Study design: Literature review. Objectives: To map traumatic spinal cord injury (TSCI) globally and provide a framework for an ongoing repository of data for prevention. Setting: An initiative of the ISCoS Prevention Committee. Methods: The results obtained from the search of Medline/Embase using search phrases: TSCI incidence, aetiology, prevalence and survival were analysed. Stratification of data into green/yellow/red quality 'zones' allowed comparison between data. Results: Reported global prevalence of TSCI is insufficient (236-1009 per million). Incidence data was comparable only for regions in North America (39 per million), Western Europe (15 per million) and Australia (16 per million). The major cause of TSCI in these regions involves four-wheeled motor vehicles, in contrast to South-east Asia where two-wheeled (and non-standard) road transport predominates. Southern Asia and Oceania have falls from rooftops and trees as the primary cause. Highfall rates are also seen in developed regions with aged populations (Japan/Western Europe). Violence/ self-harm (mainly firearm-related) was higher in North America (15%) than either Western Europe (6%) or Australia (2%). Sub-Saharan Africa has the highest reported violence-related TSCI in the world (38%). Rates are also high in north Africa/Middle East (24%) and Latin America (22%). Developed countries have significantly improved TSCI survival compared with developing countries, particularly for tetraplegia. Developing countries have the highest 1-year mortality rates and in some countries in sub-Saharan Africa the occurrence of a spinal injury is likely to be a fatal condition within a year. Conclusion: Missing prevalence and insufficient incidence data is a recurrent feature of this review. The piecemeal approach to epidemiological reporting of TSCI, particularly failing to include sound regional denominators has exhausted its utility. Minimum data collection standards are required.

Blockade of brain m-opioid receptor (m-OR) and d-opioid receptor (d-OR) was investigated in recently abstinent alcohol-dependent subjects (N ¼ 21) maintained on naltrexone. Subjects completed a 19-day inpatient protocol, which included alcohol abstinence followed by naltrexone treatment (50 mg) on days 15-19. Blood samples were collected after the first administration of naltrexone to evaluate serum levels of naltrexone and 6-b-naltrexol. Regional brain m-OR binding potential (BP) and d-OR K i was measured using [ 11 C]carfentanil (CAR) positron emission tomography (PET) and [11 C]methyl naltrindole ([ 11 C]MeNTI) PET, respectively, before (day 5) and during naltrexone treatment (day 18). Naltrexone inhibition of [ 11 C]CAR BP was near maximal across all brain regions of interest with little variability across subjects (mean + SD% inhibition ¼ 94.9 + 4.9%). Naltrexone only partially inhibited the [ 11 C]MeNTI K i and there was more variability across subjects (mean + SD% inhibition ¼ 21.1 + 14.49%). Peak serum levels of naltrexone were positively correlated with % inhibition of d-OR K i in neocortex and basal ganglia. Peak serum levels of naltrexone were not correlated with % inhibition of m-OR BP. Peak levels of 6-b-naltrexol were not significantly correlated with % inhibition of m-OR BP or d-OR K i . Thus, the FDA recommended therapeutic dose of naltrexone was sufficient to produce near complete inhibition of the m-OR in recently abstinent alcohol dependent subjects. The lower percent inhibition of d-OR and greater variability in d-OR blockade by naltrexone across subjects may contribute to individual differences in treatment outcomes to naltrexone. Further investigations on the relationship between individual differences in d-OR blockade by naltrexone and clinical outcomes should be explored.

Drug reinforcement may represent the primary behavioral-pharmacological mechanism underlying two types of problematic use of benzodiazepines--recreational abuse by polydrug abusers and inappropriate chronic use by patients. High dose polydrug abuse for the purpose of getting high is readily recognized as a significant social problem. Inappropriate chronic benzodiazepine use is more subtle but relatively common: for anxiolytics, 36% of past-year users (3% of the adult population in the US) report using these drugs for 4 consecutive months or longer. The risks of such long-term use are much better documented than the benefits. This paper provides a current review of various problems that have been identified with the long-term use and the recreational abuse of benzodiazepines, including memory impairment, risk of accidents, falls and hip fractures in the elderly, a withdrawal syndrome, brain damage, overuse in the elderly, overuse by chronic pain patients, overuse by alcoholics and recreational abuse among alcoholics and polydrug abusers. A comprehensive review of the literature on benzodiazepine reinforcing effects in humans and laboratory animals is also provided. Drug self-administration studies in humans and laboratory animals provide models of both types of problematic benzodiazepine use. Recreational abuse of benzodiazepines has been modeled in human research with polydrug abusers and in laboratory animal studies, which show that the reinforcing effect of benzodiazepines is intermediate relative to other sedative compounds and is increased in subjects with histories of previous sedative drug self-administration. The problem of inappropriate long-term use of benzodiazepines by people without histories of drug abuse has been partially modeled in human studies showing that benzodiazepines function as reinforcers in subjects with anxiety, insomnia, and histories of moderate alcohol consumption, and in preclinical studies showing stable, low-rate benzodiazepine self-injection with concurrent physical dependence under conditions of continuous availability. Both human and animal research suggests that the drug history and current behavioral context may be important in the establishment of benzodiazepines as reinforcers. Limited human and animal research provides little support for the common belief that physical dependence enhances benzodiazepine reinforcement.

A continuing challenge for preclinical research on anxiolytic drugs is to capture the affective dimension that characterizes anxiety and aggression, either in their adaptive forms or when they become of clinical concern. Experimental protocols for the preclinical study of anxiolytic drugs typically involve the suppression of conditioned or unconditioned social and exploratory behavior (e.g., punished drinking or social interactions) and demonstrate the reversal of this behavioral suppression by drugs acting on the benzodiazepine-GABAA complex. Less frequently, aversive events engender increases in conditioned or unconditioned behavior that are reversed by anxiolytic drugs (e.g., fear-potentiated startle). More recently, putative anxiolytics which target 5-HT receptor subtypes produced effects in these traditional protocols that often are not systematic and robust. We propose ethological studies of vocal expressions in rodents and primates during social confrontations, separation from social companions, or exposure to aversive environmental events as promising sources of information on the affective features of behavior. This approach focuses on vocal and other display behavior with clear functional validity and homology. Drugs with anxiolytic effects that act on the benzodiazepine-GABAA receptor complex and on 5-HT1A receptors systematically and potently alter specific vocalizations in rodents and primates in a pharmacologically reversible manner; the specificity of these effects on vocalizations is evident due to the effectiveness of low doses that do not compromise other physiological and behavioral processes. Antagonists at the benzodiazepine receptor reverse the effects of full agonists on vocalizations, particularly when these occur in threatening, startling and distressing contexts. With the development of antagonists at 5-HT receptor subtypes, it can be anticipated that similar receptor-specificity can be established for the effects of 5-HT anxiolytics.

Background The endogenous opioid system plays a significant role in alcohol dependence. The goal of the current study was to investigate regional brain mu opioid receptor (MOR) and delta opioid receptor (DOR) availability in recently abstinent alcohol-dependent and age-matched healthy control men and women with Positron Emission Tomography (PET) imaging. Methods Alcohol dependent subjects completed an inpatient protocol, which included medically supervised withdrawal and PET imaging on day 5 of abstinence. Control subjects completed PET imaging following an overnight stay. PET scans with the MOR selective ligand [11C]carfentanil (CFN) were completed in 25 alcohol dependent and 30 control subjects. Most of these same subjects (20 alcohol dependent and 18 controls) also completed PET scans with the DOR selective ligand [11C]methyl-naltrindole (MeNTL). Results Volume of interest and statistical parametric mapping analyses indicated that alcohol dependent subjects had significantly higher [11C]CFN binding potential (BPND) than healthy controls in multiple brain regions including the ventral striatum when adjusting for age, gender and smoking status. There was an inverse relationship between [11C]CFN BPND and craving in several brain regions in alcohol dependent subjects. Groups did not differ in [11C]MeNTL BPND; however, [11C]MeNTL BPND in caudate was positively correlated with recent alcohol drinking in alcohol dependent subjects. Conclusions Our observation of higher [11C]CFN BPND in alcohol dependent subjects can result from up regulation of MOR and/or reduction in endogenous opioid peptides following long-term alcohol consumption, dependence and/or withdrawal. Alternatively, the higher [11C]CFN BPND in alcohol dependent subjects may be an etiological difference that predisposed these individuals to alcohol dependence or may have developed as a result of increased exposure to childhood adversity, stress and other environmental factors known to increase MOR. Although the direction of group differences in [11C]MeNTL BPND was similar in many brain regions, differences did not achieve statistical significance, perhaps as a result of our limited sample size. Additional research is needed to further clarify these relationships. The finding that alcohol dependent subjects had higher [11C]CFN BPND is consistent with a prominent role of the MOR in alcohol dependence.

Over 300,000 individuals enter treatment for cannabis use disorders (CUDs) in the U.S. annually. Cannabis withdrawal is associated with poor CUD treatment outcomes, but no prior studies have examined sex differences in withdrawal among treatment-seeking cannabis users. Treatment-seeking cannabis users (45 women and 91 men) completed a Marijuana Withdrawal Checklist (MWC) at treatment intake to retrospectively characterize withdrawal symptoms experienced during their most recent quit attempt. Composite Withdrawal Discomfort Scale (WDS) scores were calculated using the 14 items on the MWC that correspond to valid cannabis withdrawal symptoms described in DSM-5. Demographic and substance use characteristics, overall WDS scores, and scores on individual WDS symptoms were compared between women and men. Women had higher overall WDS scores than men, and women had higher scores than men on six individual symptoms in two domains, mood symptoms (irritability, restlessness, increased anger, violent outbursts) and gastrointestinal symptoms (nausea, stomach pain). Follow-up analyses isolating the incidence and severity of WDS symptoms demonstrated that women generally reported a higher number of individual withdrawal symptoms than men, and that they reported experiencing some symptoms as more severe. This is the first report to demonstrate that women seeking treatment for CUDs may experience more withdrawal then men during quit attempts. Prospective studies of sex differences in cannabis withdrawal are warranted.

The use of nonhuman primates (NHP) is invaluable for drug abuse research. The laboratory animals most closely related to humans are NHP. The phylogeny, anatomy, physiology, neurochemistry, and behavior of NHP are more similar to humans than other laboratory species. There is now an extensive body of literature documenting the neuroanatomical, neurochemical, and neuropharmacological similarities between NHP and humans and the differences between NHP and other laboratory species in dopamine, norepinephrine, serotonin, opioid, and gamma aminobutyric acid systems. Comprehensive studies comparing pharmacokinetics in humans, monkeys, dogs, and rats have shown that data in monkeys are the most predictive of human pharmacokinetic parameters. The long life span and extended adolescent period for NHP permits intensive, long-term investigations and the use of within-subject experimental designs similar to those used in human laboratory studies. Within-subject designs require fewer subjects than standard between-group designs and permit the careful evaluation of individual differences. NHP have been used extensively in drug abuse research for over 40 years and have provided useful information on the behavioral processes associated with drug abuse and addiction as well as drug abuse liability in humans. This review focuses on important species differences between rodents and NHP and on the value of NHP in bridging the gap between rodents and humans to enhance the ability to generalize preclinical findings to human drug abuse.

Alcohol self-administration and consumption were sensitive to increases in response requirement and duration of alcohol abstinence, while seeking was only enhanced by duration of alcohol abstinence. This animal model may be useful to further examine the interactions between environmental cues and behaviors associated with seeking and consumption of alcohol and to evaluate the efficacy of potential alcohol treatment drugs on these behaviors.