Effect of drugs of abuse on social behaviour

Sex differences in the social motivation of rats: Insights from social operant conditioning, behavioural economics, and video tracking

BACKGROUND

Social behaviour plays a key role in mental health and wellbeing, and developing greater understanding of mechanisms underlying social interaction-particularly social motivation-holds substantial transdiagnostic impact. Common rodent behavioural assays used to assess social behaviour are limited in their assessment of social motivation, whereas the social operant conditioning model can provide unique and valuable insights into social motivation. Further characterisation of common experimental parameters that may influence social motivation within the social operant model, as well as complementary methodological and analytical approaches, are warranted.

METHODS

This study investigated the effects of biological sex, housing condition, and time-of-day, on social motivation using the social operant model. This involved training rats to lever press (FR1) for 60-s access to a social reward (same-sex conspecific stimulus). Subjects were male and female Wistar rats, housed under individual or paired conditions, and sessions were conducted either in the mid-late light phase (ZT6-10) or early-mid dark phase (ZT13-17). A behavioural economics approach was implemented to measure social demand and the influence of stimulus partner sex (same- vs. opposite-sex stimulus) on social operant responding. Additionally, video tracking analyses were conducted to assess the degree of convergence between social appetitive and consummatory behaviours.

RESULTS

Biological sex, housing conditions, the interaction between sex and housing, and stimulus partner sex potently influenced social motivation, whereas time-of-day did not. Behavioural economics demonstrated that sex, housing, and their interaction influence both the hedonic set-point and elasticity of social demand. Video analysis of social interaction during social operant sessions revealed that social appetitive and consummatory behaviours are not necessarily convergent, and indicate potential social satiety. Lastly, oestrus phase of female experimental and stimulus rats did not impact social motivation within the model.

CONCLUSIONS

Social isolation-dependent sex differences exist in social motivation for rats, as assessed by social operant conditioning. The social operant model represents an optimal preclinical assay that comprehensively evaluates social motivation and offers a platform for future investigations of neurobiological mechanisms underlying sex differences in social motivation. These findings highlight the importance of continued consideration and inclusion of sex as a biological variable in future social operant conditioning studies. Humans are social creatures-our everyday interactions with others and the support this provides play a key role in our wellbeing. For those experiencing mental health conditions, people's motivation to engage with others can wane, which can lead them to withdraw from those who support them. Therefore, to develop better treatment strategies for these conditions, we need to gain a deeper understanding of social motivation. Studying social behaviour in animals can facilitate this investigation of social motivation as it allows for a causal understanding of underlying neurobiology that is not possible in human experiments. An optimal way to study social motivation in animals is using the social operant conditioning model, where rats learn to press a lever that opens a door and allows them to interact with another rat for a short time. This study characterised the social operant model by testing whether sex, housing conditions, time-of-day, and the sex of the stimulus partner influence rats' motivation to seek interaction with another rat. We found that female rats were more socially motivated than males, and that rats living alone were more motivated than those living with another rat; interestingly, this effect of housing affected females more than males. Regardless of sex, rats were more motivated to interact with a rat of the opposite sex. These findings provide insights into sex differences in social motivation in rats and new insights into the social operant model which will help guide future research into social motivation and other mental health conditions.

Modulation of social and depression behaviors in cholestatic and drug-dependent mice: possible role of opioid receptors

Objectives

Social behavior, a set of motivating activities critical for survival, is disturbed in cholestasis conditions and many substance abusers as well as psychiatric disorders. The documented loss of social interest in cholestatic patients may be associated with depressive symptoms. Interestingly, the endogenous opioid system is involved in the modulation of depression.

Methods in this research

, we assessed the effect of cholestasis and drug dependence on social and depression behaviors using the Three-Chamber Paradigm Test, Forced Swim Test (FST), and Tail Suspension Test (TST) as well as Open Field Test (OFT) in male NMRI mice.

Results

The results indicated that alone administration of morphine and tramadol, as well as co-administration of them, increased social motivation and novelty but decreased depression in bile duct ligated mice. Whereas, alone administration of naloxone (a µ-opioid receptor antagonist) and co-administration of it along with morphine and tramadol decreased social motivation and novelty while enhanced depression in the sham-operated and bile duct ligated mice. These administrations of drugs did not change locomotor activity compared to the control group.

Conclusion

In conclusion, it appears that (i) both cholestasis and drug dependence impaired social motivation behavior, as well as induced depression-like behavior in the bile duct, ligated mice, (ii) alone administration of morphine and tramadol as well as co-treatment of them may protect against cholestasis and drug dependence induced abnormal behaviors, (iii) µ-opioid receptors play an important role in modulation of social motivation and depression behaviors in mice.

Kratom (M. speciosa) exposure during adolescence caused long-lasting cognitive behavioural deficits associated with perturbated brain metabolism pathways in adult rats

Kratom (M. speciosa Korth) is an herbal plant native to Southeast Asia. The leaves have been widely used to alleviate pain and opioid withdrawal symptoms. However, the increasing trend of recreational use of kratom among youth is concerning because substance abuse may render the adolescent brain more susceptible to neuropathological processes, causing dramatic consequences that persist into adulthood. Therefore, the present study aimed to investigate the long-term effects of mitragynine, the main alkaloid and lyophilized kratom decoction (LKD) exposure during adolescence on cognitive behaviours and brain metabolite profiles in adult rats. Adolescent male Sprague-Dawley rats were given mitragynine (3, 10 or 30mg/kg) or LKD orally for 15 consecutive days during postnatal days 31-45 (PND31-45). Behavioural testing was performed during adulthood (PND70-84) and the brains were subjected to metabolomic analysis. The results show that a high dose of mitragynine impaired long-term object recognition memory. Social behaviour and spatial learning were not affected, but both mitragynine and LKD impaired reference memory. Brain metabolomic study revealed several altered metabolic pathways that may be involved in the cognitive behavioural effects of LKD and mitragynine exposure. These pathways include arachidonic acid, taurine and hypotaurine, pantothenate and CoA biosynthesis, and tryptophan metabolism, while the N-isovalerylglycine was identified as the potential biomarker. In summary, adolescent kratom exposure can cause long-lasting cognitive behavioural deficits and alter brain metabolite profiles that are still evident in adulthood. This finding also indicates that the adolescent brain is vulnerable to the impact of early kratom use.

Coordination of social behaviors by the bed nucleus of the stria terminalis

The bed nucleus of the stria terminalis (BNST) is a sexually dimorphic, neuropeptide-rich node of the extended amygdala that has been implicated in responses to stress, drugs of abuse, and natural rewards. Its function is dysregulated in neuropsychiatric disorders that are characterized by stress- or drug-induced alterations in mood, arousal, motivation, and social behavior. However, compared to the BNST's role in mood, arousal, and motivation, its role in social behavior has remained relatively understudied. Moreover, the precise cell types and circuits underlying the BNST's role in social behavior have only recently begun to be explored using modern neuroscience techniques. Here, we systematically review the existing literature investigating the neurobiological substrates within the BNST that contribute to the coordination of various sex-dependent and sex-independent social behavioral repertoires, focusing largely on pharmacological and circuit-based behavioral studies in rodents. We suggest that the BNST coordinates social behavior by promoting appropriate assessment of social contexts to select relevant behavioral outputs and that disruption of socially relevant BNST systems by stress and drugs of abuse may be an important factor in the development of social dysfunction in neuropsychiatric disorders.

Menthol Flavor in E-Cigarette Vapor Modulates Social Behavior Correlated With Central and Peripheral Changes of Immunometabolic Signalings

The use of electronic cigarette (e-cigarette) has been increasing dramatically worldwide. More than 8,000 flavors of e-cigarettes are currently marketed and menthol is one of the most popular flavor additives in the electronic nicotine delivery systems (ENDS). There is a controversy over the roles of e-cigarettes in social behavior, and little is known about the potential impacts of flavorings in the ENDS. In our study, we aimed to investigate the effects of menthol flavor in ENDS on the social behavior of long-term vapor-exposed mice with a daily intake limit, and the underlying immunometabolic changes in the central and peripheral systems. We found that the addition of menthol flavor in nicotine vapor enhanced the social activity compared with the nicotine alone. The dramatically reduced activation of cellular energy measured by adenosine 5′ monophosphate-activated protein kinase (AMPK) signaling in the hippocampus were observed after the chronic exposure of menthol-flavored ENDS. Multiple sera cytokines including C5, TIMP-1, and CXCL13 were decreased accordingly as per their peripheral immunometabolic responses to menthol flavor in the nicotine vapor. The serum level of C5 was positively correlated with the alteration activity of the AMPK-ERK signaling in the hippocampus. Our current findings provide evidence for the enhancement of menthol flavor in ENDS on social functioning, which is correlated with the central and peripheral immunometabolic disruptions; this raises the vigilance of the cautious addition of various flavorings in e-cigarettes and the urgency of further investigations on the complex interplay and health effects of flavoring additives with nicotine in e-cigarettes.

Pharmacogenetic excitation of the median raphe region affects social and depressive-like behavior and core body temperature in male mice

AIMS

Median raphe region (MRR) is an important bottom-up regulatory center for various behaviors as well as vegetative functions, but detailed descriptions and links between the two are still largely unexplored.

METHODS

Pharmacogenetics was used to study the role of MRR in social (sociability, social interaction, resident intruder test) and emotional behavior (forced swim test) parallel with some vegetative changes (biotelemetry: core body temperature). Additionally, to validate pharmacogenetics, the effect of clozapine-N-oxide (CNO), the ligand of the artificial receptor, was studied by measuring (i) serum and brainstem concentrations of CNO and clozapine; (ii) MRR stimulation induced neurotransmitter release in hippocampus; (iii) CNO induced changes in body temperature and locomotor activity.

KEY FINDINGS

MRR stimulation decreased locomotion, increased friendly social behavior in the resident intruder test and enhanced depressive-like behavior. The latter was accompanied by diminished decrease in core body temperature. Thirty minutes after CNO injection clozapine was predominant in the brainstem. Nonetheless, peripheral CNO injection was able to induce glutamate release in the hippocampus. CNO had no immediate (<30 min) or chronic (repeated injections) effect on the body temperature or locomotion.

SIGNIFICANCE

We confirmed the role of MRR in locomotion, social and depressive-like behavior. Most interestingly, only depressive-like behavior was accompanied by changed body temperature regulation, which was also observed in human depressive disorders previously. This indicates clinical relevance of our findings. Despite low penetration, CNO acts centrally, but does not influence the examined basic parameters, being suitable for repeated behavioral testing.

Cardiorespiratory Fitness Predicts Higher Inhibitory Control in Patients With Substance Use Disorder

Impaired inhibitory control has been shown in individuals with substance use disorder (SUD). Cardiorespiratory fitness has been described as a potential factor to improve inhibitory control; however, the benefits in individuals with SUD are unclear. The aim of this study was to investigate the relationship between cardiorespiratory fitness with general and drug-specific inhibitory control in individuals with SUD. Sixty-two male participants under treatment for SUD performed a general and drug-specific inhibitory control test (go/no-go) and a cardiorespiratory fitness test. Cardiorespiratory fitness, age, and years of drug use were inversely associated with reaction time for both general and drug-specific inhibitory control. In addition, the regression models showed that cardiorespiratory fitness predicts general and drug-specific inhibitory control adjusted for age and time of drug use. However, cardiorespiratory fitness predicts equally both general and drug-specific inhibitory control. These findings suggest that increasing cardiorespiratory fitness could provide benefits in the inhibitory function of individuals with SUD.

Regulation of aggressive behaviors by nicotinic acetylcholine receptors: Animal models, human genetics, and clinical studies

Neuropsychiatric disorders are frequently complicated by aggressive behaviors. For some individuals, existing behavioral and psychopharmacological treatments are ineffective or confer significant side effects, necessitating development of new ways to treat patients with severe aggression. Nicotinic acetylcholine receptors (nAChRs) are a large and diverse family of ligand-gated ion channels expressed throughout the brain that influence behaviors highly relevant for neuropsychiatric disorders, including attention, mood, and impulsivity. Nicotine and other drugs targeting nAChRs can reduce aggression in animal models of offensive, defensive, and predatory aggression, as well as in human laboratory studies. Human genetic studies have suggested a relationship between the CHRNA7 gene encoding the alpha-7 nAChR and aggressive behavior, although these effects are heterogeneous and strongly influenced by genetic background and environment. Here we review animal, human genetic, and clinical studies supporting a consistent role of nicotine and nAChR signaling in modulation of aggressive behaviors. We integrate findings from recent studies of aggression neuroscience, discuss the circuitry that may be involved in these effects of nAChRs, and identify multiple key questions that must be answered prior to safe and effective translation for human patients. This article is part of the special issue on 'Contemporary Advances in Nicotine Neuropharmacology'.

Of mice and men on MDMA: A translational comparison of the neuropsychobiological effects of 3,4-methylenedioxymethamphetamine ('Ecstasy')

MDMA (3,4-methylendioxymethamphetamine), also known as Ecstasy, is a stimulant drug recreationally used by young adults usually in dance clubs and raves. Acute MDMA administration increases serotonin, dopamine and noradrenaline by reversing the action of the monoamine transporters. In this work, we review the studies carried out over the last 30 years on the neuropsychobiological effects of MDMA in humans and mice and summarise the current knowledge. The two species differ with respect to the neurochemical consequences of chronic MDMA, since it preferentially induces serotonergic dysfunction in humans and dopaminergic neurotoxicity in mice. However, MDMA alters brain structure and function and induces hormonal, psychomotor, neurocognitive, psychosocial and psychiatric outcomes in both species, as well as physically damaging and teratogen effects. Pharmacological and genetic studies in mice have increased our knowledge of the neurochemical substrate of the multiple effects of MDMA. Future work in this area may contribute to developing pharmacological treatments for MDMA-related disorders.

Neuroimaging Impaired Response Inhibition and Salience Attribution in Human Drug Addiction: A Systematic Review

The impaired response inhibition and salience attribution (iRISA) model proposes that impaired response inhibition and salience attribution underlie drug seeking and taking. To update this model, we systematically reviewed 105 task-related neuroimaging studies (n > 15/group) published since 2010. Results demonstrate specific impairments within six large-scale brain networks (reward, habit, salience, executive, memory, and self-directed networks) during drug cue exposure, decision making, inhibitory control, and social-emotional processing. Addicted individuals demonstrated increased recruitment of these networks during drug-related processing but a blunted response during non-drug-related processing, with the same networks also being implicated during resting state. Associations with real-life drug use, relapse, therapeutic interventions, and the relevance to initiation of drug use during adolescence support the clinical relevance of the results. Whereas the salience and executive networks showed impairments throughout the addiction cycle, the reward network was dysregulated at later stages of abuse. Effects were similar in alcohol, cannabis, and stimulant addiction.

Cardiorespiratory Fitness Predicts Greater Vagal Autonomic Activity in Drug Users Under Stress

While drug use has been shown to impair cardiac autonomic regulation, exercise might overcome some of the damage. Herein, we describe how individuals with substance use disorder (SUD) have their heart rate variability (HRV) and drug-related behaviors negatively affected in response to a stressor. However, we show how cardiorespiratory fitness may attenuate those impairments in autonomic control. Fifteen individuals with SUD were matched with 15 non-SUD individuals by age, weight, height, and fitness level, and had their HRV responses under stress induced by the Cold Pressor Test (CPT). The SUD group had lower mean of R-R intervals before and after the CPT when compared with the non-SUD group. In addition, in individuals with SUD, higher cardiorespiratory fitness level predicted greater vagal activity before, during, and after CPT. Moreover, for individuals with SUD, days of abstinence predicted greater mean of R-R intervals during recovery from the CPT. Finally, years of drug use negatively predicted mean of R-R intervals during recovery. Thus, our results suggest that chronic drug use impairs cardiac autonomic regulation at rest and after a physical stress. However, cardiorespiratory fitness might attenuate these impairments by increasing vagal autonomic activity.

Knowledge, attitude and practice of dental professionals towards substance use

Introduction:

The dentist must be aware of this drug use in their individual patients to: (1) avoid possible contraindications during dental treatment, (2) be aware of the many oral and craniofacial manifestations of such drug use, (3) be able to provide necessary dental treatment to combat the dental/oral ravages of drug use, and (4) be able to refer such patients, if so desired by the patient.

Aims and Objectives:

The aim of the study is (1) To determine the knowledge of abusive drugs among dentists and (2) To determine the attitude and role of dentists in identifying patients with abusive drugs.

Subjects and Methods:

A modified 27-item questionnaire was formulated and distributed among the study. The participants were to return the filled questionnaire to the investigators within a week. A total of 203 validated entries were collected. Data were entered into Microsoft Excel 2007 and analyzed in SPSS V20. Associations between categorical variables were determined using Chi-square or Fisher's exact test. P < 0.05 was considered statistically significant.

Results:

Irrespective of the educational qualification drugs are perceived harmful with definite oral manifestations, and dentists should be concerned with identifying individuals with drugs. It is believed that trying drugs once could lead to possible addiction and that dental practitioners should have their skills developed to handle cases and referred to deaddiction centers with modification of treatment plans.

Conclusions:

Educating dental graduates and postgraduates about the oral implications of drugs intake and making it a part of the dental curriculum may help us dealing with the global issues of drugs. Even making dental students a part in counseling and part of the behavioral therapies advocated in treating drug addicts.

Prenatal cocaine exposure and its impact on cognitive functions of offspring: a pathophysiological insight

It is estimated that approximately 0.5%-3% of fetuses are prenatally exposed to cocaine (COC). The neurodevelopmental implications of this exposure are numerous and include motor skill impairments, alterations of social function, predisposition to anxiety, and memory function and attention deficits; these implications are commonly observed in experimental studies and ultimately affect both learning and IQ. According to previous studies, the clinical manifestations of prenatal COC exposure seem to persist at least until adolescence. The pathophysiological cellular processes that underlie these impairments include dysfunctional myelination, disrupted dendritic architecture, and synaptic alterations. On a molecular level, various neurotransmitters such as serotonin, dopamine, catecholamines, and γ-aminobutyric acid seem to participate in this process. Finally, prenatal COC abuse has been also associated with functional changes in the hormones of the hypothalamic-pituitary-adrenal axis that mediate neuroendocrine responses. The purpose of this review is to summarize the neurodevelopmental consequences of prenatal COC abuse, to describe the pathophysiological pathways that underlie these consequences, and to provide implications for future research in the field.

Adolescent cannabinoid exposure effects on natural reward seeking and learning in rats

RATIONALE

Adolescence is characterized by endocannabinoid (ECB)-dependent refinement of neural circuits underlying emotion, learning, and motivation. As a result, adolescent cannabinoid receptor stimulation (ACRS) with phytocannabinoids or synthetic agonists like "Spice" cause robust and persistent changes in both behavior and circuit architecture in rodents, including in reward-related regions like medial prefrontal cortex and nucleus accumbens (NAc).

OBJECTIVES AND METHODS

Here, we examine persistent effects of ACRS with the cannabinoid receptor 1/2 specific agonist WIN55-212,2 (WIN; 1.2 mg/kg/day, postnatal day (PD) 30-43), on natural reward-seeking behaviors and ECB system function in adult male Long Evans rats (PD 60+).

RESULTS

WIN ACRS increased palatable food intake, and altered attribution of incentive salience to food cues in a sign-/goal-tracking paradigm. ACRS also blunted hunger-induced sucrose intake, and resulted in increased anandamide and oleoylethanolamide levels in NAc after acute food restriction not seen in controls. ACRS did not affect food neophobia or locomotor response to a novel environment, but did increase preference for exploring a novel environment.

CONCLUSIONS

These results demonstrate that ACRS causes long-term increases in natural reward-seeking behaviors and ECB system function that persist into adulthood, potentially increasing liability to excessive natural reward seeking later in life.

Differential effects of MDMA and cocaine on inhibitory avoidance and object recognition tests in rodents

INTRODUCTION

Drug addiction continues being a major public problem faced by modern societies with different social, health and legal consequences for the consumers. Consumption of psychostimulants, like cocaine or MDMA (known as ecstasy) are highly prevalent and cognitive and memory impairments have been related with the abuse of these drugs.

AIM

The aim of this work was to review the most important data of the literature in the last 10 years about the effects of cocaine and MDMA on inhibitory avoidance and object recognition tests in rodents.

DEVELOPMENT

The object recognition and the inhibitory avoidance tests are popular procedures used to assess different types of memory. We compare the effects of cocaine and MDMA administration in these tests, taking in consideration different factors such as the period of life development of the animals (prenatal, adolescence and adult age), the presence of polydrug consumption or the role of environmental variables. Brain structures involved in the effects of cocaine and MDMA on memory are also described.

CONCLUSIONS

Cocaine and MDMA induced similar impairing effects on the object recognition test during critical periods of lifetime or after abstinence of prolonged consumption in adulthood. Deficits of inhibitory avoidance memory are observed only in adult rodents exposed to MDMA. Psychostimulant abuse is a potential factor to induce memory impairments and could facilitate the development of future neurodegenerative disorders.

Improving cerebral oxygenation, cognition and autonomic nervous system control of a chronic alcohol abuser through a three-month running program

The abusive use of alcohol has shown to be associated to cerebral damage, impaired cognition, poor autonomic nervous control, impaired cardiovascular health, increased levels of stress and anxiety, depression symptoms and poor quality of life. Aerobic exercise has shown to be an efficient tool to reduce and overcome these issues. In this case report, a patient (forty-four years old, male) under treatment in public psychiatric hospital, classified as having a substance use disorder, underwent a three-month running program. The maximal oxygen consumption increased from 24.2 ml/kg/min to 30.1 ml/kg/min, running time increased from 6 min to 45 min (650%) and distance covered from 765 m to 8700 m (1037.2%). In prefrontal cortex oxygenation, oxyhemoglobin levels improved by 76.1%, deoxyhemoglobin decreased 96.9% and total hemoglobin increased 78.8% during exercise. Reaction time in the cognitive test during rest decreased 23%, and the number of correct answers increased by 266.6%. Parasympathetic cardiac parameters increased in several heart rate variability indices. Thus, we conclude that running exercise performed by an alcoholic patient hospitalized in a psychiatric hospital improves cerebral function, cognition and cardiovascular health.

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The subject improved the maximum consumption of oxygen.

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The subject increased the prefrontal cortex oxygenation, cognition and parasympathetic control.

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The subject decreased the need of intervention.

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First study to show long-term effects of exercise in the brain hemodynamics of an alcoholic

An emerging role for the lateral habenula in aggressive behavior

Inter-male aggression is an essential component of social behavior in organisms from insects to humans. However, when expressed inappropriately, aggression poses significant threats to the mental and physical health of both the aggressor and the target. Inappropriate aggression is a common feature of numerous neuropsychiatric disorders in humans and has been hypothesized to result from the atypical activation of reward circuitry in response to social targets. The lateral habenula (LHb) has recently been identified as a major node of the classical reward circuitry and inhibits the release of dopamine from the midbrain to signal negative valence. Here, we discuss the evidence linking LHb function to aggression and its valence, arguing that strong LHb outputs to the ventral tegmental area (VTA) and the dorsal raphe nucleus (DRN) are likely to play roles in aggression and its rewarding components. Future studies should aim to elucidate how various inputs and outputs of the LHb shape motivation and reward in the context of aggression.

Multi-system state shifts and cognitive deficits induced by chronic morphine during abstinence

Chronic morphine administration induces neural plasticity followed by withdraw. And clinic observation indicates that obvious cognitive deficits are found during withdrawal. However, current neural substrates that regulate dysfunction in withdrawal are unknown. In our studies, chronic morphine administration was used to induce the spontaneous withdrawal model in rats. A series of cognitive abilities was tested to explore brain function. To further evaluate the neural substrates of dysfunction, Manganese-enhanced MRI(MEMRI) was used to map the dysfunctional regions in vivo.We observed that chronic morphine administration could induce obvious withdrawal behaviors in abstinence followed by cognitive impairments, such as impairments in working memory, reward, interaction and enhancement of anxiety. Our in-vivo MEMRI data using the voxel-wise comparisons showed that the manganese-enhanced signal intensity (VMI) within morphine withdrawal groups was increased in cingulate cortex (Cg), secondary motor cortex (M2), CA3 subfield of hippocampus, dorsal striatum (D-striatum), retrosplenial cortex (RS), shell subregion of NAc (AcbSh), core subregion of NAc (AcbC), central nucleus of amygdala (CeC), basolateral amygdaloid nucleus (BLA), central amygdaloid nucleus (CeM), anterior hypothalamic area, central (AHC), ventral tegmental area (VTA) and scaphoid thalamic nucleus (SC).However, decreasing of VMI was found in the ventrolateral striatum (V-striatum) and lateral posterior thalamic nucleus (LP) compared to the control group. These brain regions were beleived to be components of the memory, executive, limbic and regulatory systems. Therefore, our present studies indicate that withdrawal induced by chronic morphine adiministration could disturb brain function leading to multi-systems state shifts and cognitive deficits in abstinence.

The effects of alcohol on emotion in social drinkers

Understanding why people drink alcohol and in some cases develop drinking problems has long puzzled researchers, clinicians, and patients alike. In the mid-1940s and early 1950s, experimental research began to systematically investigate alcohol's hedonic properties. Presumably, alcohol consumption would prove reinforcing as a consequence of its capacity either to relieve stress or to brighten positive emotional experiences. This article reviews experimental research through the years examining the impact of alcohol on both the relief of negative affect and the enhancement of positive affect. It covers initial accounts that emphasized direct pharmacological effects of ethanol on the central nervous system. These early studies offered surprisingly tepid support for the premise that alcohol improved emotional states. Next, studies conducted in the 1970s are considered. Informed by social learning theory and employing advances derived from experimental psychology, this research sought to better understand the complex effects of alcohol on emotion. Coverage of this work is followed by discussion of current formulations, which integrate biological and behavioral approaches with the study of cognitive, affective, and social processes. These current perspectives provide insight into the particular conditions under which alcohol can boost emotional experiences. Finally, future research directions and clinical implications are considered.

Prenatal, perinatal, and adolescent exposure to marijuana: Relationships with aggressive behavior

This manuscript reviews research exploring the relationship between prenatal, perinatal, and adolescent exposure to marijuana and aggressive behavior, including physical aggression. Areas of inquiry include animal research, as well as human research, on prenatal exposure and on marijuana use during adolescence. Potential psychosocial and psychopharmacological mechanisms are identified, as well as relevant confounds. The prenatal marijuana exposure literature provides minimal support for a direct relationship with aggressive behavior in childhood. The adolescent use literature suggests a marginal (at best) association between acute intoxication and aggressive behavior, and an association between chronic use and aggressive behavior heavily influenced by demographic variables, rather than direct, psychopharmacological mechanisms. Cannabis withdrawal symptoms also may include aggression and anger, but there is little evidence to suggest that these effects are large or specific to withdrawal from marijuana compared to other substances. This review will offer recommendations for clinical care and public policy, as well as important questions for future research.