Riluzole augmentation in treatment-refractory obsessive-compulsive disorder: a series of 13 cases, with long-term follow-up

Acute administration of the NMDA receptor antagonists ketamine and MK-801 reveals dysregulation of glutamatergic signalling and sensorimotor gating in the Sapap3 knockout mouse model of compulsive-like behaviour

Obsessive-compulsive disorder (OCD) is characterised by excessive intrusive thoughts that may cause an individual to engage in compulsive behaviours. Frontline pharmacological treatments (i.e., selective serotonin reuptake inhibitors (SSRIs)) leave approximately 40% of patients refractory to treatment. To investigate the possibility of novel pharmacological therapies for OCD, as well as the potential mechanisms underlying its pathology, we used the Sapap3 knockout (KO) mouse model of OCD, which exhibits increased anxiety and compulsive grooming behaviours. Firstly, we investigated whether administration of the NMDA receptor (NMDAR) antagonist ketamine (30 mg/kg), would reduce anxiety and grooming behaviour in Sapap3 KO mice. Anxiety-like behaviour was measured via time spent in the light component of the light-dark box test. Grooming behaviour was recorded and scored in freely moving mice. In line with previous works conducted in older animals (i.e. typically between 6 and 9 months of age), we confirmed here that Sapap3 KO mice exhibit an anxious, compulsive grooming, hypolocomotive and reduced body weight phenotype even at a younger age (i.e., 2-3 months of age). However, we found that acute administration of ketamine did not cause a reduction in anxiety or grooming behaviour. We then investigated in vivo glutamatergic function via the administration of a different NMDAR antagonist, MK-801 (0.25 mg/kg), prior to locomotion and prepulse inhibition assays. We found evidence of altered functional NMDAR activity, as well as sexually dimorphic prepulse inhibition, a measure of sensorimotor gating, in Sapap3 KO mice. These results are suggestive of in vivo glutamatergic dysfunction and their functional consequences, enabling future research to further investigate novel treatments for OCD.

Spinal cord and brain concentrations of riluzole after oral and intrathecal administration: A potential new treatment route for amyotrophic lateral sclerosis

Riluzole is the only treatment known to improve survival in patients with Amyotrophic Lateral Sclerosis (ALS). However, oral riluzole efficacy is modest at best, further it is known to have large inter-individual variability of serum concentration and clearance, is formulated as an oral drug in a patient population plagued with dysphagia, and has known systemic side-effects like asthenia (limiting patient compliance) and elevated liver enzymes. In this context, we postulated that continuous intrathecal (IT) infusion of low doses of riluzole could provide consistent elevations of the drug spinal cord (SC) concentrations at or above those achieved with oral dosing, without increasing the risk for adverse events associated with systemic drug exposure or off-target side effects in the brain. We developed a formulation of riluzole for IT delivery and conducted our studies in purpose-bred hound dogs. Our non-GLP studies revealed that IT infusion alone was able to increase SC concentrations above those provided by oral administration, without increasing plasma concentrations. We then conducted two GLP studies that combined IT infusion with oral administration at human equivalent dose, to evaluate SC and brain concentrations of riluzole along with assessments of safety and tolerability. In the 6-week study, the highest IT dose (0.2 mg/hr) was well tolerated by the animals and increased SC concentrations above those achieved with oral riluzole alone, without increasing brain concentrations. In the 6-month study, the highest dose tested (0.4 mg/hr) was not tolerated and yielded SC significantly above those achieved in all previous studies. Our data show the feasibility and safety profile of continuous IT riluzole delivery to the spinal cord, without concurrent elevated liver enzymes, and minimal brain concentrations creating another potential therapeutic route of delivery to be used in isolation or in combination with other therapeutics."

The Pharmacological Treatment of Obsessive-Compulsive Disorder

Pharmacological treatment is a mainstay of the care of individuals with obsessive-compulsive disorder. Robust evidence supports the use of the selective serotonin reuptake inhibitors and the older tricyclic drug clomipramine. Other antidepressants are less effective (or have been insufficiently studied). When first-line treatment with these agents, and with appropriate psychotherapy, is ineffective, several augmentation strategies are available, though their evidentiary support is weaker. A substantial minority of patients have persistent symptoms despite optimal evidence-based treatment. Further work and more treatment options are needed.

Treatment-resistant OCD: Pharmacotherapies in adults

Serotonin reuptake inhibitor (SRI) medications are well established as first-line pharmacotherapeutic treatment for Obsessive-Compulsive Disorder (OCD). However, despite the excellent safety profile and demonstrated efficacy of these medications, a substantial proportion of individuals with OCD fail to attain sufficient benefit from SRIs. In this narrative review, we discuss clinical features of OCD that have been associated with poorer response to SRIs, and we present pharmacotherapeutic interventions that have been explored as augmenting or alternative treatments for treatment-resistant OCD. We additionally highlight non-SRI interventions for OCD that are currently under investigation. Pharmacotherapeutic interventions were identified via expert consensus. To assess the evidence base for individual pharmacotherapies, targeted searches for relevant English-language publications were performed on standard biomedical research databases, including MEDLINE. Information relevant to ongoing registered clinical trials in OCD was obtained by search of ClinicalTrials.gov. Pharmacotherapies are grouped for review in accordance with the general principles of Neuroscience-based Nomenclature (NbN). Clinical features of OCD that may suggest poorer response to SRI treatment include early age of onset, severity of illness, duration of untreated illness, and the presence of symmetry/ordering or hoarding-related symptoms. Based on evolving pathophysiologic models of OCD, diverse agents engaging serotonin, dopamine, norepinephrine, glutamate, and anti-inflammatory pathways have been explored as alternative or adjunctive therapies for treatment-resistant OCD and have at least preliminary evidence of efficacy. Medications with dopamine antagonist activity remain the most robustly evidence-based of augmenting interventions, yet dopamine antagonists benefit only a minority of those who try them and carry elevated risks of adverse effects. Interventions targeting glutamatergic and anti-inflammatory pathways are less well evidenced, but may offer more favorable benefit to risk profiles. Ongoing research should explore whether specific interventions may benefit individuals with particular features of treatment-resistant OCD.

The stressed synapse 2.0: pathophysiological mechanisms in stress-related neuropsychiatric disorders

Stress is a primary risk factor for several neuropsychiatric disorders. Evidence from preclinical models and clinical studies of depression have revealed an array of structural and functional maladaptive changes, whereby adverse environmental factors shape the brain. These changes, observed from the molecular and transcriptional levels through to large-scale brain networks, to the behaviours reveal a complex matrix of interrelated pathophysiological processes that differ between sexes, providing insight into the potential underpinnings of the sex bias of neuropsychiatric disorders. Although many preclinical studies use chronic stress protocols, long-term changes are also induced by acute exposure to traumatic stress, opening a path to identify determinants of resilient versus susceptible responses to both acute and chronic stress. Epigenetic regulation of gene expression has emerged as a key player underlying the persistent impact of stress on the brain. Indeed, histone modification, DNA methylation and microRNAs are closely involved in many aspects of the stress response and reveal the glutamate system as a key player. The success of ketamine has stimulated a whole line of research and development on drugs directly or indirectly targeting glutamate function. However, the challenge of translating the emerging understanding of stress pathophysiology into effective clinical treatments remains a major challenge.

Memantine and Riluzole Exacerbate, Rather Than Ameliorate Behavioral Deficits Induced by 8-OH-DPAT Sensitization in a Spatial Task

Chronic sensitization to serotonin 1A and 7 receptors agonist 8-OH-DPAT induces compulsive checking and perseverative behavior. As such, it has been used to model obsessive-compulsive disorder (OCD)-like behavior in mice and rats. In this study, we tested spatial learning in the 8-OH-DPAT model of OCD and the effect of co-administration of memantine and riluzole—glutamate-modulating agents that have been shown to be effective in several clinical trials. Rats were tested in the active place avoidance task in the Carousel maze, where they learned to avoid the visually imperceptible shock sector. All rats were subcutaneously injected with 8-OH-DPAT (0.25 mg/kg) or saline (control group) during habituation. During acquisition, they were pretreated with riluzole (1 mg/kg), memantine (1 mg/kg), or saline solution 30 min before each session and injected with 8-OH-DPAT (“OH” groups) or saline (“saline” groups) right before the experiment. We found that repeated application of 8-OH-DPAT during both habituation and acquisition significantly increased locomotion, but it impaired the ability to avoid the shock sector. However, the application of 8-OH-DPAT in habituation had no impact on the learning process if discontinued in acquisition. Similarly, memantine and riluzole did not affect the measured parameters in the “saline” groups, but in the “OH” groups, they significantly increased locomotion. In addition, riluzole increased the number of entrances and decreased the maximum time avoided of the shock sector. We conclude that monotherapy with glutamate-modulating agents does not reduce but exacerbates cognitive symptoms in the animal model of OCD.

Specialty knowledge and competency standards for pharmacotherapy for adult obsessive-compulsive disorder

Obsessive-compulsive disorder (OCD) affects approximately one person in 40 and causes substantial suffering. Evidence-based treatments can benefit many; however, optimal treatment can be difficult to access. Diagnosis is frequently delayed, and pharmacological and psychotherapeutic interventions often fail to follow evidence-based guidelines. To ameliorate this distressing situation, the International OCD Accreditation Task Force of the Canadian Institute for Obsessive-Compulsive Disorders has developed knowledge and competency standards for specialized treatments for OCD through the lifespan. These are foundational to evidence-based practice and will form the basis for upcoming ATF development of certification/accreditation programs. Here, we present specialty standards for the pharmacological treatment of adult OCD. We emphasize the importance of integrating pharmacotherapy with clear diagnosis, appreciation of complicating factors, and evidence-based cognitive behavioral therapy. Clear evidence exists to inform first- and second-line pharmacological treatments. In disease refractory to these initial efforts, multiple strategies have been investigated, but the evidence is more equivocal. These standards summarize this limited evidence to give the specialist practitioner a solid basis on which to make difficult decisions in complex cases. It is hoped that further research will lead to development of a clear, multi-step treatment algorithm to support each step in clinical decision-making.

Pharmacotherapeutic Strategies and New Targets in OCD

Effective pharmacological and psychotherapeutic treatments are well established for obsessive-compulsive disorder (OCD). Serotonin reuptake inhibitors (SRIs) are first-line treatment and are of benefit to about half of patients. Augmentation of SRI treatment with low-dose neuroleptics is an evidence-based second-line strategy. Specialty psychotherapy is also used as both first-line and second-line treatment and can benefit many. However, a substantial number of patients do not respond to these treatments. New alternatives are urgently needed. This review summarizes evidence for these established pharmacotherapeutic strategies, and for others that have been investigated in refractory disease but are not supported by the same level of evidence. We focus on three neurotransmitter systems in the brain: serotonin, dopamine, and glutamate. We summarize evidence from genetic, neuroimaging, animal model, and other lines of investigation that probe these three systems in patients with OCD. We also review recent work on predictors of response to current treatments. While many studies suggest abnormalities that may provide insight into the pathophysiology of the disorder, most studies have been small, and non-replication of reported findings has been common. Nevertheless, the gradual accrual of evidence for neurotransmitter dysregulation may in time lead the way to new pharmacological strategies.

Randomized Controlled Trial of Riluzole Augmentation for Posttraumatic Stress Disorder: Efficacy of a Glutamatergic Modulator for Antidepressant-Resistant Symptoms

OBJECTIVE

Current pharmacologic treatments for posttraumatic stress disorder (PTSD) have shown limited efficacy, prompting a call to investigate new classes of medications. The current study investigated the efficacy of glutamate modulation with riluzole augmentation for combat-related PTSD symptoms resistant to treatment with selective serotonin reuptake inhibitors (SSRIs) or serotonin-norepinephrine reuptake inhibitors (SNRIs).

METHODS

A randomized, double-blind, placebo-controlled, parallel trial was conducted at Walter Reed National Military Medical Center and Syracuse VA Medical Center between December 2013 and November 2017. Veterans and active duty service members with combat-related PTSD (per the Clinician Administered PTSD Scale [CAPS]) who were not responsive to SSRI or SNRI pharmacotherapy were randomized to 8-week augmentation with a starting dose of 100 mg/d of riluzole (n = 36) or placebo (n = 38) and assessed weekly for PTSD symptoms, anxiety, depression, disability, and side effects.

RESULTS

Intent-to-treat analyses (N = 74) of the primary outcome (CAPS for DSM-IV) showed no significant between-group difference in change in overall PTSD symptoms (F = 0.64, P = .422), with a small effect size (d = 0.25). There was clinically significant within-group improvement in overall PTSD symptoms in both groups, with a greater mean (SD) decrease in CAPS score in the riluzole group (-21.1 [18.9]) than in the placebo group (-16.7 [17.2]). Exploratory analyses of PTSD symptom clusters showed significantly greater improvement on hyperarousal symptoms in the riluzole group as measured by the PTSD Checklist-Specific-Subscale D (d = 0.48) and near-significant findings on the CAPS Subscale D. Riluzole augmentation was not superior to placebo on change in depression, anxiety, or disability severity.

CONCLUSIONS

Although preliminary, the exploratory findings of this study offer some evidence that riluzole augmentation of an SSRI or SNRI may selectively improve PTSD hyperarousal symptoms without changes in overall PTSD symptoms, depression, anxiety, or disability. Additional investigation of the mechanism of the efficacy of riluzole for hyperarousal symptoms is warranted.

TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT02155829.

A single nucleotide polymorphism in SLC1A1 gene is associated with age of onset of obsessive-compulsive disorder

Different genetic polymorphisms in the SLC1A1 have been shown to be associated with obsessive-compulsive disorder. Rs301430 is a T/C functional polymorphism affecting the gene expression and extrasynaptic glutamate concentration.We observed that Rs301430 influence age at onset in obsessive-compulsive disorder.

The Glutamate and the Immune Systems: New Targets for the Pharmacological Treatment of OCD

BACKGROUND

In the last decades the pharmacological treatment of obsessivecompulsive disorder (OCD) has been significantly promoted by the effectiveness of selective serotonin (5-HT) reuptake inhibitors (SSRIs) and the subsequent development of the 5-HT hypothesis of OCD. However, since a large majority of patients (between 40% and 60 %) do not respond to SSRIs or strategies based on the modulation of the 5-HT system, it is now essential to search for other possible therapeutic targets.

AIMS

The aim of this paper was to review current literature through a PubMed and Google Scholar search of novel hypotheses and related compounds for the treatment of OCD, with a special focus on the glutammate and the immune systems.

DISCUSSION

The literature indicates that glutamate, the main excitatory neurotransmitter, might play an important role in the pathophysiology of OCD. In addition, a series of clinical studies also supports the potential efficacy of drugs modulating the glutamate system. The role of the immune system alterations in OCD in both children and adults needs to be more deeply elucidated. In children, a subtype of OCD has been widely described resulting from infections driven by group A streptococcus β-hemolitic and belonging to the so-called "pediatric autoimmune neuropsychiatric disorders associated with streptococcus" (PANDAS). In adults, available findings are meager and controversial, although interesting.

CONCLUSION

The glutamate and the immune systems represent two intriguing topics of research that hold promise for the development of open novel treatment strategies in OCD.

Effects of persistent sodium current blockade in respiratory circuits depend on the pharmacological mechanism of action and network dynamics

The mechanism(s) of action of most commonly used pharmacological blockers of voltage-gated ion channels are well understood; however, this knowledge is rarely considered when interpreting experimental data. Effects of blockade are often assumed to be equivalent, regardless of the mechanism of the blocker involved. Using computer simulations, we demonstrate that this assumption may not always be correct. We simulate the blockade of a persistent sodium current (I_NaP), proposed to underlie rhythm generation in pre-Bötzinger complex (pre-BötC) respiratory neurons, via two distinct pharmacological mechanisms: (1) pore obstruction mediated by tetrodotoxin and (2) altered inactivation dynamics mediated by riluzole. The reported effects of experimental application of tetrodotoxin and riluzole in respiratory circuits are diverse and seemingly contradictory and have led to considerable debate within the field as to the specific role of I_NaP in respiratory circuits. The results of our simulations match a wide array of experimental data spanning from the level of isolated pre-BötC neurons to the level of the intact respiratory network and also generate a series of experimentally testable predictions. Specifically, in this study we: (1) provide a mechanistic explanation for seemingly contradictory experimental results from in vitro studies of I_NaP block, (2) show that the effects of I_NaP block in in vitro preparations are not necessarily equivalent to those in more intact preparations, (3) demonstrate and explain why riluzole application may fail to effectively block I_NaP in the intact respiratory network, and (4) derive the prediction that effective block of I_NaP by low concentration tetrodotoxin will stop respiratory rhythm generation in the intact respiratory network. These simulations support a critical role for I_NaP in respiratory rhythmogenesis in vivo and illustrate the importance of considering mechanism when interpreting and simulating data relating to pharmacological blockade.

The application of pharmacological agents that affect transmembrane ionic currents in neurons is a commonly used experimental technique. A simplistic interpretation of experiments involving these agents suggests that antagonist application removes the impacted current and that subsequently observed changes in activity are attributable to the loss of that current’s effects. The more complex reality, however, is that different drugs may have distinct mechanisms of action, some corresponding not to a removal of a current but rather to a changing of its properties. We use computational modeling to explore the implications of the distinct mechanisms associated with two drugs, riluzole and tetrodotoxin, that are often characterized as sodium channel blockers. Through this approach, we offer potential explanations for disparate findings observed in experiments on neural respiratory circuits and show that the experimental results are consistent with a key role for the persistent sodium current in respiratory rhythm generation.

No effect of riluzole and memantine on learning deficit following quinpirole sensitization - An animal model of obsessive-compulsive disorder

RATIONALE

Chronic quinpirole (QNP) sensitization is an established animal model relevant to obsessive-compulsive disorder (OCD) that has been previously shown to induce several OCD-like behavioral patterns, such as compulsive-like checking and increased locomotion.

OBJECTIVES

In current study we explored the effect of antiglutamatergic drugs, memantine and riluzole, on cognitive and behavioral performance of QNP sensitized rats.

METHODS

During habituation phase, the rats (N = 56) were injected with QNP (0.25 mg/kg) or saline solution (every other day up to 10 injections) and placed into rotating arena without foot shocks for 50-min exploration. Active place avoidance task in rotating arena with unmarked to-be-avoided shock sector was used during acquisition phase. Rats were injected with memantine (1 mg/kg or 5 mg/kg), riluzole (1 mg/kg or 5 mg/kg) or saline solution 30 min before the trial and with QNP (0.25 mg/kg) or saline right before they were placed inside the rotating arena with 60° unmarked shock sector. Locomotion and number of entrances into the shock sector were recorded.

RESULTS

QNP sensitization led to a robust deficit in place learning. However, neither memantine nor riluzole did reverse or alleviate the deficit induced by QNP. Contrarily, memantine significantly aggravated QNP induced deficit.

CONCLUSIONS

The exacerbation of cognitive deficit following antiglutamatergic agents could be mediated by decreased glutamate concentration in nucleus accumbens and decreased hippocampal activation in the QNP sensitization model.

Riluzole Serum Concentration in Pediatric Patients Treated for Obsessive-Compulsive Disorder

PURPOSE/BACKGROUND

The goals of this study were to determine whether pediatric serum concentration of riluzole is similar to that observed in adults and to determine whether riluzole serum concentration is associated with adverse effects or efficacy in children and adolescents with treatment-refractory obsessive-compulsive disorder.

METHODS/PROCEDURES

Data were drawn from previously published studies: 1 open-label trial and 1 randomized controlled trial with an open-label extension phase. Serum was drawn at 24, 36, and 52 weeks in 37 patients who were taking approximately 100 mg riluzole daily (mean dose at 24 weeks, 99 ± 28 mg).

FINDINGS/RESULTS

Across all samples, serum riluzole concentration ranged from 7 to 963 ng/mL. At week 24 (n = 37), the median concentration was 76 ng/mL (interquartile range, 53-172 ng/mL). Within-patient concentration was relatively stable. One subject who had the highest serum concentration levels during the study developed pancreatitis after exiting the study. The patient had recently added fluvoxamine to the riluzole regimen. Controlling for concomitant fluvoxamine (in 6 participants) and time of draw, serum riluzole concentration was not associated with obsessive-compulsive disorder symptom severity, nor was it associated with adverse effect profile.

IMPLICATIONS/CONCLUSIONS

The dose of riluzole used in these pediatric subjects seems to have achieved serum concentration levels similar to those observed in adults. However, as previously reported in adults, the serum concentration had no discernable relationship to efficacy or adverse effects.

Glutamate-Modulating Drugs as a Potential Therapeutic Strategy in Obsessive-Compulsive Disorder

OBJECTIVE

Obsessive-compulsive disorder (OCD) is a mental disease commonly associated with severe distress and impairment of social functioning. Serotonin reuptake inhibitors and/or cognitive behavioural therapy are the therapy of choice, however up to 40% of patients do not respond to treatment. Glutamatergic signalling has also been implicated in OCD. The aim of the current study was to review the clinical evidence for therapeutic utility of glutamate-modulating drugs as an augmentation or monotherapy in OCD patients.

METHODS

We conducted a search of the MEDLINE database for clinical studies evaluating the effect of glutamate-modulating drugs in OCD.

RESULTS

Memantine is the compound most consistently showing a positive effect as an augmentation therapy in OCD. Anti-convulsant drugs (lamotrigine, topiramate) and riluzole may also provide therapeutic benefit to some OCD patients. Finally, ketamine may be of interest due to its potential for a rapid onset of action.

CONCLUSION

Further randomized placebo-controlled trials in larger study populations are necessary in order to draw definitive conclusions on the utility of glutamate-modulating drugs in OCD. Furthermore, genetic and epigenetic factors, clinical symptoms and subtypes predicting treatment response to glutamate-modulating drugs need to be investigated systematically.

Management of obsessive-compulsive disorder comorbid with bipolar disorder

Obsessive-compulsive disorder (OCD) is one of the most common comorbidities in bipolar disorder (BD). Clinicians often get perplexed in making treatment decisions when encountering comorbid OCD and BD as treatment of OCD by pharmacotherapy may induce or exacerbate mood instability and psychotherapeutic approaches for OCD may not be feasible in acute manic or depressive state of BD. In this study, we reviewed literature, whether existing guideline-based treatments of BD may be effective in OCD and whether newer agents will be of use for treating this comorbidity. We could find that treatment of such comorbid disorder is largely understudied. Adjuvant topiramate or olanzapine- selective serotonin reuptake inhibitor/clomipramine combination along with mood stabilizer is found to be effective for treating OCD in BD. Use of other conventional pharmacological agents and psychotherapy for treating comorbid OCD in BD lacks evidence and is limited to case reports. Our review also highlights the need for further studies regarding the treatment strategies in this highly prevalent comorbid disorder.

N-acetylcysteine augmentation therapy for moderate-to-severe obsessive-compulsive disorder: randomized, double-blind, placebo-controlled trial

WHAT IS KNOWN AND OBJECTIVE

N-acetylcysteine (NAC) has been proposed as a potential therapy for obsessive-compulsive disorder (OCD) as it may regulate the exchange of glutamate and prevent its pre-oxidant effects. The aim of the present double-blind, placebo-controlled trial was to assess the efficacy and tolerability of NAC augmentation in moderate-to-severe (OCD) treatment.

METHODS

In this randomized, double-blind, two-centre, placebo-controlled, 10-week trial, patients with moderate-to-severe OCD were enrolled. Patients were randomized into two parallel groups to receive fluvoxamine (200 mg daily) plus placebo or fluvoxamine (200 mg daily) plus NAC (2000 mg daily). A total of 44 patients (22 in each group) were visited to evaluate response to therapy using the Yale-Brown Obsessive-Compulsive Scale (Y-BOCS) at baseline, and at weeks 4, 8 and 10. Side effects were recorded using predesigned checklists upon each visit.

RESULTS AND DISCUSSION

Repeated-measures ANOVA showed a significant effect for time × treatment interaction (Greenhouse-Geisser corrected: F = 5·14, d.f. = 1·64, P = 0·012) in the Y-BOCS total score and a significant effect for time × treatment interaction (Greenhouse-Geisser corrected: F = 5·44, d.f. = 1·54, P = 0·011) in the Y-BOCS obsession subscale between the two groups.

WHAT IS NEW AND CONCLUSION

Our results showed that NAC might be effective as an augmentative agent in the treatment of moderate-to-severe OCD.

TRIAL REGISTRATION

Iranian Registry of Clinical Trials (www.irct.ir): IRCT201405271556N60.

Glutamatergic agents for OCD and related disorders

Pharmacotherapy remains inadequate for many patients with OCD; there is an urgent need for alternative pharmacological strategies. Convergent evidence suggests imbalance in glutamate, the brain's primary excitatory neurotransmitter, in some patients. This has motivated interest in glutamate modulators in patients who are unresponsive to standard pharmacotherapeutic approaches. While no glutamate modulator can be considered proven as an efficacious treatment of OCD, promising suggestions of benefit have been reported for memantine and riluzole. The evidence is thinner for N-acetylcysteine, but this agent's low cost and benign side effect profile make it a reasonable consideration in certain patients. Intriguing research on D-cycloserine and ketamine suggest potential benefit as well. It is notable that these agents all work by different, and in some cases opposite, mechanisms; this suggests that we have much to learn about the role of glutamate dysregulation in the etiology of OCD, and of glutamate modulators in its treatment.

Riluzole augmentation in treatment-refractory obsessive-compulsive disorder: a pilot randomized placebo-controlled trial

OBJECTIVE

Obsessive-compulsive disorder (OCD) affects approximately 2.5% of the population and is associated with significant morbidity. Many patients receive little benefit from the best available treatments, and even those who do respond often suffer from significant residual symptoms. Convergent evidence suggests that abnormalities in glutamate homeostasis and neurotransmission may contribute to OCD and that glutamate-modulating medications may be of benefit in patients whose symptoms are refractory to standard interventions. Small open-label trials of augmentation of serotonin reuptake inhibitor (SRI) pharmacotherapy with the glutamate modulator riluzole have suggested benefit in adults with refractory symptoms. We report a pilot randomized placebo-controlled trial of riluzole augmentation of ongoing SRI treatment in SRI-refractory patients.

METHOD

Outpatients (n = 27) and inpatients (n = 11) with DSM-IV OCD on stable SRI pharmacotherapy were randomized between November 2006 and December 2012 to receive riluzole 50 mg or placebo twice a day and followed for 12 weeks after a 2-week placebo lead-in phase.

RESULTS

Riluzole was well tolerated; 1 patient experienced moderate nausea, but none discontinued treatment due to side effects. While there was nominally greater Y-BOCS improvement in the riluzole group (our primary outcome) compared to placebo, it did not reach statistical significance. In the outpatient subsample, a trend suggesting benefit from riluzole augmentation for obsessions (P = .056, 2-tailed, uncorrected) was found in a secondary analysis. Among outpatients, more achieved at least a partial response (> 25% improvement) with riluzole than with placebo (P = .02 in a secondary analysis).

CONCLUSIONS

Riluzole may be of benefit to a subset of patients. Larger samples would be required to detect effects of the order suggested by the nominal improvement in our outpatient subsample.

TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT00523718.

Glutamate modulators in the treatment of obsessive-compulsive disorder

Established treatments for obsessive-compulsive disorder (OCD) are of benefit in approximately 3 of every 4 patients, but refractory disease remains distressingly common, and many treatment responders continue to experience considerable morbidity. This motivates a search for new insights into pathophysiology that may inform novel treatment strategies. Much recent work has focused on the neurotransmitter glutamate. Several lines of neurochemical and genetic evidence suggests that glutamate dysregulation may contribute to OCD, although much remains unclear. The off-label use of a number of pharmacological agents approved for other indications has been investigated in refractory OCD. We summarize investigations of memantine, riluzole, ketamine, D-cycloserine, glycine, N-acetylserine, topiramate, and lamotrigine. Evidence exists for benefit from each of these in some patients; though none has been proven effective with sufficient clarity to be considered part of standard care, these agents are options in individuals whose symptoms are refractory to better-established therapeutic strategies.

Clinical effectiveness of interventions for treatment-resistant anxiety in older people: a systematic review

BACKGROUND

Anxiety and related disorders include generalised anxiety disorder, obsessive-compulsive disorder, panic disorder, post-traumatic stress disorder and phobic disorders (intense fear of an object or situation). These disorders share the psychological and physical symptoms of anxiety, but each disorder has its own set of characteristic symptoms. Anxiety disorders can be difficult to recognise, particularly in older people (those aged over 65 years). Older people tend to be more reluctant to discuss mental health issues and there is the perception that older people are generally more worried than younger adults. It is estimated that between 3 and 14 out of every 100 older people have an anxiety disorder. Despite treatment, some people will continue to have symptoms of anxiety. People are generally considered to be 'resistant' or 'refractory' to treatment if they have an inadequate response or do not respond to their first treatment. Older adults with an anxiety disorder find it difficult to manage their day-to-day lives and are at an increased risk of comorbid depression, falls, physical and functional disability, and loneliness.

OBJECTIVE

To evaluate the effectiveness of pharmacological, psychological and alternative therapies in older adults with an anxiety disorder who have not responded, or have responded inadequately, to treatment.

DATA SOURCES

Electronic databases (MEDLINE, MEDLINE In-Process and Other Non-Indexed citations, EMBASE, The Cochrane Library databases, PsycINFO and Web of Science) were searched from inception to September 2013. Bibliographies of relevant systematic reviews were hand-searched to identify additional potentially relevant studies. ClinicalTrials.gov was searched for ongoing and planned studies.

REVIEW METHODS

A systematic review of the clinical effectiveness of treatments for treatment-resistant anxiety in older adults was carried out.

RESULTS

No randomised controlled trial or prospective comparative observational study was identified meeting the prespecified inclusion criteria. Therefore, it was not possible to draw any conclusions on clinical effectiveness.

LIMITATIONS

As no study was identified in older adults, there is uncertainty as to which treatments are clinically effective for older adults with an anxiety disorder who have not responded to prior treatment. The comprehensive methods implemented to carry out this review are a key strength of the research presented. However, this review highlights the extreme lack of research in this area, identifying no comparative studies, which is a marked limitation.

CONCLUSIONS

Specific studies evaluating interventions in older adults with an anxiety disorder who have not responded to first-line treatment are needed to address the lack of evidence. The lack of evidence in this area means that older adults are perhaps receiving inappropriate treatment or are not receiving a particular treatment because there is limited evidence to support its use. At this time there is scope to develop guidance on service provision and, as a consequence, to advance the standard of care received by older adults with a treatment-resistant anxiety disorder in primary and secondary care. Evaluation of the relative clinical effectiveness and acceptability of pharmacological and psychological treatment in older adults with an anxiety disorder that has not responded to first-line treatment is key future research to inform decision-making of clinicians and patients. An important consideration would be the enrolment of older adults who would be representative of older adults in general, i.e. those with multiple comorbid physical and mental disorders who might require polypharmacy.

STUDY REGISTRATION

The protocol for the systematic review is registered on PROSPERO (registration number CRD42013005612).

FUNDING

The National Institute for Health Research Health Technology Assessment programme.

Assessment and management of treatment-refractory obsessive-compulsive disorder in children

OBJECTIVE

To review the assessment and treatment of treatment-refractory pediatric obsessive-compulsive disorder (OCD).

METHOD

A PubMed search was conducted to identify controlled trials in pediatric OCD. In addition, practice guidelines for the treatment of adults and children were further reviewed for references in treatment-refractory OCD across the lifespan.

RESULTS

Pharmacotherapy with selective serotonin reuptake inhibitors (SSRIs) and cognitive-behavioral therapy (CBT) were found to be effective treatments for pediatric OCD. Evidence suggests that CBT is also effective even in pediatric patients with refractory OCD symptoms. Antipsychotic augmentation, raising SSRI dosage, and several glutamate-modulating agents have some evidence of efficacy in adults with treatment-refractory OCD but have not been studied in pediatric populations.

CONCLUSION

Several pharmacological treatment options exist for children with refractory OCD symptoms. However, little evidence-based data exist to guide treatment for our most challenging pediatric OCD patients. Further research is needed to evaluate the efficacy/side effect profile of commonly used interventions in treatment-refractory pediatric OCD.

Pharmacological treatment of obsessive-compulsive disorder

Obsessive-compulsive disorder (OCD) affects up to 2.5% of the population of the course of a lifetime and produces substantial morbidity. Approximately 70% of patients can experience significant symptomatic relief with appropriate pharmacotherapy. Selective serotonin reuptake inhibitors are the mainstay of pharmacological treatment. These drugs are typically used at higher doses and for longer periods than in depression. Proven second-line treatments include the tricyclic clomipramine and the addition of low-dose neuroleptic medications. OCD refractory to available treatments remains a profound clinical challenge.

Global resting-state functional magnetic resonance imaging analysis identifies frontal cortex, striatal, and cerebellar dysconnectivity in obsessive-compulsive disorder

BACKGROUND

Obsessive-compulsive disorder (OCD) is associated with regional hyperactivity in cortico-striatal circuits. However, the large-scale patterns of abnormal neural connectivity remain uncharacterized. Resting-state functional connectivity studies have shown altered connectivity within the implicated circuitry, but they have used seed-driven approaches wherein a circuit of interest is defined a priori. This limits their ability to identify network abnormalities beyond the prevailing framework. This limitation is particularly problematic within the prefrontal cortex (PFC), which is large and heterogeneous and where a priori specification of seeds is therefore difficult. A hypothesis-neutral, data-driven approach to the analysis of connectivity is vital.

METHODS

We analyzed resting-state functional connectivity data collected at 3T in 27 OCD patients and 66 matched control subjects with a recently developed data-driven global brain connectivity (GBC) method, both within the PFC and across the whole brain.

RESULTS

We found clusters of decreased connectivity in the left lateral PFC in both whole-brain and PFC-restricted analyses. Increased GBC was found in the right putamen and left cerebellar cortex. Within regions of interest in the basal ganglia and thalamus, we identified increased GBC in dorsal striatum and anterior thalamus, which was reduced in patients on medication. The ventral striatum/nucleus accumbens exhibited decreased global connectivity but increased connectivity specifically with the ventral anterior cingulate cortex in subjects with OCD.

CONCLUSIONS

These findings identify previously uncharacterized PFC and basal ganglia dysconnectivity in OCD and reveal differentially altered GBC in dorsal and ventral striatum. Results highlight complex disturbances in PFC networks, which could contribute to disrupted cortical-striatal-cerebellar circuits in OCD.

Pediatric anxiety disorders: from neuroscience to evidence-based clinical practice

The objective of this narrative review of the literature is to describe the epidemiology, etiology, pathophysiology, diagnosis, and treatment of pediatric anxiety disorders. We aim to guide clinicians in understanding the biology of anxiety disorders and to provide general guidelines for the proper diagnoses and treatment of these conditions early in life. Anxiety disorders are prevalent, associated with a number of negative life outcomes, and currently under-recognized and under-treated. The etiology involves both genes and environmental influences modifying the neural substrate in a complex interplay. Research on pathophysiology is still in its infancy, but some brain regions, such as the amygdala and the prefrontal cortex, have been implicated in fear and anxiety. Current practice is to establish diagnosis based purely on clinical features, derived from clinical interviews with the child, parents, and teachers. Treatment is effective using medication, cognitive behavioral therapy, or a combination of both. An introduction to the neuroscience behind anxiety disorders combined with an evidence-based approach may help clinicians to understand these disorders and treat them properly in childhood.

From pathophysiology to novel antidepressant drugs: glial contributions to the pathology and treatment of mood disorders

Several structural and cellular changes, including marked glial anomalies, have been observed in association with major depressive disorder. Here we review these cellular alterations and highlight the importance of glial cell pathology, especially astroglial dysfunction, in the pathophysiology of neuropsychiatric disorders with a particular interest in major depressive disorder. The functional role of astrocytes in glutamate uptake and glutamate/glutamine cycling is discussed, as is the deleterious effects of chronic stress on glial cell function. Lastly, we discuss the effect of antidepressants on glial cell function and the possibility of targeting glial cells in the quest to develop novel therapeutics.

Isoforms of the neuronal glutamate transporter gene, SLC1A1/EAAC1, negatively modulate glutamate uptake: relevance to obsessive-compulsive disorder

The SLC1A1 gene, which encodes the neuronal glutamate transporter, EAAC1, has consistently been implicated in obsessive-compulsive disorder (OCD) in genetic studies. Moreover, neuroimaging, biochemical and clinical studies support a role for glutamatergic dysfunction in OCD. Although SLC1A1 is an excellent candidate gene for OCD, little is known about its regulation at the genomic level. Here, we report the identification and characterization of three alternative SLC1A1/EAAC1 mRNAs: a transcript derived from an internal promoter, termed P2 to distinguish it from the transcript generated by the primary promoter (P1), and two alternatively spliced mRNAs: ex2skip, which is missing exon 2, and ex11skip, which is missing exon 11. All isoforms inhibit glutamate uptake from the full-length EAAC1 transporter. Ex2skip and ex11skip also display partial colocalization and interact with the full-length EAAC1 protein. The three isoforms are evolutionarily conserved between human and mouse, and are expressed in brain, kidney and lymphocytes under nonpathological conditions, suggesting that the isoforms are physiological regulators of EAAC1. Moreover, under specific conditions, all SLC1A1 transcripts were differentially expressed in lymphocytes derived from subjects with OCD compared with controls. These initial results reveal the complexity of SLC1A1 regulation and the potential clinical utility of profiling glutamatergic gene expression in OCD and other psychiatric disorders.

Antipsychotic augmentation of serotonin reuptake inhibitors in treatment-resistant obsessive-compulsive disorder: a meta-analysis of double-blind, randomized, placebo-controlled trials

Because of the high number of patients with obsessive-compulsive disorder (OCD) not responding satisfactorily to initial monotherapy with serotonin reuptake inhibitors (SRIs), the evaluation of additional treatment options is highly relevant. To examine efficacy of add-on pharmacotherapy with antipsychotics, a systematic literature search was applied to identify all double-blind, randomized, placebo-controlled trials (DB-PC-RCTs) determining the efficacy of antipsychotic augmentation of SRIs in treatment-resistant OCD. The primary outcome of the pooled meta-analytic data analysis was response to the adjunctive antipsychotic treatment measured by both the rates of participants achieving response [defined as ≥ 35% reduction in Yale-Brown Obsessive-Compulsive Scale (YBOCS)] and mean changes in YBOCS total score. Twelve DB-PC-RCTs investigating quetiapine (N = 5), risperidone (N = 3), olanzapine (N = 2), aripiprazole (N = 1) and haloperidol (N = 1) with a total of 394 subjects were included. Significantly more patients responded to augmentation with antipsychotics than with placebo [relative risk = 2.10, 95% confidence intervals (CI) 1.16-3.80]. Additionally, the mean reduction of the YBOCS total score revealed an efficacy in favour of the antipsychotic medication [standardized mean difference (SMD) = 0.54, 95% CI 0.15-0.93]. Significant efficacy was identifiable only for risperidone, but not for quetiapine and olanzapine. The results regarding aripiprazole and haloperidol were inconsistent. Overall, about one-third of SRI-resistant OCD patients benefited from an augmentation strategy with antipsychotics. Based on the favourable risk:benefit ratio, risperidone can be considered as the agent of first choice and should be preferred to quetiapine and olanzapine. Further trials, mainly with higher antipsychotic doses, are required to optimize pharmacological treatment recommendations for SRI-refractory OCD.

Glutamate abnormalities in obsessive compulsive disorder: neurobiology, pathophysiology, and treatment

Obsessive compulsive disorder is prevalent, disabling, incompletely understood, and often resistant to current therapies. Established treatments consist of specialized cognitive-behavioral psychotherapy and pharmacotherapy with medications targeting serotonergic and dopaminergic neurotransmission. However, remission is rare, and more than a quarter of OCD sufferers receive little or no benefit from these approaches, even when they are optimally delivered. New insights into the disorder, and new treatment strategies, are urgently needed. Recent evidence suggests that the ubiquitous excitatory neurotransmitter glutamate is dysregulated in OCD, and that this dysregulation may contribute to the pathophysiology of the disorder. Here we review the current state of this evidence, including neuroimaging studies, genetics, neurochemical investigations, and insights from animal models. Finally, we review recent findings from small clinical trials of glutamate-modulating medications in treatment-refractory OCD. The precise role of glutamate dysregulation in OCD remains unclear, and we lack blinded, well-controlled studies demonstrating therapeutic benefit from glutamate-modulating agents. Nevertheless, the evidence supporting some important perturbation of glutamate in the disorder is increasingly strong. This new perspective on the pathophysiology of OCD, which complements the older focus on monoaminergic neurotransmission, constitutes an important focus of current research and a promising area for the ongoing development of new therapeutics.

Psychotherapy and medication management strategies for obsessive-compulsive disorder

Obsessive-compulsive disorder (OCD) is a chronic anxiety disorder. While medication and psychotherapy advances have been very helpful to patients, many patients do not respond adequately to initial trials of serotonergic medication or cognitive-behavioral therapy (CBT) and require multiple treatment trials or combination therapies. Comorbidity may also influence treatment response. The role of streptococcal infections in pediatric OCD has become an area of intense scrutiny and controversy. In this article, current treatment methods for OCD will be reviewed, with special attention to strategies for treating OCD in children and in patients with comorbid tic disorders. Alternative psychotherapy strategies for patients who are highly anxious about starting CBT, such as cognitive therapy or augmentation with D-cycloserine, will be reviewed. Newer issues regarding use of antibiotics, neuroleptics, and glutamate modulators in OCD treatment will also be explored.

Glutamate, obsessive-compulsive disorder, schizophrenia, and the stability of cortical attractor neuronal networks

A computational neuroscience approach to the symptoms of obsessive-compulsive disorder based on a stochastic neurodynamical framework is described. An increased depth in the basins of attraction of attractor neuronal network states in the brain makes each state too stable, so that it tends to remain locked in that state, and cannot easily be moved on to another state. It is suggested that the different symptoms that may be present in obsessive--compulsive disorder could be related to changes of this type in different brain regions. In integrate-and-fire network simulations, an increase in the NMDA and/or AMPA receptor conductances, which increases the depth of the attractor basins, increases the stability of attractor networks, and makes them less easily moved on to another state by a new stimulus. Increasing GABA-receptor activated currents can partly reverse this overstability. There is now some evidence for overactivity in glutamate transmitter systems in obsessive-compulsive disorder, and the hypothesis presented here shows how some of the symptoms of obsessive-compulsive disorder could be produced by the increase in the stability of attractor networks that is produced by increased glutamatergic activity. In schizophrenia, a reduction of the firing rates of cortical neurons caused for example by reduced NMDA receptor function, present in schizophrenia, can lead to instability of the high firing rate attractor states that normally implement short-term memory and attention, contributing to the cognitive and negative symptoms of schizophrenia. Reduced cortical inhibition caused by a reduction of GABA neurotransmission, present in schizophrenia, can lead to instability of the spontaneous firing states of cortical networks, leading to a noise-induced jump to a high firing rate attractor state even in the absence of external inputs, contributing to the positive symptoms of schizophrenia.

Sarcosine therapy for obsessive compulsive disorder: a prospective, open-label study

BACKGROUND

Several lines of evidence implicate glutamatergic neurotransmission in the pathophysiology of obsessive compulsive disorder (OCD). Sarcosine is an endogenous antagonist of glycine transporter-1. By blocking glycine uptake, sarcosine may increase the availability of synaptic glycine and enhance N-methyl-d-aspartate (NMDA) subtype glutamatergic neurotransmission. In this 10-week open-label trial, we examined the potential benefit of sarcosine treatment in OCD patients.

METHOD

Twenty-six outpatients with OCD and baseline Yale-Brown Obsessive Compulsive Scale (YBOCS) scores higher than 16 were enrolled. Drug-naive subjects (group 1, n = 8) and those who had discontinued serotonin reuptake inhibitors for at least 8 weeks at study entry (group 2, n = 6) received sarcosine monotherapy. The other subjects (group 3, n = 12) received sarcosine as adjunctive treatment. A flexible dosage schedule of sarcosine 500 to 2000 mg/d was applied. The primary outcome measures were Y-BOCS and Hamilton Anxiety Inventory, rated at weeks 0, 2, 4, 6, 8, and 10. Results were analyzed by repeated-measures analysis of variance.

RESULTS

Data of 25 subjects were eligible for analysis. The mean ± SD Y-BOCS scores decreased from 27.6 ± 5.8 to 22.7 ± 8.7, indicating a mean decrease of 19.8% ± 21.7% (P = 0.0035). Eight (32%) subjects were regarded as responders with greater than 35% reduction of Y-BOCS scores. Five of the responders achieved the good response early by week 4. Although not statistically significant, drug-naive (group 1) subjects had more profound and sustained improvement and more responders than the subjects who had received treatment before (groups 2 and 3). Sarcosine was tolerated well; only one subject withdrew owing to transient headache.

CONCLUSION

Sarcosine treatment can achieve a fast therapeutic effect in some OCD patients, particularly those who are treatment naive. The study supports the glycine transporter-1 as a novel target for developing new OCD treatment. Large-series placebo-controlled, double-blind studies are recommended.

Pharmacotherapy of compulsive hoarding

Compulsive hoarding is a common and potentially disabling disorder. This article reviews studies of the effects of hoarding on response to serotonin reuptake inhibitor (SRI) medications in patients with obsessive-compulsive disorder (OCD), as well as recent studies of pharmacotherapy specifically for patients with the compulsive hoarding syndrome. Taken together, the results of these studies indicate that the "conventional wisdom" that compulsive hoarding does not respond well to SRI treatment is wrong. SRIs appear to be as effective for compulsive hoarders as for nonhoarding OCD patients. A case is presented of a compulsive hoarding patient who responded well to pharmacotherapy with a novel agent. Symptom improvement from pharmacotherapy of compulsive hoarding appears to be at least as great as that resulting from cognitive-behavioral therapy (CBT). However, the combination of pharmacotherapy and CBT for compulsive hoarding is likely more effective than either treatment alone.

Advances in pharmacotherapy for pediatric anxiety disorders

Pediatric anxiety disorders are prevalent, chronic, and often lead to significant impaired functioning that impacts both short- and long-term outcomes for children and adolescents. Treatment options include pharmacotherapy and psychosocial interventions. This presentation will review treatment advances specifically for pharmacotherapy. Current research supports serotonin reuptake inhibitors as the medication class to be the first-line treatment option for pediatric anxiety disorders. Available evidence for the efficacy of other classes of medications will be reviewed, along with the available approaches to manage partial responders and nonresponders. The risks and benefits of pharmacotherapy will also be reviewed. In addition, recent research has shown the potential promise of novel agents that act upon other neural systems implicated in the development of pediatric anxiety disorders. Novel compounds that affect the glutamate system will be discussed.

Review of the use of the glutamate antagonist riluzole in psychiatric disorders and a description of recent use in childhood obsessive-compulsive disorder

The antiglutamatergic drug riluzole (Rilutek) is presently being used off label in the treatment of psychiatric conditions in adult patients and, increasingly, in children. This article briefly reviews the pharmacology of this drug and its current investigative and clinical uses and adverse effects. It also reports on our experience to date in the study of the drug in children, with emphasis on adverse effects noted so far in these younger patients.

Current trends in drug treatment of obsessive-compulsive disorder

This article aims to highlight current trends in the pharmacologic management of obsessive-compulsive disorder (OCD). A systematic search of the electronic database MEDLINE was conducted. The first case report of clomipramine efficacy in the management OCD more than 40 years ago gave new hope for the treatment of this debilitating disorder. Selective serotonin reuptake inhibitors (SSRIs) proved to have a similar efficacy profile compared with clomipramine but had a superior tolerability profile. While many patients with OCD respond to SSRIs or clomipramine, the treatment of those with refractory OCD remains challenging. Different augmentation agents in treatment-resistant OCD have been explored, with antipsychotic agents having the largest supporting evidence base. Nevertheless, new pharmacologic treatment options are required and are under investigation.

The Genetics of Obsessive-Compulsive Disorder

OCD is a psychiatric disorder with a lifetime prevalence of 1-3% and is a significant cause of disability worldwide. Family studies indicate that OCD has a significant hereditable component, with relatives of OCD cases being 4 times more likely to develop the disorder than the general population. Linkage studies in OCD have generally been underpowered and have failed to reach the statistical threshold for genome-wide significance, but they have nevertheless been useful for revealing potential regions of interest for future candidate gene studies. Candidate gene studies in OCD have thus far focused on genes involved in the serotonergic, dopaminergic, and glutamatergic pathways. These studies have been for the most part inconclusive, and failures to replicate have been the norm until very recently. The only genetic association replicated by multiple groups was with a glutamate transporter gene (SLC1A1). Genome-wide association studies in OCD are in progress, but final results have not yet been reported. As with the study of many other psychiatric disorders, an improved understanding of OCD will only be achieved (1) with larger collaborative efforts involving more probands, (2) the use of probands and controls drawn from epidemiologically-based populations rather than clinical samples, (3) developing a more precise phenotypic description of OCD and (4) measuring important environmental influences that affect OCD pathogenesis and severity.

Autism spectrum and obsessive-compulsive disorders: OC behaviors, phenotypes and genetics

Autism spectrum disorders (ASDs) are a phenotypically and etiologically heterogeneous set of disorders that include obsessive-compulsive behaviors (OCB) that partially overlap with symptoms associated with obsessive-compulsive disorder (OCD). The OCB seen in ASD vary depending on the individual's mental and chronological age as well as the etiology of their ASD. Although progress has been made in the measurement of the OCB associated with ASD, more work is needed including the potential identification of heritable endophenotypes. Likewise, important progress toward the understanding of genetic influences in ASD has been made by greater refinement of relevant phenotypes using a broad range of study designs, including twin and family-genetic studies, parametric and nonparametric linkage analyses, as well as candidate gene studies and the study of rare genetic variants. These genetic analyses could lead to the refinement of the OCB phenotypes as larger samples are studied and specific associations are replicated. Like ASD, OCB are likely to prove to be multidimensional and polygenic. Some of the vulnerability genes may prove to be generalist genes influencing the phenotypic expression of both ASD and OCD while others will be specific to subcomponents of the ASD phenotype. In order to discover molecular and genetic mechanisms, collaborative approaches need to generate shared samples, resources, novel genomic technologies, as well as more refined phenotypes and innovative statistical approaches. There is a growing need to identify the range of molecular pathways involved in OCB related to ASD in order to develop novel treatment interventions.

Obsessive-compulsive disorder: diagnostic and treatment issues

This article reviews current issues in the diagnosis and treatment of obsessive-compulsive disorder (OCD). The introduction of the selective serotonin reuptake inhibitors and of cognitive-behavioral therapy were significant advances for treating OCD. Nevertheless, there is a need to improve awareness of OCD and its management, and to develop novel approaches to treatment-refractory patients. Although the diagnostic criteria for OCD have remained unchanged for some time, there are several areas where potential modification may be useful. There is a growing evidence base on OCD symptom dimensions and subtyping, and it is timely to consider incorporating some of these emerging data into diagnostic classification systems.

Symptom dimensions and subtypes of obsessive-compulsive disorder: a developmental perspective

In the absence of definitive etiological markers for obsessive-compulsive disorder (OCD% obsessive-compulsive (OC) symptom dimensions may offer a fruitful point of orientation. These dimensions can be understood as defining potentially overlapping clinical features that may be continuous with "normal" worries first evident in childhood. Although the understanding of the dimensional structure of OC symptoms is still imperfect, a recent large-scale meta-analysis has confirmed the presence of at least four separa ble symptom dimensions in children, as well as adults, with OCD. A dimensional approach does not exclude other methods to parse OCD. Thus far, a pediatric age of onset, the presence of other family members with OCD, and the individual's "tic-related" status appear to be potentially useful categorical distinctions. Although the OC symptom dimensions appear to be valid for all ages, it is unlikely that the underlying genetic vulnerability factors and neurobiological substrates for each of these symptom dimensions are the same across the course of development.

Obsessive-compulsive disorder and related disorders: a comprehensive survey

Our aim was to present a comprehensive, updated survey on obsessive-compulsive disorder (OCD) and obsessive-compulsive related disorders (OCRDs) and their clinical management via literature review, critical analysis and synthesis. Information on OCD and OCRD current nosography, clinical phenomenology and etiology, may lead to a better comprehension of their management. Clinicians should become familiar with the broad spectrum of OCD disorders, since it is a pivotal issue in current clinical psychiatry.

Riluzole in the treatment of mood and anxiety disorders

Recent advances implicate amino acid neurotransmission in the pathophysiology and treatment of mood and anxiety disorders. Riluzole, which is approved and marketed for the treatment of amyotrophic lateral sclerosis, is thought to be neuroprotective through its modulation of glutamatergic neurotransmission. Riluzole has multiple molecular actions in vitro; the two that have been documented to occur at physiologically realistic drug concentrations and are therefore most likely to be clinically relevant are inhibition of certain voltage-gated sodium channels, which can lead to reduced neurotransmitter release, and enhanced astrocytic uptake of extracellular glutamate.Although double-blind, placebo-controlled trials are lacking, several open-label trials have suggested that riluzole, either as monotherapy or as augmentation of standard therapy, reduces symptoms of obsessive-compulsive disorder, unipolar and bipolar depression, and generalized anxiety disorder. In studies of psychiatrically ill patients conducted to date, the drug has been quite well tolerated; common adverse effects include nausea and sedation. Elevation of liver function tests is common and necessitates periodic monitoring, but has been without clinical consequence in studies conducted to date in psychiatric populations. Case reports suggest utility in other conditions, including trichotillomania and self-injurious behaviour associated with borderline personality disorder. Riluzole may hold promise for the treatment of several psychiatric conditions, possibly through its ability to modulate pathologically dysregulated glutamate levels, and merits further investigation.

Glutamatergic Synaptic Dysfunction and Obsessive-Compulsive Disorder

Obsessive-compulsive disorder (OCD) is a debilitating neuropsychiatric condition estimated to afflict 1-3% of the world population. The estimated financial impact in the treatment and management of OCD is in the billions of dollars annually in the US alone. At present there is a marked lack of evidence on the specific causes of OCD. Current hypotheses largely focus on the serotonin (5-HT) system on the basis of the effectiveness of selective serotonin reuptake inhibitors (SSRIs) in alleviating symptoms of patients with OCD, yet a considerable fraction of patients are non-responsive or minimally responsive to these agents. Despite this fact, SSRIs have remained the primary pharmacological treatment avenue for OCD. In recent years, multiple lines of evidence have implicated glutamatergic synaptic dysfunction within the cortico-striatal-thalamo-cortical (CSTC) brain circuit in the etiology of OCD and related disorders, thereby prompting intensified effort in the development and evaluation of agents that modulate glutamatergic neurotransmission for the treatment of OCD. With this in mind, here we review the following topics with respect to synaptic dysfunction and the neural circuitry underlying OCD: (1) evidence supporting the critical involvement of the CSTC circuit, (2) genetic studies supporting the involvement of glutamatergic dysfunction, (3) insights from genetic animal models of OCD, and (4) preliminary findings with glutamatergic neurotransmission-modulating agents in the treatment of OCD. Given the putative mechanistic overlap between OCD and the broader OC-spectrum of disorders, unraveling the synaptic basis of OCD has potential to translate into more effective treatments for an array of poorly understood human disorders.