Persistent Brain Connectivity Changes in Healthy Volunteers Following Nitrous Oxide Inhalation.

Background: Nitrous oxide holds promise in the treatment of major depressive disorder. Its psychotropic effects and NMDA receptor antagonism have led to comparisons with ketamine. Despite longstanding use, persistent effects of nitrous oxide on the brain have not been characterized. Methods: Sixteen healthy volunteers were recruited in a double-blind crossover study. In randomized order, individuals underwent a 1-hour inhalation of either 50% nitrous oxide/oxygen or air/oxygen mixtures. At least two 7.5-minute echo-planar resting-state functional magnetic resonance imaging scans were obtained before and at 2 and 24 hours after each inhalation (average 130 min/participant). Using the time series of preprocessed, motion artifact-scrubbed, and nuisance covariate-regressed imaging data, interregional signal correlations were measured and converted to T scores. Hierarchical clustering and linear mixed-effects models were employed. Results: Nitrous oxide inhalation produced changes in global brain connectivity that persisted in the occipital cortex at 2 and 24 hours postinhalation (p < .05, false discovery rate-corrected). Analysis of resting-state networks demonstrated robust strengthening of connectivity between regions of the visual network and those of the dorsal attention network, across 2 and 24 hours after inhalation (p < .05, false discovery rate-corrected). Weaker changes in connectivity were found between the visual cortex and regions of the frontoparietal and default mode networks. Parallel analyses following air/oxygen inhalation yielded no significant changes in functional connectivity. Conclusions: Nitrous oxide inhalation in healthy volunteers revealed persistent increases in global connectivity between regions of primary visual cortex and dorsal attention network. These findings suggest that nitrous oxide inhalation induces neurophysiological cortical changes that persist for at least 24 hours.

Episodic Memories Among Irritable Bowel Syndrome (IBS) Patients: An Important Aspect of the IBS Symptom Experience.

Objective: Some IBS patients possess detailed memories of the events surrounding their bowel symptom onset ("episodic memories"). In this exploratory study we sought to: (1) examine memory relationship with gastrointestinal (GI) symptom severity, extraintestinal symptoms, and mood; (2) qualitatively explore memory valence and content in IBS patients with or without episodic memories. Methods: Referral IBS patients n = 29; age 47.0± 2.2 years, 79.3% female) enrolled in this cross-sectional, mixed methods research study. Participants completed validated specific memory instruments [Autobiographical Memory Test (AMT), Sentence Completion for Events from the Past Test (SCEPT)] and relevant questionnaires [IBS symptoms 10-cm visual analog scale); SF-36 Health-related quality of life (HRQOL); Perley-Guze and PHQ-15/12: somatization; Beck Depression/Anxiety Inventories). Qualitative analysis examined the content and valence of general memories. Results: 14/29 (48.3%) of IBS subjects endorsed episodic memories of IBS symptom onset, often GI infections/enteritis (35.7%). Recall of the exact year (69%) and month (60%) of symptom onset were common. Episodic memories were associated with greater IBS symptom severity/bother, higher anxiety/depression, and poorer HRQOL. Though AMT and SCEPT memory specificity were not different based on episodic memories, overgeneralization to negatively-valenced cues in the AMT was associated with more severe IBS in those without episodic memory. Qualitative analysis revealed no observable differences in topic focus of IBS patients with and without episodic memories. Conclusions: IBS patients often endorse episodic memories associated with symptom onset, and this recall seems to associate with more severe symptoms. Overgeneralization responses to negative stimuli may lead to worse bowel symptoms in those without episodic memories. IBS memory specificity may associate with qualitative differences in processing psychosocial experiences and might be important to IBS pathophysiology.

Vagus nerve stimulation: An update on a novel treatment for treatment-resistant depression.

In this review, we provide an overview of essential clinical trials examining the effect of vagal nerve stimulation (VNS) in treatment-resistant depression (TRD), the applicable neuroanatomy of the vagus nerve, and the proposed mechanism of action (MOA) of VNS in TRD. Vagal nerve stimulation (VNS) is currently the only FDA-approved neurostimulation treatment for severe treatment-resistant depression (TRD). The implanted VNS device sends electrical impulses to the left cervical vagus nerve, resulting in stimulation of afferent vagal brainstem pathways known to be associated with mood regulation. Within the last decade, several clinical trials have attempted to further elucidate this effect specifically in TRD. Early clinical trials including the D01, D02, and D03 trials showed promising evidence of the antidepressant efficacy and durability of VNS as a treatment for TRD. Later trials comparing VNS and treatment-as-usual (TAU) resulted in similar findings regarding antidepressant efficacy and durability. VNS was additionally found to be beneficial in improving quality of life and suicidality among unipolar TRD patients and depression among bipolar TRD patients. Ongoing and future studies such as the RECOVER trial continue to investigate the psychiatric benefits of VNS within the TRD population. Although the MOA of VNS in TRD is still not fully understood, recent brain imaging studies and animal studies have proven instrumental in addressing this knowledge gap.

Tricyclic Antidepressants and Monoamine Oxidase Inhibitors: Are They Too Old for a New Look?

Through unintentional discovery, monoamine oxidase inhibitors (MAOIs) and tricyclic antidepressants (TCAs) were the first antidepressant classes to be used clinically and have been widely available for over half a century. From the 1950s to the 1980s, these two classes of antidepressants were the sole antidepressant tools available to psychiatrists. With the advent of the selective serotonin reuptake inhibitors (SSRIs) in the 1980s and 1990s, the prescribing of the MAOIs and TCAs has fallen significantly worldwide. In this chapter, we take a closer look at the arc of MAOI discovery and clinical use, and how these two classes of drugs compare to each other. This is important because relatively few studies compare these older classes of drugs to the newer classes of antidepressants. Finally, we argue that TCAs, and particularly MAOIs, should continue to play an important role in the modern treatment of depression, especially in the treatment-resistant patient.

Beliefs about GI medications and adherence to pharmacotherapy in functional GI disorder outpatients.

OBJECTIVES: Pharmacotherapy is a mainstay in functional gastrointestinal (GI) disorder (FGID) management, but little is known about patient attitudes toward medication regimens. Understanding patient concerns and adherence to pharmacotherapy is particularly important for off-label medication use (e.g., antidepressants) in FGID. METHODS: Consecutive tertiary GI outpatients completed the Beliefs About Medications questionnaire (BMQ). Subjects were categorized as FGID and structural GI disease (SGID) using clinician diagnoses and Rome criteria; GI-specific medications and doses were recorded, and adherence to medication regimens was determined by patient self-report. BMQ domains (overuse, harm, necessity, and concern) were compared between FGID and SGID, with an interest in how these beliefs affected medication adherence. Psychiatric measures (depression, anxiety, and somatization) were assessed to gauge their influence on medication beliefs. RESULTS: A total of 536 subjects (mean age 54.7±0.7 years, range 22-100 years; n=406, 75.7% female) were enrolled over a 5.5-year interval: 341 (63.6%) with FGID (IBS, 64.8%; functional dyspepsia, 51.0%, ≥2 FGIDs, 38.7%) and 142 (26.5%) with SGID (IBD, 28.9%; GERD, 23.2%). PPIs (n=231, 47.8%), tricyclic antidepressants (TCAs) (n=167, 34.6%), and anxiolytics (n=122, 25.3%) were common medications prescribed. FGID and SGID were similar across all BMQ domains (P>0.05 for overuse, harm, necessity, and concern). SGID subjects had higher necessity-concern framework (NCF) scores compared with FGID subjects (P=0.043). FGID medication adherence correlated negatively with concerns about medication harm (r=-0.24, P<0.001) and overuse (r=-0.15, P=0.001), whereas higher NCF differences predicted medication compliance (P=0.006). Medication concern and overuse scores correlated with psychiatric comorbidity among FGID subjects (P<0.03 for each). FGID patients prescribed TCAs (n=142, 41.6%) expressed a greater medication necessity (17.4±0.4 vs. 16.2±0.4, P=0.024) and found their GI regimen to be more helpful (P=0.054). FGID subjects not on TCAs expressed a greater apprehension about medication overuse (10.7±0.3 vs. 9.7±0.2, P=0.002) on the BMQ. CONCLUSIONS: FGID subjects report medication necessity and concern scores comparable to patients with SGID but have negative perceptions about medications, particularly in the presence of psychiatric comorbidity; these factors may affect treatment adherence and willingness to initiate neuromodulator regimens.

Witnessed versus unwitnessed random urine tests in the treatment of opioid dependence.

BACKGROUND AND OBJECTIVES: Clinics licensed to provide pharmacotherapy for opiate dependence disorder are required to perform random urine drug screen (RUDS) tests. The results provide the empirical basis of individual treatment and programmatic effectiveness, and public health policy. Patients consent to witnessed testing but most tests are unwitnessed. The purpose of the present study was to compare treatment effectiveness estimates derived from witnessed versus unwitnessed urine samples. METHODS: We adopted a policy requiring visually witnessed urine drug screens (WUDS) and studied its impact (a single group, pretest-posttest design) on the RUDS test results in 115 male veterans enrolled in the St. Louis VA Opioid Treatment Program. RESULTS: The percentage of opioid-positive urine samples increased significantly following implementation of WUDS (25% vs. 41%, χ(2) = 66.5, p < .001). CONCLUSIONS AND SCIENTIFIC SIGNIFICANCE: Results of this preliminary study suggest that random testing alone does not ensure the integrity of UDS testing. Outcome calculations based on random unwitnessed tests may overestimate the effectiveness of opioid dependence disorder treatment.

Improvement in sexual functioning in patients with type 2 diabetes and depression treated with bupropion.

OBJECTIVE: Major depressive disorder (MDD) and type 2 diabetes have independent adverse effects on sexual functioning (SF). Bupropion (BU) reportedly has few sexual side effects, but its use in diabetes has not been studied. RESEARCH DESIGN AND METHODS: This article reports a planned secondary analysis of SF in 90 patients with type 2 diabetes treated with BU for MDD. RESULTS: At baseline, 71.1% of patients had insufficient SF. Mean Sexual Energy Scale (SES) scores improved during treatment (P < 0.0001), as did the percentage with sufficient SF (30.6 vs. 68.1%, P = 0.001). Patients with persistent hyperglycemia had higher rates of sexual dysfunction; however, SES improvement was evident in some with persistent depression or hyperglycemia (18.2% and 25.9%, respectively). CONCLUSIONS: Insufficient SF is prevalent and may be suspected in patients with MDD and type 2 diabetes. BU treatment of MDD had few sexual side effects and was associated with significant improvements in SF.

Antidepressant pharmacotherapy in adults with type 2 diabetes: rates and predictors of initial response.

OBJECTIVE Initial treatment with antidepressant medication is insufficiently effective in some patients with type 2 diabetes, and factors predicting treatment outcome are poorly understood. RESEARCH DESIGN AND METHODS Aggregate data from two published trials were analyzed to determine the rates and predictors of response to antidepressant pharmacotherapy in adults with type 2 diabetes using conventional markers of initial treatment outcome (improvement, response, partial remission, and remission). Three hundred eighty-seven patients who received up to 16 weeks of open-label, acute-phase treatment using bupropion (n = 93) or sertraline (n = 294) were studied. Logistic regression was used to identify predictors of poor treatment outcome. Candidate predictors included age, race, sex, initial Beck Depression Inventory (iBDI) score, treatment received (sertraline or bupropion), family history of depression, extant diabetes complications (eDC), and A1C level. RESULTS Of 387 patients initiated on treatment, 330 (85.3%) met criteria for improvement, 232 (59.9%) for response, 207 (53.5%) for partial remission, and 179 (46.3%) for full remission. Significant independent predictors of poor outcome included eDC (for no improvement); sertraline treatment, eDC, and younger age (for nonresponse); sertraline treatment, eDC, and higher iBDI (for failure to partially remit); and younger age and higher iBDI (for failure to fully remit). Higher pain scores predicted three of the four markers of poor outcome in the subset with pain data. CONCLUSIONS In patients with type 2 diabetes, poor initial response to antidepressant medication is predicted by multiple factors. Auxiliary treatment of pain and impairment may be required to achieve better outcomes.