Cerebral metabolism and mood in remitted opiate dependence

Regional cerebral metabolism alterations and functional connectivity in individuals with opioid use disorder: An integrated resting-state PET/fMRI study

Individuals with opioid use disorder (OUD) have been reported to show abnormal brain metabolism and impaired coupling among brain networks such as the default mode network (DMN), salience network (SN), and executive control network (ECN). However, the characteristics of brain glucose metabolism and its related functions in the brain networks in individuals with OUD remain unknown. Thirty-six individuals with OUD and thirty matched healthy controls (HCs) were recruited in this integrated positron emission tomography/magnetic resonance imaging (PET/MRI) study. Differences in glucose metabolism were analyzed by using 18F-fluorodeoxyglucose (18F-FDG), and the corresponding coupling characteristics of the individuals with OUD were also analyzed. The individuals with OUD showed widespread bilateral hypometabolism in the middle temporal gyrus (MTG), superior temporal gyrus, angular gyrus, supramarginal gyrus, inferior parietal lobe, Rolandic operculum, and left insula, but obvious hypermetabolism in the brainstem and left cerebellum. Meanwhile, in individuals with OUD, the hypometabolism of right MTG which is included in the DMN was accompanied by decreased coupling with the left superior frontal gyrus and right superior parietal gyrus which are included in the ECN. Furthermore, individuals with OUD showed a positive correlation between the duration of heroin use and glucose metabolism of the left MTG. The individuals with OUD were characterized by widespread bilateral hypometabolism in the temporal and parietal regions but obvious hypermetabolism in the brainstem and left cerebellum. The results suggest that the hypometabolism in the temporal and parietal regions might be related to DMN dysfunction and the hypermetabolism in the brainstem and left cerebellum may be compensate for other brain regions showing hypometabolism. In particular, hypometabolism in the self-referential-related DMN regions in OUD might attenuate their relationships with the inhibitory-control-related ECN regions. These findings highlight the importance of evaluating the metabolic and functional profiles of the right MTG in future studies on the treatment of OUD.

Ketogenic diet: a potential adjunctive treatment for substance use disorders

Substance use disorders (SUD) can lead to serious health problems, and there is a great interest in developing new treatment methods to alleviate the impact of substance abuse. In recent years, the ketogenic diet (KD) has shown therapeutic benefits as a dietary therapy in a variety of neurological disorders. Recent studies suggest that KD can compensate for the glucose metabolism disorders caused by alcohol use disorder by increasing ketone metabolism, thereby reducing withdrawal symptoms and indicating the therapeutic potential of KD in SUD. Additionally, SUD often accompanies increased sugar intake, involving neural circuits and altered neuroplasticity similar to substance addiction, which may induce cross-sensitization and increased use of other abused substances. Reducing carbohydrate intake through KD may have a positive effect on this. Finally, SUD is often associated with mitochondrial damage, oxidative stress, inflammation, glia dysfunction, and gut microbial disorders, while KD may potentially reverse these abnormalities and serve a therapeutic role. Although there is much indirect evidence that KD has a positive effect on SUD, the small number of relevant studies and the fact that KD leads to side effects such as metabolic abnormalities, increased risk of malnutrition and gastrointestinal symptoms have led to the limitation of KD in the treatment of SUD. Here, we described the organismal disorders caused by SUD and the possible positive effects of KD, aiming to provide potential therapeutic directions for SUD.

Neuroimaging reveals distinct brain glucose metabolism patterns associated with morphine consumption in Lewis and Fischer 344 rat strains

Vulnerability to addiction may be given by the individual's risk of developing an addiction during their lifetime. A challenge in the neurobiology of drug addiction is understanding why some people become addicted to drugs. Here, we used positron emission tomography (PET) and statistical parametric mapping (SPM) to evaluate changes in brain glucose metabolism in response to chronic morphine self-administration (MSA) in two rat strains with different vulnerability to drug abuse, Lewis (LEW) and Fischer 344 (F344). Four groups of animals were trained to self-administer morphine or saline for 15 days. 2-deoxy-2-[¹⁸F]-fluoro-d-glucose (FDG)-PET studies were performed on the last day of MSA (acquisition phase) and after 15 days of withdrawal. PET data were analyzed using SPM12. LEW-animals self-administered more morphine injections per session than F344-animals. We found significant brain metabolic differences between LEW and F344 strains in the cortex, hypothalamus, brainstem, and cerebellum. In addition, the different brain metabolic patterns observed after the MSA study between these rat strains indicate differences in the efficiency of neural substrates to translate the drug effects, which could explain the differences in predisposition to morphine abuse between one individual and another. These findings have important implications for the use of these rat strains in translational morphine and opiate research.

Predictors of Daily Pain Medication Use in Individuals with Recurrent Back Pain

PURPOSE

A key component to chronic pain management regimens is the use of analgesic medications. Psychological factors, such as mood states, may also affect the use of pain medications for individuals with chronic pain, but few observational studies have examined how these factors may predict pain medication use at the daily level.

METHODS

Daily assessments from 104 individuals with back pain were used to examine fluctuations in daily pain intensity, mood, sleep quality, and physical activity as predictors of the likelihood of pain medication (opioid and non-opioid) use and levels of medication use on the same day.

RESULTS

Pain intensity and mood ratings significantly predicted whether participants used pain medication on the same day, while only pain intensity predicted whether participants used more medication than usual. Further, current opioid users were more likely to increase the amount of their medication use on days of higher pain.

DISCUSSION

This article identifies fluctuations in daily pain intensity and mood as salient predictors of daily pain medication use in individuals with recurrent back pain. The current study is among the first to highlight both pain and mood states as predictors of daily pain medication use in individuals with back pain, though future studies may expand on these findings through the use of higher-resolution daily medication use variables.

Resting-state Abnormalities in Heroin-dependent Individuals

Drug addiction is a major health problem worldwide. Recent neuroimaging studies have shed light into the underlying mechanisms of drug addiction as well as its consequences to the human brain. The most vulnerable, to heroin addiction, brain regions have been reported to be specific prefrontal, parietal, occipital, and temporal regions, as well as, some subcortical regions. The brain regions involved are usually linked with reward, motivation/drive, memory/learning, inhibition as well as emotional control and seem to form circuits that interact with each other. So, along with neuroimaging studies, recent advances in resting-state dynamics might allow further assessments upon the multilayer complexity of addiction. In the current manuscript, we comprehensively review and discuss existing resting-state neuroimaging findings classified into three overlapping and interconnected groups: functional connectivity alterations, structural deficits and abnormal topological properties. Moreover, behavioral traits of heroin-addicted individuals as well as the limitations of the currently available studies are also reviewed. Finally, in need of a contemporary therapy a multimodal therapeutic approach is suggested using classical treatment practices along with current neurotechonologies, such as neurofeedback and goal-oriented video-games.

Neuroimaging the Effectiveness of Substance Use Disorder Treatments

Neuroimaging techniques to measure the function and biochemistry of the human brain such as positron emission tomography (PET), proton magnetic resonance spectroscopy ((1)H MRS), and functional magnetic resonance imaging (fMRI), are powerful tools for assessing neurobiological mechanisms underlying the response to treatments in substance use disorders. Here, we review the neuroimaging literature on pharmacological and behavioral treatment in substance use disorder. We focus on neural effects of medications that reduce craving (e.g., naltrexone, bupropion hydrochloride, baclofen, methadone, varenicline) and that improve cognitive control (e.g., modafinil, N-acetylcysteine), of behavioral treatments for substance use disorders (e.g., cognitive bias modification training, virtual reality, motivational interventions) and neuromodulatory interventions such as neurofeedback and transcranial magnetic stimulation. A consistent finding for the effectiveness of therapeutic interventions identifies the improvement of executive control networks and the dampening of limbic activation, highlighting their values as targets for therapeutic interventions in substance use disorders.

Factors Associated with Opioid Use in a Cohort of Patients Presenting for Surgery

Objectives. Patients taking opioids prior to surgery experience prolonged postoperative opioid use, worse clinical outcomes, increased pain, and more postoperative complications. We aimed to compare preoperative opioid users to their opioid naïve counterparts to identify differences in baseline characteristics. Methods. 107 patients presenting for thoracotomy, total knee replacement, total hip replacement, radical mastectomy, and lumpectomy were investigated in a cross-sectional study to characterize the associations between measures of pain, substance use, abuse, addiction, sleep, and psychological measures (depressive symptoms, Posttraumatic Stress Disorder symptoms, somatic fear and anxiety, and fear of pain) with opioid use. Results. Every 9-point increase in the Screener and Opioid Assessment for Patients with Pain-Revised (SOAPP-R) score was associated with 2.37 (95% CI 1.29–4.32) increased odds of preoperative opioid use (p = 0.0005). The SOAPP-R score was also associated with 3.02 (95% CI 1.36–6.70) increased odds of illicit preoperative opioid use (p = 0.007). Also, every 4-point increase in baseline pain at the future surgical site was associated with 2.85 (95% CI 1.12–7.27) increased odds of legitimate preoperative opioid use (p = 0.03). Discussion. Patients presenting with preoperative opioid use have higher SOAPP-R scores potentially indicating an increased risk for opioid misuse after surgery. In addition, legitimate preoperative opioid use is associated with preexisting pain.

Methadone maintenance dose modulates anterior cingulate glutamate levels in heroin-dependent individuals: A preliminary in vivo (1)H MRS study

Mu-opioid receptor agonists alter brain glutamate (GLU) levels in laboratory animals. This clinical study used proton magnetic resonance spectroscopy ((1)H MRS) to examine regional brain GLU levels during experimental manipulation of methadone (MTD) maintenance dose under double-blind, within-subject conditions in seven heroin-dependent volunteers. Subjects were scanned first at a high MTD dose (100 mg/day), underwent a 3-week outpatient MTD dose taper, and then were scanned again at a low MTD dose (10-25 mg/day; modified for participant comfort). Five age- and cigarette smoking-matched controls were scanned once. In vivo short echo time (TE = 22 ms), single voxel (1)H MRS data from midline pregenual anterior cingulate cortex (ACC) and thalamus (4.5 cm(3) each) were collected using PRESS on a 4-Tesla MRI system. Absolute metabolite levels were quantified. GLU levels in the ACC, but not the thalamus, were higher at the low relative to the high MTD dose in heroin-dependent subjects. No other metabolites differed by MTD dose, or between control vs. heroin-dependent subjects (at either MTD dose). GLU levels in the ACC were inversely related to the duration of cigarette smoking (controls) and heroin use (experimental group). Future studies are warranted to investigate the relationship between GLU levels during treatment (and detoxification), and withdrawal symptoms or relapse.

Self-loathing aspects of depression reduce postoperative opioid cessation rate

OBJECTIVE

We previously reported that increased preoperative Beck Depression Inventory II (BDI-II) scores were associated with a 47% (95% CI 24%-64%) reduction in the rate of opioid cessation following surgery. We aimed to identify the underlying factors of the BDI-II (affective/cognitive vs somatic) associated with a decreased rate of opioid cessation after surgery.

METHODS

We conducted a secondary analysis of the data from a previously reported prospective, longitudinal, observational study of opioid use after five distinct surgical procedures (total hip replacement, total knee replacement, thoracotomy, mastectomy, and lumpectomy) in 107 patients. The primary endpoint was time to opioid cessation. After exploratory factor analysis of the BDI-II, mean summary scores were calculated for each identified factor. These scores were evaluated as predictors of time to opioid cessation using Cox proportional hazards regression.

RESULTS

The exploratory factor analysis produced three factors (self-loathing symptoms, motivational symptoms, emotional symptoms). All three factors were significant predictors in univariate analysis. Of the three identified factors of the BDI-II, only preoperative self-loathing symptoms (past failure, guilty feelings, self-dislike, self-criticalness, suicidal thoughts, worthlessness) independently predicted a significant decrease in opioid cessation rate after surgery in the multivariate analysis (HR 0.86, 95% CI 0.75-0.99, P value 0.037).

CONCLUSIONS

Our results identify a set of negative cognitions predicting prolonged time to postoperative opioid cessation. Somatic symptoms captured by the BDI-II were not primarily responsible for the association between preoperative BDI-II scores and postoperative prolonged opioid use.

Reduced responses to heroin-cue-induced craving in the dorsal striatum: effects of long-term methadone maintenance treatment

Methadone maintenance treatment (MMT) is safe and effective for heroin addiction, but the neural basis of the length effects of long-term MMT on brain activity during craving in former heroin addicts is unclear. This study explored it by comparing the brain activations of heroin addicts with different length of MMT during pictorial presentation of heroin-related cue. Fifteen male former heroin addicts successfully treated by MMT less than 1 year (Group A), 15 matched patients with 2-3 year MMT (Group B) and 17 healthy controls underwent functional magnetic resonance imaging while heroin-related and neutral stimuli were present to them. Subjective cue-elicited craving was measured with visual analog scale before and after imaging. Then, partial correlation analysis to reveal the relationship between drug-related blood oxygen level dependent (BOLD) signal intensity and heroin or methadone use history. Finally, self-reported craving was not different between Group A and B before and after scanning. Compared with Group A, Group B had a significant reduced brain activity to heroin-related minus neural cues in the bilateral caudate. After controlling for the variable heroin use history, the drug-related BOLD signal intensity in the bilateral caudate was negatively correlated with MMT duration and total methadone consumption. When MMT history was controlled, the drug-related activity intensity in right caudate had a positive correlation with heroin daily dosage. Long-term MMT may improve heroin-craving response by modulating the impaired function in the bilateral dorsal striatum caused by former heroin use.

Possible etiology of improvements in both quality of life and overlapping gastroesophageal reflux disease by proton pump inhibitor treatment in a prospective randomized controlled trial

Background

Symptoms suggestive of functional dyspepsia (FD) and irritable bowel syndrome (IBS) frequently overlap with those of gastroesophageal reflux disease. Despite the high prevalence of symptomatic overlap, the underlying etiology remains poorly defined. We assessed the correlation of symptomatic relief and health-related quality of life (HRQoL) with healing of reflux esophagitis to further derive insights into the underlying etiology.

Methods

626 patients with reflux esophagitis were enrolled into one of two treatment groups (classical healing concept or the complete remission concept) to investigate differences in treatment intensity. Patients were treated with pantoprazole until esophageal mucosal healing. Remission was followed for up to 6 months without treatment. Gastro-intestinal symptoms and HRQoL were analyzed using disease-specific, psychometrically validated patient-reported outcome instruments (ReQuest™, GERDyzer™).

Results

Symptomatic burden reflected by ReQuest™ substantially decreased from baseline to end of treatment by 83% and 88% in either treatment group, respectively. ReQuest™ scores significantly decreased in patients with or without heartburn and in those with symptoms suggestive of FD and IBS, indicating response of all symptom categories to treatment (p < 0.005). Therapy-associated relief of symptoms was paralleled by substantial gains in HRQoL, which continued to stabilize post-treatment.

Conclusions

Pantoprazole is effective in relieving upper and lower gastro-intestinal symptoms overlapping with erosive esophagitis, and provides sustained improvement in HRQoL post-treatment. Our results propose a link between both healing of erosive esophagitis and the slower remission of upper and lower gastro-intestinal symptoms. Since the improvement observed is likely to be multifactorial, the possibility for an immune-mediated etiology and identification of putative susceptibility factors by genome-wide association study may provide focus for future research.

Trial registration

ClinicalTrials.gov identifier: NCT00325676.

Acute effects of heroin on emotions in heroin-dependent patients

BACKGROUND

Euphoria has been described in heroin-dependent individuals after heroin administration. However, affective disturbances and disorders are common in heroin dependence. The present study examined the acute effects of heroin on emotions in heroin-dependent patients.

METHODS

This randomized controlled crossover trial included 28 heroin-dependent patients (67.9% male, n = 19) in stable heroin-assisted treatment and 20 healthy controls. The patients were administered heroin or saline (placebo), the controls were administered saline. Data measuring mood, affects and heroin craving (BDI, AMRS, STAI, STAXI, and HCQ) were assessed before and 60 minutes after substance injection.

RESULTS

Before substance injection, heroin-dependent patients showed significantly higher levels of anxiety and depression than healthy controls (p < .0001). Heroin administration-but not placebo administration-was associated with a significant decrease in all negative emotions, including craving, and a significant increase in emotional well-being (p < .0001), irrespective of perceived intoxication and sedation. After the experiment, the patients did not differ from healthy controls in their emotions, once they had received heroin.

CONCLUSIONS

Heroin dampens craving, negative emotions, and increases positive emotions. These findings indicate that heroin regulates emotions and underscore the clinical benefit of opioid substitution treatment for heroin-dependent patients.

Cingulate biochemistry in heroin users on substitution pharmacotherapy

OBJECTIVE

High doses of opiate substitution pharmacotherapy are associated with greater treatment retention and lower illicit drug consumption, although the neurobiological bases of these benefits are poorly understood. Dysfunction of the anterior cingulate cortex (ACC) is associated with greater addiction severity and mood dysregulation in opiate users, such that the beneficial effects of substitution pharmacotherapy may relate to normalisation of ACC function. This study aimed to investigate the differential impact of methadone compared with buprenorphine on dorsal ACC biochemistry. A secondary aim was to explore the differential effects of methadone and buprenorphine on dorsal ACC biochemistry in relation to depressive symptoms.

METHODS

Twenty-four heroin-dependent individuals stabilised on methadone (n=10) or buprenorphine (n=14) and 24 healthy controls were scanned using proton Magnetic Resonance Spectroscopy and compared for metabolite concentrations of N-acetylaspartate, glutamate/glutamine, and myo-inositol.

RESULTS

(1) Methadone was associated with normalisation of dorsal ACC biochemistry (increased N-acetylaspartate and glutamate/glutamine levels, and decreased myo-inositol levels) in a dose-dependent manner; (2) buprenorphine-treated individuals had higher myo-inositol and glutamate/glutamine levels than methadone-treated patients in the right dorsal ACC; and (3) myo-inositol levels were positively correlated with depressive symptoms in participants stabilised on buprenorphine.

CONCLUSIONS

These findings point to a beneficial role of high-dose methadone on dorsal ACC biochemistry, and suggest a link between elevated myo-inositol levels and depressive symptoms in the context of buprenorphine treatment.

Alpha-synuclein and heroin craving in opiate-dependent patients on injectable heroin maintenance

Research suggests that alpha-synuclein (SNCA) and NACP-Rep1, a polymorphic complex microsatellite repeat ~10 kb upstream of the SNCA gene translational start, may be involved in substance-use behaviors and craving. This study was the first to examine the effects of diacetylmorphine (DAM) on peripheral SNCA protein expression along with craving in opiate-dependent patients and to compare their NACP-Rep1 allele lengths with those of healthy controls. Using an experimental design, opiate-dependent patients on injectable heroin maintenance were investigated at four time points, twice pre- and post-injection of DAM. SNCA protein levels of 30 DAM-maintained patients were measured using enzyme-linked immunosorbent assay. Participant-rated effects were assessed in 42 patients by Tiffany's Heroin Craving Questionnaire (HCQ), Gossop's Short Opiate Withdrawal Scale and Visual Analogs. NACP-Rep1 alleles of 42 patients and 101 controls were analyzed. One-way repeated-measures ANOVAs provided significant overall effects for SNCA protein content (P = 0.028), craving (P < 0.001), withdrawal symptomatology (P < 0.001) and mood (P < 0.001), indicating that DAM injections may not only reduce craving but also SNCA protein expression. However, there was no association between protein expression and craving. Relative to controls, patients had significantly longer NACP-Rep1 alleles (P < 0.001). NACP-Rep1 allele lengths correlated positively with HCQ total scores averaged across all time points (r = 0.420; P = 0.006) as well as with post-DAM HCQ total scores in the morning (r = 0.488, P = 0.001) and afternoon (r = 0.423, P = 0.005). The findings provide evidence of a contributory role of SNCA and NACP-Rep1 for opiate dependence.

Development of a powdered activated carbon in bar adsorptive micro-extraction for the analysis of morphine and codeine in human urine

In the present work, bar adsorptive microextraction using an activated carbon (AC) adsorbent phase followed by liquid desorption and high-performance liquid chromatography with diode array detection was developed to monitor morphine (MOR) and codeine (COD) in human urine. Under optimized experimental conditions, assays performed in aqueous media spiked at the 30.0 µg/L level yielded recoveries of 41.3 ± 1.3% for MOR and 38.4 ± 1.7% for COD, respectively. The textural and surface chemistry properties of the AC phase were also correlated with the analytical data for a better understanding of the overall enrichment process. The analytical performance showed good precision (relative standard deviation < 8.0%), suitable detection limits (0.90 and 0.06 µg/L for MOR and COD, respectively) and convenient linear dynamic ranges (r(2) > 0.991) from 10.0 to 330.0 µg/L. By using the standard addition methodology, the applications of this analytical approach to water and urine matrices allowed remarkable performance to monitor MOR and COD at the trace level. This new confirmatory method proved to be a suitable alternative to other sorptive micro-extraction methodologies in monitoring trace levels of opiate-related compounds, because it was easy to implement, reliable, sensitive and required a low sample volume.

Sustained attention in patients receiving and abstinent following methadone maintenance treatment for opiate dependence: performance and neuroimaging results

OBJECTIVE

Impairments in the function of attention exacerbate the course of opiate dependence and may play a role in the relapsing nature of the disorder. This study used clinical measures and positron emission tomography (PET) to assess the functioning of sustained attention in subjects with a history of opiate dependence.

METHODS

A test of auditory sustained attention was administered to 10 subjects receiving methadone maintenance treatment, 13 formerly opiate-dependent subjects in protracted abstinence, and 14 healthy Comparison subjects. Simultaneous measurement of regional glucose metabolism was made by [(18)F] flourodeoxyglucose PET. Subjects groups were compared on the measures of sustained attention and regional cerebral glucose metabolism.

RESULTS

Healthy Comparison subjects scored significantly better than either methadone-maintained or abstinent former opiate addicts on measures of sustained attention. Formerly opiate-dependent subjects in protracted abstinence scored better than methadone-maintained subjects on sustained attention. Methadone-maintained subjects demonstrated a relative reduction in regional cerebral glucose metabolism in the right supramarginal gyrus, and the thalamus bilaterally. The Comparison subjects without a history of opiate dependence demonstrated a relative increase in regional cerebral glucose metabolism in the right anterior cingulate gyrus, the right medial superior frontal gyrus and the thalamus bilaterally.

CONCLUSIONS

Subjects with a history of opiate dependence have impairments in the functioning of sustained attention, and abnormalities in brain regions identified as important in attention processing. Impairments in attention performance persist in subjects who enjoy prolonged abstinence from opiates.

Gray matter density negatively correlates with duration of heroin use in young lifetime heroin-dependent individuals

Numerous studies have documented cognitive impairments and hypoactivity in the prefrontal and anterior cingulate cortices in drug users. However, the relationships between opiate dependence and brain structure changes in heroin users are largely unknown. In the present study, we measured the density of gray matter (DGM) with voxel-based morphometry in 30 lifetime heroin-dependent individuals who had abstained from drug use for 5 months, and 34 healthy participants. The DGM of the prefrontal, temporal and cingulate cortices significantly decreased in heroin addicts relative to the healthy group. Critically, partial correlation analysis, which controlled for age, education and gender factors as well as nicotine use and heroin abstinence duration, showed that the duration of heroin use negatively correlated with the DGM in heroin-dependent individuals. These results provide compelling evidence for structural abnormality in heroin-dependent individuals and further suggest that duration of heroin use is a critical factor leading to brain damage.

Low prefrontal perfusion linked to depression symptoms in methadone-maintained opiate-dependent patients

BACKGROUND

Clinically depressed patients without substance use disorders, compared to controls, exhibit significantly lower resting regional cerebral blood flow (rCBF) in the prefrontal cortex (PFC). In this study, we examined the link between resting rCBF in the PFC and current depressive symptoms in methadone-maintained opiate-dependent (MM) patients with or without major depression.

METHODS

Arterial spin labeled perfusion fMRI at 3 Tesla was used to measure resting rCBF in 21 MM patients. Perfusion data were analyzed using SPM2. The relationship between Beck Depression Inventory (BDI) score and resting rCBF was examined in a single regression analysis.

RESULTS

The BDI scores ranged between 0 and 18 (m=7.0, S.D.=4.8), and 30% of the sample had mild to moderate depression symptoms according to BDI scores. A negative correlation was observed between BDI scores and relative rCBF in the bilateral ventrolateral prefrontal cortex, and middle frontal gyri.

CONCLUSIONS

The inverse relationship between prefrontal paralimbic rCBF and depression scores suggests a link between reduced fronto-limbic activity and depressive symptoms in MM patients. A significant subgroup of opiate-dependent patients has clinical or sub-clinical depression that is often undetected; our data identify brain substrates of depression symptoms that may also be a potential marker of relapse in this population. Treatment strategies targeting these brain regions may improve outcomes in depressed substance abusers.