Oxytocin receptor gene methylation: converging multilevel evidence for a role in social anxiety

Social anxiety disorder (SAD) is a commonly occurring and highly disabling disorder. The neuropeptide oxytocin and its receptor (OXTR) have been implicated in social cognition and behavior. This study-for the first time applying a multilevel epigenetic approach-investigates the role of OXTR gene methylation in categorical, dimensional, and intermediate neuroendocrinological/neural network phenotypes of social anxiety. A total of 110 unmedicated patients with SAD and matched 110 controls were analyzed for OXTR methylation by direct sequencing of sodium bisulfite-converted DNA extracted from whole blood. Furthermore, OXTR methylation was investigated regarding SAD-related traits (Social Phobia Scale (SPS) and Social Interaction Anxiety Scale (SIAS)), salivary cortisol response during the Trier social stress test (TSST), and amygdala responsiveness to social phobia related verbal stimuli using fMRI. Significantly decreased OXTR methylation particularly at CpG Chr3: 8 809 437 was associated with (1) the categorical phenotype of SAD (p<0.001, Cohen's d=0.535), (2) increased SPS and SIAS scores (p<0.001), (3) increased cortisol response to the TSST (p=0.02), and (4) increased amygdala responsiveness during social phobia-related word processing (right: p(corr)<0.001; left: p(corr)=0.005). Assuming that decreased OXTR methylation confers increased OXTR expression, the present finding may reflect a compensatory upregulation for pathologically reduced oxytocin levels or a causally relevant increased OXTR activation in SAD and related traits. OXTR methylation patterns might thus serve as peripheral surrogates of oxytocin tone and aid in establishing accessible biomarkers of SAD risk allowing for indicated preventive interventions and personalized treatment approaches targeting the oxytocin system.

Neural correlates of procedural variants in cognitive-behavioral therapy: a randomized, controlled multicenter FMRI study

BACKGROUND

Cognitive behavioral therapy (CBT) is an effective treatment for panic disorder with agoraphobia (PD/AG). It is unknown, how variants of CBT differentially modulate brain networks involved in PD/AG. This study was aimed to evaluate the effects of therapist-guided (T+) versus self-guided (T-) exposure on the neural correlates of fear conditioning in PD/AG.

METHOD

In a randomized, controlled multicenter clinical trial in medication-free patients with PD/AG who were treated with 12 sessions of manualized CBT, functional magnetic resonance imaging (fMRI) was used during fear conditioning before (t1) and after CBT (t2). Quality-controlled fMRI data from 42 patients and 42 healthy subjects (HS) were obtained. Patients were randomized to two variants of CBT (T+, n = 22, and T-, n = 20).

RESULTS

The interaction of diagnosis (PD/AG, HS), treatment group (T+, T-), time point (t1, t2) and stimulus type (conditioned stimulus: yes, no) revealed activation in the left hippocampus and the occipitotemporal cortex. The T+ group demonstrated increased activation of the hippocampus at t2 (t2 > t1), which was positively correlated with treatment outcome, and a decreased connectivity between the left inferior frontal gyrus and the left hippocampus across time (t1 > t2).

CONCLUSION

After T+ exposure, contingency-encoding processes related to the posterior hippocampus are augmented and more decoupled from processes of the left inferior frontal gyrus, previously shown to be dysfunctionally activated in PD/AG. Linking single procedural variants to neural substrates offers the potential to inform about the optimization of targeted psychotherapeutic interventions.

RGS2 ggenetic variation: association analysis with panic disorder and dimensional as well as intermediate phenotypes of anxiety

Accumulating evidence from mouse models points to the G protein-coupled receptor RGS2 (regulator of G-protein signaling 2) as a promising candidate gene for anxiety in humans. Recently, RGS2 polymorphisms were found to be associated with various anxiety disorders, e.g., rs4606 with panic disorder (PD), but other findings have been negative or inconsistent concerning the respective risk allele. To further examine the role of RGS2 polymorphisms in the pathogenesis of PD, we genotyped rs4606 and five additional RGS2 tag single nucleotide polymorphisms (SNPs; rs16834831, rs10801153, rs16829458, rs1342809, rs1890397) in two independent PD samples, comprising 531 matched case/control pairs. The functional SNP rs4606 was nominally associated with PD when both samples were combined. The upstream SNP rs10801153 displayed a Bonferroni-resistant significant association with PD in the second and the combined sample (P = 0.006 and P = 0.017). We furthermore investigated the effect of rs10801153 on dimensional anxiety traits, a behavioral avoidance test (BAT), and an index for emotional processing in the respective subsets of the total sample. In line with categorical results, homozygous risk (G) allele carriers displayed higher scores on the Agoraphobic Cognitions Questionnaire (ACQ; P = 0.015) and showed significantly more defensive behavior during fear provoking situations (P = 0.001). Furthermore, significant effects on brain activation in response to angry (P = 0.013), happy (P = 0.042) and neutral faces (P = 0.032) were detected. Taken together, these findings provide further evidence for the potential role of RGS2 as a candidate gene for PD.

Effects of mood induction on consumers with vs. without compulsive buying propensity: an experimental study

Compulsive buying (CB) is excessive and leads to impairment and distress. Several studies aimed to explore the phenomenology and antecedents of CB, especially affective states. However, these studies mostly used retrospective self-report and mostly focused on compulsive buyers only. Therefore, this study aims to directly compare consumers with CB propensity and controls on experimental proxies of buying behavior and to investigate 1) effects of neutral vs. negative mood inductions and 2) whether mood effects on buying behavior are specific to CB. Forty female consumers with CB propensity and 40 female controls were randomly assigned to a neutral or negative mood induction. Buying related behavior (likelihood to expose oneself to a shopping situation, urge and probability to buy, willingness to pay) was assessed. Consumers with CB propensity differed from controls in all buying behavior aspects except for willingness to pay. Neither main effects of mood nor group×mood interaction effects on buying behavior were found. However, consumers with CB propensity were emotionally more strongly affected by a negative mood induction. Although negative affect has previously been reported to precede buying episodes in CB, our findings do not indicate specific negative mood effects on buying, neither in CB nor in controls.

The functional -1019C/G HTR1A polymorphism and mechanisms of fear

Serotonin receptor 1A gene (HTR1A) knockout mice show pronounced defensive behaviour and increased fear conditioning to ambiguous conditioned stimuli. Such behaviour is a hallmark of pathological human anxiety, as observed in panic disorder with agoraphobia (PD/AG). Thus, variations in HTR1A might contribute to neurophysiological differences within subgroups of PD/AG patients. Here, we tested this hypothesis by combining genetic with behavioural techniques and neuroimaging. In a clinical multicentre trial, patients with PD/AG received 12 sessions of manualized cognitive-behavioural therapy (CBT) and were genotyped for HTR1A rs6295. In four subsamples of this multicentre trial, exposure behaviour (n=185), defensive reactivity measured using a behavioural avoidance test (BAT; before CBT: n=245; after CBT: n=171) and functional magnetic resonance imaging (fMRI) data during fear conditioning were acquired before and after CBT (n=39). HTR1A risk genotype (GG) carriers more often escaped during the BAT before treatment. Exploratory fMRI results suggest increased activation of the amygdala in response to threat as well as safety cues before and after treatment in GG carriers. Furthermore, GG carriers demonstrated reduced effects of CBT on differential conditioning in regions including the bilateral insulae and the anterior cingulate cortex. Finally, risk genotype carriers demonstrated reduced self-initiated exposure behaviour to aversive situations. This study demonstrates the effect of HTR1A variation on defensive behaviour, amygdala activity, CBT-induced neural plasticity and normalization of defence behaviour in PD/AG. Our results, therefore, translate evidence from animal studies to humans and suggest a central role for HTR1A in differentiating subgroups of patients with anxiety disorders.

Effects of stress and relaxation on pain perception in subjects with pain-free occlusional disharmony compared with healthy controls

OBJECTIVES

The significance of occlusal disharmony for the development of painful temporomandibular disorder (TMD) is controversial. The ongoing biomechanical strain caused by occlusal disharmony might lead to sensitization processes in the nociceptive system. Understanding these processes might be an important step toward understanding the possible relationship between occlusal disharmony and TMD. In this study, we therefore investigated whether subjects with occlusal disharmony (n = 22) differ from healthy controls (n = 26) in their pain perception and pain modulation by stress and relaxation.

MATERIALS AND METHODS

Trigeminal and extratrigeminal experimental pain perception (pinprick, heat, and pressure pain) was assessed before and after stress (mental arithmetic) and relaxation (viewing of low-arousal pictures).

RESULTS

There were no group differences in pain perception at baseline or during the stress task. Compared with controls, the occlusal disharmony group exhibited an inadequate reduction in pain perception during relaxation, which was significant for the extratrigeminal site (P < 0.01) and reached a trend for significance at the trigeminal site (P = 0.1).

CONCLUSIONS

These results suggest that subjects with occlusal disharmony show signs of disturbed endogenous pain inhibition during relaxation.

CLINICAL RELEVANCE

There is evidence for the presence of sensitization of the nociceptive system in subjects with occlusal disharmony. Possibly, deficient inhibition of extratrigeminal and trigeminal pain perception by relaxation might contribute to the development of TMD or other chronic pain disorders.

Gender-specific association of variants in the AKR1C1 gene with dimensional anxiety in patients with panic disorder: additional evidence for the importance of neurosteroids in anxiety?

BACKGROUND

Neurosteroids are synthesized both in brain and peripheral steroidogenic tissue from cholesterol or steroidal precursors. Neurosteroids have been shown to be implicated in neural proliferation, differentiation, and activity. Preclinical and clinical studies also suggest a modulatory role of neurosteroids in anxiety-related phenotypes. However, little is known about the contribution of genetic variants in genes relevant for the neurosteroidogenesis to anxiety disorders.

METHODS

We performed an association analysis of single nucleotide polymorphisms (SNPs) in five genes related to the neurosteroidal pathway with emphasis on progesterone and allopregnanolone biosynthesis (steroid-5-alpha-reductase 1A (SRD5A1), aldo-keto reductase family 1 C1-C3 (AKR1C1-AKR1C3) and translocator protein 18 kDA (TSPO) with panic disorder (PD) and dimensional anxiety in two German PD samples (cases N = 522, controls N = 1,115).

RESULTS

Case-control analysis for PD and SNPs in the five selected genes was negative in the combined sample. However, we detected a significant association of anticipatory anxiety with two intronic SNPs (rs3930965, rs41314625) located in the gene AKR1C1 surviving correction for multiple testing in PD patients. Stratification analysis for gender revealed a female-specific effect of the associations of both SNPs.

CONCLUSIONS

These results suggest a modulatory effect of AKR1C1 activity on anxiety levels, most likely through changes in progesterone and allopregnanolone levels within and outside the brain. In summary, this is the first evidence for the gender-specific implication of the AKR1C1 gene in the expression of anticipatory anxiety in PD. Further analyses to unravel the functional role of the SNPs detected here and replication analyses are needed to validate our results.

Implicit affective evaluation of somatosensory sensations in patients with noncardiac chest pain

BACKGROUND AND OBJECTIVES

Etiological models of noncardiac chest pain (NCCP) stress the importance of abnormal implicit affective evaluations of somatosensory sensations, but this has never been studied empirically. The aim was therefore to assess implicit affective evaluations of somatosensory stimuli in NCCP using an experimental design.

METHODS

A total of 34 patients with NCCP, 24 patients with cardiac chest pain, and 46 healthy controls, took part in the study. Participants completed a tactile modification of the Affect Misattribution Procedure (tAMP) and answered self-report measures on anxiety sensitivity, somatosensory amplification, and somatic symptom distress.

RESULTS

A 3 × 3-ANOVA revealed that most negative judgments were found in the aversive condition, but this effect was not specific to patients with NCCP. Anxiety sensitivity was positively associated with negative implicit evaluations of aversive tactile stimuli in the tAMP.

LIMITATIONS

The task seemed to be too difficult for older participants. Also, future studies should apply clinically more relevant, e.g., heart related, stimuli that are more ecologically valid than the electrical stimulation of the finger used as a proxy for aversive somatosensory sensations here.

CONCLUSIONS

Against theoretical assumptions, patients with NCCP do not seem to show a stronger implicit negative interpretation bias concerning somatosensory sensations in comparison to patients either with cardiac chest pain, or without chest pain. Nevertheless, anxiety sensitivity seems to contribute significantly to implicit affective interpretations of somatic sensations. Further studies are required investigating the relevance of implicit interpretative processes for the course of NCCP and distressing somatic symptoms in general.

Anticipating agoraphobic situations: the neural correlates of panic disorder with agoraphobia

BACKGROUND

Panic disorder with agoraphobia is characterized by panic attacks and anxiety in situations where escape might be difficult. However, neuroimaging studies specifically focusing on agoraphobia are rare. Here we used functional magnetic resonance imaging (fMRI) with disorder-specific stimuli to investigate the neural substrates of agoraphobia.

METHOD

We compared the neural activations of 72 patients suffering from panic disorder with agoraphobia with 72 matched healthy control subjects in a 3-T fMRI study. To isolate agoraphobia-specific alterations we tested the effects of the anticipation and perception of an agoraphobia-specific stimulus set. During fMRI, 48 agoraphobia-specific and 48 neutral pictures were randomly presented with and without anticipatory stimulus indicating the content of the subsequent pictures (Westphal paradigm).

RESULTS

During the anticipation of agoraphobia-specific pictures, stronger activations were found in the bilateral ventral striatum and left insula in patients compared with controls. There were no group differences during the perception phase of agoraphobia-specific pictures.

CONCLUSIONS

This study revealed stronger region-specific activations in patients suffering from panic disorder with agoraphobia in anticipation of agoraphobia-specific stimuli. Patients seem to process these stimuli more intensively based on individual salience. Hyperactivation of the ventral striatum and insula when anticipating agoraphobia-specific situations might be a central neurofunctional correlate of agoraphobia. Knowledge about the neural correlates of anticipatory and perceptual processes regarding agoraphobic situations will help to optimize and evaluate treatments, such as exposure therapy, in patients with panic disorder and agoraphobia.

Internal focus of attention in anxiety-sensitive females up-regulates amygdale activity: an fMRI study

Cognitive behavioral models of panic disorder (PD) stress the importance of an increased attentional focus towards bodily symptoms in the onset and maintenance of this debilitating anxiety disorder. In this fMRI mental tracking paradigm, we looked at the effects of focusing one's attention internally (interoception) vs. externally (exteroception) in a well-studied group at risk for PD-that is anxiety-sensitive females (AS-high). We hypothesized that AS-high subjects compared to control subjects will present higher arousal and decreased valence scores during interoception and parallel higher activity in brain areas which are associated with fear and interoception. 24 healthy female students with high levels of anxiety sensitivity and 24 healthy female students with normal levels of anxiety sensitivity serving as control group were investigated by 3 T fMRI. Subjects either focused their attention on their heartbeats (internal condition) or on neutral tones (external condition). Task performance was monitored by reporting the number of heartbeats or tones after each block. State of arousal and emotional valence were also assessed. The high anxiety-sensitive group reported higher arousal scores compared to controls during the course of the experiment. Simultaneously, fMRI results indicated higher activation in anxiety-sensitive participants than in controls during interoception in a network of cortical and subcortical brain regions (thalamus, amygdala, parahippocampus) that overlaps with known fear circuitry structures. In particular, the activity of the right amygdala was up-regulated. Future prospective-longitudinal studies are needed to validate the role of the amygdala for transition to disorder. Attention to internal body functions up-regulates the activity of interoceptive and fear-relevant brain regions in anxiety-sensitive females, a high-risk group for the development of anxiety disorders.

Health anxiety--an indicator of higher interoceptive sensitivity?

BACKGROUND AND OBJECTIVES

According to cognitive-behavioral models, health anxiety arises from the misattribution of normal bodily sensations as signs of a severe illness. Consequently, higher levels of interoceptive accuracy might be critically involved in the development of health anxiety.

METHODS

To test this central assumption of cognitive behavioral models of health anxiety, we assessed interoceptive accuracy in a sample of college students (N = 100). Two interoceptive tasks (detection of one's own heartbeat using the Schandry paradigm and detection of nonspecific skin conductance fluctuations, NSCFs) were used.

RESULTS

We found no indication for a positive association between facets of health anxiety and a higher interoceptive accuracy in the two tasks. In fact, worse heartbeat perception was associated with higher health anxiety as measured by two questionnaires whereas perception of NSCFs was not significantly related to any facet of health anxiety. In addition, we found a bias to overestimate NSCFs in people with heightened health anxiety.

LIMITATIONS

Because a sample of college students served as participants, the generalization of the findings is limited and further studies in patients with the diagnosis of hypochondriasis are necessary.

CONCLUSIONS

The findings of both interoceptive paradigms suggest that health anxiety is not associated with better but rather with less accurate and biased interoceptive sensitivity. Probably, not a heightened interoceptive sensitivity but rather the bias in overestimating harmless somatic cues is more relevant for the maintenance of health anxiety. Our results are in line with recent research in other somatoform disorders.

Timing matters: change depends on the stage of treatment in cognitive behavioral therapy for panic disorder with agoraphobia

OBJECTIVE

The mechanisms of action underlying treatment are inadequately understood. This study examined 5 variables implicated in the treatment of panic disorder with agoraphobia (PD/AG): catastrophic agoraphobic cognitions, anxiety about bodily sensations, agoraphobic avoidance, anxiety sensitivity, and psychological flexibility. The relative importance of these process variables was examined across treatment phases: (a) psychoeducation/interoceptive exposure, (b) in situ exposure, and (c) generalization/follow-up.

METHOD

Data came from a randomized controlled trial of cognitive behavioral therapy for PD/AG (n = 301). Outcomes were the Panic and Agoraphobia Scale (Bandelow, 1995) and functioning as measured in the Clinical Global Impression scale (Guy, 1976). The effect of process variables on subsequent change in outcome variables was calculated using bivariate latent difference score modeling.

RESULTS

Change in panic symptomatology was preceded by catastrophic appraisal and agoraphobic avoidance across all phases of treatment, by anxiety sensitivity during generalization/follow-up, and by psychological flexibility during exposure in situ. Change in functioning was preceded by agoraphobic avoidance and psychological flexibility across all phases of treatment, by fear of bodily symptoms during generalization/follow-up, and by anxiety sensitivity during exposure.

CONCLUSIONS

The effects of process variables on outcomes differ across treatment phases and outcomes (i.e., symptomatology vs. functioning). Agoraphobic avoidance and psychological flexibility should be investigated and therapeutically targeted in addition to cognitive variables.

Relationship between social anxiety and perceived trustworthiness

Four different patterns of biased ratings of facial expressions of emotions have been found in socially anxious participants: higher negative ratings of (1) negative, (2) neutral, and (3) positive facial expressions than nonanxious controls. As a fourth pattern, some studies have found no group differences in ratings of facial expressions of emotion. However, these studies usually employed valence and arousal ratings that arguably may be less able to reflect processing of social information. We examined the relationship between social anxiety and face ratings for perceived trustworthiness given that trustworthiness is an inherently socially relevant construct. Improving on earlier analytical strategies, we evaluated the four previously found result patterns using a Bayesian approach. Ninety-eight undergraduates rated 198 face stimuli on perceived trustworthiness. Subsequently, participants completed social anxiety questionnaires to assess the severity of social fears. Bayesian modeling indicated that the probability that social anxiety did not influence judgments of trustworthiness had at least three times more empirical support in our sample than assuming any kind of negative interpretation bias in social anxiety. We concluded that the deviant interpretation of facial trustworthiness is not a relevant aspect in social anxiety.

Drinking motives in alcohol use disorder patients with and without social anxiety disorder

The high comorbidity of alcohol use disorders (AUD) and social anxiety disorder (SAD) is often explained by excessive drinking in social situations to self-medicate social anxiety. Indeed, the motive to drink alcohol to lower social fears was found to be elevated in socially anxious persons. However, this social anxiety specific motive has not been directly investigated in primarily alcohol dependent individuals. We explored social anxiety, the motivation to drink alcohol in order to cope with social fears, and social anxiety as a consequence of drinking in AUD with and without comorbid SAD. Male AUD inpatients with (AUD+SAD group, N=23) and without comorbid SAD (N=37) completed a clinical interview and a questionnaire assessment. AUD+SAD patients reported higher levels of depression and an elevated motive to drink due to social anxiety but did not experience more social fears as a consequence of drinking. Previous results concerning alcohol drinking motives in order to relieve social fears could be replicated in a clinical AUD sample. Additionally, our findings suggest comorbid AUD+SAD patients to be more burdened regarding broader psychopathological symptoms. Thus, accessibility to SAD-specific screening and treatment procedures may be beneficial for primary AUD patients.

Internal and external attention in speech anxiety

BACKGROUND AND OBJECTIVES

Cognitive models of social phobia propose that socially anxious individuals engage in heightened self-focused attention. Evidence for this assumption was provided by dot probe and feedback tasks measuring attention and reactions to internal cues. However, it is unclear whether similar patterns of attentional processing can be revealed while participants actually engage in a social situation. The current study used a novel paradigm, simultaneously measuring attention to internal and external stimuli in anticipation of and during a speech task.

METHODS

Participants with speech anxiety and non-anxious controls were asked to press a button in response to external or internal probes, while giving a speech on a controversial topic in front of an audience. The external probe consisted of a LED attached to the head of one spectator and the internal probe was a light vibration, which ostensibly signaled changes in participants' pulse or skin conductance.

RESULTS

The results indicate that during speech anticipation, high speech anxious participants responded significantly faster to internal probes than low speech anxious participants, while during the speech no differences were revealed between internal and external probes.

LIMITATIONS

Generalization of our results is restricted to speech anxious individuals.

CONCLUSIONS

Our results provide support for the pivotal role of self-focused attention in anticipatory social anxiety. Furthermore, they provide a new framework for understanding interaction effects of internal and external attention in anticipation of and during actual social situations.

Specificity of homework compliance effects on treatment outcome in CBT: evidence from a controlled trial on panic disorder and agoraphobia

OBJECTIVES

Although homework assignments are an integral component of cognitive-behavioral therapy (CBT) and relate to positive therapy outcomes, it is unclear whether specific homework types and their completion have specific effects on outcome.

METHOD

Data from N = 292 patients (75% female, mean age 36 years) with panic disorder and agoraphobia and treated with standardized CBT were analyzed with homework compliance quality and quantity for different types of homework serving as predictors for different outcome variables.

RESULTS

Quality ratings of homework completion were stronger outcome predictors than quantitative compliance ratings. Exposure homework was a better outcome predictor than homework relating to psychoeducation and self-monitoring.

CONCLUSION

Different aspects of homework compliance and specific homework types might differentially relate to CBT outcome.

Effect of cognitive-behavioral therapy on neural correlates of fear conditioning in panic disorder

BACKGROUND

Learning by conditioning is a key ability of animals and humans for acquiring novel behavior necessary for survival in a changing environment. Aberrant conditioning has been considered a crucial factor in the etiology and maintenance of panic disorder with agoraphobia (PD/A). Cognitive-behavioral therapy (CBT) is an effective treatment for PD/A. However, the neural mechanisms underlying the effects of CBT on conditioning processes in PD/A are unknown.

METHODS

In a randomized, controlled, multicenter clinical trial in medication-free patients with PD/A who were treated with 12 sessions of manualized CBT, functional magnetic resonance imaging (fMRI) was used during fear conditioning before and after CBT. Quality-controlled fMRI data from 42 patients and 42 healthy subjects were obtained.

RESULTS

After CBT, patients compared to control subjects revealed reduced activation for the conditioned response (CS+ > CS-) in the left inferior frontal gyrus (IFG). This activation reduction was correlated with reduction in agoraphobic symptoms from t1 to t2. Patients compared to control subjects also demonstrated increased connectivity between the IFG and regions of the "fear network" (amygdalae, insulae, anterior cingulate cortex) across time.

CONCLUSIONS

This study demonstrates the link between cerebral correlates of cognitive (IFG) and emotional ("fear network") processing during symptom improvement across time in PD/A. Further research along this line has promising potential to support the development and further optimization of targeted treatments.

Meta-analysis argues for a female-specific role of MAOA-uVNTR in panic disorder in four European populations

Panic disorder (PD) is a common mental disorder, ranking highest among the anxiety disorders in terms of disease burden. The pathogenesis of PD is multifactorial with significant heritability, however only a few convincing risk genes have been reported thus far. One of the most promising candidates is the gene encoding monoamine oxidase A (MAOA), due to its key role in monoaminergic neurotransmission, established validity of animal models, and the efficacy of MAO inhibitors in the treatment of PD. A promoter repeat polymorphism in MAOA (MAOA-uVNTR) impacts on gene expression; high-expression alleles have been reported to increase the risk for PD. To further scrutinize the role of this polymorphism, we performed a formal meta-analysis on MAOA-uVNTR and PD using original data from four published European (Estonian, German, Italian, and Polish) samples and genotypes from three hitherto unpublished German PD samples, resulting in the largest (n = 1,115 patients and n = 1,260 controls) genetic study on PD reported to date. In the unpublished samples, evidence for association of MAOA-uVNTR with PD was obtained in one of the three samples. Results of the meta-analysis revealed a significant and female-specific association when calculating an allelic model (OR = 1.23, P = 0.006). This sex-specific effect might be explained by a gene-dose effect causing higher MAOA expression in females. Taken together, our meta-analysis therefore argues that high-expression MAOA-uVNTR alleles significantly increase the risk towards PD in women. However, epigenetic mechanisms might obfuscate the genetic association, calling for ascertainment in larger samples as well as assessment of the MAOA promoter methylation status therein.

Dynamics of defensive reactivity in patients with panic disorder and agoraphobia: implications for the etiology of panic disorder

BACKGROUND

The learning perspective of panic disorder distinguishes between acute panic and anxious apprehension as distinct emotional states. Following animal models, these clinical entities reflect different stages of defensive reactivity depending upon the imminence of interoceptive or exteroceptive threat cues. The current study tested this model by investigating the dynamics of defensive reactivity in a large group of patients with panic disorder and agoraphobia (PD/AG).

METHODS

Three hundred forty-five PD/AG patients participated in a standardized behavioral avoidance test (being entrapped in a small, dark chamber for 10 minutes). Defense reactivity was assessed measuring avoidance and escape behavior, self-reports of anxiety and panic symptoms, autonomic arousal (heart rate and skin conductance), and potentiation of the startle reflex before and during exposure of the behavioral avoidance test.

RESULTS

Panic disorder and agoraphobia patients differed substantially in their defensive reactivity. While 31.6% of the patients showed strong anxious apprehension during this task (as indexed by increased reports of anxiety, elevated physiological arousal, and startle potentiation), 20.9% of the patients escaped from the test chamber. Active escape was initiated at the peak of the autonomic surge accompanied by an inhibition of the startle response as predicted by the animal model. These physiological responses resembled the pattern observed during the 34 reported panic attacks.

CONCLUSIONS

We found evidence that defensive reactivity in PD/AG patients is dynamically organized ranging from anxious apprehension to panic with increasing proximity of interoceptive threat. These data support the learning perspective of panic disorder.

Depression does not affect the treatment outcome of CBT for panic and agoraphobia: results from a multicenter randomized trial

BACKGROUND

Controversy surrounds the questions whether co-occurring depression has negative effects on cognitive-behavioral therapy (CBT) outcomes in patients with panic disorder (PD) and agoraphobia (AG) and whether treatment for PD and AG (PD/AG) also reduces depressive symptomatology.

METHODS

Post-hoc analyses of randomized clinical trial data of 369 outpatients with primary PD/AG (DSM-IV-TR criteria) treated with a 12-session manualized CBT (n = 301) and a waitlist control group (n = 68). Patients with comorbid depression (DSM-IV-TR major depression, dysthymia, or both: 43.2% CBT, 42.7% controls) were compared to patients without depression regarding anxiety and depression outcomes (Clinical Global Impression Scale [CGI], Hamilton Anxiety Rating Scale [HAM-A], number of panic attacks, Mobility Inventory [MI], Panic and Agoraphobia Scale, Beck Depression Inventory) at post-treatment and follow-up (categorical). Further, the role of severity of depressive symptoms on anxiety/depression outcome measures was examined (dimensional).

RESULTS

Comorbid depression did not have a significant overall effect on anxiety outcomes at post-treatment and follow-up, except for slightly diminished post-treatment effect sizes for clinician-rated CGI (p = 0.03) and HAM-A (p = 0.008) when adjusting for baseline anxiety severity. In the dimensional model, higher baseline depression scores were associated with lower effect sizes at post-treatment (except for MI), but not at follow-up (except for HAM-A). Depressive symptoms improved irrespective of the presence of depression.

CONCLUSIONS

Exposure-based CBT for primary PD/AG effectively reduces anxiety and depressive symptoms, irrespective of comorbid depression or depressive symptomatology.

Gender differences in associations of glutamate decarboxylase 1 gene (GAD1) variants with panic disorder

BACKGROUND

Panic disorder is common (5% prevalence) and females are twice as likely to be affected as males. The heritable component of panic disorder is estimated at 48%. Glutamic acid dehydrogenase GAD1, the key enzyme for the synthesis of the inhibitory and anxiolytic neurotransmitter GABA, is supposed to influence various mental disorders, including mood and anxiety disorders. In a recent association study in depression, which is highly comorbid with panic disorder, GAD1 risk allele associations were restricted to females.

METHODOLOGY/PRINCIPAL FINDINGS

Nineteen single nucleotide polymorphisms (SNPs) tagging the common variation in GAD1 were genotyped in two independent gender and age matched case-control samples (discovery sample n = 478; replication sample n = 584). Thirteen SNPs passed quality control and were examined for gender-specific enrichment of risk alleles associated with panic disorder by using logistic regression including a genotype×gender interaction term. The latter was found to be nominally significant for four SNPs (rs1978340, rs3762555, rs3749034, rs2241165) in the discovery sample; of note, the respective minor/risk alleles were associated with panic disorder only in females. These findings were not confirmed in the replication sample; however, the genotype×gender interaction of rs3749034 remained significant in the combined sample. Furthermore, this polymorphism showed a nominally significant association with the Agoraphobic Cognitions Questionnaire sum score.

CONCLUSIONS/SIGNIFICANCE

The present study represents the first systematic evaluation of gender-specific enrichment of risk alleles of the common SNP variation in the panic disorder candidate gene GAD1. Our tentative results provide a possible explanation for the higher susceptibility of females to panic disorder.