Prolonged avoidance training exacerbates OCD-like behaviors in a rodent model

Obsessive-compulsive disorder (OCD) is characterized by compulsive behaviors that often resemble avoidance of perceived danger. OCD can be treated with exposure-with-response prevention (ERP) therapy in which patients are exposed to triggers but are encouraged to refrain from compulsions, to extinguish compulsive responses. The compulsions of OCD are strengthened by many repeated exposures to triggers, but little is known about the effects of extended repetition of avoidance behaviors on extinction. Here we assessed the extent to which overtraining of active avoidance affects subsequent extinction-with-response prevention (Ext-RP) as a rodent model of ERP, in which rats are extinguished to triggers, while the avoidance option is prevented. Male rats conditioned for 8d or 20d produced similar avoidance behavior to a tone paired with a shock, however, the 20d group showed a severe impairment of extinction during Ext-RP, as well as heightened anxiety. Furthermore, the majority of overtrained (20d) rats (75%) exhibited persistent avoidance following Ext-RP. In the 8d group, only a minority of rats (37%) exhibited persistent avoidance, and this was associated with elevated activity (c-Fos) in the prelimbic cortex and nucleus accumbens. In the 20d group, the minority of non-persistent rats (25%) showed elevated activity in the insular-orbital cortex and paraventricular thalamus. Lastly, extending the duration of Ext-RP prevented the deleterious effects of overtraining on extinction and avoidance. These rodent findings suggest that repeated expression of compulsion-like behaviors biases individuals toward persistent avoidance and alters avoidance circuits, thereby reducing the effectiveness of current extinction-based therapies.

Functional disruption in prefrontal-striatal network in obsessive-compulsive disorder

Obsessive-compulsive disorder (OCD) is characterized by intrusive thoughts and repetitive, compulsive behaviors. While a cortico-striatal-limbic network has been implicated in the pathophysiology of OCD, the neural correlates of this network in OCD are not well understood. In this study, we examined resting state functional connectivity among regions within the cortico-striatal-limbic OCD neural network, including the rostral anterior cingulate cortex, dorsolateral prefrontal cortex, ventrolateral prefrontal cortex, orbitofrontal cortex, ventromedial prefrontal cortex, amygdala, thalamus and caudate, in 44 OCD and 43 healthy participants. We then examined relationships between OCD neural network connectivity and OCD symptom severity in OCD participants. OCD relative to healthy participants showed significantly greater connectivity between the left caudate and bilateral dorsolateral prefrontal cortex. We also found a positive correlation between left caudate-bilateral dorsolateral prefrontal cortex connectivity and depression scores in OCD participants, such that greater positive connectivity was associated with more severe symptoms. This study makes a significant contribution to our understanding of functional networks and their relationship with depression in OCD.

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.

Functional Disruption of Cerebello-thalamo-cortical Networks in Obsessive-Compulsive Disorder

BACKGROUND

Obsessive-compulsive disorder (OCD) is characterized by intrusive thoughts and repetitive, compulsive behaviors. Neuroimaging studies have implicated altered connectivity among the functional networks of the cerebral cortex in the pathophysiology of OCD. However, there has been no comprehensive investigation of the cross-talk between the cerebellum and functional networks in the cerebral cortex.

METHODS

This functional neuroimaging study was completed by 44 adult participants with OCD and 43 healthy control participants. We performed large-scale data-driven brain network analysis to identify functional connectivity patterns using resting-state functional magnetic resonance imaging data.

RESULTS

Participants with OCD showed lower functional connectivity within the somatomotor network and greater functional connectivity among the somatomotor network, cerebellum, and subcortical network (e.g., thalamus and pallidum; all p < .005). Network-based statistics analyses demonstrated one component comprising connectivity within the somatomotor network that showed lower connectivity and a second component comprising connectivity among the somatomotor network, and motor regions in particular, and the cerebellum that showed greater connectivity in participants with OCD relative to healthy control participants. In participants with OCD, abnormal connectivity across both network-based statistics-derived components positively correlated with OCD symptom severity (p = .006).

CONCLUSIONS

To our knowledge, this study is the first comprehensive investigation of large-scale network alteration across the cerebral cortex, subcortical regions, and cerebellum in OCD. Our findings highlight a critical role of the cerebellum in the pathophysiology of OCD.

Theta-Burst Transcranial Magnetic Stimulation for Posttraumatic Stress Disorder

OBJECTIVE

Posttraumatic stress disorder (PTSD) is a highly prevalent psychiatric disorder associated with disruption in social and occupational function. Transcranial magnetic stimulation (TMS) represents a novel approach to PTSD, and intermittent theta-burst stimulation (iTBS) is a new, more rapid administration protocol with data supporting efficacy in depression. The authors conducted a sham-controlled study of iTBS for PTSD.

METHODS

Fifty veterans with PTSD received 10 days of sham-controlled iTBS (1,800 pulses/day), followed by 10 unblinded sessions. Primary outcome measures included acceptability (retention rates), changes in PTSD symptoms (clinician- and self-rated), quality of life, social and occupational function, and depression, obtained at the end of 2 weeks; analysis of variance was used to compare active with sham stimulation. Secondary outcomes were evaluated 1 month after treatment, using mixed-model analyses. Resting-state functional MRI was acquired at pretreatment baseline on an eligible subset of participants (N=26) to identify response predictors.

RESULTS

Retention was high, side effects were consistent with standard TMS, and blinding was successful. At 2 weeks, active iTBS was significantly associated with improved social and occupational function (Cohen's d=0.39); depression was improved with iTBS compared with the sham treatment (d=-0.45), but the difference fell short of significance, and moderate nonsignificant effect sizes were observed on self-reported PTSD symptoms (d=-0.34). One-month outcomes, which incorporated data from the unblinded phase of the study, indicated superiority of active iTBS on clinician- and self-rated PTSD symptoms (d=-0.74 and -0.63, respectively), depression (d=-0.47), and social and occupational function (d=0.93) (all significant). Neuroimaging indicated that clinical improvement was significantly predicted by stronger (greater positive) connectivity within the default mode network and by anticorrelated (greater negative) cross-network connectivity.

CONCLUSIONS

iTBS appears to be a promising new treatment for PTSD. Most clinical improvements from stimulation occurred early, which suggests a need for further investigation of optimal iTBS time course and duration. Consistent with previous neuroimaging studies of TMS, default mode network connectivity played an important role in response prediction.

Immune-Related Comorbidities in Childhood-Onset Obsessive Compulsive Disorder: Lifetime Prevalence in the Obsessive Compulsive Disorder Collaborative Genetics Association Study

Objective: To evaluate the lifetime prevalence of infectious, inflammatory, and autoimmune disorders in a multisite study of probands with childhood-onset obsessive compulsive disorder (OCD) and their first-degree relatives. Methods: Medical questionnaires were completed by 1401 probands and 1045 first-degree relatives in the OCD Collaborative Genetics Association Study. Lifetime prevalence of immune-related diseases was compared with the highest available population estimate and reported as a point estimate with 95% adjusted Wald interval. Worst-episode OCD severity and symptom dimensions were assessed with the Yale-Brown Obsessive Compulsive Scale (YBOCS) and Symptom Checklist (YBOCS-CL). Results: Probands reported higher-than-expected prevalence of scarlet fever (4.0 [3.1-5.2]% vs. 1.0%-2.0%, z = 1.491, p < 0.001, n = 1389), encephalitis or meningitis (1.4 [0.9-2.1]% vs. 0.1%-0.4%, z = 5.913, p < 0.001, n = 1393), rheumatoid arthritis (1.1 [0.6-2.0]% vs. 0.2%-0.4%, z = 3.416, p < 0.001, n = 949) and rheumatic fever (0.6 [0.3-1.2]% vs. 0.1%-0.2%, z = 3.338, p < 0.001, n = 1390), but not systemic lupus erythematosus, diabetes, asthma, multiple sclerosis, psoriasis, or inflammatory bowel disease. First-degree relatives reported similarly elevated rates of scarlet fever, rheumatic fever, and encephalitis or meningitis independent of OCD status. There was no association between worst-episode severity and immune-related comorbidities, although probands reporting frequent ear or throat infections had increased severity of cleaning-/contamination-related symptoms (mean factor score 2.5 ± 0.9 vs. 2.3 ± 1.0, t = 3.183, p = 0.002, n = 822). Conclusion: These data suggest high rates of streptococcal-related and other immune-mediated diseases in patients with childhood-onset OCD and are consistent with epidemiological studies in adults noting familial clustering. Limitations include potential reporting bias and absence of a control group, underscoring the need for further prospective studies characterizing medical and psychiatric disease clusters and their interactions in children. Such studies may ultimately improve our understanding of OCD pathogenesis and aid in the development of adjunctive immune-modulating therapeutic strategies.

Trichotillomania comorbidity in a sample enriched for familial obsessive-compulsive disorder

BACKGROUND

This study addresses the strength of associations between trichotillomania (TTM) and other DSM-IV Axis I conditions in a large sample (n = 2606) enriched for familial obsessive-compulsive disorder (OCD), to inform TTM classification.

METHODS

We identified participants with TTM in the Johns Hopkins OCD Family Study (153 families) and the OCD Collaborative Genetics Study, a six-site genetic linkage study of OCD (487 families). We used logistic regression (with generalized estimating equations) to assess the strength of associations between TTM and other DSM-IV disorders.

RESULTS

TTM had excess comorbidity with a number of conditions from different DSM-IV chapters, including tic disorders, alcohol dependence, mood disorders, anxiety disorders, impulse-control disorders, and bulimia nervosa. However, association strengths (odds ratios) were highest for kleptomania (6.6), pyromania (5.8), OCD (5.6), skin picking disorder (4.4), bulimia nervosa (3.5), and pathological nail biting (3.4).

CONCLUSIONS

TTM is comorbid with a number of psychiatric conditions besides OCD, and it is strongly associated with other conditions involving impaired impulse control. Though DSM-5 includes TTM as an OCD-related disorder, its comorbidity pattern also emphasizes the impulsive, appetitive aspects of this condition that may be relevant to classification.

Network Functional Architecture and Aberrant Functional Connectivity in Post-Traumatic Stress Disorder: A Clinical Application of Network Convergence

Posttraumatic stress disorder (PTSD) is associated with disrupted functional connectivity in multiple neural networks. Multinetwork models of PTSD hypothesize that aberrant regional connectivity emerges from broad network-level disruptions. However, few studies have tested how characteristics of network-level organization influence regional functional connectivity in PTSD. This gap in knowledge impacts both our understanding of the pathophysiology of the disorder and the development of network-targeted PTSD treatments. We acquired resting-state imaging from a naturalistic sample of patients with PTSD (n = 42) and healthy controls (n = 42). Group differences in functional connectivity were identified using region of interest analyses and estimations of within- and between neural network activity; PTSD patients demonstrated reduced amygdala-orbitofrontal connectivity and increased default mode network (DMN) connectivity compared with controls. We then used convergence-a novel measure representing the capacity for functional integration-to test whether differences in functional architecture underlie connectivity signatures of PTSD. This approach found that reduced frontoparietal network (FPN) convergence was associated with reduced amygdala-orbitofrontal connectivity. Furthermore, in controls only, increased DMN convergence was associated with reduced DMN-to-salience network connectivity, and increased FPN convergence was associated with reduced FPN-to-ventral attention network connectivity. These results suggest that FPN functional architecture may underlie insufficiencies in top-down control in PTSD, with results broadly supporting the notion that networks' functional architecture influences the breakdown of normative functional relationships in PTSD. This work also indicates the potential of convergence to be applied to clinical populations in future research studies.

Transcranial Direct Current Stimulation for Affective Symptoms and Functioning in Chronic Low Back Pain: A Pilot Double-Blinded, Randomized, Placebo-Controlled Trial

BACKGROUND AND OBJECTIVE

Chronic low back pain (CLBP) is highly prevalent, with a substantial psychosocial burden. Pain has both sensory and affective components. The latter component is a significant driver of disability and psychiatric comorbidity but is often inadequately treated. Previously we reported that noninvasive transcranial direct current stimulation (tDCS) may modulate pain-associated affective distress. Here we tested whether 10 daily tDCS sessions aimed to inhibit the left dorsal anterior cingulate cortex (dACC), a region strongly implicated in the affective component of pain, would produce selective reduction in pain-related symptoms.

METHODS

In this multisite, double-blinded, randomized placebo-controlled trial (RCT), 21 CLBP patients received 10 weekday sessions of 2-mA active tDCS or sham (20 minutes/session). A cathodal electrode was placed over FC1 (10-20 electroencephalography coordinates), and an identical anodal return electrode was placed over the contralateral mastoid. Participants rated pain intensity, acceptance, interference, disability, and anxiety, plus general anxiety and depression.

RESULTS

Regression analysis noted significantly less pain interference (P =0.002), pain disability (P =0.001), and depression symptoms (P =0.003) at six-week follow-up for active tDCS vs sham. Omnibus tests suggested that these improvements were not merely due to baseline (day 1) group differences.

CONCLUSIONS

To our knowledge, this is the first double-blinded RCT of multiple tDCS sessions targeting the left dACC to modulate CLBP's affective symptoms. Results are encouraging, including several possible tDCS-associated improvements. Better-powered RCTs are needed to confirm these effects. Future studies should also consider different stimulation schedules, additional cortical targets, high-density multi-electrode tDCS arrays, and multimodal approaches.

Use of machine learning in predicting clinical response to transcranial magnetic stimulation in comorbid posttraumatic stress disorder and major depression: A resting state electroencephalography study

BACKGROUND

Repetitive transcranial magnetic stimulation (TMS) is clinically effective for major depressive disorder (MDD) and investigational for other conditions including posttraumatic stress disorder (PTSD). Understanding the mechanisms of TMS action and developing biomarkers predicting response remain important goals. We applied a combination of machine learning and electroencephalography (EEG), testing whether machine learning analysis of EEG coherence would (1) predict clinical outcomes in individuals with comorbid MDD and PTSD, and (2) determine whether an individual had received a TMS course.

METHODS

We collected resting-state 8-channel EEG before and after TMS (5 Hz to the left dorsolateral prefrontal cortex). We used Lasso regression and Support Vector Machine (SVM) to test the hypothesis that baseline EEG coherence predicted the outcome and to assess if EEG coherence changed after TMS.

RESULTS

In our sample, clinical response to TMS were predictable based on pretreatment EEG coherence (n = 29). After treatment, 13/29 had more than 50% reduction in MDD self-report score 12/29 had more than 50% reduction in PTSD self-report score. For MDD, area under roc curve was for MDD was 0.83 (95% confidence interval 0.69-0.94) and for PTSD was 0.71 (95% confidence interval 0.54-0.87). SVM classifier was able to accurately assign EEG recordings to pre- and post-TMS treatment. The accuracy for Alpha, Beta, Theta and Delta bands was 75.4 ± 1.5%, 77.4 ± 1.4%, 73.8 ± 1.5%, and 78.6 ± 1.4%, respectively, all significantly better than chance (50%, p < 0.001).

LIMITATION

Limitations of this work include lack of sham condition, modest sample size, and a sparse electrode array. Despite these methodological limitations, we found validated and clinically meaningful results.

CONCLUSIONS

Machine learning successfully predicted non-response to TMS with high specificity, and identified pre- and post-TMS status using EEG coherence. This approach may provide mechanistic insights and may also become a clinically useful screening tool for TMS candidates.

Acute effects of aerobic exercise on negative affect and obsessions and compulsions in individuals with obsessive-compulsive disorder

BACKGROUND

The acute effects of aerobic exercise on improved mood and anxiety reduction have been demonstrated across clinical and nonclinical populations. Limited work has evaluated the acute effects of aerobic exercise on negative affect, obsessions, and compulsions in patients with Obsessive Compulsive Disorder (OCD).

METHOD

Fifty-five patients (64% female) with treatment-resistant OCD were randomized to either 12 weeks of aerobic exercise (AE) or health education contact (HEC) control. Participants rated negative affect (i.e., mood and anxiety), obsessions and compulsions before and after each weekly AE or HEC session. Multilevel models were constructed to evaluate the effect of intervention condition, treatment week (time), and their interaction in terms of acute change in affect, obsession, and compulsions.

RESULTS

Results reflected a main effect of condition, such that AE resulted in significantly larger increases in positive mood, and reductions in anxiety and compulsions, as compared to HEC. There was also a main effect of time in predicting acute anxiety reduction, such that linear reductions in anxiety over the course of treatment were observed. No significant effects were observed for acute changes in obsessions.

LIMITATIONS

The sample was small and was limited in demographic heterogeneity. Bouts of aerobic exercise were not standardized in terms of duration and mode, which could impact affective response to exercise, and acute affective OCD effects were exclusively self-reported.

DISCUSSION

The current findings may help elucidate potential mechanisms of action of exercise on OCD outcomes. In addition, these results point toward the potential of designing exercise interventions that can teach patients to utilize individual bouts of physical activity, "in-the-moment" to improve mood and reduce anxiety and compulsions.

Evolution of gamma knife capsulotomy for intractable obsessive-compulsive disorder

For more than half a century, stereotactic neurosurgical procedures have been available to treat patients with severe, debilitating symptoms of obsessive-compulsive disorder (OCD) that have proven refractory to extensive, appropriate pharmacological, and psychological treatment. Although reliable predictors of outcome remain elusive, the establishment of narrower selection criteria for neurosurgical candidacy, together with a better understanding of the functional neuroanatomy implicated in OCD, has resulted in improved clinical efficacy for an array of ablative and non-ablative intervention techniques targeting the cingulum, internal capsule, and other limbic regions. It was against this backdrop that gamma knife capsulotomy (GKC) for OCD was developed. In this paper, we review the history of this stereotactic radiosurgical procedure, from its inception to recent advances. We perform a systematic review of the existing literature and also provide a narrative account of the evolution of the procedure, detailing how the procedure has changed over time, and has been shaped by forces of evidence and innovation. As the procedure has evolved and adverse events have decreased considerably, favorable response rates have remained attainable for approximately one-half to two-thirds of individuals treated at experienced centers. A reduction in obsessive-compulsive symptom severity may result not only from direct modulation of OCD neural pathways but also from enhanced efficacy of pharmacological and psychological therapies working in a synergistic fashion with GKC. Possible complications include frontal lobe edema and even the rare formation of delayed radionecrotic cysts. These adverse events have become much less common with new radiation dose and targeting strategies. Detailed neuropsychological assessments from recent studies suggest that cognitive function is not impaired, and in some domains may even improve following treatment. We conclude this review with discussions covering topics essential for further progress of this therapy, including suggestions for future trial design given the unique features of GKC therapy, considerations for optimizing stereotactic targeting and dose planning using biophysical models, and the use of advanced imaging techniques to understand circuitry and predict response. GKC, and in particular its modern variant, gamma ventral capsulotomy, continues to be a reliable treatment option for selected cases of otherwise highly refractory OCD.

Obsessive-Compulsive Personality Symptoms Predict Poorer Response to Gamma Ventral Capsulotomy for Intractable OCD

Gamma ventral capsulotomy (GVC) is a radiosurgical procedure which aims to create lesions in the ventral part of the anterior limb of the internal capsule (ALIC). It has been used as a treatment option for patients with intractable obsessive-compulsive disorder (OCD) who do not respond to several first-line treatments attempts. However, changes in personality disorder symptoms after GVC have not been investigated. The aims of this study are to investigate changes in personality disorder symptoms after GVC and to search for baseline personality disorder symptoms that may predict clinical response to GVC. Fourteen treatment-intractable OCD patients who underwent GVC completed the Structured Clinical Interview for DSM-IV Personality Disorders (SCID-II) at baseline and one year after the procedure. Wilcoxon signed-rank test was performed to investigate personality disorder symptom changes before and after surgery. Linear regression models were utilized to predict treatment response, using baseline personality disorder symptoms as independent variables. We did not observe any quantitative changes in personality disorder symptoms after GVC, compared with baseline. Higher severity of obsessive-compulsive personality disorder symptoms at baseline was correlated with worse treatment response after GVC for OCD (β = -0.085, t-value = -2.52, p-value = 0.027). These findings advocate for the safety of the GVC procedure in this specific population of intractable OCD patients, in terms of personality disorder symptom changes. They also highlight the importance of taking into account the severity of obsessive-compulsive personality disorder symptoms when GVC is indicated for intractable OCD patients.

Neuroimaging Correlates of Suicidality in Decision-Making Circuits in Posttraumatic Stress Disorder

In depression, brain and behavioral correlates of decision-making differ between individuals with and without suicidal thoughts and behaviors. Though promising, it remains unknown if these potential biomarkers of suicidality will generalize to other high-risk clinical populations. To preliminarily assess whether brain structure or function tracked suicidality in individuals with posttraumatic stress disorder (PTSD), we measured resting-state functional connectivity and cortical thickness in two functional networks involved in decision-making, a ventral fronto-striatal reward network and a lateral frontal cognitive control network. Neuroimaging data and self-reported suicidality ratings, and suicide-related hospitalization data were obtained from 50 outpatients with PTSD and also from 15 healthy controls, and all were subjected to seed-based resting-state functional connectivity and cortical thickness analyses using a priori seeds from reward and cognitive control networks. First, general linear models (GLM) were used to evaluate whether ROI-to-ROI functional connectivity was predictive of self-reported suicidality after false discovery rate (FDR)-correction for multiple comparisons and covariance of age and depression symptoms. Next, regional cortical thickness statistics were included as predictors of ROI-to-ROI functional connectivity in follow-up GLMs evaluating structure-function relationships. Functional connectivity between reward regions was positively correlated with suicidality (p-FDR ≤ 0.05). Functional connectivity of the lateral pars orbitalis to anterior cingulate/paracingulate control regions also tracked suicidality (p-FDR ≤ 0.05). Furthermore, cortical thickness in anterior cingulate/paracingulate was associated with functional correlates of suicidality in the control network (p-FDR < 0.05). These results provide a preliminary demonstration that biomarkers of suicidality in decision-making networks observed in depression may generalize to PTSD and highlight the promise of these circuits as transdiagnostic biomarkers of suicidality.

A Prospective Study of the Impact of Transcranial Alternating Current Stimulation on EEG Correlates of Somatosensory Perception

The (8-12 Hz) neocortical alpha rhythm is associated with shifts in attention across sensory systems, and is thought to represent a sensory gating mechanism for the inhibitory control of cortical processing. The present preliminary study sought to explore whether alpha frequency transcranial alternating current stimulation (tACS) could modulate endogenous alpha power in the somatosensory system, and whether the hypothesized modulation would causally impact perception of tactile stimuli at perceptual threshold. We combined electroencephalography (EEG) with simultaneous brief and intermittent tACS applied over primary somatosensory cortex at individuals' endogenous alpha frequency during a tactile detection task (n = 12 for EEG, n = 20 for behavior). EEG-measured pre-stimulus alpha power was higher on non-perceived than perceived trials, and analogous perceptual correlates emerged in early components of the tactile evoked response. Further, baseline normalized tactile detection performance was significantly lower during alpha than sham tACS, but the effect did not last into the post-tACS time period. Pre- to post-tACS changes in alpha power were linearly dependent upon baseline state, such that alpha power tended to increase when pre-tACS alpha power was low, and decrease when it was high. However, these observations were comparable in both groups, and not associated with evidence of tACS-induced alpha power modulation. Nevertheless, the tactile stimulus evoked response potential (ERP) revealed a potentially lasting impact of alpha tACS on circuit dynamics. The post-tACS ERP was marked by the emergence of a prominent peak ∼70 ms post-stimulus, which was not discernible post-sham, or in either pre-stimulation condition. Computational neural modeling designed to simulate macroscale EEG signals supported the hypothesis that the emergence of this peak could reflect synaptic plasticity mechanisms induced by tACS. The primary lesson learned in this study, which commanded a small sample size, was that while our experimental paradigm provided some evidence of an influence of tACS on behavior and circuit dynamics, it was not sufficient to induce observable causal effects of tACS on EEG-measured alpha oscillations. We discuss limitations and suggest improvements that may help further delineate a causal influence of tACS on cortical dynamics and perception in future studies.

Gamma Ventral Capsulotomy in Intractable Obsessive-Compulsive Disorder

BACKGROUND

Despite the development of effective pharmacologic and cognitive behavioral treatments for obsessive-compulsive disorder (OCD), some patients continue to be treatment-refractory and severely impaired. Fiber tracts connecting orbitofrontal and dorsal anterior cingulate cortex with subcortical nuclei have been the target of neurosurgical lesions as well as deep brain stimulation in these patients. We report on the safety and efficacy of ventral gamma capsulotomy for patients with intractable OCD.

METHODS

Fifty-five patients with severely disabling, treatment-refractory OCD received bilateral lesions in the ventral portion of the anterior limb of the internal capsule over a 20-year period using the Leksell Gamma Knife. The patients were prospectively followed over 3 years with psychiatric, neurologic, and neuropsychological assessments of safety and efficacy, as well as structural neuroimaging.

RESULTS

Thirty-one of 55 patients (56%) had an improvement in the primary efficacy measure, the Yale-Brown Obsessive Compulsive Scale, of ≥35% over the 3-year follow-up period. Patients had significant improvements in depression, anxiety, quality of life, and global functioning. Patients tolerated the procedure well without significant acute adverse events. Five patients (9%) developed transient edema that required short courses of dexamethasone. Three patients (5%) developed cysts at long-term follow-up, 1 of whom developed radionecrosis resulting in an ongoing minimally conscious state.

CONCLUSIONS

Gamma Knife ventral capsulotomy is an effective radiosurgical procedure for many treatment-refractory OCD patients. A minority of patients developed cysts at long-term follow-up, 1 of whom had permanent neurological sequelae.

5 Hz Repetitive transcranial magnetic stimulation for posttraumatic stress disorder comorbid with major depressive disorder

BACKGROUND

Standard clinical protocols for repetitive transcranial magnetic stimulation (rTMS) for major depressive disorder (MDD) apply 10 Hz pulses over left prefrontal cortex, yet little is known about the effects of rTMS in more diagnostically complex depressed patients.

OBJECTIVE/HYPOTHESIS

Posttraumatic stress disorder (PTSD) is commonly comorbid with MDD, and while rTMS has been shown to alleviate PTSD symptoms in preliminary studies, ideal parameters remain unclear. We conducted a prospective, open-label study of 5 Hz rTMS for patients with comorbid PTSD + MDD and hypothesized stimulation would reduce symptoms of both disorders.

METHODS

Outpatients (N = 40) with PTSD + MDD and at least moderate global severity were enrolled. 5 Hz rTMS included up to 40 daily sessions followed by a 5-session taper. Symptoms were measured using the PTSD Checklist (PCL-5) and Inventory of Depressive Symptomatology, Self-Report (IDS-SR). Baseline-to-endpoint changes were analyzed.

RESULTS

The intent-to-treat population included 35 participants. Stimulation significantly reduced PTSD symptoms (PCL-5 baseline mean ± SD score 52.2 ± 13.1 versus endpoint 34.0 ± 21.6; p < .001); 23 patients (48.6%) met a pre-defined categorical PTSD response criteria. MDD symptoms also improved significantly (IDS-SR, baseline 47.8 ± 11.9 to endpoint 30.9 ± 18.9; p < .001); 15 patients (42.9%) demonstrated categorical response and 12 (34.3%) remitted. PTSD and MDD symptom change was highly correlated (r = 0.91, p < .001).

LIMITATIONS

Unblinded single-arm study, with modest sample size.

CONCLUSION

Significant and clinically meaningful reductions in both MDD and PTSD symptoms were observed following stimulation. The preliminary efficacy of 5 Hz rTMS for both symptom domains in patients with comorbid disorders supports future controlled studies.

Personality measures after gamma ventral capsulotomy in intractable OCD

BACKGROUND

Neurosurgeries such as gamma ventral capsulotomy (GVC) are an option for otherwise intractable obsessive-compulsive disorder (OCD) patients. In general, clinical and neuropsychological status both improve after GVC. However, its consequences on personality traits are not well-studied. The objective of this study was to investigate personality changes after one year of GVC in intractable OCD patients.

METHODS

The personality assessment was conducted using the Revised NEO Personality Inventory (NEO PI-R) and Cloninger's Temperament and Character Inventory (TCI) in 14 intractable OCD patients before and one year after GVC. Comparisons of personality features between treatment responders (n=5) and non-responders (n=9) were performed. Multiple linear regression was also used for predicting changes in clinical and global functioning variables.

RESULTS

Overall, no deleterious effect was found in personality after GVC. Responders had a reduction in neuroticism (p=0.043) and an increase in extraversion (p=0.043). No significant changes were observed in non-responders. Increases in novelty seeking and self-directedness, and decreases in persistence and cooperativiness predicted OCD symptom improvement. Similary, improvement in functioning was also predicted by hgher novelty seeking and self-directedness after GVC, whereas better functioning was also associated with lower reward dependence and cooperativeness after surgery.

CONCLUSIONS

The pattern of changes in personality traits after GVC was generally towards that observed in nonclinical population, and does not raise safety concerns.

Transcranial magnetic stimulation for treatment-resistant depression: Naturalistic treatment outcomes for younger versus older patients

BACKGROUND

Repetitive transcranial magnetic stimulation (TMS) has been shown to be safe and effective for treatment-resistant depression (TRD) in the general adult population. Efficacy among older (≥60 years) patients, who have a greater burden of cognitive, physical, and functional impairment compared to their younger counterparts, remains unclear. The current study aimed to characterize antidepressant response to an acute course of TMS therapy among patients aged ≥60 years compared to those <60 years in naturalistic clinical practice settings.

METHODS

Data were retrospectively collected and pooled for adults with TRD (N =231; n =75 aged ≥60 years and n = 156 <60 years) who underwent an acute course of outpatient TMS therapy at two outpatient clinics. Self-report depression scales were administered at baseline and end of acute treatment. Change on continuous measures and categorical outcomes were compared across older vs. younger patients.

RESULTS

Both age groups showed significant improvements in depression symptoms. Response and remission rates did not differ between groups. Age group was not a significant predictor of change in depression severity, nor of clinical response or remission, in a model controlling for other predictors (all p>.05).

LIMITATIONS

Limitations include reliance on self-report clinical measures and variability in comorbidity and concurrent pharmacotherapy due to the naturalistic nature of the study.

CONCLUSIONS

Results suggest that effectiveness of TMS for TRD is not differentially modified by age. Based on these naturalistic data, age alone should not be considered a contraindication or poor prognostic indicator of the antidepressant efficacy of TMS.

Transcranial direct current stimulation may modulate extinction memory in posttraumatic stress disorder

BACKGROUND

Abnormalities in fear extinction and recall are core components of posttraumatic stress disorder (PTSD). Data from animal and human studies point to a role of the ventromedial prefrontal cortex (vmPFC) in extinction learning and subsequent retention of extinction memories. Given the increasing interest in developing noninvasive brain stimulation protocols for psychopathology treatment, we piloted whether transcranial direct current stimulation (tDCS) during extinction learning, vs. during consolidation of extinction learning, might improve extinction recall in veterans with warzone-related PTSD.

METHODS

Twenty-eight veterans with PTSD completed a 2-day Pavlovian fear conditioning, extinction, and recall paradigm. Participants received one 10-min session of 2 mA anodal tDCS over AF3, intended to target the vmPFC. Fourteen received tDCS that started simultaneously with extinction learning onset, and the remaining 14 participants received tDCS during extinction consolidation. Normalized skin conductance reactivity (SCR) was the primary outcome measure. Linear mixed effects models were used to test for effects of tDCS on late extinction and early extinction recall 24 hr later.

RESULTS

During early recall, veterans who received tDCS during extinction consolidation showed slightly lower SCR in response to previously extinguished stimuli as compared to veterans who received tDCS simultaneous with extinction learning (p = .08), generating a medium effect size (Cohen's d = .38). There was no significant effect of tDCS on SCR during late extinction.

CONCLUSIONS

These preliminary findings suggest that testing the effects of tDCS during consolidation of fear extinction may have promise as a way of enhancing extinction recall.