Neurobiological mechanisms in addictive and psychiatric disorders

Mapping structural covariance networks of emotional withdrawal symptoms in males with methamphetamine use disorder during abstinence

Individuals with methamphetamine use disorder (MUD) often experience anxiety and depressive symptoms during abstinence, which can worsen the likelihood of relapse. Thus, it is essential to understand the neuro-mechanism behind methamphetamine use and its associated emotional withdrawal symptoms in order to develop effective clinical strategies. This study aimed to evaluate associations between emotional withdrawal symptoms and structural covariance networks (SCNs) based on cortical thickness (CTh) across the brain. The CTh measures were obtained from Tl-weighted MRI data from a sample of 48 males with MUD during abstinence and 48 male healthy controls. The severity of anxiety and depressive symptoms was assessed by the Hamilton Anxiety Scale (HAMA) and depression (HAMD) scales. Two important nodes belonging to the brain reward system, the right rostral anterior cingulate cortex (rACC) and medial prefrontal cortex (medPFC), were selected as seeds to conduct SCNs and modulation analysis by emotional symptoms. MUDs showed higher structural covariance between the right rACC and regions in the dorsal attention, right frontoparietal, auditory, visual and limbic networks. They also displayed higher structural covariance between the right medPFC and regions in the limbic network. Moreover, the modulation analysis showed that higher scores on HAMA were associated with increased covariance between the right rACC and the left parahippocampal and isthmus cingulate cortex in the default mode network. These outcomes shed light on the complex neurobiological mechanisms underlying methamphetamine use and its associated emotional withdrawal symptoms and may provide new insights into the development of effective treatments for MUD.

Viral-mediated expression of Erk2 in the nucleus accumbens regulates responses to rewarding and aversive stimuli

Second-messenger signaling within the mesolimbic reward circuit is involved in both the long-lived effects of stress and in the underlying mechanisms that promote drug abuse liability. To determine the direct role of kinase signaling within the nucleus accumbens, specifically mitogen-activated protein kinase 1 (ERK2), in mood- and drug-related behavior, we used a herpes-simplex virus to up- or down-regulate ERK2 in adult male rats. We then exposed rats to a battery of behavioral tasks including the elevated plus-maze, open field test, forced-swim test, conditioned place preference, and finally cocaine self-administration. Herein, we show that viral overexpression or knockdown of ERK2 in the nucleus accumbens induces distinct behavioral phenotypes. Specifically, over expression of ERK2 facilitated depression- and anxiety-like behavior while also increasing sensitivity to cocaine. Conversely, down-regulation of ERK2 attenuated behavioral deficits, while blunting sensitivity to cocaine. Taken together, these data implicate ERK2 signaling, within the nucleus accumbens, in the regulation of affective behaviors and modulating sensitivity to the rewarding properties of cocaine.

Irisin attenuates ethanol-induced behavioral deficits in mice through activation of Nrf2 and inhibition of NF-κB pathways

This study aims to investigate the effect of irisin on ethanol-induced behavioral deficits and explore the underlying mechanisms. A mouse model of ethanol addiction/withdrawal was constructed through chronic ethanol administration. Depressive-like behaviors were evaluated by the tail suspension test and forced swimming test, and anxiety-like behaviors were evaluated by the marble-burying test and elevated plus maze test. The expression of Nrf2 was measured by western blotting. Levels of inflammatory mediators (NF-κB, TNF-α, IL-1β and IL-6) and oxidative stress factors (ROS, MDA, GSH and SOD) were detected by ELISA. The ethanol-induced PC12/BV2 cell injury model was used to elucidate whether the effect of irisin on ethanol-induced neurological injury was related to anti-inflammatory and antioxidant mechanisms. Ethanol-induced ethanol preference and emotional deficits were improved by chronic irisin treatment; however, these improvements were partly reversed by cotreatment with the Nrf2 inhibitor ML385. Further results implied that the improvement effect of irisin on behavioral abnormalities may be related to its anti-inflammatory and antioxidant effects. In detail, irisin inhibited ethanol-induced abnormal expression of ROS and MDA and upregulated the expression of GSH and SOD. Meanwhile, irisin treatment inhibited ethanol-induced overexpression of NF-κB, TNF-α, IL-1β and IL-6 in the hippocampus and cerebral cortex. The regulation of oxidative stress factors by irisin was reversed after ML385 treatment. In the in vitro study, overexpression of oxidative stress factors in ethanol-treated PC12 cells was inhibited by irisin treatment; however, the prevention was reversed after the knockdown of Nrf2 siRNA. Moreover, ethanol-induced overexpression of inflammatory mediators in BV2 cells was also inhibited by irisin treatment. Irisin improved depressive and anxiety-like behaviors induced by ethanol addiction/withdrawal in mice, and this protection was greatly associated with the NF-κB-mediated anti-inflammatory signaling pathway and Nrf2-mediated antioxidative stress signaling pathway.

Emerging Roles of FTO in Neuropsychiatric Disorders

FTO (fat mass and obesity associated) is a recently discovered gene related to obesity and expressed in various tissues of the human body, especially with high expression in the brain. Earlier studies have found that FTO is involved in several biological processes, including brain development and function. In particular, recent studies have found that FTO is a demethylase of N6-methyladenosine (m6A) and it can affect neurological function through the m6A modification of mRNA. At present, a number of studies have shown that FTO is associated with many neuropsychiatric disorders. This paper reviews the discovery, structure, function, and tissue expression of FTO followed by discussing the relationship between FTO and neuropsychiatric diseases. In addition, the potential roles of FTO gene in drug addiction, major depression (MDD), and schizophrenia (SCZ) through regulating m6A modification of dopamine related genes were also highlighted.

Associations Between Attention Deficit/Hyperactivity Disorder and Internet Gaming Disorder Symptoms Mediated by Depressive Symptoms and Hopelessness Among College Students

PURPOSE

The mediating role of depressive symptoms and hopelessness on the relationship between attention deficit/hyperactivity disorder (ADHD) and internet gaming disorder (IGD) symptoms has not yet been elucidated. This study assessed this mediating effect in college students.

PARTICIPANTS AND METHODS

Participants consisted of 1236 freshmen recruited at a local university. Symptoms of ADHD, IGD, depression and hopelessness were measured using self-report scales. The effect of ADHD on IGD mediated by depression and hopelessness was analyzed by Haye's PROCESS macro for SPSS (Model 6) using the bias-corrected percentile bootstrap method with 5000 bootstrapped samples.

RESULTS

Symptoms of ADHD, depression and hopelessness were common in college students and were strongly associated with the appearance of IGD symptoms. ADHD symptoms of college students impacted their IGD symptoms directly and indirectly via depressive symptoms and hopelessness. The total effect of ADHD symptoms on IGD symptoms was 0.075 (standard error [SE]: 0.009, 95% confidence interval [CI] 0.057, 0.093), with a direct effect of 0.037 (SE: 0.010, 95% CI 0.018, 0.056, effect ratio: 49.3%), and total indirect effect was 0.038 (SE: 0.005, 95% CI 0.029, 0.050, effect ratio: 50.7%).

CONCLUSION

Depressive symptoms and hopelessness can mediate the relationship between ADHD and IGD symptoms among college students. These findings point to the importance of evaluating ADHD, depressive and hopelessness symptoms for the prevention and treatment of adult IGD.

Pre-clinical models of reward deficiency syndrome: A behavioral octopus

Individuals with mood disorders or with addiction, impulsivity and some personality disorders can share in common a dysfunction in how the brain perceives reward, where processing of natural endorphins or the response to exogenous dopamine stimulants is impaired. Reward Deficiency Syndrome (RDS) is a polygenic trait with implications that suggest cross-talk between different neurological systems that include the known reward pathway, neuroendocrine systems, and motivational systems. In this review we evaluate well-characterized animal models for their construct validity and as potential models for RDS. Animal models used to study substance use disorder, major depressive disorder (MDD), early life stress, immune dysregulation, attention deficit hyperactivity disorder (ADHD), post traumatic stress disorder (PTSD), compulsive gambling and compulsive eating disorders are discussed. These disorders recruit underlying reward deficiency mechanisms in multiple brain centers. Because of the widespread and remarkable array of associated/overlapping behavioral manifestations with a common root of hypodopaminergia, the basic endophenotype recognized as RDS is indeed likened to a behavioral octopus. We conclude this review with a look ahead on how these models can be used to investigate potential therapeutics that target the underlying common deficiency.

Amphetamine Derivatives as Monoamine Oxidase Inhibitors

Amphetamine and its derivatives exhibit a wide range of pharmacological activities, including psychostimulant, hallucinogenic, entactogenic, anorectic, or antidepressant effects. The mechanisms of action underlying these effects are usually related to the ability of the different amphetamines to interact with diverse monoamine transporters or receptors. Moreover, many of these compounds are also potent and selective monoamine oxidase inhibitors. In the present work, we review how structural modifications on the aromatic ring, the amino group and/or the aliphatic side chain of the parent scaffold, modulate the enzyme inhibitory properties of hundreds of amphetamine derivatives. Furthermore, we discuss how monoamine oxidase inhibition might influence the pharmacology of these compounds.

Transgenerational influence of parental morphine exposure on pain perception, anxiety-like behavior and passive avoidance memory among male and female offspring of Wistar rats

Accumulating evidence suggests that epigenetic mechanisms play an important role in the formation and maintenance of memory within the brain. Moreover, the effect of parental drug-exposure before gestation on behavioral state of offspring has been little studied. The main objective of the current study is to evaluate the effect of parental morphine exposure on avoidance memory, morphine preference and anxiety-like behavior of offspring. The total of 32 males and 32 females were used for mating. The animals were treated with morphine. The offspring according to their parental morphine treatment was divided into four groups (n=16) including paternally treated, maternally treated, both of parents treated and naïve animals. The pain perception, anxiety-like behavior, and avoidance memory were evaluated in the offspring. In the current study, the total of 256 offspring was used for the experiments (4 tasks × 4 groups of offspring × 8 female offspring × 8 male offspring). The finding revealed that the avoidance memory and visceral pain were reduced significantly in male and female offspring with at least one morphine-treated parent. Moreover, anxiety-like behavior was reduced significantly in the male offspring with at least one morphine-treated parent. While anxiety-like behavior was increased significantly in female offspring that were treated by morphine either maternally or both of parents. The data revealed that the endogenous opioid system may be altered in the offspring of morphine-treated parent(s), and epigenetic role could be important. However, analysis of variance signified the important role of maternal inheritance.

Morphine Exposure and Enhanced Depression-like Behaviour Confronting Chronic Stress in Adult Male Offspring Rat

Introduction:

Opioid addiction is an important concern in the World. Reports demonstrate that substance use disorder could influence genetic and environmental factors, and children of addicts have a higher rate of psychopathology. In this study, we investigated depression-like behavior among offspring of morphine-exposed rat parents.

Methods:

Adult male and female Wistar rats received morphine for 21 consecutive days and then let them were free of drugs for ten days. Offspring of these rats were divided into three distinct groups: maternal morphine-exposed, paternal morphine-exposed, and both maternal and paternal morphine-exposed. We used sucrose preference and Forced Swim Test (FST) to measure depression-like behavior. Also, we induced chronic mild stress using repeated corticosterone injection and evaluated depression-like behavior in offspring of morphine-exposed parents compared with offspring of healthy ones.

Results:

Results indicated that depression-like behaviors in the offspring of morphine-exposed rats were higher than those in the offspring of the control group in confronting with chronic mild stress. Additionally, mild chronic stress can produce an exaggerated effect on depression-like behavior in offspring of the morphine-exposed parent(s) compared with those of the control group.

Conclusion:

Our data support the previous hypothesis that the depression rate is higher in the children of addicts. We verified that even when mother or father was clean of opioid in the time of gestation, their children would be susceptible to depression. Dysregulation of hypothalamic-pituitary-adrenal axis and changing in neuronal features in the hippocampus increased depression-like behavior in the offspring of morphine-exposure parents.

Rostrocaudal subregions of the ventral tegmental area are differentially impacted by chronic stress

RATIONALE

The ventral tegmental area (VTA) is implicated in the pathophysiology of depression and addictive disorders and is subject to the detrimental effects of stress. Chronic stress may differentially alter the activity pattern of its different subregions along the rostrocaudal and dorsoventral axes, which may relate to the variable behavioral sensitivity to stress mediated by these subregions.

OBJECTIVES

Here, chronic stress-exposed rats were tested for depressive-like reactivity. In situ hybridization for zif268 as a marker of neuronal activation was combined with in vivo single-unit recording of dopaminergic neurons to assess modifications in the activity of the rostral VTA (rVTA) and caudal VTA (cVTA). Changes in the expression of stress-responsive glucocorticoid receptors (GR) and brain-derived neurotrophic factor (BDNF) were also assessed.

RESULTS

Stress-induced anhedonia-like, hyper-anxious, and passive-like responding were associated with reductions in dopaminergic burst activity in the cVTA and an increase in local GABAergic activity, particularly in GABA_A receptor sensitivity. On the other hand, stress increased single-spiking activity, burst activity, and zif268 mRNA levels in the rVTA, which were associated with increased glutamatergic tonus and enhanced GR and AMPA receptor (AMPAR) expression. rVTA and cVTA activity differentially correlated with sucrose preference and passivity measures.

CONCLUSIONS

These data demonstrate that the rVTA and cVTA respond differently to stress and suggest that while cVTA activity may be related to passivity-like states, the activity of both subregions appears to be related to anhedonia and the processing of incentive value. These region-dependent abnormalities indicate the multi-modular composition of the VTA, which could provide multiple substrates for different symptom features.

A Shared Molecular and Genetic Basis for Food and Drug Addiction: Overcoming Hypodopaminergic Trait/State by Incorporating Dopamine Agonistic Therapy in Psychiatry

This article focuses on the shared molecular and neurogenetics of food and drug addiction tied to the understanding of reward deficiency syndrome. Reward deficiency syndrome describes a hypodopaminergic trait/state that provides a rationale for commonality in approaches for treating long-term reduced dopamine function across the reward brain regions. The identification of the role of DNA polymorphic associations with reward circuitry has resulted in new understanding of all addictive behaviors.

The Molecular Neurobiology of Twelve Steps Program & Fellowship: Connecting the Dots for Recovery

There are some who suggest that alcoholism and drug abuse are not diseases at all and that they are not consequences of a brain disorder as espoused recently by the American Society of Addiction Medicine (ASAM). Some would argue that addicts can quit on their own and moderate their alcohol and drug intake. When they present to a treatment program or enter the 12 Step Program & Fellowship, many addicts finally achieve complete abstinence. However, when controlled drinking fails, there may be successful alternatives that fit particular groups of individuals. In this expert opinion, we attempt to identify personal differences in recovery, by clarifying the molecular neurobiological basis of each step of the 12 Step Program. We explore the impact that the molecular neurobiological basis of the 12 steps can have on Reward Deficiency Syndrome (RDS) despite addiction risk gene polymorphisms. This exploration has already been accomplished in part by Blum and others in a 2013 Springer Neuroscience Brief. The purpose of this expert opinion is to briefly, outline the molecular neurobiological and genetic links, especially as they relate to the role of epigenetic changes that are possible in individuals who regularly attend AA meetings. It begs the question as to whether "12 steps programs and fellowship" does induce neuroplasticity and continued dopamine D2 receptor proliferation despite carrying hypodopaminergic type polymorphisms such as DRD2 A1 allele. "Like-minded" doctors of ASAM are cognizant that patients in treatment without the "psycho-social-spiritual trio," may not be obtaining the important benefits afforded by adopting 12-step doctrines. Are we better off with coupling medical assisted treatment (MAT) that favors combining dopamine agonist modalities (DAM) as possible histone-deacetylase activators with the 12 steps followed by a program that embraces either one or the other? While there are many unanswered questions, at least we have reached a time when "science meets recovery," and in doing so, can further redeem joy in recovery.

Familial risk for alcohol dependence and developmental changes in BMI: the moderating influence of addiction and obesity genes

AIM

Familial loading for alcohol dependence (AD) and variation in genes reported to be associated with AD or BMI were tested in a longitudinal study.

MATERIALS & METHODS

Growth curve analyses of BMI data collected at approximately yearly intervals and obesity status (BMI > 30) were examined.

RESULTS

High-risk males were found to have higher BMI than low-risk males, beginning at age 15 years (2.0 kg/m(2) difference; p = 0.046), persisting through age 19 years (3.3 kg/m(2) difference; p = 0.005). CHRM2 genotypic variance predicted longitudinal BMI and obesity status. Interactions with risk status and sex were also observed for DRD2 and FTO gene variation.

CONCLUSION

Variation at loci implicated in addiction may be influential in determining susceptibility to increased BMI in childhood and adolescence.

Yoga as an adjunct treatment for alcohol dependence: a pilot study

OBJECTIVES

This pilot study explores the feasibility of yoga as part of a treatment program for alcohol dependence.

DESIGN

Eighteen alcohol dependent patients were randomized to receive either treatment as usual or treatment as usual plus yoga. Assessments were taken at baseline and six month follow-up.

SETTING

'Riddargatan 1': an outpatient alcohol treatment clinic located in Stockholm, Sweden.

INTERVENTIONS

Treatment as usual consisted of psychological and pharmacological interventions for alcohol dependence. The 10-week yoga intervention included a weekly group yoga session. Participants were encouraged to practice the yoga movements at home once per day.

MAIN OUTCOME MEASURES

Alcohol consumption (timeline follow-back method, DSM-IV criteria for alcohol dependence, and the Short Alcohol Dependence Data questionnaire), affective symptoms (the Hospital Anxiety and Depression Scale), quality of life (Sheehan Disability Scale) and stress (the Perceived Stress Scale and saliva cortisol).

RESULTS

Yoga was found to be a feasible and well accepted adjunct treatment for alcohol dependence. Alcohol consumption reduced more in the treatment as usual plus yoga group (from 6.32 to 3.36 drinks per day) compared to the treatment as usual only group (from 3.42 to 3.08 drinks per day). The difference was, however, not statistically significant (p = 0.17).

CONCLUSIONS

Larger studies are needed to adequately assess the efficacy and long-term effectiveness of yoga as an adjunct treatment for alcohol dependence.

Neuropsychiatric Genetics of Happiness, Friendships, and Politics: Hypothesizing Homophily ("Birds of a Feather Flock Together") as a Function of Reward Gene Polymorphisms

Mindful of the new evolutionary ideas related to an emerging scientific focus known as omics, we propose that spiritual, social, and political behaviors may be tied in part to inheritable reward gene polymorphisms, as has been demonstrated for the addictions. If so, analyses of gene polymorphisms may assist in predicting liberalism or conservatism in partisan attachments. For example, both drinking (alcohol) and obesity seem to cluster in large social networks and are influenced by friends having the same genotype, in particular the DRD2 A1 allele. Likewise, voting, voting turnout and attachment to a particular political ideology is differentially related to various reward genes (e.g., 5HTT, MOA, DRD2, and DRD4), possibly predicting liberalism or conservatism. Moreover, voters' genetic information may predict presidential outcomes more than the actual issues at hand or the presidential candidates themselves. Thus, political discussions on TV, radio, or other media may be morphed by one's reward gene polymorphisms and as such, may explain the prevalence of generations of die-hard republicans and equally entrenched democratic legacies. Indeed, even in politics, birds of a feather (homophily) flock together. We caution that our proposal should be viewed mindfully awaiting additional research before definitive statements or conclusions can be derived from the studies to date, and we encourage large scale studies to confirm these earlier reports.

Generational association studies of dopaminergic genes in reward deficiency syndrome (RDS) subjects: selecting appropriate phenotypes for reward dependence behaviors

Abnormal behaviors involving dopaminergic gene polymorphisms often reflect an insufficiency of usual feelings of satisfaction, or Reward Deficiency Syndrome (RDS). RDS results from a dysfunction in the "brain reward cascade," a complex interaction among neurotransmitters (primarily dopaminergic and opioidergic). Individuals with a family history of alcoholism or other addictions may be born with a deficiency in the ability to produce or use these neurotransmitters. Exposure to prolonged periods of stress and alcohol or other substances also can lead to a corruption of the brain reward cascade function. We evaluated the potential association of four variants of dopaminergic candidate genes in RDS (dopamine D1 receptor gene [DRD1]; dopamine D2 receptor gene [DRD2]; dopamine transporter gene [DAT1]; dopamine beta-hydroxylase gene [DBH]).

METHODOLOGY

We genotyped an experimental group of 55 subjects derived from up to five generations of two independent multiple-affected families compared to rigorously screened control subjects (e.g., N = 30 super controls for DRD2 gene polymorphisms). Data related to RDS behaviors were collected on these subjects plus 13 deceased family members.

RESULTS

Among the genotyped family members, the DRD2 Taq1 and the DAT1 10/10 alleles were significantly (at least p < 0.015) more often found in the RDS families vs. controls. The TaqA1 allele occurred in 100% of Family A individuals (N = 32) and 47.8% of Family B subjects (11 of 23). No significant differences were found between the experimental and control positive rates for the other variants.

CONCLUSIONS

Although our sample size was limited, and linkage analysis is necessary, the results support the putative role of dopaminergic polymorphisms in RDS behaviors. This study shows the importance of a nonspecific RDS phenotype and informs an understanding of how evaluating single subset behaviors of RDS may lead to spurious results. Utilization of a nonspecific "reward" phenotype may be a paradigm shift in future association and linkage studies involving dopaminergic polymorphisms and other neurotransmitter gene candidates.

Stressing zebrafish for behavioral genetics

The stress response is a normal reaction to a real or perceived threat. However, stress response systems that are overwhelmed or out of balance can increase both the incidence and severity of diseases including addiction and mood and anxiety disorders. Using an animal model with both genetic diversity and large family size can help discover the specific genetic and environmental contributions to these behavioral diseases. The stress response has been studied extensively in teleosts because of their importance in food production. The zebrafish (Danio rerio) is a major model organism with a strong record for use in developmental biology, genetic screening, and genomic studies. More recently, the stress response of larval and adult zebrafish has been documented. High-throughput automated tracking systems make possible behavioral readouts of the stress response in zebrafish. This non-invasive measure of the stress response can be combined with mutagenesis methods to dissect the genes involved in complex stress response behaviors in vertebrates. Understanding the genetic and epigenetic basis for the stress response in vertebrates will help to develop advanced screening and therapies for stress-aggravated diseases such as addiction and mood and anxiety disorders.

Endocannabinoid-mediated synaptic plasticity and addiction-related behavior

Endogenous cannabinoids (eCBs) are retrograde messengers that provide feedback inhibition of both excitatory and inhibitory transmission in brain through the activation of presynaptic CB₁ receptors. Substantial evidence indicates that eCBs mediate various forms of short- and long-term plasticity in brain regions involved in the etiology of addiction. The present review provides an overview of the mechanisms through which eCBs mediate various forms of synaptic plasticity and discusses evidence that eCB-mediated plasticity is disrupted following exposure to a variety of abused substances that differ substantially in pharmacodynamic mechanism including alcohol, psychostimulants and cannabinoids. The possible involvement of dysregulated eCB signaling in maladaptive behaviors that evolve over long-term drug exposure is also discussed, with a particular focus on altered behavioral responses to drug exposure, deficient extinction of drug-related memories, increased drug craving and relapse, heightened stress sensitivity and persistent affective disruption (anxiety and depression).

Alcohol consumption enhances antiretroviral painful peripheral neuropathy by mitochondrial mechanisms

A major dose-limiting side effect of human immunodeficiency virus/acquired immunodeficiency syndrome (HIV/AIDS) chemotherapies, such as the nucleoside reverse transcriptase inhibitors (NRTIs), is a small-fiber painful peripheral neuropathy, mediated by its mitochondrial toxicity. Co-morbid conditions may also contribute to this dose-limiting effect of HIV/AIDS treatment. Alcohol abuse, which alone also produces painful neuropathy, is one of the most important co-morbid risk factors for peripheral neuropathy in patients with HIV/AIDS. Despite the prevalence of this problem and its serious impact on the quality of life and continued therapy in HIV/AIDS patients, the mechanisms by which alcohol abuse exacerbates highly active antiretroviral therapy (HAART)-induced neuropathic pain has not been demonstrated. In this study, performed in rats, we investigated the cellular mechanism by which consumed alcohol impacts antiretroviral-induced neuropathic pain. NRTI 2',3'-dideoxycytidine (ddC; 50 mg/kg) neuropathy was mitochondrial-dependent and PKCε-independent, and alcohol-induced painful neuropathy was PKCε-dependent and mitochondrial-independent. At low doses, ddC (5 mg/kg) and alcohol (6.5% ethanol diet for 1 week), which alone do not affect nociception, together produce profound mechanical hyperalgesia. This hyperalgesia is mitochondrial-dependent but PKCε-independent. These experiments, which provide the first model for studying the impact of co-morbidity in painful neuropathy, support the clinical impression that alcohol consumption enhances HIV/AIDS therapy neuropathy, and provide evidence for a role of mitochondrial mechanisms underlying this interaction.

Prenatal alcohol exposure: fetal programming and later life vulnerability to stress, depression and anxiety disorders

Children with fetal alcohol spectrum disorder (FASD) exhibit cognitive, neuropsychological and behavioral problems, and numerous secondary disabilities including depression and anxiety disorders. Dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis is common in depression/anxiety, reflected primarily in increased HPA tone or activity. Prenatal alcohol exposure (PAE) increases HPA tone and results in HPA dysregulation throughout life, paralleling many of the HPA changes in depression/anxiety. We review data demonstrating altered HPA function and increased depression/anxiety in FASD. In the context of the stress-diathesis model, we discuss the hypothesis that fetal programming of the HPA axis by PAE alters neuroadaptive mechanisms that mediate the stress response, thus sensitizing the organism to stressors encountered later in life, and mediating, at least partly, the increased vulnerability to depression/anxiety disorders. Furthermore, we present evidence demonstrating sex-specific alterations in both hormonal and behavioral responsiveness to tasks measuring depressive- and anxiety-like behaviors in PAE offspring. Overall, the research suggests that the stress-diathesis model provides a powerful approach for elucidating mechanisms underlying the increased vulnerability to mental illness among individuals with FASD, and developing appropriate treatments for these individuals. Dr. Seymour Levine's seminal work on the long-term consequences of early life experiences formed a framework for the development of the research described in this review.

Risk factors for depression in truck drivers

OBJECTIVE

Depression is a major public health problem. Work stress is associated with depression and workers whose jobs impose high levels of psychological demands, such as truck drivers, may be at increased risk. The aim of this study was to investigate the prevalence and correlates of depression in truck drivers.

METHOD

This was a cross-sectional study of 300 male truck drivers. Presence and severity of depression were assessed by the Mini International Neuropsychiatric Interview followed by the Beck Depression Inventory Short Form. Relevant demographic, clinical and occupational data were collected using a purpose-built questionnaire.

RESULTS

The prevalence of depression among truck drivers was 13.6%. Multivariate analysis showed that being 45 years or older had a protective effect (OR=0.19; P=0.02), whereas low educational level (OR=3.03; P=0.01), use of stimulants (OR=5.03; P<0.01) and wage-earning (OR=2.84; P=0.01), as opposed to self-employment, increased the risk for depression.

CONCLUSIONS

Truck drivers are at increased risk for depression when compared to the general population. Efforts to increase awareness of this problem and to limit the use of stimulants, as well as measures to improve job satisfaction, particularly among the wage-earning drivers, may have a positive impact on mental health in these workers.

Social stress, therapeutics and drug abuse: preclinical models of escalated and depressed intake

The impact of ostensibly aversive social stresses on triggering, amplifying and prolonging intensely rewarding drug taking is an apparent contradiction in need of resolution. Social stress encompasses various types of significant life events ranging from maternal separation stress, brief episodes of social confrontations in adolescence and adulthood, to continuous subordination stress, each with its own behavioral and physiological profile. The neural circuit comprising the VTA-accumbens-PFC-amygdala is activated by brief episodes of social stress, which is critical for the DA-mediated behavioral sensitization and increased stimulant consumption. A second neural circuit comprising the raphe-PFC-hippocampus is activated by continuous subordination stress and other types of uncontrollable stress. In terms of the development of therapeutics, brief maternal separation stress has proven useful in characterizing compounds acting on subtypes of GABA, glutamate, serotonin and opioid receptors with anxiolytic potential. While large increases in alcohol and cocaine intake during adulthood have been seen after prolonged maternal separation experiences during the first two weeks of rodent life, these effects may be modulated by additional yet to be identified factors. Brief episodes of defeat stress can engender behavioral sensitization that is relevant to escalated and prolonged self-administration of stimulants and possibly opioids, whereas continuous subordination stress leads to anhedonia-like effects. Understanding the intracellular cascade of events for the transition from episodic to continuous social stress in infancy and adulthood may provide insight into the modulation of basic reward processes that are critical for addictive and affective disorders.

The relationship between depressive symptom levels and subsequent increases in substance use among youth with severe emotional disturbance

OBJECTIVE

This study examined the relationship between levels of depressive symptoms and subsequent increases in substance use among 784 youth with severe emotional disturbance enrolled in Medicaid-funded behavioral health care plans.

METHOD

Youth at five sites nationwide were interviewed about their emotional and behavior problems, as well as their use of cigarettes, alcohol, and drugs--at both baseline and follow-up.

RESULTS

(1) Levels of depressive symptoms were significantly associated with concurrent substance use at baseline. (2) Baseline levels of depressive symptoms predicted subsequent changes in substance use, especially use of illicit drugs and multiple drugs. (3) These findings remained significant, even after controlling for sociodemographic, family, and individual characteristics.

CONCLUSIONS

These results indicate that depressive symptoms early in life may signal a risk for increasing involvement in substance use among severe emotional disturbed youth. This finding has important clinical implications for the prevention of substance misuse in this population.

Coregulation, Dysregulation, Self-Regulation: An Integrative Analysis and Empirical Agenda for Understanding Adult Attachment, Separation, Loss, and Recovery

An integrative framework is proposed for understanding how multiple biological and psychological systems are regulated in the context of adult attachment relationships, dysregulated by separation and loss experiences, and, potentially, re-regulated through individual recovery efforts. Evidence is reviewed for a coregulatory model of normative attachment, defined as a pattern of interwoven physiology between romantic partners that results from the conditioning of biological reward systems and the emergence of felt security within adult pair bonds. The loss of coregulation can portend a state of biobehavioral dysregulation, ranging from diffuse psychophysiological arousal and disorganization to a full-blown (and highly organized) stress response. The major task for successful recovery is adopting a self-regulatory strategy that attenuates the dysregulating effects of the attachment disruption. Research evidence is reviewed across multiple levels of analysis, and the article concludes with a series of testable research questions on the interconnected nature of attachment, loss, and recovery processes.

Facilitation of avoidance behaviour in mice chronically treated with heroin or methadone

Although the repercussion of chronic treatment with large amounts of opioids on cognitive performance is a matter of concern, the effects of opioid drugs on passive avoidance learning have been scarcely studied. Here, we analyzed the effects of prolonged administration of heroin and methadone, as well as the impact of suffering repeated episodes of withdrawal on fear-motivated learning using the passive avoidance test. Mice received chronic treatment (39 days) with methadone (10 mg/kg/24 h), associated or not with repeated withdrawal episodes, or with heroin (5 mg/kg/12 h). Our results show that, regardless of the type of treatment received, all mice displayed similar basal thermal nociceptive thresholds during 25 days of treatment. In the hot plate test, both methadone and heroin induced antinociception 30 min after drug administration. The analgesic effect was absent when measured 4 h after heroin and 12 h after methadone. Pain behavioural responses elicited by growing intensities of electric shock, applied on day 28th of treatment, were similar in all groups of mice. Our results indicate that chronic opioid treatment had promnesic effects on passive avoidance behaviour in mice, unrelated to changes in the nociceptive state.

Implicit learning, executive function and hedonic activity in chronic polydrug abusers, currently abstinent polydrug abusers and controls

AIMS

The study seeks to evaluate impairments of implicit learning and executive function in chronic polydrug abusers. It was hypothesized that implicit learning and executive function correlate with anhedonia.

DESIGN

A cross-sectional group comparison.

SETTINGS

Department of Psychiatry, University of Tübingen, Germany. Participants A total of 25 male polydrug abusers with opiate dependence, n = 26 polydrug abusers abstinent for more than 3 months and n = 26 non-drug-using healthy males.

SETTING

Abstinent polydrug abusers were recruited from a community treatment centre, current polydrug abusers from local drug counselling services and controls through advertisements.

MEASUREMENTS

A psychological battery assessing implicit learning (serial reaction-time task), various executive functions (latent inhibition, delayed matching-to-sample, Trail Making Test, acquisition and modification of conditioned responses, figural reasoning) and verbal logic memory was administered. Hedonic thoughts and activities as well as depressive symptoms were assessed through questionnaires.

FINDINGS

In chronic polydrug abusers, there were moderate impairments of implicit learning, of acquisition, reversal and extinction of conditioned responses, of latent inhibition as well as anhedonia, while working memory was spared. In the abstinent group, cognitive performance was normal except for latent inhibition and more anhedonia and depression than in controls.

CONCLUSIONS

The findings suggest that current polydrug abusers suffer from impairment of many cognitive functions and from anhedonia. During abstinence, there is near normal cognitive function but still anhedonia. Anhedonia was correlated with implicit learning but not with executive function.

Links between depression and substance abuse in adolescents: neurobiological mechanisms

Adolescence is a high-risk period for development of both depressive and substance use disorders. These two disorders frequently co-occur in adolescents and are associated with significant morbidity and mortality. Given the added economic and psychosocial burden associated with the comorbid condition, identification of risk factors associated with their co-occurrence is of great public health importance. Research with adult animals and humans has indicated several common neurobiological systems that link depressive and addictive disorders. Given the ongoing maturation of these systems throughout adolescence and early adult life, it is not clear how these neurobiological processes influence development and progression of both disorders. A better understanding of the pathophysiological mechanisms leading to the onset and course of these disorders during adolescence will be helpful in developing more effective preventive and treatment strategies, and thereby allow these youth to reach their full potential as adults.

Second-hand exposure to aerosolized intravenous anesthetics propofol and fentanyl may cause sensitization and subsequent opiate addiction among anesthesiologists and surgeons

We hypothesize that aerosolization of anesthetics administered intravenously to patients in the operating room may be an unintended source of exposure to physicians. This may lead to inadvertent sensitization, which is associated with an increased risk for developing addiction. This may contribute to the over-representation of certain specialties among physicians with addiction. We retrospectively reviewed the de-identified demographic information of all licensed physicians treated for substance abuse in the State of Florida since 1980, to determine if medical specialty was associated with addiction in this group of individuals. Then, to identify the potential for exposure, two mass spectrometry assays were developed to detect two intravenously administered drugs, fentanyl and propofol, in air. Since 1980, 7.6% of licensed Florida physicians underwent treatment for addiction. Addiction in anesthesiologists was higher than expected. Opiate abuse was greater in anesthesiologists and surgeons compared to other specialties. Aerosolized fentanyl was detected in the air of the cardiothoracic operating room, in patients' expiratory circuits, and in the headspace above sharps boxes, but not in adjoining hallways. Aerosolized propofol was detected in the expirations of a patient undergoing transurethral prostatectomy. While access and stress may place anesthesiologists and surgeons at greater risk for substance abuse, an additional risk factor may be unintended occupational exposure to addictive drugs. This report provides preliminary evidence of detection of aerosolized intravenous anesthetics using two newly developed analytical methods. We conclude that the potential exists for chronic exposure to low levels of airborne intravenously administered drugs. Further studies are under way to determine the significance of this exposure.

Decreased sensitivity to the effects of dopamine D1-like, but not D2-like, receptor antagonism in the posterior hypothalamic region/anterior ventral tegmental area on brain reward function during chronic exposure to nicotine in rats

Chronic administration of nicotine induces adaptations in central nervous system function to counteract nicotine's acute effects. When nicotine administration ceases, these adaptations remain unopposed and may lead to drug withdrawal. The present studies were conducted to assess the effects of chronic nicotine administration on dopamine D1- and D2-like receptor activity in the posterior hypothalamus/anterior ventral tegmental area (VTA). An intracranial self-stimulation discrete trial procedure that provides current intensity thresholds was used to provide a measure of brain reward function in rats. Previous studies showed that systemic administration of dopamine D1- or D2-like receptor antagonists induced elevations in brain reward thresholds in drug-free rats, indicative of a decrease in brain reward function. We show here that injections of the D1-like receptor antagonist SCH 23390 (1-4 microg total bilateral dose) into the posterior hypothalamus/anterior VTA differentially elevated brain reward thresholds in rats chronically treated with nicotine (9 mg/kg/day, salt) versus saline-treated rats. The nicotine-treated rats were less sensitive to the threshold elevating effects of D1-like receptor antagonism. By contrast, the D2-like receptor antagonist eticlopride (1-4 microg total bilateral dose) injected into the posterior hypothalamus/anterior VTA significantly elevated brain reward thresholds in saline- and nicotine-treated rats. No differential effect of eticlopride on brain reward thresholds in saline- and nicotine-treated rats was observed. Decreased sensitivity to D1-like receptor antagonism in the posterior hypothalamus/anterior VTA may partly mediate the development of tolerance to the reinforcing effects of nicotine and the manifestation of negative affective signs associated with cessation of nicotine administration.