sex specific effects. However, none of these markers were significant in stage 2 in either sex individually or combined. Our data suggests that common variations in the CREB1 gene do not appear to increase susceptibility for MDD or related phenotypes.

The neurobiology of anxiety disorders: brain imaging, genetics, and psychoneuroendocrinology

Anxiety disorders are highly comorbid with each other and with major depressive disorder. As syndromes, anxiety and mood disorders share many symptoms, and several treatments are effective for both. Despite this overlap, there exist many distinguishing features that support the continued classification of individual anxiety disorders that are distinct from each other and from major depression. The goal of this article is to describe the key biological similarities and differences between anxiety disorders.

Implications of modifying the duration requirement of generalized anxiety disorder in developed and developing countries

BACKGROUND

A number of western studies have suggested that the 6-month duration requirement of generalized anxiety disorder (GAD) does not represent a critical threshold in terms of onset, course, or risk factors of the disorder. No study has examined the consequences of modifying the duration requirement across a wide range of correlates in both developed and developing countries.

METHOD

Population surveys were carried out in seven developing and 10 developed countries using the WHO Composite International Diagnostic Interview (total sample=85,052). Prevalence and correlates of GAD were compared across mutually exclusive GAD subgroups defined by different minimum duration criteria.

RESULTS

Lifetime prevalence estimates for GAD lasting 1 month, 3 months, 6 months and 12 months were 7.5%, 5.2%, 4.1% and 3.0% for developed countries and 2.7%, 1.8%, 1.5% and 1.2% for developing countries, respectively. There was little difference between GAD of 6 months' duration and GAD of shorter durations (1-2 months, 3-5 months) in age of onset, symptom severity or persistence, co-morbidity or impairment. GAD lasting >or=12 months was the most severe, persistently symptomatic and impaired subgroup.

CONCLUSIONS

In both developed and developing countries, the clinical profile of GAD is similar regardless of duration. The DSM-IV 6-month duration criterion excludes a large number of individuals who present with shorter generalized anxiety episodes which may be recurrent, impairing and contributory to treatment-seeking. Future iterations of the DSM and ICD should consider modifying the 6-month duration criterion so as to better capture the diversity of clinically salient anxiety presentations.

Current considerations in the treatment of generalized anxiety disorder

Generalized anxiety disorder (GAD) is a chronic disorder that frequently co-occurs with a variety of co-morbidities in patients with somatic conditions and other mental disorders. GAD is highly prevalent and is one of the most common anxiety disorders seen by primary care physicians. The individual and societal cost associated with GAD is high and the marked level of impairment experienced by patients with this disorder is equivalent in magnitude to that reported in patients with major depressive disorder. Furthermore, patients with GAD are at risk of suicide or suicide attempts, and are frequent users of healthcare services. Thus, GAD is a serious and chronic condition that requires appropriate long-term treatment. The focus of acute treatment for patients with GAD is the improvement of symptoms, while the primary goal of long-term clinical management is remission, i.e. the complete resolution of both symptoms and functional impairment. The consensus across current treatment guidelines is that first-line treatment for patients with GAD should consist of an antidepressant, either a selective serotonin reuptake inhibitor (SSRI) such as sertraline, paroxetine or escitalopram, or a selective serotonin noradrenaline (norepinephrine) reuptake inhibitor (SNRI) such as venlafaxine or duloxetine. However, the SSRIs and SNRIs have efficacy limitations, such as lack of response in many patients, a 2- to 4-week delay before the onset of symptom relief, lack of full remission, and risk of relapse. In addition, there are troublesome adverse effects associated with both the SSRIs and SNRIs. Evidence from early clinical studies of the atypical antipsychotics in the treatment of anxiety and GAD indicate that they may have a potential role in the treatment of GAD, either as monotherapy or as augmentation to standard treatment.

Genetic and environmental influences on the co-morbidity between depression, panic disorder, agoraphobia, and social phobia: a twin study

BACKGROUND

Major depression (MD) and anxiety disorders such as panic disorder (PD), agoraphobia (AG), and social phobia (SP) are heritable and highly co-morbid. However, the relative importance of genetic and environmental etiology of the covariation between these disorders, particularly the relationship between PD and AG, is less clear.

METHODS

This study measured MD, PD, and AG in a population sample of 5,440 twin pairs and 1,245 single twins, about 45% of whom were also scored for SP. Prevalences, within individual co-morbidity and twin odds ratios for co-morbidity, are reported. A behavioral genetic analysis of the four disorders using the classical twin design was conducted.

RESULTS

Odds ratios for MD, PD, AG, and SP in twins of individuals diagnosed with one of the four disorders were increased. Heritability estimates under a threshold-liability model for MD, PD, AG, and SP respectively were .33 (CI: 0.30-0.42), .38 (CI: 0.24-0.55), .48 (CI: 0.37-0.65), and .39 (CI: 0.16-0.65), with no evidence for any variance explained by the common environment shared by twins. We find that a common genetic factor explains a moderate proportion of variance in these four disorders. The genetic correlation between PD and AG was .83.

CONCLUSION

MD, PD, AG, and SP strongly co-aggregate within families and common genetic factors explain a moderate proportion of variance in these four disorders. The high genetic correlation between PD and AG and the increased odds ratio for PD and AG in siblings of those with AG without PD suggests a common genetic etiology for PD and AG.

Genetic approaches to modeling anxiety in animals

Anxiety disorders are a growing health problem world-wide. However, the causative factors, etiology, and underlying mechanisms of anxiety disorders, as for most psychiatric disorders, remain relatively poorly understood. The current status of clinical research indicates that anxiety traits and anxiety disorder in man have a genetic component, and therefore genetic modeling in animals is a logical approach to gain a greater insight into their neurobiology. However, it is also clear that the nature of these genetic contributions is highly complex. Moreover, the success of this approach is largely contingent upon the utility of available behavioral paradigms for modeling anxiety-related behaviors in mice. Animal genetic models provide a unique and comprehensive methodological tool to aid discovery into the etiology, neurobiology, and ultimately, the therapy of human anxiety disorders. The approach, however, is challenged with a number of complexities. In particular, the heterogeneous nature of anxiety disorders in man coupled with the associated multifaceted and descriptive diagnostic criteria, create challenges in both animal modeling and in clinical research. In this article, we describe some of the powerful modem genetic techniques that are uniquely amenable to the laboratory mouse and thus provide a strategy for approaching some of these challenges. Moreover, we focus on recent advances which have highlighted the relative contribution of genetic modeling in animals to the understanding of underlying neurobiology and genetic basis of anxiety disorders.

Association study between GABA receptor genes and anxiety spectrum disorders

BACKGROUND

Human anxiety disorders are complex diseases with relatively unknown etiology. Dysfunction of the Gamma-aminobutyric acid (GABA) system has been implicated in many neuropsychiatric conditions, including anxiety and depressive disorders. In this investigation, we explored four GABA receptor genes for their possible associations with genetic risk for anxiety disorders and depression.

METHODS

Our study sample consisted of 589 cases and 539 controls selected from a large population-based twin registry based upon a latent genetic risk factor shared by several anxiety disorders, major depression, and neuroticism. We subjected these to a two-stage protocol, in which all candidate genetic markers were screened for association in stage 1 (N=376), the positive results of which were tested for replication in stage 2 (N=752). We analyzed data from 26 single nucleotide polymorphisms (SNPs) from four GABA receptor genes: GABRA2, GABRA3, GABRA6, and GABRG2.

RESULTS

Of the 26 SNPs genotyped in stage 1, we identified two markers in GABRA3 that met the threshold (P < or = .1) to be tested in stage 2. Phenotypic associations of these two markers failed to replicate in stage 2.

CONCLUSIONS

These findings suggest that common variation in the GABRA2, GABRA3, GABRA6, and GABRG2 genes does not play a major role in liability to anxiety spectrum disorders.

Age-specific familial risks of anxiety. A nation-wide epidemiological study from Sweden

OBJECTIVE

Familial risks of anxiety have been assessed in small case-control studies, usually based on reported, but not medically verified, anxiety in family members; thus the degree of familial clustering of these diseases remains to be established.

METHODS

The Multigeneration Register, in which all men (sons) and women (daughters) born in Sweden from 1932 onward are registered together with their parents, was linked to hospital admission data. Standardized incidence ratios (SIRs) were calculated as the ratio of the observed to the expected number of cases of men and women with mothers and/or fathers affected by anxiety, compared with men and women whose mothers and/or fathers were not affected by anxiety.

RESULTS

A total of 55,642 and 57,196 cases of anxiety were recorded in offspring and parents, respectively. The overall significant SIRs among men and women with a mother, father or both parents hospitalized for anxiety varied between 1.90 and 5.10. Maternal transmission of anxiety was slightly higher than paternal and the highest SIRs were found in the youngest age groups and among those with both parents affected by anxiety. The degree of parental transmission of anxiety was similar for both men and women.

CONCLUSIONS

This study has provided the first data on age-specific familial clustering of anxiety, based on medically confirmed records. The risks were so high that hereditary factors were considered to be likely to contribute, possibly modified by environmental factors. Age-specific risks tables would be helpful for clinical counseling.

Family history of psychological problems in generalized anxiety disorder

The current investigation examined self-reported family history of psychological problems in a large sample of individuals diagnosed with generalized anxiety disorder (GAD) and nonanxious controls. The GAD participants were all individuals receiving cognitive-behavioral therapy as part of two large randomized clinical trials. Family history information was obtained from the Anxiety Disorders Interview Schedule-Revised (ADIS-R; DiNardo & Barlow, 1988). The results indicate that, compared to control participants, individuals with GAD were more likely to have family members with anxiety problems, but not other psychological problems. Possible mechanisms for the familial transmission of GAD are discussed.

Catechol-O-methyltransferase contributes to genetic susceptibility shared among anxiety spectrum phenotypes

BACKGROUND

Catechol-O-methyltransferase (COMT) has been investigated for its possible role in a wide range of psychiatric phenotypes. In particular, several studies support association of this gene with panic disorder and other anxiety-related traits.

METHODS

We examined the COMT gene for association with genetic risk across a range of anxiety spectrum phenotypes. We used multivariate structural equation modeling to select twin pairs scoring at the extremes of a latent genetic risk factor shared by neuroticism, several anxiety disorders, and major depression from a large population-based twin sample. With one member from each of these pairs, the resulting sample of 589 cases and 539 control subjects were entered into a two-stage association study in which genetic markers were screened in stage 1, the positive results of which were tested for replication in stage 2.

RESULTS

The functional val158met polymorphism (rs4680) plus nine other single nucleotide polymorphism markers selected to capture the major allelic variation across the COMT locus were analyzed for differences between cases and control subjects. Although the val (G) allele of rs4680 showed marginally significant association in our combined stage 1 plus stage 2 sample, a high-risk haplotype of this allele with the A allele of rs165599 was significantly over-represented in cases (p = 1.97e-5, odds ratio = 1.95). This haplotype also predicted individual differences in neuroticism and risk for several anxiety disorders and major depression. Consistent with prior studies, our findings are female-specific.

CONCLUSIONS

Variations in the COMT gene contribute to genetic risk shared across a range of anxiety-related phenotypes.

Association study between the serotonin 1A receptor (HTR1A) gene and neuroticism, major depression, and anxiety disorders

The serotonin neurotransmitter system in general, and the serotonin 1A receptor in particular, has been broadly implicated in the pathophysiology of mood and anxiety disorders, although the results of genetic association studies have been mixed. In this study, we examined the serotonin 1A receptor gene, HTR1A, for its association with shared genetic risk across a range of anxiety and depression-related phenotypes. Using multivariate structural equation modeling, we selected twin pairs from the population-based Virginia Adult Twin Study of Psychiatric and Substance Use Disorders scoring at the extremes of a latent genetic risk factor that underlies susceptibility to neuroticism, major depression, and several anxiety disorders. One member from each selected pair was entered into a 2-stage, case-control association study for the HTR1A gene. In the resulting sample of 589 cases and 539 controls, four SNPs spanning the HTR1A locus, including the C(-1019)G functional promoter polymorphism (rs6295), were screened in stage 1, the positive results of which were tested for replication in stage 2. While one marker met threshold significance criteria in stage 1, this association was not replicated in stage 2. Post-hoc analyses did not reveal association to any of the specific psychiatric phenotypes. Our data suggests that the HTR1A gene may not play a major role in the genetic susceptibility underlying depressive and anxiety-related phenotypes.