The multi-generational familial aggregation of interstitial cystitis, other chronic nociplastic pain disorders, depression, and panic disorder

BACKGROUND

Interstitial cystitis/painful bladder syndrome (IC) is a chronic pelvic pain condition which has high comorbidity with other nociplastic, or unexplained, pain disorders [e.g. fibromyalgia (FM), irritable bowel syndrome (IBS), and myalgic encephalomyelitis/chronic fatigue (ME/CFS)] and some psychiatric conditions [major depressive disorder (MDD) and panic disorder (PD)]. Here we investigated the shared familiality of IC and these other nociplastic and psychiatric conditions.

METHODS

Subjects were identified in the Utah Population Database, which links genealogy data back to the 1800s to medical record diagnosis billing code data back to 1995. We computed the relative risk of each of these disorders among first (FDR), second (SDR), and third-degree relatives (TDR) of six proband groups: IC, FM, IBS, ME/CFS, PD, and MDD. Given the known familial aggregation of each of these disorders, we conducted our analyses to test for heritable interrelationships using proband subgroups whose members did not have the diagnosis assessed in their relatives.

RESULTS

We observed strong evidence for heritable interrelationships among all six disorders. Most analyses indicated significantly increased risk for each of the six disorders in FDR, SDR, and TDR of all or most proband groups. Out of 30 possible bidirectional disorder interrelationships, 26 were significant among FDR, 23 were significant among SDR, and 7 were significant among TDR. Clustering was observed in both close and distant relatives.

CONCLUSIONS

Our results support a common, heritable component to IC and other nociplastic and psychiatric conditions.

Prevalence and correlates of lifetime suicide attempt in obsessive-compulsive disorder with major depression

BACKGROUND

Little is known about specific obsessive-compulsive clinical features associated with lifetime history of suicide attempt in individuals with obsessive-compulsive disorder (OCD) and major depression.

METHODS

The study sample included 515 adults with OCD and a history of major depression. In exploratory analyses, we compared the distributions of demographic characteristics and clinical features in those with and without a history of attempted suicide and used logistic regression to evaluate the association between specific obsessive-compulsive clinical features and lifetime suicide attempt.

RESULTS

Sixty-four (12%) of the participants reported a lifetime history of suicide attempt. Those who had attempted suicide were more likely to report having experienced violent or horrific images (52% vs. 30%; p < 0.001). The odds of lifetime suicide attempt were more than twice as great in participants with versus without violent or horrific images (O.R. = 2.46, 95%, CI = 1.45-4.19; p < 0.001), even after adjustment for other risk correlates of attempted suicide, including alcohol dependence, post-traumatic stress disorder, parental conflict, excessive physical discipline, and number of episodes of depression. The association between violent or horrific images and attempted suicide was especially strong in men, 18-29 year olds, those with post-traumatic stress disorder, and those with particular childhood adversities.

CONCLUSIONS

Violent or horrific images are strongly associated with lifetime suicide attempts in OCD-affected individuals with a history of major depression. Prospective clinical and epidemiological studies are needed to elucidate the basis of this relationship.

Exome sequencing in obsessive-compulsive disorder reveals a burden of rare damaging coding variants

Obsessive-compulsive disorder (OCD) affects 1-2% of the population, and, as with other complex neuropsychiatric disorders, it is thought that rare variation contributes to its genetic risk. In this study, we performed exome sequencing in the largest OCD cohort to date (1,313 total cases, consisting of 587 trios, 41 quartets and 644 singletons of affected individuals) and describe contributions to disease risk from rare damaging coding variants. In case-control analyses (n = 1,263/11,580), the most significant single-gene result was observed in SLITRK5 (odds ratio (OR) = 8.8, 95% confidence interval 3.4-22.5, P = 2.3 × 10^-6). Across the exome, there was an excess of loss of function (LoF) variation specifically within genes that are LoF-intolerant (OR = 1.33, P = 0.01). In an analysis of trios, we observed an excess of de novo missense predicted damaging variants relative to controls (OR = 1.22, P = 0.02), alongside an excess of de novo LoF mutations in LoF-intolerant genes (OR = 2.55, P = 7.33 × 10^-3). These data support a contribution of rare coding variants to OCD genetic risk.

Heterogeneity in Fear Processing across and within Anxiety, Eating, and Compulsive Disorders

BACKGROUND

To assess within and across diagnosis variability we examined fear processing in healthy controls (HC) and three diagnostic groups that share symptoms of pathological anxiety: obsessive compulsive disorder (OCD); social anxiety disorder (SAD), and anorexia nervosa (AN).

METHODS

Unmedicated adults (N=166) participated in a paradigm assessing associative fear acquisition, extinction, extinction recall, and fear renewal. Data were analyzed from two perspectives: comparison of each disorder to HC and exploratory latent class analysis (LCA) of the combined data.

RESULTS

The diagnosis-based analyses indicated significantly increased fear renewal in OCD and trends toward decreased extinction recall in OCD and increased renewal in SAD. The LCA indicated four Response Types, none of which were congruent with the diagnostic categories. Most participants had a normative response (50%) or a moderate extinction recall deficit (30%). The two remaining groups (8% each) had more extreme responses: one showed complete failure of extinction recall; the other persistent arousal in expectation of, but prior to, actual conditioning (threat sensitivity).

LIMITATIONS

Due to small sample size (N=20) results for AN are regarded as preliminary.

CONCLUSIONS

Our diagnosis-based findings are consistent with previous data suggesting an association between pathological anxiety and difficulties maintaining fear extinction. The LCA reveal substantial within-diagnosis heterogeneity in fear processing and support inclusion of empirically driven approaches as a complement to standard analyses. This heterogeneity may also have implications for treatment, particularly cognitive behavioral therapy, which relies on strengthening extinction recall and requires patients to tolerate anxious expectation in order to engage with feared situations.

General personality dimensions, impairment and treatment response in obsessive-compulsive disorder

General personality dimensions are associated with clinical severity and treatment response in individuals with depression and many anxiety disorders, but little is known about these relationships in individuals with obsessive-compulsive disorder (OCD). Individuals in the current study included 705 adults with OCD who had participated in family and genetic studies of the disorder. Participants self-completed the Neuroticism, Extraversion, Openness Personality Inventory or Neuroticism, Extraversion, Openness Five-Factor Inventory-3. Relationships between personality scores, and subjective impairment and OCD treatment response, were evaluated. The odds of subjective impairment increased with (unit increase in) the neuroticism score (odds ratio, OR = 1.03; 95% CI = 1.01-1.04; p < 0.01) and decreased with extraversion scores (OR = 0.98; 95% CI = 0.96-0.99; p < 0.01). The odds of reporting a good response to serotonin/selective serotonin reuptake inhibitors (OR = 1.02; 95% CI = 1.01-1.04; p < 0.01) or cognitive behavioural therapy (OR = 1.03; 95% CI = 1.01-1.05; p < 0.01) increased with the extraversion score. The magnitude of these relationships did not change appreciably after adjusting for other clinical features related to one or more of the personality dimensions. The findings suggest that neuroticism and extraversion are associated with subjective impairment, and that extraversion is associated with self-reported treatment response, in individuals with OCD. © 2019 John Wiley & Sons, Ltd.

Impaired generalization of reward but not loss in obsessive-compulsive disorder

BACKGROUND

Generalizing from past experiences can be adaptive by allowing those experiences to guide behavior in new situations. Generalizing too much, however, can be maladaptive. For example, individuals with pathological anxiety are believed to overgeneralize emotional responses from past threats, broadening their scope of fears. Whether individuals with pathological anxiety overgeneralize in other situations remains unclear.

METHODS

The present study (N = 57) used a monetary sensory preconditioning paradigm with rewards and losses to address this question in individuals with obsessive-compulsive disorder (OCD) and social anxiety disorder (SAD), comparing them to healthy comparison subjects (HC). In all groups, we tested direct learning of associations between cues and reward vs. loss outcomes, as well as generalization of learning to novel choice options.

RESULTS

We found no differences between the three groups in the direct learning of stimuli with their outcomes: all subjects demonstrated intact stimulus-response learning by choosing rewarding options and avoiding negative ones. However, OCD subjects were less likely to generalize from rewards than either the SAD or HC groups, and this impairment was not found for losses. Additionally, greater deficits in reward generalization were correlated with severity of threat estimation, as measured by a subscale of the Obsessive Beliefs Questionnaire, both within OCD and across all groups.

CONCLUSIONS

These findings suggest that a compromised ability to generalize from rewarding events may impede adaptive behavior in OCD and in those susceptible to high estimation of threat.

Impact of Receiving Secondary Results from Genomic Research: A 12-Month Longitudinal Study

The impact of returning secondary results from exome sequencing (ES) on patients/participants is important to understand as ES is increasingly utilized in clinical care and research. Participants were recruited from studies using ES and were separated into two arms: 107 who had ES and were offered the choice to learn secondary results (ES group) and 85 who had not yet had ES (No ES group). Questionnaires were administered at baseline and 1 and 12 months, following results disclosure (ES group) or enrollment (No ES group). While the majority (65%) elected to learn all results following pre-test counseling, it was reduced from the 76% who indicated a desire for all results at baseline. Thirty-seven percent received results associated with an increased personal disease risk. There were no differences in changes in any of the psychological and social measures from baseline to post-results disclosure between the ES and No ES groups. Receiving a wide range of secondary findings appeared to have little measurable impact on most participants. The experience of learning secondary results may be related to participants' previous experiences with genetics, as well as the genetic counseling provided. Future research with a more diverse, genetically naïve group, as well as scalable methods of delivery, is needed.

Temporal discounting across three psychiatric disorders: Anorexia nervosa, obsessive compulsive disorder, and social anxiety disorder

BACKGROUND

Temporal discounting refers to the tendency for rewards to lose value as the expected delay to receipt increases. Individuals with anorexia nervosa (AN) have been found to show reduced temporal discounting rates, indicating a greater preference for delayed rewards compared to healthy peers. Obsessive-compulsive disorder (OCD) and social anxiety disorder (SAD) commonly co-occur with AN, and anxiety has been related to development and prognosis of AN. We examined whether reduced temporal discounting is present across these potentially related disorders, and explored the relationship between temporal discounting and anxiety transdiagnostically.

METHODS

One hundred ninety six individuals (75 healthy controls (HC); 50 OCD; 27 AN; 44 SAD) completed two temporal discounting tasks in which they chose between smaller-sooner and larger-later monetary rewards. Two measures of discounting-discount rate and discount factor-were compared between diagnostic groups, and associations with anxious traits were examined.

RESULTS

Individuals with AN showed decreased temporal discounting compared to HC. OCD and SAD groups did not differ significantly from HC. Across the sample, anxiety was associated with decreased discounting; more anxious individuals showed a greater preference for delayed reward.

CONCLUSIONS

We replicated the findings that individuals with AN show an increased preference for delayed reward relative to HC and that individuals with OCD do not differ from HC. We also showed that individuals with SAD do not differ from HC in discounting. Across this large sample, two measures of anxious temperament were associated with temporal discounting. These data raise new questions about the relationship between this dimensional trait and psychopathology.

Genome Wide Association Study (GWAS) between Attention Deficit Hyperactivity Disorder (ADHD) and Obsessive Compulsive Disorder (OCD)

Objective: The aim of this study was to identify any potential genetic overlap between attention deficit hyperactivity disorder (ADHD) and obsessive compulsive disorder (OCD). We hypothesized that since these disorders share a sub-phenotype, they may share common risk alleles. In this manuscript, we report the overlap found between these two disorders. Methods: A meta-analysis was conducted between ADHD and OCD, and polygenic risk scores (PRS) were calculated for both disorders. In addition, a protein-protein analysis was completed in order to examine the interactions between proteins; p-values for the protein-protein interaction analysis was calculated using permutation. Conclusion: None of the single nucleotide polymorphisms (SNPs) reached genome wide significance and there was little evidence of genetic overlap between ADHD and OCD.

The Role of Response Inhibition in Medicated and Unmedicated Obsessive-Compulsive Disorder Patients: Evidence from the Stop-Signal Task

BACKGROUND

Numerous studies have investigated response inhibition (RI) in obsessive-compulsive disorder (OCD), with many reporting that OCD patients demonstrate deficits in RI as compared to controls. However, reported effect sizes tend to be modest and results have been inconsistent, with some studies finding intact RI in OCD. To date, no study has examined the effect of medications on RI in OCD patients.

METHODS

We analyzed results from a stop-signal task to probe RI in 65 OCD patients (32 of whom were medicated) and 58 healthy controls (HCs).

RESULTS

There was no statistically significant difference in stop-signal reaction time between the OCD group and the HC group, or between the medicated and unmedicated OCD patients. However, variability was significantly greater in the medicated OCD group compared to the unmedicated group.

CONCLUSIONS

These results indicate that some samples of OCD patients do not have deficits in RI, making it unlikely that deficient RI underlies repetitive behaviors in all OCD patients. Future research is needed to fully elucidate the impact of medication use on stop-signal performance. Implications for future research on the cognitive processes underlying repetitive thoughts and behaviors are discussed.

ADHD and executive functioning deficits in OCD youths who hoard

Hoarding is common among youth with obsessive compulsive disorder (OCD), with up to 26% of OCD youth exhibiting hoarding symptoms. Recent evidence from adult hoarding and OCD cohorts suggests that hoarding symptoms are associated with executive functioning deficits similar to those observed in subjects with attention deficit hyperactivity disorder (ADHD). However, while hoarding behavior often onsets during childhood, there is little information about executive function deficits and ADHD in affected children and adolescents. The study sample included 431 youths (ages 6-17 years) diagnosed with OCD who participated in the OCD Collaborative Genetics Study and the OCD Collaborative Genetics Association Study and completed a series of clinician-administered and parent report assessments, including diagnostic interviews and measures of executive functioning (Behavior Rating Inventory of Executive Functioning; BRIEF) and hoarding severity (Hoarding Rating Scale-Interview; HRS-I). 113 youths (26%) had clinically significant levels of hoarding compulsions. Youths with and without hoarding differed significantly on most executive functioning subdomains and composite indices as measured by the parent-rated BRIEF. Groups did not differ in the frequency of full DSM-IV ADHD diagnoses; however, the hoarding group had significantly greater number of inattention and hyperactivity symptoms compared to the non-hoarding group. In multivariate models, we found that overall BRIEF scores were related to hoarding severity, adjusting for age, gender and ADHD symptoms. These findings suggest an association between hoarding and executive functioning deficits in youths with OCD, and assessing executive functioning may be important for investigating the etiology and treatment of children and adolescents with hoarding and OCD.

Attention bias in adults with anorexia nervosa, obsessive-compulsive disorder, and social anxiety disorder

BACKGROUND

Attention bias to threat (selective attention toward threatening stimuli) has been frequently found in anxiety disorder samples, but its distribution both within and beyond this category is unclear. Attention bias has been studied extensively in social anxiety disorder (SAD) but relatively little in obsessive compulsive disorder (OCD), historically considered an anxiety disorder, or anorexia nervosa (AN), which is often characterized by interpersonal as well as body image/eating fears.

METHODS

Medication-free adults with SAD (n = 43), OCD (n = 50), or AN (n = 30), and healthy control volunteers (HC, n = 74) were evaluated for attention bias with an established dot probe task presenting images of angry and neutral faces. Additional outcomes included attention bias variability (ABV), which summarizes fluctuation in attention between vigilance and avoidance, and has been reported to have superior reliability. We hypothesized that attention bias would be elevated in SAD and associated with SAD severity.

RESULTS

Attention bias in each disorder did not differ from HC, but within the SAD group attention bias correlated significantly with severity of social avoidance. ABV was significantly lower in OCD versus HC, and it correlated positively with severity of OCD symptoms within the OCD group.

CONCLUSIONS

Findings do not support differences from HC in attention bias to threat faces for SAD, OCD, or AN. Within the SAD sample, the association of attention bias with severity of social avoidance is consistent with evidence that attention bias moderates development of social withdrawal. The association of ABV with OCD diagnosis and severity is novel and deserves further study.

PREPULSE INHIBITION DEFICITS ONLY IN FEMALES WITH OBSESSIVE-COMPULSIVE DISORDER

BACKGROUND

Deficits in sensorimotor gating have been hypothesized to underlie the inability to inhibit repetitive thoughts and behaviors. To test this hypothesis, this study assessed prepulse inhibition (PPI), a measure of sensorimotor gating, across three psychiatric disorders (obsessive-compulsive disorder [OCD], social anxiety disorder [SAD], and anorexia nervosa [AN]) whose clinical presentations include repetitive thoughts and behaviors

METHODS

We tested acoustic PPI in unmedicated individuals with OCD (n = 45), SAD (n = 37), and AN (n = 26), and compared their results to matched healthy volunteers (n = 62). All participants completed a structured clinical interview and a clinical assessment of psychiatric symptom severity.

RESULTS

Percent PPI was significantly diminished in females with OCD compared to healthy female volunteers (P = .039). No other differences between healthy volunteers and participants with disorders (male or female) were observed. Percent PPI was not correlated with severity of obsessions and compulsions, as measured by the Yale-Brown Obsessive Compulsive Scale.

CONCLUSIONS

This is the first study to assess PPI in participants with SAD or AN, and the largest study to assess PPI in participants with OCD. We found PPI deficits only in females with OCD, which suggests that the cortico-striato-pallido-thalamic and pontine circuitry (believed to underlie PPI) differs between males and females with OCD. Given that PPI deficits were only present in females with OCD and not related to repetitive thoughts and behaviors, our results do not support the hypothesis that sensorimotor gating deficits, as measured by PPI, underlie the inability to inhibit repetitive thoughts and behaviors in individuals with OCD, SAD, and AN.

Whole-genome association analysis of treatment response in obsessive-compulsive disorder

Up to 30% of patients with obsessive-compulsive disorder (OCD) exhibit an inadequate response to serotonin reuptake inhibitors (SRIs). To date, genetic predictors of OCD treatment response have not been systematically investigated using genome-wide association study (GWAS). To identify specific genetic variations potentially influencing SRI response, we conducted a GWAS study in 804 OCD patients with information on SRI response. SRI response was classified as 'response' (n=514) or 'non-response' (n=290), based on self-report. We used the more powerful Quasi-Likelihood Score Test (the MQLS test) to conduct a genome-wide association test correcting for relatedness, and then used an adjusted logistic model to evaluate the effect size of the variants in probands. The top single-nucleotide polymorphism (SNP) was rs17162912 (P=1.76 × 10(-8)), which is near the DISP1 gene on 1q41-q42, a microdeletion region implicated in neurological development. The other six SNPs showing suggestive evidence of association (P<10(-5)) were rs9303380, rs12437601, rs16988159, rs7676822, rs1911877 and rs723815. Among them, two SNPs in strong linkage disequilibrium, rs7676822 and rs1911877, located near the PCDH10 gene, gave P-values of 2.86 × 10(-6) and 8.41 × 10(-6), respectively. The other 35 variations with signals of potential significance (P<10(-4)) involve multiple genes expressed in the brain, including GRIN2B, PCDH10 and GPC6. Our enrichment analysis indicated suggestive roles of genes in the glutamatergic neurotransmission system (false discovery rate (FDR)=0.0097) and the serotonergic system (FDR=0.0213). Although the results presented may provide new insights into genetic mechanisms underlying treatment response in OCD, studies with larger sample sizes and detailed information on drug dosage and treatment duration are needed.

Dependent personality, separation anxiety disorder and other anxiety disorders in OCD

BACKGROUND

The purpose of this study was to investigate whether dependent personality and/or general personality dimensions might explain the strong relationships between separation anxiety disorder (Sep-AD) and three other anxiety disorders (agoraphobia, panic disorder and social anxiety disorder) in individuals with obsessive compulsive disorder (OCD).

METHODS

Using data from 509 adult participants collected during the OCD Collaborative Genetic Study, we used logistic regression models to evaluate the relationships between Sep-AD, dependent personality score, general personality dimensions and three additional anxiety disorders.

RESULTS

The dependent personality score was strongly associated with Sep-AD and the other anxiety disorders in models adjusted for age at interview, age at onset of OC symptoms and worst ever OCD severity score. Several general personality dimensions, especially neuroticism, extraversion and conscientiousness, were also related to Sep-AD and the other anxiety disorders. Sep-AD was not independently related to these anxiety disorders, in multivariate models including general personality and dependent personality disorder scores.

CONCLUSIONS

The results suggest that Sep-AD in childhood and these other anxiety disorders in adulthood are consequences of dependent personality disorder (for agoraphobia and panic disorder) or introversion (for social phobia). It is unknown whether these results would be similar in a non-OCD sample.

Genome-wide association study in obsessive-compulsive disorder: results from the OCGAS

Obsessive-compulsive disorder (OCD) is a psychiatric condition characterized by intrusive thoughts and urges and repetitive, intentional behaviors that cause significant distress and impair functioning. The OCD Collaborative Genetics Association Study (OCGAS) is comprised of comprehensively assessed OCD patients with an early age of OCD onset. After application of a stringent quality control protocol, a total of 1065 families (containing 1406 patients with OCD), combined with population-based samples (resulting in a total sample of 5061 individuals), were studied. An integrative analyses pipeline was utilized, involving association testing at single-nucleotide polymorphism (SNP) and gene levels (via a hybrid approach that allowed for combined analyses of the family- and population-based data). The smallest P-value was observed for a marker on chromosome 9 (near PTPRD, P=4.13 × 10(-)(7)). Pre-synaptic PTPRD promotes the differentiation of glutamatergic synapses and interacts with SLITRK3. Together, both proteins selectively regulate the development of inhibitory GABAergic synapses. Although no SNPs were identified as associated with OCD at genome-wide significance level, follow-up analyses of genome-wide association study (GWAS) signals from a previously published OCD study identified significant enrichment (P=0.0176). Secondary analyses of high-confidence interaction partners of DLGAP1 and GRIK2 (both showing evidence for association in our follow-up and the original GWAS study) revealed a trend of association (P=0.075) for a set of genes such as NEUROD6, SV2A, GRIA4, SLC1A2 and PTPRD. Analyses at the gene level revealed association of IQCK and C16orf88 (both P<1 × 10(-)(6), experiment-wide significant), as well as OFCC1 (P=6.29 × 10(-)(5)). The suggestive findings in this study await replication in larger samples.

Hoarding in Children and Adolescents with Obsessive-Compulsive Disorder

Compared to studies in adults, there have been few studies of hoarding in children and adolescents with obsessive-compulsive disorder (OCD). In the current study, we evaluated OCD clinical features, Axis I disorders, and social reciprocity scores in 641 children and adolescents with OCD, of whom 163 (25%) had hoarding compulsions and 478 did not. We found that, as a group, youth with hoarding had an earlier age at onset and more severe lifetime OCD symptoms, poorer insight, more difficulty making decisions and completing tasks, and more overall impairment. The hoarding group also had a greater lifetime prevalence of panic disorder, specific phobia, Tourette disorder, and tics. As measured with the Social Reciprocity Scale, the hoarding group had more severe deficits in parent-rated domains of social communication, social motivation, and restricted interests and repetitive behavior. In a multivariable model, the overall social reciprocity score, age at onset of OCD symptoms, symmetry obsessions, and indecision were independently related to hoarding in these children and adolescents with OCD. These features should be considered as candidate risk factors for the development of hoarding behavior in pediatric OCD.

Evidence for linkage and association of GABRB3 and GABRA5 to panic disorder

Panic disorder (PD) is a debilitating anxiety disorder characterized by episodes of intense fear with autonomic and psychological symptoms that lead to behavioral impairment. A convergence of genetic and biological evidence implicates gamma-aminobutyric acid type A receptor subunits on chromosome 15q12 as candidate genes for PD. This study investigated 120 Caucasian, multiplex PD pedigrees using regional microsatellites (chr15q11-13) and found support for linkage (logarithm of odds (LOD) ⩾2), with a prominent parent-of-origin effect. Genotyping with 10 single-nucleotide polymorphisms (SNPs) showed linkage to GABRB3 (rs11631421, LOD=4.6) and GABRA5 (rs2075716, LOD=2.2), and allelic association to GABRB3 (rs8024564, p=0.005; rs8025575, p=0.02) and GABRA5 (rs35399885, p=0.05). Genotyping of an independent Sardinian PD trio sample also supported association in the region, again with a parent-of-origin effect. These findings provide genetic evidence for the involvement of the genes GABRB3 and GABRA5 in the susceptibility to PD.

Clinical correlates and genetic linkage of social and communication difficulties in families with obsessive-compulsive disorder: Results from the OCD Collaborative Genetics Study

Some individuals with obsessive-compulsive disorder (OCD) have autistic-like traits, including deficits in social and communication behaviors (pragmatics). The objective of this study was to determine if pragmatic impairment aggregates in OCD families and discriminates a clinically and genetically distinct subtype of OCD. We conducted clinical examinations on, and collected DNA samples from, 706 individuals with OCD in 221 multiply affected OCD families. Using the Pragmatic Rating Scale (PRS), we compared the prevalence of pragmatic impairment in OCD-affected relatives of probands with and without pragmatic impairment. We also compared clinical features of OCD-affected individuals in families having at least one, versus no, individual with pragmatic impairment, and assessed for linkage to OCD in the two groups of families. The odds of pragmatic impairment were substantially greater in OCD-affected relatives of probands with pragmatic impairment. Individuals in high-PRS families had greater odds of separation anxiety disorder and social phobia, and a greater number of schizotypal personality traits. In high-PRS families, there was suggestive linkage to OCD on chromosome 12 at marker D12S1064 and on chromosome X at marker DXS7132 whereas, in low-PRS families, there was suggestive linkage to chromosome 3 at marker D3S2398. Pragmatic impairment aggregates in OCD families. Separation anxiety disorder, social phobia, and schizotypal personality traits are part of a clinical spectrum associated with pragmatic impairment in these families. Specific regions of chromosomes 12 and X are linked to OCD in high-PRS families. Thus, pragmatic impairment may distinguish a clinically and genetically homogeneous subtype of OCD.

Genome-wide association study of obsessive-compulsive disorder

Obsessive-compulsive disorder (OCD) is a common, debilitating neuropsychiatric illness with complex genetic etiology. The International OCD Foundation Genetics Collaborative (IOCDF-GC) is a multi-national collaboration established to discover the genetic variation predisposing to OCD. A set of individuals affected with DSM-IV OCD, a subset of their parents, and unselected controls, were genotyped with several different Illumina SNP microarrays. After extensive data cleaning, 1465 cases, 5557 ancestry-matched controls and 400 complete trios remained, with a common set of 469,410 autosomal and 9657 X-chromosome single nucleotide polymorphisms (SNPs). Ancestry-stratified case-control association analyses were conducted for three genetically-defined subpopulations and combined in two meta-analyses, with and without the trio-based analysis. In the case-control analysis, the lowest two P-values were located within DLGAP1 (P=2.49 × 10(-6) and P=3.44 × 10(-6)), a member of the neuronal postsynaptic density complex. In the trio analysis, rs6131295, near BTBD3, exceeded the genome-wide significance threshold with a P-value=3.84 × 10(-8). However, when trios were meta-analyzed with the case-control samples, the P-value for this variant was 3.62 × 10(-5), losing genome-wide significance. Although no SNPs were identified to be associated with OCD at a genome-wide significant level in the combined trio-case-control sample, a significant enrichment of methylation QTLs (P<0.001) and frontal lobe expression quantitative trait loci (eQTLs) (P=0.001) was observed within the top-ranked SNPs (P<0.01) from the trio-case-control analysis, suggesting these top signals may have a broad role in gene expression in the brain, and possibly in the etiology of OCD.

Meta-analysis of association between obsessive-compulsive disorder and the 3' region of neuronal glutamate transporter gene SLC1A1

The neuronal glutamate transporter gene SLC1A1 is a candidate gene for obsessive-compulsive disorder (OCD) based on linkage studies and convergent evidence implicating glutamate in OCD etiology. The 3' end of SLC1A1 is the only genomic region with consistently demonstrated OCD association, especially when analyzing male-only probands. However, specific allele associations have not been consistently replicated, and recent OCD genome-wide association and meta-analysis studies have not incorporated all previously associated SLC1A1 SNPs. To clarify the nature of association between SLC1A1 and OCD, pooled analysis was performed on all available relevant raw study data, comprising a final sample of 815 trios, 306 cases and 634 controls. This revealed weak association between OCD and one of nine tested SLC1A1 polymorphisms (rs301443; uncorrected P = 0.046; non-significant corrected P). Secondary analyses of male-affecteds only (N = 358 trios and 133 cases) demonstrated modest association between OCD and a different SNP (rs12682807; uncorrected P = 0.012; non-significant corrected P). Findings of this meta-analysis are consistent with the trend of previous candidate gene studies in psychiatry and do not clarify the putative role of SLC1A1 in OCD pathophysiology. Nonetheless, it may be important to further examine the potential associations demonstrated in this amalgamated sample, especially since the SNPs with modest associations were not included in the more highly powered recent GWAS or in a past meta-analysis including five SLC1A1 polymorphisms. This study underscores the need for much larger sample sizes in future genetic association studies and suggests that next-generation sequencing may be beneficial in examining the potential role of rare variants in OCD.

Designing case-control studies: decisions about the controls

The authors quantified, first, the effect of misclassified controls (i.e., individuals who are affected with the disease under study but who are classified as controls) on the ability of a case-control study to detect an association between a disease and a genetic marker, and second, the effect of leaving misclassified controls in the study, as opposed to removing them (thus decreasing sample size). The authors developed an informativeness measure of a study's ability to identify real differences between cases and controls. They then examined this measure's behavior when there are no misclassified controls, when there are misclassified controls, and when there were misclassified controls but they have been removed from the study. The results show that if, for example, 10% of controls are misclassified, the study's informativeness is reduced to approximately 81% of what it would have been in a sample with no misclassified controls, whereas if these misclassified controls are removed from the study, the informativeness is only reduced to about 90%, despite the reduced sample size. If 25% are misclassified, those figures become approximately 56% and 75%, respectively. Thus, leaving the misclassified controls in the control sample is worse than removing them altogether. Finally, the authors illustrate how insufficient power is not necessarily circumvented by having an unlimited number of controls. The formulas provided by the authors enable investigators to make rational decisions about removing misclassified controls or leaving them in.

Meta-analyses of genome-wide linkage scans of anxiety-related phenotypes

Genetic factors underlying trait neuroticism, reflecting a tendency towards negative affective states, may overlap genetic susceptibility for anxiety disorders and help explain the extensive comorbidity amongst internalizing disorders. Genome-wide linkage (GWL) data from several studies of neuroticism and anxiety disorders have been published, providing an opportunity to test such hypotheses and identify genomic regions that harbor genes common to these phenotypes. In all, 11 independent GWL studies of either neuroticism (n=8) or anxiety disorders (n=3) were collected, which comprised of 5341 families with 15 529 individuals. The rank-based genome scan meta-analysis (GSMA) approach was used to analyze each trait separately and combined, and global correlations between results were examined. False discovery rate (FDR) analysis was performed to test for enrichment of significant effects. Using 10 cM intervals, bins nominally significant for both GSMA statistics, P(SR) and P(OR), were found on chromosomes 9, 11, 12, and 14 for neuroticism and on chromosomes 1, 5, 15, and 16 for anxiety disorders. Genome-wide, the results for the two phenotypes were significantly correlated, and a combined analysis identified additional nominally significant bins. Although none reached genome-wide significance, an excess of significant P(SR)P-values were observed, with 12 bins falling under a FDR threshold of 0.50. As demonstrated by our identification of multiple, consistent signals across the genome, meta-analytically combining existing GWL data is a valuable approach to narrowing down regions relevant for anxiety-related phenotypes. This may prove useful for prioritizing emerging genome-wide association data for anxiety disorders.

Homeobox genes in obsessive-compulsive disorder

BACKGROUND

Despite evidence that obsessive-compulsive disorder (OCD) is a familial neuropsychiatric condition, progress aimed at identifying genetic determinants of the disorder has been slow. The OCD Collaborative Genetics Study (OCGS) has identified several OCD susceptibility loci through linkage analysis.

METHODS

In this study we investigate two regions on chromosomes 15q and 1q by first refining the linkage region using additional short tandem repeat polymorphic (STRP) markers. We then performed association analysis on single nucleotide polymorphisms (SNP) genotyped (markers placed every 2-4 kb) in the linkage regions in the OCGS sample of 376 rigorously phenotyped affected families.

RESULTS

Three SNPs are most strongly associated with OCD: rs11854486 (P = 0.00005 [0.046 after adjustment for multiple tests]; genetic relative risk (GRR) = 11.1 homozygous and 1.6 heterozygous) and rs4625687 [P = 0.00007 (after adjustment = 0.06); GRR = 2.4] on 15q; and rs4387163 (P = 0.0002 (after adjustment = 0.08); GRR = 1.97) on 1q. The first SNP is adjacent to NANOGP8, the second SNP is in MEIS2, and the third is 150 kb between PBX1 and LMX1A.

CONCLUSIONS

All the genes implicated by association signals are homeobox genes and are intimately involved in neurodevelopment. PBX1 and MEIS2 exert their effects by the formation of a heterodimeric complex, which is involved in development of the striatum, a brain region involved in the pathophysiology of OCD. NANOGP8 is a retrogene of NANOG, a homeobox transcription factor known to be involved in regulation of neuronal development. These findings need replication; but support the hypothesis that genes involved in striatal development are implicated in the pathogenesis of OCD.

Is obsessive-compulsive disorder an anxiety disorder, and what, if any, are spectrum conditions? A family study perspective

BACKGROUND

Experts have proposed removing obsessive-compulsive disorder (OCD) from the anxiety disorders section and grouping it with putatively related conditions in DSM-5. The current study uses co-morbidity and familiality data to inform these issues.

METHOD

Case family data from the OCD Collaborative Genetics Study (382 OCD-affected probands and 974 of their first-degree relatives) were compared with control family data from the Johns Hopkins OCD Family Study (73 non-OCD-affected probands and 233 of their first-degree relatives).

RESULTS

Anxiety disorders (especially agoraphobia and generalized anxiety disorder), cluster C personality disorders (especially obsessive-compulsive and avoidant), tic disorders, somatoform disorders (hypochondriasis and body dysmorphic disorder), grooming disorders (especially trichotillomania and pathological skin picking) and mood disorders (especially unipolar depressive disorders) were more common in case than control probands; however, the prevalences of eating disorders (anorexia and bulimia nervosa), other impulse-control disorders (pathological gambling, pyromania, kleptomania) and substance dependence (alcohol or drug) did not differ between the groups. The same general pattern was evident in relatives of case versus control probands. Results in relatives did not differ markedly when adjusted for demographic variables and proband diagnosis of the same disorder, though the strength of associations was lower when adjusted for OCD in relatives. Nevertheless, several anxiety, depressive and putative OCD-related conditions remained significantly more common in case than control relatives when adjusting for all of these variables simultaneously.

CONCLUSIONS

On the basis of co-morbidity and familiality, OCD appears related both to anxiety disorders and to some conditions currently classified in other sections of DSM-IV.

Family history of alcohol use disorders among adults with panic disorder in the community

OBJECTIVE

Clinical studies suggest a familial association between panic disorder and alcohol use disorders but this relationship has not been examined in a representative community sample. The objective of this study is to examine the familial association between panic disorder and alcohol use disorders among adults in the community.

METHOD

Data were drawn from the NESARC, a nationally representative sample of over 43,000 adults in the United States. Rates of alcohol use disorders were examined using the family history method in first-degree relatives (FDRs) of adults with panic disorder. Analyses were adjusted for demographics, alcohol use disorders in the proband, and anxiety disorders in the FDRs.

RESULTS

First-degree relatives of adults with panic disorder have significantly higher odds of alcohol use disorders, compared with FDRs of adults without panic disorder. These associations persist after adjusting for demographic characteristics, alcohol use disorders in the proband, and anxiety disorders in the FDR's.

CONCLUSIONS

Consistent with findings from clinical studies, this is the first population-based study to show a familial link between panic disorder and alcohol use disorders. This association appears independent of the influence of comorbidity of alcohol use disorders and anxiety disorders, suggesting a potential familial and/or genetic pathway. Future longitudinal studies will be needed to further understand the mechanism of this observed association.

Comprehensive family-based association study of the glutamate transporter gene SLC1A1 in obsessive-compulsive disorder

SLC1A1 encodes a neuronal glutamate transporter and is a promising candidate gene for obsessive-compulsive disorder (OCD). Several independent research groups have reported significant associations between OCD and single nucleotide polymorphisms (SNPs) in this gene. Previously, we evaluated 13 SNPs in, or near, SLC1A1 and reported a strong association signal with rs301443, a SNP 7.5 kb downstream of the gene [Shugart et al. (2009); Am J Med Genet Part B 150B:886–892]. The aims of the current study were first, to further investigate this finding by saturating the region around rs301443; and second, to explore the entire gene more thoroughly with a dense panel of SNP markers. We genotyped an additional 111 SNPs in or near SLC1A1, covering from 9 kb upstream to 84 kb downstream of the gene at average spacing of 1.7 kb per SNP, and conducted family-based association analyses in 1,576 participants in 377 families.We found that none of the surrounding markers were in linkage disequilibrium with rs301443, nor were any associated with OCD. We also found that SNP rs4740788, located about 8.8 kb upstream of the gene, was associated with OCD in all families (P = 0.003) and in families with male affecteds (P = 0.002). A three-SNP haplotype (rs4740788–rs10491734–rs10491733) was associated with OCD in the total sample (P = 0.00015) and in families with male affecteds (P = 0.0007). Although of nominal statistical significance considering the number of comparisons, these findings provide further support for the involvement of SLC1A1 in the pathogenesis of OCD.

Separation anxiety disorder in OCD

BACKGROUND

A history of separation anxiety disorder (SAD) is frequently reported by patients with obsessive-compulsive disorder (OCD). The purpose of this study was to determine if there are clinical differences between OCD-affected individuals with, versus without, a history of SAD.

METHODS

Using data collected during the OCD Collaborative Genetic Study, we studied 470 adult OCD participants; 80 had a history of SAD, whereas 390 did not. These two groups were compared as to onset and severity of OCD, lifetime prevalence of Axis I disorders, and number of personality disorder traits.

RESULTS

OCD participants with a history of SAD were significantly younger than the non-SAD group (mean, 34.2 versus 42.2 years; P<.001). They had an earlier age of onset of OCD symptoms (mean, 8.0 versus 10.5 years; P<.003) and more severe OCD, as measured by the Yale-Brown Obsessive Compulsive Scale (mean, 27.5 versus 25.0; P<.005). In addition, those with a history of SAD had a significantly greater lifetime prevalence of agoraphobia (odds ratio (OR) = 2.52, 95% confidence interval (CI) = 1.4-4.6, P<.003), panic disorder (OR = 1.84, CI = 1.03-3.3 P<.04), social phobia (OR = 1.69, CI 1.01-2.8, P<.048), after adjusting for age at interview, age at onset of OCD, and OCD severity in logistic regression models. There was a strong relationship between the number of dependent personality disorder traits and SAD (adjusted OR = 1.42, CI = 1.2-1.6, P<.001).

CONCLUSIONS

A history of SAD is associated with anxiety disorders and dependent personality disorder traits in individuals with OCD.

Bayesian linkage analysis of categorical traits for arbitrary pedigree designs

BACKGROUND

Pedigree studies of complex heritable diseases often feature nominal or ordinal phenotypic measurements and missing genetic marker or phenotype data.

METHODOLOGY

We have developed a Bayesian method for Linkage analysis of Ordinal and Categorical traits (LOCate) that can analyze complex genealogical structure for family groups and incorporate missing data. LOCate uses a Gibbs sampling approach to assess linkage, incorporating a simulated tempering algorithm for fast mixing. While our treatment is Bayesian, we develop a LOD (log of odds) score estimator for assessing linkage from Gibbs sampling that is highly accurate for simulated data. LOCate is applicable to linkage analysis for ordinal or nominal traits, a versatility which we demonstrate by analyzing simulated data with a nominal trait, on which LOCate outperforms LOT, an existing method which is designed for ordinal traits. We additionally demonstrate our method's versatility by analyzing a candidate locus (D2S1788) for panic disorder in humans, in a dataset with a large amount of missing data, which LOT was unable to handle.

CONCLUSION

LOCate's accuracy and applicability to both ordinal and nominal traits will prove useful to researchers interested in mapping loci for categorical traits.

A screen of SLC1A1 for OCD-related alleles

SLC1A1, which encodes the neuronal and epithelial glutamate transporter, is a promising candidate gene for obsessive-compulsive disorder (OCD). In this study, we conducted capillary electrophoresis single-strand conformation polymorphism (CE-SSCP) screen for all 12 identified exons, including all coding regions and approximately 50 bp of flanking introns of the human SLC1A1 in 378 OCD-affected individuals. Full sequencing was completed on samples that showed an aberrant SSCP tracing for identification of the underlying sequence variants. Our aim was to determine if there are differences in the frequencies of relatively common alleles, or rare functional alleles, in 378 OCD cases and 281 ethnically matched controls. We identified one nonsynonymous coding SNP (c.490A > G, T164A) and three synonymous coding SNP (c.81G > C, A27A; c.414A > G, T138T; c.1110T > C, T370T) in case samples. We found no statistical differences in genotype and allele frequencies of common cSNPs in SLC1A1 between the OCD cases and controls. The rare variant T164A was found only in one family. Further investigation of this variant is necessary to determine whether and how it is related to OCD. There was no other evidence of significant accumulation of deleterious coding mutations in SLC1A1 in the OCD cases.

Association of a polyadenylation polymorphism in the serotonin transporter and panic disorder

BACKGROUND

Genetic markers in the serotonin transporter are associated with panic disorder (PD). The associated polymorphisms do not include the serotonin transporter-linked polymorphic region and display no obvious functional attributes. A common polymorphism (rs3813034) occurs in one of the two reported polyadenylation signals for the serotonin transporter and is in linkage disequilibrium with the PD-associated markers. If functional, rs3813034 might be the risk factor that explains the association of the serotonin transporter and PD.

METHODS

Quantitative polymerase chain reaction on human brain samples (n = 65) and lymphoblast cultures (n = 71) was used to test rs3813034 for effects on expression of the polyadenylation forms of the serotonin transporter. rs3813034 was also tested for association in a sample of PD cases (n = 307) and a control sample (n = 542) that has similar population structure.

RESULTS

The balance of the two polyadenylation forms of the serotonin transporter is associated with rs3813034 in brain (p < .001) and lymphoblasts (p < .001). The balance of the polyadenylation forms is also associated with gender in brain only (p < .05). Association testing of rs3813034 in PD identified a significant association (p = .0068) with a relative risk of 1.56 and 1.81 for the heterozygous and homozygous variant genotypes, respectively.

CONCLUSIONS

rs3813034 is a functional polymorphism in the serotonin transporter that alters the balance of the two polyadenylation forms of the serotonin transporter. rs3813034 is a putative risk factor for PD and other behavioral disorders that involve dysregulation of serotonergic neurotransmission.

A linkage search for joint panic disorder/bipolar genes

There is comorbidity and a possible genetic connection between Bipolar disease (BP) and panic disorder (PD). Genes may exist that increase risk to both PD and BP. We explored this possibility using data from a linkage study of PD (120 multiplex families; 37 had > or =1 BP member). We calculated 2-point lodscores maximized over male and female recombination fractions by classifying individuals with PD and/or BP as affected (PD + BP). Additionally, to shed light on possible heterogeneity, we examine the pedigrees containing a bipolar member (BP+) separately from those that do not (BP-), using a Predivided-Sample Test (PST). Linkage evidence for common genes for PD + BP was obtained on chromosomes 2 (lodscore = 4.6) and chromosome 12 (lodscore = 3.6). These locations had already been implicated using a PD-only diagnosis, although at both locations this was larger when a joint PD + BP diagnosis was used. Examining the BP+ families and BP- families separately indicates that both BP+ and BP- pedigrees are contributing to the peaks on chromosomes 2 and 12. However, the PST indicates different evidence of linkage is obtained from BP+ and BP- pedigrees on chromosome 13. Our findings are consistent with risk loci for the combined PD + BP phenotype on chromosomes 2 and 12. We also obtained evidence of heterogeneity on chromosome 13. The regions on chromosomes 12 and 13 identified here have previously been implicated as regions of interest for multiple psychiatric disorders, including BP.

A family-based association study of the glutamate transporter gene SLC1A1 in obsessive-compulsive disorder in 378 families

SLC1A encodes the neuronal and epithelial glutamate transporter and was previously tested as a candidate for obsessive-compulsive disorder (OCD) by several research groups. Recently, three independent research groups reported significant association findings between OCD and several genetic variants in SLC1A1. This study reports the results from a family-based association study, which examined the association between 13 single nucleotide polymorphisms (SNPs) within or in proximity to the SLC1A1 gene. Although we did not replicate association findings for those significant SNPs reported by previous studies, our study indicated a strong association signal with the SNP RS301443 (P-value = 0.000067; Bonferroni corrected P-value = 0.0167) under a dominant model, with an estimated odds ratio of 3.5 (confidence interval: 2.66-4.50). Further, we conducted single SNP analysis after stratifying the full data set by the gender status of affected in each family. The P-value for RS301443 in families with the male affected was 0.00027, and the P-value in families with female affected was 0.076. The fact that we identified a signal which was not previously reported by the other research groups may be due to differences in study designs and sample ascertainment. However, it is also possible that this significant SNP may be part of a regulator for SLC1A1, given that it is roughly 7.5 kb away from the boundary of the SLC1A1 gene. However, this potential finding needs to be validated biologically. Further functional studies in this region are planned by this research group.

Obsessive-compulsive disorder: subclassification based on co-morbidity

BACKGROUND

Obsessive-compulsive disorder (OCD) is probably an etiologically heterogeneous condition. Many patients manifest other psychiatric syndromes. This study investigated the relationship between OCD and co-morbid conditions to identify subtypes.

METHOD

Seven hundred and six individuals with OCD were assessed in the OCD Collaborative Genetics Study (OCGS). Multi-level latent class analysis was conducted based on the presence of eight co-morbid psychiatric conditions [generalized anxiety disorder (GAD), major depression, panic disorder (PD), separation anxiety disorder (SAD), tics, mania, somatization disorders (Som) and grooming disorders (GrD)]. The relationship of the derived classes to specific clinical characteristics was investigated.

RESULTS

Two and three classes of OCD syndromes emerge from the analyses. The two-class solution describes lesser and greater co-morbidity classes and the more descriptive three-class solution is characterized by: (1) an OCD simplex class, in which major depressive disorder (MDD) is the most frequent additional disorder; (2) an OCD co-morbid tic-related class, in which tics are prominent and affective syndromes are considerably rarer; and (3) an OCD co-morbid affective-related class in which PD and affective syndromes are highly represented. The OCD co-morbid tic-related class is predominantly male and characterized by high conscientiousness. The OCD co-morbid affective-related class is predominantly female, has a young age at onset, obsessive-compulsive personality disorder (OCPD) features, high scores on the 'taboo' factor of OCD symptoms, and low conscientiousness.

CONCLUSIONS

OCD can be classified into three classes based on co-morbidity. Membership within a class is differentially associated with other clinical characteristics. These classes, if replicated, should have important implications for research and clinical endeavors.

Sapap3 and pathological grooming in humans: Results from the OCD collaborative genetics study

SAP90/PSD95-associated protein (SAPAP) family proteins are post-synaptic density (PSD) components that interact with other proteins to form a key scaffolding complex at excitatory (glutamatergic) synapses. A recent study found that mice with a deletion of the Sapap3 gene groomed themselves excessively, exhibited increased anxiety-like behaviors, and had cortico-striatal synaptic defects, all of which were preventable with lentiviral-mediated expression of Sapap3 in the striatum; the behavioral abnormalities were also reversible with fluoxetine. In the current study, we sought to determine whether variation within the human Sapap3 gene was associated with grooming disorders (GDs: pathologic nail biting, pathologic skin picking, and/or trichotillomania) and/or obsessive-compulsive disorder (OCD) in 383 families thoroughly phenotyped for OCD genetic studies. We conducted family-based association analyses using the FBAT and GenAssoc statistical packages. Thirty-two percent of the 1,618 participants met criteria for a GD, and 65% met criteria for OCD. Four of six SNPs were nominally associated (P < 0.05) with at least one GD (genotypic relative risks: 1.6-3.3), and all three haplotypes were nominally associated with at least one GD (permuted P < 0.05). None of the SNPs or haplotypes were significantly associated with OCD itself. We conclude that Sapap3 is a promising functional candidate gene for human GDs, though further work is necessary to confirm this preliminary evidence of association.

Gender differences in genetic linkage and association on 11p15 in obsessive-compulsive disorder families

Several clinical and genetic studies have reported gender differences in obsessive-compulsive disorder (OCD). Previously, we conducted a linkage genome scan using multipoint allele-sharing methods to test for linkage in 219 families participating in the OCD Collaborative Genetics Study. When these families were stratified by proband's gender, suggestive linkage to chromosome 11p15 at marker D11S2362 (KAC(all) = 2.92, P = 0.00012) was detected in families with male probands, but not in the ones with female probands. We have since conducted fine mapping with a denser microsatellite marker panel in the region of 11p15, and detected a significant linkage signal at D11S4146 (KAC(all) = 5.08, P < 0.00001) in the families of male probands. Subsequently, 632 SNPs were genotyped spanning a 4.0 Mb region of the 1 LOD unit interval surrounding the linkage peak in the original families and an additional 165 families. Six SNPs were associated with OCD (P < 0.001): two SNPs were identified when all the families were included, and four SNPs only in male proband families. No SNP showed significant association with the OCD phenotype only in the families with a female proband. The results suggest a possible gender effect in the etiology of OCD.

Association and linkage analysis of candidate genes GRP, GRPR, CRHR1, and TACR1 in panic disorder

Panic disorder (PD) is a debilitating anxiety disorder, characterized by recurrent episodes of intense fear that are accompanied by autonomic and psychological symptoms leading to behavioral impairment. Basic research implicates neuropeptide-signaling genes in the modulation of anxiety and stress. The genes encoding corticotropin releasing hormone receptor 1 (CRHR1), tachykinin receptor 1 (TACR1), gastrin releasing peptide (GRP), and gastrin releasing peptide receptor (GRPR) were selected as candidates for PD based on their biology. Linkage and association analysis in 120 multiplex U.S. PD pedigrees was performed using 21 single nucleotide polymorphisms (SNPs). Parametric and non-parametric linkage tests in pedigrees, for single point and multipoint analysis, revealed limited support for genetic linkage to TACR1 (parametric and non-parametric lod scores approximately 1). The family-based association test (FBAT) generated nominal support for allelic association in TACR1 (P = 0.02), and GRP (P = 0.02), findings which must be considered in the light of multiple comparisons. Further exploration of the GRP and TACR1 findings in large case-control PD samples may provide more definitive evidence implicating these loci in the genetic etiology of PD.

Evidence for potential relationship between SLC1A1 and a putative genetic linkage region on chromosome 14q to obsessive-compulsive disorder with compulsive hoarding

Obsessive-compulsive disorder (OCD) is likely a disorder involving complex genetic transmission. This suggests that multiple genetic and environmental factors are involved in its etiology. This is complicated further by the probability of genetic heterogeneity for this phenotype. In this report, we describe a preliminary approach to deal with both complexities. SLC1A1, a glutamate transporter gene on chromosome 9p, was originally proposed to be related to OCD based on two linkage studies, and subsequently association of OCD to the gene has been replicated. Additionally, genetic linkage to a subtype of OCD, compulsive hoarding, has been reported on chromosome 14q. We hypothesized that both genomic regions contribute to OCD in some instances. Using the analytic program GENEFINDER we found that conditioning linkage on chromosome 14q to a marker adjacent to SLC1A1, reduced the size of the linkage region on chromosome 14q and provided evidence for interaction between the regions on chromosomes 9p and 14q.

A randomized trial of interpersonal therapy versus supportive therapy for social anxiety disorder

Seventy patients seeking treatment for social anxiety disorder (SAD) were randomly assigned to 14 weekly individual sessions of interpersonal therapy (IPT) or supportive therapy (ST). We hypothesized that IPT, a psychotherapy with established efficacy for depression and other psychiatric disorders, would lead to greater improvement than ST. Patients in both groups experienced significant improvement from pretreatment to posttreatment. However, improvement with IPT was not superior to improvement with ST. Mean scores on the Liebowitz Social Anxiety Scale decreased from 67.7 to 46.9 in the IPT group and 64.5 to 49.8 in the ST group. There were also no differences in proportion of responders between IPT and ST. Only for a scale measuring concern about negative evaluation (Brief Fear of Negative Evaluation Scale) was IPT superior. Limitations of this initial controlled trial of IPT include a nonsequential recruitment strategy and overlap in the administration of the two therapies. It is recommended that future studies of IPT for SAD include a more carefully defined control therapy condition, different therapists administering each therapy, a larger sample, and a more rigorous strategy for long-term follow-up assessments.

Further development of YBOCS dimensions in the OCD Collaborative Genetics study: symptoms vs. categories

Despite progress in identifying homogeneous subphenotypes of obsessive-compulsive disorder (OCD) through factor analysis of the Yale Brown Obsessive-Compulsive Scale Symptom Checklist (YBOCS-SC), prior solutions have been limited by a reliance on presupposed symptom categories rather than discrete symptoms. Furthermore, there have been few attempts to evaluate the familiality of OCD symptom dimensions. The purpose of this study was to extend prior work by this collaborative group in category-based dimensions by conducting the first-ever exploratory dichotomous factor analysis using individual OCD symptoms, comparing these results to a refined category-level solution, and testing the familiality of derived factors. Participants were 485 adults in the six-site OCD Collaborative Genetics Study, diagnosed with lifetime OCD using semi-structured interviews. YBOCS-SC data were factor analyzed at both the individual item and symptom category levels. Factor score intraclass correlations were calculated using a subsample of 145 independent affected sib pairs. The item- and category-level factor analyses yielded nearly identical 5-factor solutions. While significant sib-sib associations were found for four of the five factors, Hoarding and Taboo Thoughts were the most robustly familial (r ICC>or=0.2). This report presents considerable converging evidence for a five-factor structural model of OCD symptoms, including separate factor analyses employing individual symptoms and symptom categories, as well as sibling concordance. The results support investigation of this multidimensional model in OCD genetic linkage studies.

Sex-specific clinical correlates of hoarding in obsessive-compulsive disorder

Little is known about whether the clinical correlates of hoarding behavior are different in men and women with obsessive-compulsive disorder (OCD). In the current study, we evaluated the association of hoarding with categories of obsessions and compulsions, psychiatric disorders, personality dimensions, and other clinical characteristics separately in 151 men and 358 women with OCD who were examined during the OCD Collaborative Genetics Study. We found that, among men but not women, hoarding was associated with aggressive, sexual, and religious obsessions and checking compulsions. In men, hoarding was associated with generalized anxiety disorder and tics whereas, among women, hoarding was associated with social phobia, post-traumatic stress disorder, body dysmorphic disorder, nail biting, and skin picking. In women but not men, hoarding was associated with schizotypal and dependent personality disorder dimensions, and with low conscientiousness. These findings indicate that specific clinical correlates of hoarding in OCD are different in men and women and may reflect sex-specific differences in the course, expression, and/or etiology of hoarding behavior in OCD.

Demographic and clinical characteristics associated with treatment status in family members with obsessive-compulsive disorder

This study investigated the demographic and clinical factors that influence treatment status in family members with obsessive compulsive disorder (OCD). Six hundred and two subjects from the OCD Collaborative Genetics Study were interviewed using the Structured Clinical Interview for DSM-IV (SCID) to diagnose Axis I disorders, and the Yale-Brown Obsessive Compulsive Scale (Y-BOCS) for assessment of OCD symptoms. The demographic and clinical data were compared between subjects who had received treatment and those who had not. A precipitous onset of symptoms, severe illness, multiple obsessions and compulsions, and co-morbid affective disorders were all positively associated with receiving treatment. Older age and the presence of obsessive compulsive personality disorder (OCPD) or OCPD traits were negatively associated with treatment. Gender and age at onset of symptoms did not predict treatment history. The mean duration from onset of symptoms to receiving treatment was 13.8+/-SD 11.9 years, but there was a direct relationship between current age and time to treatment, with younger subjects receiving treatment sooner. Clinical factors are predominant in predicting treatment status in family members with OCD. Although the mean duration from onset of symptoms to treatment was long, younger family members appear to receive treatment sooner.

Panic disorder, social anxiety disorder, and a possible medical syndrome previously linked to chromosome 13

BACKGROUND

Several studies have identified increased medical problems among individuals with panic disorder (PD). We previously found that specific conditions--interstitial cystitis (IC), mitral valve prolapse (MVP), migraines, and thyroid disorders--aggregated non-randomly among panic families (we called this the "PD syndrome") and that families with and without the syndrome were genetically distinguishable on chromosome 13. We present data from a new case-control study that replicates and extends the syndrome phenotype clinically.

METHODS

Probands with a definite diagnosis and family history of PD (n=219), social anxiety disorder (SAD; n=199), or both (n=173) and 102 control subjects with no personal/family history of anxiety were interviewed with the SADS-LA diagnostic instrument. Medical history was obtained via medical checklist and the family history screen; IC symptoms were assessed with criteria developed by the National Institute for Diabetes and Digestive and Kidney Diseases. Subjects and interviewers were unaware of the syndrome hypothesis; final best-estimate diagnoses were blind to syndrome data.

RESULTS

Probands with PD or SAD, as compared with control subjects, were five or more times as likely to report IC symptoms and twice as likely to report MVP and migraines (other genitourinary and cardiovascular problems were not elevated). First-degree relatives of probands with PD or SAD were also at increased risk for IC, MVP, thyroid problems, and headaches, regardless of whether the proband reported the same condition.

CONCLUSIONS

These findings are consistent with previous data supporting a PD syndrome and further suggest that this syndrome might include other anxiety disorders well.

A comparison between screened NIMH and clinically interviewed control samples on neuroticism and extraversion

The National Institute of Mental Health (NIMH) has supported the collection of DNA samples on over 4000 subjects for use primarily as controls in psychiatric genetic studies. These subjects, though screened online, were not directly interviewed or assessed on family history. We compared this sample to one that was directly interviewed using structured diagnostic assessments on comparable measures of neuroticism and extraversion. The screened sample completed an online self-report based on the Composite International Diagnostic Instrument Short-Form (CIDI-SF). The interviewed sample was assessed by clinically trained personnel using the Schedule for Affective Disorders and Schizophrenia (SADS-LA-IV) and Family History Screen; final diagnoses were made blind to trait scores by a clinician using the best-estimate procedure. Neuroticism and extraversion were assessed on the NEO five-factor inventory (NEO-FFI) and the revised Eysenck Personality Questionnaire short form (EPQ-R). We found that subjects in the NIMH-screened sample who did not report any psychiatric symptoms on the self-report were indistinguishable from interviewed diagnosis free and family history negative controls on neuroticism and extraversion. Subjects in the screened sample who screened positive for anxiety disorders, however, deviated significantly on these measures both from the screened subjects with no self-reported symptoms, as well as from subjects in the interviewed sample diagnosed with comparable disorders. These findings suggest that control groups generated from the NIMH sample should ideally be restricted to subjects free of any self-reported symptoms, regardless of the disorder being addressed, in order to maximize their reflection of diagnosis-free populations.

Hoarding in obsessive–compulsive disorder: Results from the OCD Collaborative Genetics Study

Hoarding behavior occurs frequently in obsessive-compulsive disorder (OCD). Results from previous studies suggest that individuals with OCD who have hoarding symptoms are clinically different than non-hoarders and may represent a distinct clinical group. In the present study, we compared 235 hoarding to 389 non-hoarding participants, all of whom had OCD, collected in the course of the OCD Collaborative Genetics Study. We found that, compared to non-hoarding individuals, hoarders were more likely to have symmetry obsessions and repeating, counting, and ordering compulsions; poorer insight; more severe illness; difficulty initiating or completing tasks; and indecision. Hoarders had a greater prevalence of social phobia and generalized anxiety disorder. Hoarders also had a greater prevalence of obsessive-compulsive and dependent personality disorders. Five personality traits were independently associated with hoarding: miserliness, preoccupation with details, difficulty making decisions, odd behavior or appearance, and magical thinking. Hoarding and indecision were more prevalent in the relatives of hoarding than of non-hoarding probands. Hoarding in relatives was associated with indecision in probands, independently of proband hoarding status. The findings suggest that hoarding behavior may help differentiate a distinct clinical subgroup of people with OCD and may aggregate in some OCD families. Indecision may be a risk factor for hoarding in these families.

Significant linkage to compulsive hoarding on chromosome 14 in families with obsessive-compulsive disorder: results from the OCD Collaborative Genetics Study

OBJECTIVE

Individuals with obsessive-compulsive disorder (OCD) who have compulsive hoarding behavior are clinically different from other OCD-affected individuals. The objective of this study was to determine whether there are chromosomal regions specifically linked to compulsive hoarding behavior in families with obsessive-compulsive disorder.

METHODS

The authors used multipoint allele-sharing methods to assess for linkage in 219 multiplex OCD families collected as part of the OCD Collaborative Genetics Study. The authors treated compulsive hoarding as the phenotype of interest and also stratified families into those with and without two or more relatives affected with compulsive hoarding.

RESULTS

Using compulsive hoarding as the phenotype, there was suggestive linkage to chromosome 14 at marker D14S588 (Kong and Cox logarithm of the odds ratio [LOD] [KAC(all)=2.9]). In families with two or more hoarding relatives, there was significant linkage of OCD to chromosome 14 at marker C14S1937 (KAC(all)=3.7), whereas in families with fewer than two hoarding relatives, there was suggestive linkage to chromosome 3 at marker D3S2398 (KAC(all)=2.9).

CONCLUSIONS

The findings suggest that a region on chromosome 14 is linked with compulsive hoarding behavior in families with OCD.