A therapeutic dose of zolpidem reduces thalamic GABA in healthy volunteers: a proton MRS study at 4 T

A comprehensive guide to MEGA-PRESS for GABA measurement

The aim of this guideline is to provide a series of evidence-based recommendations that allow those new to using MEGA-PRESS to produce high-quality data for the measurement of GABA levels using edited magnetic resonance spectroscopy with the MEGA-PRESS sequence at 3T. GABA is the main inhibitory neurotransmitter of the central nervous system and has been increasingly studied due to its relevance in many clinical disorders of the central nervous system. MEGA-PRESS is the most widely used method for quantification of GABA at 3T, but is technically challenging and operates at a low signal-to-noise ratio. Therefore, the acquisition of high-quality MRS data relies on avoiding numerous pitfalls and observing important caveats. The guideline was developed by a working party that consisted of experts in MRS and experts in guideline development and implementation, together with key stakeholders. Strictly following a translational framework, we first identified evidence using a systematically conducted scoping literature review, then synthesized and graded the quality of evidence that formed recommendations. These recommendations were then sent to a panel of 21 world leaders in MRS for feedback and approval using a modified-Delphi process across two rounds. The final guideline consists of 23 recommendations across six domains essential for GABA MRS acquisition (Parameters, Practicalities, Data acquisition, Confounders, Quality/reporting, Post-processing). Overall, 78% of recommendations were formed from high-quality evidence, and 91% received agreement from over 80% of the expert panel. These 23 expert-reviewed recommendations and accompanying extended documentation form a readily useable guideline to allow those new to using MEGA-PRESS to design appropriate MEGA-PRESS study protocols and generate high-quality data.

Efficacy and Safety of Zolpidem for Focal Dystonia After Neurosurgical Treatments: A Retrospective Cohort Study

Although there are several reports of the significant efficacy of zolpidem for treating dystonia, zolpidem is still considered an anecdotal treatment. Here, we evaluated the efficacy and safety of zolpidem for treating residual dystonia in patients who previously received various neurosurgical treatments majorly including deep brain stimulation and radiofrequency ablation. We retrospectively reviewed medical records from January 2021 to September 2021 to identify patients with dystonia who had been prescribed zolpidem after undergoing neurosurgery. Twenty patients were enrolled in this study, including those with blepharospasm (two), tongue dystonia (four), mouth dystonia (one), spasmodic dysphonia (two), cervical dystonia (six), focal hand dystonia (three), hemidystonia (two), blepharospasm with cervical dystonia (one), and mouth dystonia with cervical dystonia (one). Single doses of zolpidem ranged between 2.5 and 10 mg, while daily dosages ranged from 10 to 30 mg. The zolpidem dose prescribed was 5–10 mg, with single and daily doses of 7 ± 2.9 and 14.5 ± 6.0 mg, respectively. With zolpidem administration, the participants' Burke-Fahn-Marsden Dystonia Rating Scale-Movement Scale score significantly improved from 8.1 ± 6.7 to 3.7 ± 2.5 (50.6% improvement, p < 0.0001). Improvements in arm dystonia, blepharospasm, and spasmodic dysphonia were observed using the Arm Dystonia Disability Scale, Jankovic Rating Scale, and Voice Handicap Index, respectively. No improvements were observed in cervical dystonia on the Toronto Western Spasmodic Torticollis Rating Scale. Drowsiness, including three cases each of mild and moderate drowsiness, was the most frequent adverse effect (30%), which persisted for 2–3 h. Transient amnesia and rapid eye movement sleep behavior disorder occurred in two patients and one patient, respectively. Although our findings suggest that zolpidem can be a valuable treatment option for patients with residual dystonia after neurosurgical treatments, the beneficial effects for cervical dystonia were limited.

Perspectives on the pharmacological management of dystonia

Introduction: Treatment of dystonia is particularly complex due to various etiologies and heterogeneous clinical manifestation, as well as different degrees of disability. In absence of causative treatment, all symptomatic therapy should be predominantly tailored to ameliorate those symptoms (motor and non/motor) that mostly affect patients' daily life and regular activities. Many different treatment options, including oral medications, neurosurgical interventions, physical and occupational therapy are available in treatment of dystonia.Areas covered: The aim of this perspective is to point out different possibilities in pharmacological management of dystonic movements. Due to pure clinical presentation, the authors concentrate mainly on the isolated dystonias, which are presented solely as dystonic movements. Combined and complex dystonias are not instructive due to compound clinical presentation and consequently, complicated treatment. The article is based on a literature search from sources including PubMed, the Cochrane Library, Web of Science, PiCarta, and PsycINFO.Expert opinion: Although dystonia therapy should be adapted according to the individual needs, severity, age, type, symptoms distribution and acceptable side-effect profile, certain principles should be followed to reach the optimal result. Furthermore, the authors believe that a better understanding of the pathophysiology of dystonia will bring with it the development of new and improved treatment approaches and medications.

Transcranial Magnetic Stimulation and H1-Magnetic Resonance Spectroscopy Measures of Excitation and Inhibition Following Lorazepam Administration

This study aimed at better understanding the neurochemistry underlying transcranial magnetic stimulation (TMS) and magnetic resonance spectroscopy (MRS) measurements as it pertains to GABAergic activity following administration of allosteric GABA_A receptor agonist lorazepam. Seventeen healthy adults (8 females, 26.0 ± 5.4 years old) participated in a double-blind, crossover, placebo-controlled study, where participants underwent TMS and MRS two hours after drug intake (placebo or lorazepam; 2.5 mg). Neuronavigated TMS measures reflecting cortical inhibition and excitation were obtained in the left primary motor cortex. Sensorimotor cortex and occipital cortex MRS data were acquired using a 3T scanner with a MEGA-PRESS sequence, allowing water-referenced [GABA] and [Glx] (glutamate + glutamine) quantification. Lorazepam administration decreased occipital [GABA], decreased motor cortex excitability and increased GABA_A-receptor mediated motor cortex inhibition (short intracortical inhibition (SICI)). Lorazepam intake did not modulate sensorimotor [GABA] and TMS measures of intra-cortical facilitation, long-interval cortical inhibition, cortical silent period, and resting motor threshold. Furthermore, higher sensorimotor [GABA] was associated with higher cortical inhibition (SICI) following lorazepam administration, suggesting that baseline sensorimotor [GABA] may be valuable in predicting pharmacological or neuromodulatory treatment response. Finally, the differential effects of lorazepam on MRS and TMS measures, with respect to GABA, support the idea that TMS measures of cortical inhibition reflect synaptic GABAergic phasic inhibitory activity while MRS reflects extrasynaptic GABA.

Multimodal neurometabolic investigation of the effects of zolpidem on leukoencephalopathy-related apathy

BACKGROUND AND PURPOSE

The symptomatic effect of zolpidem on apathy has been reported in neurological disorders such as strokes and post-anoxic brain injuries, but not in white-matter disease of the brain.

METHODS

A 38-year-old patient presenting with severe apathy related to a genetic leukoencephalopathy but showing marked improvement of apathy after taking 10 mg of zolpidem was studied. To understand what may mediate such a clinical effect, a multimodal neurometabolic approach using ¹⁸ F fluorodeoxyglucose positron emission tomography (FDG-PET) and a dedicated magnetic resonance spectroscopy (MRS) sequence for gamma aminobutyric acid (GABA) and glutamine + glutamate metabolism was undertaken.

RESULTS

Pre-zolpidem FDG-PET showed hypometabolism in the orbitofrontal cortex, dorsolateral cortex and basal ganglia compared to healthy controls. Post-zolpidem, FDG-PET displayed increased metabolism in the orbitofrontal cortex together with improvement in the emotional and auto-activation domains of apathy. There was no improvement in the cognitive domain of apathy, and no change in metabolism in the dorsolateral frontal cortex. Post-zolpidem, MRS showed increased GABA and glutamine + glutamate levels in the frontal cortex and pallidum.

CONCLUSION

Our multimodal neurometabolic study suggests that the effects of zolpidem on apathy are related to increased metabolism in the orbitofrontal cortex and basal ganglia secondary to GABA modulation. Zolpidem may improve apathy in other white-matter disorders.

Thalamic Gamma Aminobutyric Acid Level Changes in Major Depressive Disorder After a 12-Week Iyengar Yoga and Coherent Breathing Intervention

Objective: To determine if a 12-week yoga intervention (YI) was associated with increased gamma aminobutyric acid (GABA) levels and decreased depressive symptoms in participants with major depressive disorder (MDD). Methods: Subjects were randomized to a high-dose group (HDG) of three YIs a week and a low-dose group (LDG) of two YIs a week. Thalamic GABA levels were obtained using magnetic resonance spectroscopy at Scan-1 before randomization. After the assigned 12-week intervention, Scan-2 was obtained, immediately followed by a YI and Scan-3. Beck Depression Inventory II (BDI-II) scores were obtained before Scan-1 and Scan-3. Settings/Location: Screenings and interventions occurred at the Boston University Medical Center. Imaging occurred at McLean Hospital. Subjects: Subjects met criteria for MDD. Intervention: Ninety minutes of Iyengar yoga and coherent breathing at five breaths per minute plus homework. Outcome measures: GABA levels and the BDI-II. Results: BDI-II scores improved significantly in both groups. GABA levels from Scan-1 to Scan-3 and from Scan-2 to Scan-3 were significantly increased in the LDG (n = 15) and showed a trend in the total cohort. Post hoc, participants were divided into two groups based on having an increase in GABA levels at Scan-2. Increases in Scan-2 GABA levels were observed in participants whose mean time between their last YI and Scan-2 was 3.93 ± 2.92 standard deviation (SD) days, but not in those whose mean time between their last YI and Scan-2 was 7.83 ± 6.88 SD. Conclusions: This study tentatively supports the hypothesis that one of the mechanisms through which yoga improves mood is by increasing the activity of the GABA system. The observed increase in GABA levels following a YI that was no longer observed 8 days after a YI suggests that the associated increase in GABA after a YI is time limited such that at least one YI a week may be necessary to maintain the elevated GABA levels.

Zolpidem Use and Suicide Death in South Korea: A Population-Based Case-Control Study

OBJECTIVE

To investigate whether zolpidem use is associated with suicide death in adults.

METHOD

We conducted a case-control study using the National Health Insurance Service-National Sample Cohort (NHIS-NSC) database. Cases were adults with a suicide record (ICD-10 codes; X-60-X84, Y87.0) between January 1, 2004 and December 31, 2013. 10 Controls were matched to each case by age, sex, index year, region, income level, and health insurance type. Zolpidem use during 2 years before suicide was quantified. Adjusted odd ratios (aORs) with 95% confidence intervals (CIs) were estimated using conditional logistic regression.

RESULTS

The percentage of zolpidem users was significantly higher in cases (451 of 1,928 [23.4%]) than in controls (832 of 18,404 [4.5%]). After controlling for potential confounders, zolpidem use was significantly associated with suicide (aORs, 2.09; 95% CI, 1.74-2.52). Dose-response relationships were observed (for trend, p < .0001). Consistent findings were observed when analyses were restricted to suicide death (aORs, 2.08; 95% CI, 1.73-2.51) and nonmedication poisoning suicide death cases (aORs, 2.10; 95% CI, 1.74-2.53).

CONCLUSIONS

We found a significant and positive association between zolpidem use and suicide. Zolpidem should be prescribed cautiously and with due caution of increased suicide risk.

Neuroimaging insights into the link between depression and Insomnia: A systematic review

BACKGROUND

Insomnia is a common symptom of Major Depressive Disorder (MDD) and genome-wide association studies pointed to their strong genetic association. Although the prevalence of insomnia symptoms in MDD is noticeable and evidence supports their strong bidirectional association, the number of available neuroimaging findings on patients of MDD with insomnia symptoms is limited. However, such neuroimaging studies could verily improve our understanding of their shared pathophysiology and advance corresponding theories.

METHODS

Based on the preferred reporting items for systematic reviews and meta-analysis (PRISMA) guideline, we have conducted a literature search using PubMed, EMBASE, and Scopus databases and systematically explored 640 studies using various neuroimaging modalities in MDD patients with different degrees of insomnia symptoms.

RESULTS

Despite inconsistencies, current findings from eight studies suggested structural and functional disturbances in several brain regions including the amygdala, prefrontal cortex and anterior cingulate cortex and insula. The aberrant functional connectivity within and between the main hubs of the salience and default mode networks could potentially yield new insights into the link between MDD and insomnia, which needs further assessment.

LIMITATIONS

The number of studies reviewed herein is limited. The applied methods for assessing structural and functional neural mechanisms of insomnia and depression were variable.

CONCLUSION

Neuroimaging methods demonstrated the overlapping underlying neural mechanisms between MDD and insomnia. Future studies may facilitate better understanding of their pathophysiology to allow development of specific treatment.

Zolpidem for the Treatment of Dystonia

Background and Purpose: There are recent reports of zolpidem being effective for the treatment of a variety of movement disorders, due to its action on the gamma-aminobutyric acid A receptors in the thalamus, subthalamic nucleus, and globus pallidus, hence facilitating inhibitory pathways in the basal ganglia motor loop. Its beneficial effects have been described for Parkinson's disease and other related disorders. The objective of this study was to assess the therapeutic effects of zolpidem for various types of dystonia.

Methods: We conducted a literature search using MEDLINE via PubMed, Cochrane Library, EMBASE, Scopus, and Google Scholar.

Results: There were no randomized controlled trials. The literature included 6 case reports, 4 case series, and 1 non-randomized, non-controlled interventional trial. Overall, 49 adult participants (range 1–34 participants) with a mean age of 49.5 years were treated. Regardless of the dystonia subtype, a single dose of zolpidem at 10 mg causes improvement of symptoms for a mean duration of 3.4 h until patient returns to baseline. The main adverse effect noted was drowsiness, which was dose-dependent.

Conclusion: While the current available literature suggests that zolpidem may be an effective pharmacologic option for treating dystonia, however the quality of evidence remains limited. Larger sample size, methodological consistency, and randomized controlled trials with long-term patient follow-ups are necessary to come up with definitive conclusion.

γ-aminobutyric acid as a metabolite: Interpreting magnetic resonance spectroscopy experiments

The current rise in the prevalence of magnetic resonance spectroscopy experiments to measure γ-aminobutyric acid in the living human brain is an exciting and productive area of research. As research spreads into clinical populations and cognitive research, it is important to fully understand the source of the magnetic resonance spectroscopy signal and apply appropriate interpretation to the results of the experiments. γ-aminobutyric acid is present in the brain not only as a neurotransmitter, but also in high intracellular concentrations, both as a transmitter precursor and a metabolite. γ-aminobutyric acid concentrations measured by magnetic resonance spectroscopy are not necessarily implicated in neurotransmission and therefore may reflect a very different brain activity to that commonly suggested. In this perspective, we examine some of the considerations to be taken in the interpretation of any γ-aminobutyric acid signal measured by magnetic resonance spectroscopy.

The effects of AMPA blockade on the spectral profile of human early visual cortex recordings studied with non-invasive MEG

The generation of gamma-band (>30 Hz) cortical activity is thought to depend on the reciprocal connections of excitatory glutamatergic principal cells with inhibitory GABAergic interneurons. Both in vitro and in vivo animal studies have shown that blockade of glutamatergic α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors reduces the amplitude of gamma-band activity. In this registered report, we hypothesised that similar effects would be observed in humans following administration of perampanel, a first in class AMPA antagonist, used in the treatment of epilepsy. In a single-blind placebo-controlled crossover study, 20 healthy male participants completed two study days. On one day participants were given a 6 mg dose of perampanel and on the other an inactive placebo. magnetoencephalography (MEG) recordings of brain activity were taken before and two hours after drug administration, with activity in the visual cortex probed using a stimulation protocol known to induce gamma-band activity in the primary visual cortex. As hypothesised, our results indicated a decrease in gamma-band amplitudes following perampanel administration. The decreases in gamma-band amplitudes observed were temporally restricted to the early time-period of stimulus presentation (up to 400 msec) with no significant effects observed on early evoked responses or alpha rhythms. This suggests that the early time-window of induced visual gamma-band activity, thought to reflect input to the visual cortex from the lateral geniculate nucleus, is most sensitive to AMPA blocking drugs.

Zolpidem increases GABA in depressed volunteers maintained on SSRIs

Individuals with major depressive disorder (MDD) often use hypnotics like zolpidem (Ambien(®)) to improve sleep in addition to their selective serotonin reuptake inhibitor (SSRI) regimen. SSRIs act in part to restore disrupted GABAergic activity, but benzodiazepines and related drugs have been shown to lower GABA in a way that may be counter to these therapeutic effects. The present within-subject, single-blind, placebo-controlled study measured changes in GABA in the anterior cingulate (ACC) and thalamus of volunteers maintained on SSRIs for the treatment of MDD (n=14) following zolpidem (10mg) administration. In addition to neurochemical measurements obtained using proton magnetic resonance spectroscopy ((1)H MRS) at 4 T, a series of questionnaires were administered to assess subjective effects associated with acute zolpidem exposure. Zolpidem elevated GABA levels in both voxels of interest (P<0.05) in the depressed participants, which could imply normalization, given the lower baseline levels associated with depression. The subjective drug experience in the depressed cohort was similar to that reported previously by healthy volunteers, and no relationships existed between GABA increases and the observed behavioral effects. Aside from treating insomnia, using zolpidem in the presence of SSRIs may have some unidentified therapeutic effects for depressed individuals.

New perspectives on using brain imaging to study CNS stimulants

While the recent application of brain imaging to study CNS stimulants has offered new insights into the fundamental factors that contribute to their use and abuse, many gaps remain. Brain circuits that mediate pleasure, dependence, craving and relapse are anatomically, neurophysiologically and neurochemically distinct from one another, which has guided the search for correlates of stimulant-seeking and taking behavior. However, unlike other drugs of abuse, metrics for tolerance and physical dependence on stimulants are not obvious. The dopamine theory of stimulant abuse does not sufficiently explain this disorder as serotonergic, GABAergic and glutamagergic circuits are clearly involved in stimulant pharmacology and so tracking the source of the "addictive" processes must adopt a more multimodal, multidisciplinary approach. To this end, both anatomical and functional magnetic resonance imaging (MRI), MR spectroscopy (MRS) and positron emission tomography (PET) are complementary and have equally contributed to our understanding of how stimulants affect the brain and behavior. New vistas in this area include nanotechnology approaches to deliver small molecules to receptors and use MRI to resolve receptor dynamics. Anatomical and blood flow imaging has yielded data showing that cognitive enhancers might be useful adjuncts in treating CNS stimulant dependence, while MRS has opened opportunities to examine the brain's readiness to accept treatment as GABA tone normalizes after detoxification. A desired outcome of the above approaches is being able to offer evidence-based rationales for treatment approaches that can be implemented in a more broad geographic area, where access to brain imaging facilities may be limited. This article is part of the Special Issue entitled 'CNS Stimulants'.

Contributions of magnetic resonance spectroscopy to understanding development: potential applications in the study of adolescent alcohol use and abuse

A growing body of research has documented structural and functional brain development during adolescence, yet little is known about neurochemical changes that occur during this important developmental period. Magnetic resonance spectroscopy (MRS) is a well-developed technology that permits the in vivo quantification of multiple brain neurochemicals relevant to neuronal health and functioning. However, MRS technology has been underused in exploring normative developmental changes during adolescence and the onset of alcohol and drug use and abuse during this developmental period. This review begins with a brief overview of normative cognitive and neurobiological development during adolescence, followed by an introduction to MRS principles. The subsequent sections provide a comprehensive review of the existing MRS studies of development and cognitive functioning in healthy children and adolescents. The final sections of this article address the potential application of MRS in identifying neurochemical predictors and consequences of alcohol use and abuse in adolescence. MRS studies of adolescent populations hold promise for advancing our understanding of neurobiological risk factors for psychopathology by identifying the biochemical signatures associated with healthy brain development, as well as neurobiological and cognitive correlates of alcohol and substance use and abuse.

GABAergic contributions to alcohol responsivity during adolescence: insights from preclinical and clinical studies

There is a considerable body of literature demonstrating that adolescence is a unique age period, which includes rapid and dramatic maturation of behavioral, cognitive, hormonal and neurobiological systems. Most notably, adolescence is also a period of unique responsiveness to alcohol effects, with both hyposensitivity and hypersensitivity observed to the various effects of alcohol. Multiple neurotransmitter systems are undergoing fine-tuning during this critical period of brain development, including those that contribute to the rewarding effects of drugs of abuse. The role of developmental maturation of the γ-amino-butyric acid (GABA) system, however, has received less attention in contributing to age-specific alcohol sensitivities. This review integrates GABA findings from human magnetic resonance spectroscopy studies as they may translate to understanding adolescent-specific responsiveness to alcohol effects. Better understanding of the vulnerability of the GABA system both during adolescent development, and in psychiatric conditions that include alcohol dependence, could point to a putative mechanism, boosting brain GABA, that may have increased effectiveness for treating alcohol use disorders.

Frontal lobe γ-aminobutyric acid levels during adolescence: associations with impulsivity and response inhibition

BACKGROUND

The brain undergoes major remodeling during adolescence, resulting in improved cognitive control and decision-making and reduced impulsivity, components of behavior mediated in part by the maturing frontal lobe. γ-Aminobutyric acid (GABA), the main inhibitory neurotransmitter system, also matures during adolescence, with frontal lobe GABA receptors reaching adult levels late in adolescence. Thus, the objective of this study was to characterize in vivo developmental differences in brain GABA levels.

METHODS

Proton magnetic resonance spectroscopy was used at 4 T to acquire metabolite data from the anterior cingulate cortex (ACC) and the parieto-occipital cortex (POC) in adolescents (n=30) and emerging adults (n = 20).

RESULTS

ACC GABA/creatine (Cr) levels were significantly lower in adolescents relative to emerging adults, whereas no age differences were observed in the POC. Lower ACC GABA/Cr levels were significantly associated with greater impulsivity and worse response inhibition, with relationships being most pronounced for ACC GABA/Cr and No-Go response inhibition in adolescent males.

CONCLUSIONS

These data provide the first human developmental in vivo evidence confirming frontal lobe GABA maturation, which was linked to impulsiveness and cognitive control. These findings suggest that reduced GABA may be an important neurobiological mechanism in the immature adolescent brain, contributing to the reduced yet rapidly developing ability to inhibit risky behaviors and to make suboptimal decisions, which could compromise adolescent health and safety.

GABA-based evaluation of neurologic conditions: MR spectroscopy

SUMMARY

GABA serves as a major neurotransmitter of the brain and functions mainly to inhibit neural excitatory activity. Disruption of the GABAergic processes appears to occur in various neurologic and psychiatric conditions, including epilepsy, mood disorders, motor disorders such as focal dystonia and stiff-person syndrome, sleep disorders, neuroplasticity, and drug and alcohol dependence. These concentration differences may be ascertained by using MR spectroscopy to provide information on the concentration of different metabolites. This review briefly discusses advances in MR spectroscopy methods and explores the application of this technique to detect changes in GABA due to disease processes and medication-induced effects.

Reduced γ-aminobutyric acid in occipital and anterior cingulate cortices in primary insomnia: a link to major depressive disorder?

Insomnia is closely related to major depressive disorder (MDD) both cross-sectionally and longitudinally, and as such, offers potential opportunities to refine our understanding of the neurobiology of both sleep and mood disorders. Clinical and basic science data suggest a role for reduced γ-aminobutyric acid (GABA) in both MDD and primary insomnia (PI). Here, we have utilized single-voxel proton magnetic spectroscopy (1H-MRS) at 4 Tesla to examine GABA relative to total creatine (GABA/Cr) in the occipital cortex (OC), anterior cingulate cortex (ACC), and thalamus in 20 non-medicated adults with PI (12 women) and 20 age- and sex-matched healthy sleeper comparison subjects. PI subjects had significantly lower GABA/Cr in the OC (p=0.0005) and ACC (p=0.03) compared with healthy sleepers. There was no significant difference in thalamic GABA/Cr between groups. After correction for multiple comparisons, GABA/Cr did not correlate significantly with insomnia severity measures among PI subjects. This study is the first to demonstrate regional reductions of GABA in PI in the OC and ACC. Reductions in GABA in similar brain regions in MDD using 1H-MRS suggest a common reduction in cortical GABA among PI and mood disorders.

Effects of prolonged-release melatonin and zolpidem on postural stability in older adults

OBJECTIVES

A prolonged-release formulation of melatonin (PR-M) is indicated for insomnia in patients aged 55 years and older. Because hypnotics result in impairments of body sway, it was important to evaluate the effect of 2 mg PR-M on postural stability in older adults at night.

METHODS

Twenty-four healthy volunteers (12 women, 12 men, aged 55-64 years) completed a randomized, double-blind, single-dose, three-way crossover study of postural stability of PR-M 2 mg, zolpidem 10 mg (active control) or placebo. Subjects were tested for body sway 30 min before, 1.5 and 4 h after dosing. Parameters tested were the area of the 95% confidence ellipse enclosing the center of pressure (COP; [A95]) and COP path length.

RESULTS

Zolpidem significantly increased the A95 (both eyes conditions at all time points) and path length of COP. PR-M had no effect on A95 (both "eyes closed" and "eyes open" conditions at all time points) compared with placebo and increased COP path length by 10% at 4 h post-dose in open but not closed eyes condition. No serious adverse events were observed.

CONCLUSIONS

In older adults, evening PR-M intake did not impair postural stability during the night. The postural instability with zolpidem demonstrated assay sensitivity and validated the outcome.

Efficacy of zolpidem for dystonia: a study among different subtypes

Although there are some newly developed options to treat dystonia, its medical treatment is not always satisfactory. Zolpidem, an imidazopyridine agonist with a high affinity on benzodiazepine subtype receptor BZ1 (ω1), was found to improve clinical symptoms of dystonia in a limited number of case reports. To investigate what subtype of dystonia is responsive to the therapy, we conducted an open label study to assess the efficacy of zolpidem (5–20 mg) in 34 patients suffering from miscellaneous types of dystonia using the Burke–Fahn–Marsden Dystonia Rating Scale (BFMDRS). Patients were entered into the study if they had been refractory to other medications as evaluated by BFMDRS (no change in the previous two successive visits). After zolpidem therapy, the scores in the patients as a whole were decreased from 7.2 ± 7.9 to 5.5 ± 5.0 (P = 0.042). Patients with generalized dystonia, Meige syndrome/blepharospasm, and hand dystonia improved in the scale by 27.8, 17.8, and 31.0%, respectively, whereas no improvement was found in cervical dystonia patients. Overall response rate among patients were comparable to that of trihexyphenidyl. Zolpidem may be a therapeutic option for generalized dystonia, Meige syndrome, and hand dystonia including musician’s. Drowsiness was the dose-limiting factor.

Anterior cingulate proton spectroscopy glutamate levels differ as a function of smoking cessation outcome

BACKGROUND

Cigarette smoking is the leading preventable cause of death. Unfortunately, the majority of smokers who attempt to quit smoking relapse within weeks. Abnormal dorsal anterior cingulate cortex (dACC) function may contribute to tobacco smoking relapse vulnerability. Growing evidence suggests that glutamate neurotransmission is involved in mediating nicotine dependence. We hypothesized that prior to a cessation attempt, dACC glutamate levels would be lower in relapse vulnerable smokers.

METHODS

Proton magnetic resonance spectra (MRS) were obtained from dACC and a control region, the parieto-occipital cortex (POC), using two-dimensional J-resolved MRS at 4T and analyzed using LCModel. Nine nicotine-dependent women were scanned prior to making a quit attempt. Subjects then were divided into two groups; those able to maintain subsequent abstinence aided by nicotine replacement therapy (NRT) and those who slipped while on NRT (smoked any part of a cigarette after attaining at least 24h of abstinence).

RESULTS

Slip subjects exhibited significantly reduced dACC MRS glutamate (Glu/Cr) levels (p<0.03) compared to abstinent subjects. This effect was not observed in the POC control region.

CONCLUSIONS

Our preliminary findings suggest that dACC Glu levels as measured with MRS may help identify and/or be a biomarker for relapse vulnerable smokers. Future research following up on these findings may help clarify the role of dACC Glu in smoking dependence that may lead to new treatment strategies.

Modest abuse-related subjective effects of zolpidem in drug-naive volunteers

Recent case reports suggest that the short-acting benzodiazepine-like hypnotic, zolpidem, may have abuse potential among individuals who have no personal history of abusing drugs or alcohol, particularly at doses higher than those recommended for treating insomnia. This study recruited drug-naive volunteers to assess the subjective effects of multiple doses of zolpidem (0, 5, 10, or 20 mg) administered in a within-subject double-blind design. Participants (n=11) answered computerized questionnaires (Addiction Research Center Inventory, visual analog scales, and a hypothetical Drug versus Money Choice) to address the hypothesis that a supratherapeutic dose (20 mg) would increase ratings of abuse-related subjective effects, while lower therapeutic doses (5 and 10 mg) would not. Although participants rated some effects as negative at 10 and 20 mg, the highest dose engendered predominantly positive abuse-like effects such as 'High', 'Like', and 'Good Effects'. However, no dose of zolpidem was chosen over money ($0.35-$10) when participants made hypothetical choices between them. Results suggest that although individuals without a drug abuse history are not inclined to choose zolpidem when presented with an alternative reinforcer such as money, it may possess moderate abuse potential that limits its clinical utility.

The acute and late CNS glutamine response to benzodiazepine challenge: a pilot pharmacokinetic study using proton magnetic resonance spectroscopy

Benzodiazepines (BZs), which are typically used as anxiolytics, act by modulating inhibitory signaling through gamma-aminobutyric acid A (GABA)(A) receptors. Functionally, the inhibitory effects of GABA may be counterbalanced by the excitatory effects of glutamate (Glu) as the two neurotransmitter systems are metabolically linked through their synthetic intermediate glutamine (Gln). The primary aim of this study was to determine whether the effects of different BZs on the GABA and Glu/Gln systems would vary according to the pharmacokinetics of the different drugs. Proton magnetic resonance spectroscopy ((1)H MRS) was used to measure GABA, Glu, and Gln levels in six healthy adult volunteers 1h and 10 h following immediate release alprazolam, extended release alprazolam, clonazepam, or placebo. Although there were no differences between 1 and 10 h when the drugs were examined individually, there was a trend level difference between the 1- and 10-h effects of BZs on Gln when the BZs were combined. In post-hoc comparisons, the difference in the Gln to creatine (Cr) ratio was 0.04 for the BZs versus placebo at 1h and 0.01 at 10h following the administration of drug (t(11)=2.49, P=0.03 1 h; t(10)=0.65, P=0.53 10 h; no correction for multiple comparisons). An increase in Gln/Cr at 1 h post-BZ is consistent with a functionally synergistic relationship between Glu/Gln and GABA in the brain. It also suggests that MRS may have sufficient sensitivity to detect acute drug effects.

Neurochemistry of drug action: insights from proton magnetic resonance spectroscopic imaging and their relevance to addiction

Proton magnetic resonance spectroscopy ((1)H MRS) is a noninvasive imaging technique that permits measurement of particular compounds or metabolites within the tissue of interest. In the brain, (1)H MRS provides a snapshot of the neurochemical environment within a defined volume of interest. A search of the literature demonstrates the widespread utility of this technique for characterizing tumors, tracking the progress of neurodegenerative disease, and for understanding the neurobiological basis of psychiatric disorders. As of relatively recently, (1)H MRS has found its way into substance abuse research, and it is beginning to become recognized as a valuable complement in the brain imaging toolbox that also contains positron emission tomography, single-photon-emission computed tomography, and functional magnetic resonance imaging. Drug abuse studies using (1)H MRS have identified several biochemical changes in the brain. The most consistent alterations across drug class were reductions in N-acetylaspartate and elevations in myo-inositol, whereas changes in choline, creatine, and amino acid transmitters also were abundant. Together, the studies discussed herein provide evidence that drugs of abuse may have a profound effect on neuronal health, energy metabolism and maintenance, inflammatory processes, cell membrane turnover, and neurotransmission, and these biochemical changes may underlie the neuropathology within brain tissue that subsequently gives rise to the cognitive and behavioral impairments associated with drug addiction.