Addiction

7.0 T high-resolution 1H-MR spectroscopy of metabolic changes induced by chronic codeine phosphate in rat hippocampus

Codeine phosphate is used widely to treat cough and pain. It is actually a sedative, but is known to cause codeine dependence. The exact mechanisms of codeine dependence are not fully understood, but are generally believed to be related to drug-induced neuroadaptation. Metabolites changes can provide information for pathological processes and mechanisms before the shape change. It is very useful for the diagnosis and treatment of drug addiction. We used H NMR spectroscopy in vivo to measure the concentrations of cerebral metabolites in the hippocampus of rats subjected to repeated codeine treatment. After 2 months of codeine treatment, the concentration of N-acetylaspartate was significantly decreased in hippocampi, as was that of glutamate, choline, and taurine. Our study highlights the potential use of metabolic profiling to enhance our understanding of metabolite alteration associated with codeine dependence.

Modulation of the endocannabinoid system: vulnerability factor and new treatment target for stimulant addiction

Cannabis is one of the most widely used illicit substance among users of stimulants such as cocaine and amphetamines. Interestingly, increasing recent evidence points toward the involvement of the endocannabinoid system (ECBS) in the neurobiological processes related to stimulant addiction. This article presents an up-to-date review with deep insights into the pivotal role of the ECBS in the neurobiology of stimulant addiction and the effects of its modulation on addictive behaviors. This article aims to: (1) review the role of cannabis use and ECBS modulation in the neurobiological substrates of psychostimulant addiction and (2) evaluate the potential of cannabinoid-based pharmacological strategies to treat stimulant addiction. A growing number of studies support a critical role of the ECBS and its modulation by synthetic or natural cannabinoids in various neurobiological and behavioral aspects of stimulants addiction. Thus, cannabinoids modulate brain reward systems closely involved in stimulants addiction, and provide further evidence that the cannabinoid system could be explored as a potential drug discovery target for treating addiction across different classes of stimulants.

Structural brain alterations associated with schizophrenia preceded by conduct disorder: a common and distinct subtype of schizophrenia?

Conduct disorder (CD) prior to age 15 is a precursor of schizophrenia in a minority of cases and is associated with violent behavior through adulthood, after taking account of substance misuse. The present study used structural magnetic imaging to examine gray matter (GM) volumes among 27 men with schizophrenia preceded by CD (SZ+CD), 23 men with schizophrenia but without CD (SZ-CD), 27 men with CD only (CD), and 25 healthy (H) men. The groups with schizophrenia were similar in terms of age of onset and duration of illness, levels of psychotic symptoms, and medication. The 2 groups with CD were similar as to number of CD symptoms, lifelong aggressive behavior, and number of criminal convictions. Men with SZ+CD, relative to those with SZ-CD, displayed (1) increased GM volumes in the hypothalamus, the left putamen, the right cuneus/precuneus, and the right inferior parietal cortex after controlling for age, alcohol, and drug misuse and (2) decreased GM volumes in the inferior frontal region. Men with SZ+CD (relative to the SZ-CD group) and CD (relative to the H group) displayed increased GM volumes of the hypothalamus and the inferior and superior parietal lobes, which were not associated with substance misuse. Aggressive behavior, both prior to age 15 and lifetime tendency, was positively correlated with the GM volume of the hypothalamus. Thus, among males, SZ+CD represents a distinct subtype of schizophrenia. Although differences in behavior emerge in childhood and remain stable through adulthood, further research is needed to determine whether the differences in GM volumes result from abnormal neural development distinct from that of other males developing schizophrenia.

Addiction

Drug and alcohol addiction is a debilitating disorder characterized by persistent drug-seeking behaviors despite negative physiological, medical, or social consequences. Neurobiological models of addiction propose that the reinforcing effects of addictive drugs are associated with altered neurotransmission within the reward 'mesocorticolimbic' circuitry in the brain. Immense efforts are therefore designed to target the mesocorticolimbic circuitry in attenuating drug dependence and addiction-related behaviors. Yet, to date, most addiction treatments have demonstrated only limited success in reducing addiction-related behaviors. Accumulating and compelling evidence suggests that novel nonsurgical brain stimulation techniques, such as transcranial magnetic stimulation and transcranial direct current stimulation, could serve as promising tools for indexing altered neurotransmission associated with repetitive drug use, and moreover, may hold therapeutic potential for the treatment of drug dependence and addiction-related behaviors. This chapter reviews and discusses the current and potential applications of such techniques in the study and treatment of addiction; we focus on a number of common drugs of abuse, including nicotine, alcohol, cocaine, cannabis, and ecstasy.

Comorbidity of ADHD and Substance Use Disorder (SUD): a neuroimaging perspective

INTRODUCTION

ADHD has a high comorbidity with substance use disorders (SUD). Both diseases have profound social, psychological, and economic consequences and are therefore highly relevant for health systems. The high comorbidity indicates some shared underlying neurobiological substrates. Knowing these substrates may increase the understanding of the disease and help identify therapeutic processes.

METHOD

Neuroimaging studies of ADHD were reviewed and similarities with SUD identified. For this a PubMed research was conducted with the search terms ADHD, SUD, MRI or positron emission tomography (PET) or spectroscopy or imaging.

RESULTS

Similarities were found, in both PET and fMRI studies, between patients with ADHD and those with addiction-related craving. Results from structural MRI and MR spectroscopy do not support a common pathophysiological background, probably because of the lack of studies on craving.

DISCUSSION

ADHD and SUD-related craving share some neurobiological similarities. One reason may be that patients with addiction show more craving when they also suffer from ADHD. The present review thus supports the conclusion from an earlier meta-analysis of clinical studies which found that adequate treatment of ADHD reduces craving and relapse into substance use.

Brain stimulation in the study and treatment of addiction

Addiction is a devastating and chronically relapsing disorder. Repeated drug administration induces neuroadaptations associated with abnormal dopaminergic activity in the mesocorticolimbic circuitry, resulting in altered cortical neurotransmission and excitability. Electrical stimulation of specific brain regions can be used in animal models and humans to induce local activation or disruption of specific circuitries or alter neuronal excitability and cause neuroadaptations. Non-surgical stimulation of specific brain regions in human addicts can be achieved by transcranial magnetic stimulation (TMS). TMS is used for transient stimulation or disruption of neural activity in specific cortical regions, which can be used to assess cortical excitability, and to induce changes in cortical excitability. Moreover, it is suggested that repeated stimulation can cause long-lasting neuroadaptations. Therefore, TMS paradigms were used in some studies to assess the presence of altered cortical excitability associated with chronic drug consumption, while other studies have begun to assess the therapeutic potential of repetitive TMS. Similarly, transcranial direct current stimulation (tDCS) is used to modulate neuronal resting membrane potential in humans and alter cortical excitability. The current review describes how these brain stimulation techniques have recently been used for the study and treatment of addiction in animal models and humans.

Addictive illegal drugs: structural neuroimaging

Illegal addictive drugs can lead to functional or structural impairment of the central nervous system. This review provides an overview of the structural imaging findings on CT, MR imaging, and conventional angiography related to chronic and acute abuse of the most commonly abused illegal drugs, including cannabis, organic solvents, and amphetamines and opioids and their respective derivatives. Pathomechanisms include excitotoxicity, which may lead to an acute or subacute leukoencephalopathy, and vascular complications, including vasoconstriction, vasculitis, or hypertension, which may lead to intracranial hemorrhage or ischemia. Because clinical findings alone are often nonspecific, and afflicted patients are unlikely to admit to the substance abuse, the neuroradiologist may play an important role in establishing the diagnosis and, thereby, initiating treatment.

Fluorinase: a tool for the synthesis of 18F-labeled sugars and nucleosides for PET

There is an increasing interest in the preparation of 18F-labeled radiopharmaceuticals with potential applications in PET for medicinal imaging. Appropriate synthetic methods require a quick and efficient route in which to incorporate the 18F into a ligand, due to the relatively short half-life of the 18F isotope. Enzymatic methods are rare in this area; however, the discovery of a fluorinating enzyme from Streptomyces cattleya (EC 2.5.1.63) has opened up the possibility of the enzymatic synthesis and formation of C-18F bonds from the [18F]fluoride ion. In this article, the development of enzymatic preparations of 18F-labeled sugars and nucleosides as potential radiotracers using the fluorinase from S. cattleya for PET applications is reviewed. Enzymatic reactions are not traditional in PET synthesis, but this enzyme has some attractive features. The enzyme is available in an overexpressed form from Escherichia coli and it is relatively stable and can be easily purified and manipulated. Most notably, it utilizes [18F] fluoride, the form of the isotope normally generated by the cyclotron and usually in very high specific radioactivity. The disadvantage with the enzyme is that it is substrate specific; however, when the fluorinase is used in combination biotransformations with a second or third enzyme, then a range of radiolabeled nucleosides and ribose sugars can be prepared. The fluorinase enzyme has emerged as a curiosity from biosynthesis studies, but it now has some potential as a new catalyst for 18F incorporation for PET syntheses. The focus is now on delivering a user-friendly catalyst to the PET synthesis community and establishing a clinical role for some of the 18F-labeled molecules available using this technology.

Neurobiological substrates of cue-elicited craving and anhedonia in recently abstinent opioid-dependent males

AIM

Drug-related stimuli may induce craving in addicted patients, prompting drug-seeking behaviour. In addition, studies have shown addicted patients to be less sensitive to pleasant, but non-drug-related, stimuli; a condition generally referred to as anhedonia. The neural correlates of cue-induced craving and anhedonia in opioid-dependent patients are, however, not well understood. We studied brain activation patterns following visual presentation of neutral, pleasant and heroin-related cues.

METHODS

Detoxified opioid-dependent males (n=12) and healthy male control subjects (n=17) underwent functional magnetic resonance imaging (fMRI) while subjects viewed neutral, pleasant and heroin-related images. In addition, subjective cue-elicited craving (OCDUS and DDQ) and anhedonia (SHAPS) were measured.

RESULTS

Opioid-dependent subjects, but not control subjects, showed significant increases in activation in hippocampal region and subcortical limbic structures in response to heroin-related stimuli with a significant group x stimulus interaction effect for the subthalamic nucleus (STN). Control subjects, but not opioid-dependent subjects, showed significant increases in activation of anterior frontal areas and basal ganglia while viewing pleasant images with a significant group x stimulus interaction effect for bilateral anterior prefrontal cortex. Regression analyses showed a positive association between cue-elicited craving and ventral tegmental area (VTA) activation in response to heroin-related stimuli in heroin-dependent patients. In addition, a negative correlation was found between self-reported anhedonia and medial prefrontal regions in both groups.

CONCLUSIONS

Our findings suggest that the VTA is prominently involved in cue-induced opioid craving for heroin stimuli, in addition to mesolimbic and mesocortical pathways as identified in previous research. The present study also provides further evidence for the involvement of the STN in reward processing. Finally, our data support the presence of reduced brain activation in heroin-dependent patients in response to pleasant (non-drug-related) stimuli.

Neuroanatomic comparison of bipolar adolescents with and without cannabis use disorders

OBJECTIVE

Co-occurrence of substance use and bipolar disorders is both common and associated with poor treatment response and greater functional impairment than either disorder alone. The neurophysiological correlates of this co-morbidity however, remain unclear. In this pilot study, we compared brain morphometry between bipolar adolescents with co-occurring cannabis use disorders (CUD) and bipolar adolescents without any substance use disorder.

METHODS

Whole-brain structural magnetic resonance imaging (MRI) scans were obtained from 14 bipolar adolescents. Seven study participants were diagnosed with CUD before and/or shortly after their MR scan was obtained, and 7 subjects were free of any substance use disorder at the time of their MR scan as well as during longitudinal follow up. Morphologic differences were calculated using voxel-based morphometry implemented using statistical parametric mapping software (SPM2).

RESULTS

Bipolar adolescents with co-occurring CUD demonstrated decreased gray matter volume (GMV) in the left fusiform gyrus and increased GMV in the right caudate and precentral gyrus, as well as increased gray matter density in the right middle occipital and fusiform gyri and cerebellar vermis.

CONCLUSIONS

Bipolar adolescents with CUD demonstrate evidence of greater structural abnormalities than adolescents with bipolar disorder alone in frontal and temporal cortical regions, as well as in subcortical areas linked with emotion and motivational regulation. Although the limited prescan exposure to marijuana in these adolescents tentatively suggests that these findings may reflect underlying differences, the direct effect of cannabis exposure may also be involved.

Inactivation of the ventromedial prefrontal cortex mimics re-emergence of heroin seeking caused by heroin reconditioning

The purpose of this study was to investigate the role of the ventromedial prefrontal cortex (vmPFC) in the expression of extinguished heroin seeking as measured by conditioned place preference (CPP) in males Sprague-Dawley rats (n=25). Heroin place conditioning (0.3mg/kg SC x 4 sessions) was followed by a test of preference 24h later, extinction (saline x 4 sessions), heroin reconditioning (saline or 1.0mg/kg x 1 session), and a second test of place preference 24h later. Fifteen minutes prior to this test, rats received intra-vmPFC infusions (bilateral, 0.5 microl/side) of a mixture of GABA(A) (muscimol; 0.03 nmol) and a GABA(B) (baclofen; 0.3 nmol) agonists, or vehicle. As expected on the basis of previous studies, reconditioning with heroin resulted in the re-emergence of a CPP. Importantly, inactivation of the vmPFC produced the same effect in animals that did not receive heroin on the session of reconditioning. These results indicate that the vmPFC modulates expression of extinguished heroin seeking and suggest that prefrontal inhibitory mechanisms are involved in relapse to drug seeking.

Cerebral blood flow effects of acute intravenous heroin administration

We examined acute effects of intravenous diacetylmorphine (heroin) administration - which induces a characteristic biphasic response: A short rush-sensation associated with intense pleasurable feelings followed by a subjectively different period of euphoria on cerebral blood flow. This was assessed in nine male heroin dependent patients participating in a heroin maintenance program in a setting resembling everyday pattern of heroin abuse. 99mTc-HMPAO was administered 45 s (rush) and 15 min (euphoria) after administration of i.v. heroin and 45 s after administration of saline (placebo). Plasma concentration of diacetylmorphine and its metabolites were measured with high-pressure liquid chromatography (HPLC). Compared to the euphoria condition, rush was associated with blood flow increase in the left posterior cerebellar lobe, left anterior cingulate gyrus and right precuneus. Our results are in line with recent reports indicating that the cerebellum is an important component in functional brain systems subserving sensory and motor integration, learning, modulation of affect, motivation and social behaviour, which all play important roles in reinforcing properties of opioids.

SPECT neuroimaging in translational research of CNS disorders

High resolution SPECT imaging is an emerging field and there are only limited studies as yet available in this direction. Still there is continuous effort to achieve better spatial and temporal resolution in order to obtain detailed structural and functional information of different brain regions in small experimental animals. Recently, SPECT imaging system has been used to perform in vivo imaging using specific radioligands to further elucidate the role of dopaminergic, serotonergic, and cholinergic neurotransmission in relation to regional cerebral blood flow in various human CNS disorders and in gene-manipulated mouse models of neurodegeneration. Although in vivo and non-invasive translational research can be performed by high-resolution microPET imaging system, its limited spatial resolution restricts detailed anatomical and functional information of different brain regions involved in disease process. Recently developed NanoSPECT/CT imaging system has a better spatial resolution hence can be used to correlate and confirm microPET imaging data and determine the precise structural and functional anatomy of CNS disorders and their remission. Moreover SPECT imaging system reduces the cost and number of animals and provides detailed information of CNS disorders at the cellular, molecular and genetic level. Furthermore, SPECT system is economical, provides less radiation burden, and can be used to study bio-distribution of newly synthesized radioligands with increased target to non-target ratios, quality control, and clinical applications. It is envisaged that high-resolution SPECT imaging system will further improve in vivo non-invasive translational research on CNS disorders of unknown etiopathogenesis and their treatment in future.

Pattern of regional cerebral blood-flow changes induced by acute heroin administration--a perfusion MRI study

PURPOSE

Although both the subjective and physiological effects of abused psychotropic substances have been characterized, less is known about their effects on brain function. We examined the actions of intravenous diacetylmorphine (heroin), the most widely abused opioid, on regional cerebral blood flow (rCBF), as assessed by perfusion-weighted MR imaging (PWI) in a double-blind and placebo-controlled setting.

MATERIAL AND METHODS

Eight male subjects dependent of diacetylmorphine (mean age 36 years, range: 26 to 44 years), who had participated in a clinical diacetylmorphine maintenance program, underwent PWI with gadolinium injection. At two sessions separated by 2-7 days, the participants were examined 80 s after intravenous administration of either diacetylmorphine or saline. rCBF in four regions of interest (amygdala, vermis of the cerebellum, anterior cingulated cortex and thalamus) was compared with heroin versus placebo.

RESULTS

In the cerebellum, thalamus and cingulated cortex, there were no significant differences in perfusion values between diacetylmorphine and placebo. In the amygdala, perfusion values were 0.8+/-0.4 and 0.5+/-0.2 on the left, and 0.9+/-0.4 and 0.6+/-0.3 on the right, with diacetylmorphine and with placebo, respectively (t-test results were P=0.044 and P=0.033 on the left and right sides, respectively). Other differences in perfusion values between the drug and placebo did not reach statistical significance.

CONCLUSION

Perfusion MRI demonstrated differences in brain hemodynamics induced by drug intake.

How to make a rat addicted to cocaine

Procedures have been developed which provide extremely stable patterns of cocaine self-administration in rats and these have been useful in lesion and drug pretreatment studies aimed at understanding the neurobiology of cocaine reinforcement. The issue now is whether studying the neurobiology of reinforcement is the same as studying the neurobiology of addiction. If the goal is to understand a progressive and deteriorating disorder, then the self-administration procedures should model specific aspects of the progressive stages of the addiction process. Here we review theoretical strategies for modeling the addiction process and present data from a series of experiments from our laboratory showing conditions which produce a progressive change in the motivation to self-administer cocaine in rats. This phenomenon is revealed by an escalation in breakpoints on a progressive ratio schedule. The effect, which is robust and persistent, depends on dose and speed of injection. Interestingly, high drug intake can retard the development of this effect, which we argue indicates that the addiction process has a developmental sequence. Finally, we suggest that specific parameters (dose, price and availability) can be used to examine the transition from recreational use to binge-like intake.

Sexually compulsive/addictive behaviors in women: a women's healthcare issue

Sexually compulsive/addictive behavior is a pattern of sexual behaviors that cause distress and/or impairment of social functioning. It is marked by obsessive thoughts, compulsive behaviors, and the individual's inability to stop the behaviors despite negative consequences. Women experiencing sexually compulsive/addictive behavior are preoccupied with sex not as a response to desire but rather as a behavior that serves the purpose of anxiety reduction. Sexually compulsive/addictive behavior is associated with a number of health consequences, including sexually transmitted infections, unwanted pregnancies, abortions, and violence. It is important for providers to have an understanding of the addiction process, assessment, diagnosis, and interventions for these women.

[Impact of personality on the alcohol withdrawal syndrome intensity: a preliminary study with the Cloninger's model]

INTRODUCTION

The personality of alcohol dependant patients as a factor influencing the intensity of the alcohol withdrawal syndrome has been seldom examined. Cloninger's biosocial model of personality describes four temperaments (novelty seeking, harm avoidance, reward dependence, persistence) which, except for persistence, are admittedly linked to specific central neurotransmitters, and three characters. Novelty seeking is linked with low levels of mesencephalic dopamine, harm avoidance with high levels of serotonin in the septo-hippocampic system and reward dependence with low levels of noradrenaline in the ascending pathways from the locus coeruleus to the limbic system. The same neurotransmitters pathways are known to be involved in alcohol withdrawal, with a decrease of dopaminergic activity in the mesolimbic system, a decrease of serotonergic activity in the nucleus accumbens and an increase of the noradrenergic system. In view of the similarities between the neurobiological systems involved in Cloninger's model and in the neurobiological changes occurring during the withdrawal period, one would expect to observe severe withdrawal symptoms more frequently for patients with high novelty seeking, low harm avoidance and low reward dependence.

METHODS

To test this hypothesis, alcohol dependent patients according to DSM IV classification criteria who have drunk in the last twenty four hours were included in the study and received a standardized withdrawal treatment. The withdrawal syndrome intensity was examined with repeated measures of CIWA-Ar, the scores of which were correlated with TCI-R.

RESULTS

Twenty eight patients, between 30 et 65 years old and drinking 22,2 +/- 12 standard drinks per day were included. Antidepressant drugs, benzodiazepines and neuroleptics treatment introduced before hospitalisation were stopped or decreased as much as possible. A correlation matrix was carried out between all the variables which could influence withdrawal intensity (age at the hospitalisation, age at the begining of the dependance, ratio between the time of the dependance and the patients' age, the number of alcohol withdrawals carried out and the number of standard drinks per day), and showed a positive correlation between the number of standard drinks per day and withdrawal intensity at day 3 (r=0.7, p<0.000), at day 4 (r=0.52, p<0.005), at day 7 (r=0.41, p<0.036) and at day 8 (r=0.44, p<0.02); as between the ratio between the time of the dependance and the patients' age and withdrawal intensity at day 2 (r=0.43, p<0.03) and at day 5 (r=0.5, p<0.01). Therefore, partial correlations were calculated between the dimensions of personality and withdrawal intensity. The study showed a positive correlation between withdrawal intensity and harm avoidance from day 5 onwards (r=0.6 and P<0.003 at day 5, r=0.59 and P<0.004 at day 6, r=0.56 and P<0.006 at day 7, r=0.66 and P<0.001 at day 8), a negative correlation between withdrawal intensity and reward dependence at day 7 and 8 (r=- 0.45 and P<0.037 at day 7, r=- 0.49 and P<0.02 at day 8) and a negative correlation between withdrawal intensity and persistence from day 6 onwards (r=- 0.5 and P<0.017 at day 6, r=- 0.5 and P<0.019 at day 7, r=- 0.51 and P<0.014 at day 8). No correlation was found between withdrawal intensity and novelty seeking. The same relevant results were found again with the 22 patients without anti-depressant drugs' population.

DISCUSSION

Personality dimensions seem to influence alcohol withdrawal intensity once the severe symptomatology is over, while high doses of anti withdrawal treatment in the first days of abstinence may decrease the influence of personality on withdrawal symptoms. The positive correlation between harm avoidance and withdrawal intensity seems to invalidate our neurobiological hypotheses, but can be explained by clinical observations and corroborate studies assessing the influence of personality in benzodiazepine withdrawal intensity and in pain perception. This result encourages the introduction of support therapy during withdrawal and a cognitive-behavioural therapy before withdrawal in order to decrease patients' sensitivity to anxiety. The negative correlation between reward dependence and withdrawal intensity confirms the neurobiological hypotheses, but the weak correlation demands to be cautious in the interpretation of the results. The negative correlation between persistence and withdrawal intensity was expected.

CONCLUSION

The characteristics associated with persistence seem to act as protective factors during alcohol withdrawal, whereas those associated with harm avoidance appear to increase the symptoms of alcohol withdrawal. In contrast, the neurobiological hypotheses are only partially confirmed.

Neuroimaging endophenotypes: strategies for finding genes influencing brain structure and function

It is vitally important to identify the genetic determinants of complex brain-related disorders such as autism, dementia, mood disorders, and schizophrenia. However, the search for genes predisposing individuals to these illnesses has been hampered by their genetic and phenotypic complexity and by reliance upon phenomenologically based qualitative diagnostic systems. Neuroimaging endophenotypes are quantitative indicators of brain structure or function that index genetic liability for an illness. These indices will significantly improve gene discovery and help us to understand the functional consequences of specific genes at the level of systems neuroscience. Here, we review the feasibility of using neuroanatomic and neuropsychological measures as endophenotypes for brain-related disorders. Specifically, we examine specific indices of brain structure or function that are genetically influenced and associated with neurological and psychiatric illness. In addition, we review genetic approaches that capitalize on the use of quantitative traits, including those derived from brain images.

A Five-Day Gradual Reduction Regimen of Chlormadinone Reduces Premenstrual Anxiety and Depression: A Pilot Study

BACKGROUND

Anxiety and depression commonly occur in premenstrual dysphoric disorder (PMDD). The PMDD symptomatology disappears once the menstrual cycle reinitiates, resembling a withdrawal syndrome.

METHODS

The present study is a pilot, controlled, double-blind study exploring the effectiveness of a premenstrual 5-day gradual reduction regimen of chlormadinone acetate on PMDD. Volunteers received an initial dose of 10 mg (five 2-mg tablets) on the 24(th) day of the menstrual cycle and one-fifth of the dose less (one tablet) each day until a dose of 2 mg (one 2-mg tablet) was reached on the 28(th) day of the menstrual cycle. The control group received placebo with a similar regimen.

RESULTS

The 5-day gradual reduction regimen of chlormadinone significantly improved (F(3.76) = 3.29, p <0.02) the daily symptoms report (DSR) scores by the third month of treatment. The resulting relative risk was 4.09 (confidence interval: 1.15-14.57, p <0.005, 95% CI). Compared to placebo, chlormadinone clinically and statistically reduced the severity of depression, anxiety, food cravings, mood swings and cramps. A statistical reduction of symptoms such as poor coordination, irritability, feeling out of control, hopelessness, decreased interest and headache was detected but was not clinically relevant. No changes occurred in concentration difficulties, tiredness, insomnia, swelling, breast tenderness and aches. As side effects, 30% of the volunteers showed changes in the length of the menstrual cycle, and 15% experienced dyspepsia.

CONCLUSIONS

A 5-day gradual reduction regimen of chlormadinone improves some of the discomforting ailments associated with PMDD, namely, depression and anxiety.

Impact of acquisition protocols and processing streams on tissue segmentation of T1 weighted MR images

The segmentation of T1-weighted images into gray matter (GM), white matter (WM), and cerebrospinal fluid (CSF) is a fundamental processing step in neuroimaging, the results of which affect many other structural imaging analyses. Variability in the segmentation process can decrease the power of a study to detect anatomical differences, and minimizing such variability can lead to more robust results. This paper outlines a straightforward strategy that can be used (1) to select more optimal data acquisition and processing protocols and (2) to quantify the impact of such optimization. Using this approach with multiple scans of a single subject, we found that the choice of a segmentation algorithm had the largest impact on variability, while the choice of a pulse sequence had the second largest impact. The data indicate that the classification of GM is the most variable, and that the optimal protocol may differ across tissue types. Therefore, the intended use of segmentation data should play a role in optimization. Examples are provided to demonstrate that the minimization of variability is not sufficient for optimization; the overall accuracy of the approach must also be considered. Simple volumetric computations are included to illustrate the potential gain of optimization; these results show that volume estimates from optimal pathways were on average three times less variable than estimates from suboptimal pathways. Therefore, the simple strategy illustrated here can be applied to many studies to optimize tissue segmentation, which should lead to a net increase in the power of structural neuroimaging studies.

Differential progesterone effects on defensive burying and forced swimming tests depending upon a gradual decrease or an abrupt suppression schedules

A single dose of progesterone reduces the cumulative time in the defensive burying test and the immobility in the forced swim test, whereas the abrupt suppression of repeated doses increases the anxiety indicators. Whether anxiety and despair indicators reduce by a gradually decreased schedule of progesterone is unknown. Therefore, we subjected adult ovariectomized Wistar rats to open field, defensive burying and forced swim tests. One group received a constant schedule of progesterone (0.50 mg, daily), abruptly suppressed (AS) after five days. Another group received a gradual reduction schedule of progesterone (GR: 0.84, 0.67, 0.50, 0.33, 0.17 mg, each day). Control group received vehicle (VEH). The GR group displayed similar crossing in the open field test as the VEH group (F(2,19) = 8.78, p < 0.002), but also the shortest cumulative time in defensive burying (F(2,28) = 13.3, p < 0.0001) and the shortest time in freezing (F(2,24) = 6.39, p < 0.006). In the forced swim test, the GR group displayed the shortest immobility time (F(2,19) = 12.1, p < 0.0005), the lowest number of immobility periods (F(2,19) = 4.26, p < 0.03) and the longest latency to the first period of immobility (F(2,1) = 4.06, p < 0.03). It is concluded that a gradually reduced schedule of progesterone reduces anxiety and despair in the Wistar rat.

The neurobiological basis of temperament: towards a better understanding of psychopathology

The ability to characterise psychopathologies on the basis of their underlying neurobiology is critical in improving our understanding of disorder etiology and making more effective diagnostic and treatment decisions. Given the well-documented relationship between temperament (i.e. core personality traits) and psychopathology, research investigating the neurobiological substrates that underlie temperament is potentially key to our understanding of the biological basis of mental disorder. We present evidence that specific areas of the prefrontal cortex (including the dorsolateral prefrontal, anterior cingulate, and orbitofrontal cortices) and limbic structures (including the amygdala, hippocampus and nucleus accumbens) are key regions associated with three fundamental dimensions of temperament: Negative Affect, Positive Affect, and Constraint. Proposed relationships are based on two types of research: (a) research into the neurobiological correlates of affective and cognitive processes underlying these dimensions; and (b) research into the neurobiology of various psychopathologies, which have been correlated with these dimensions. A model is proposed detailing how these structures might comprise neural networks whose functioning underlies the three temperaments. Recommendations are made for future research into the neurobiology of temperament, including the need to focus on neural networks rather than individual structures, and the importance of prospective, longitudinal, multi-modal imaging studies in at-risk youth.

Imaging addiction with PET: is insight in sight?

Neurochemical imaging studies can identify molecular targets of abused drugs and link them to the underlying pathology associated with behaviors such as drug dependence, addiction and withdrawal. positron emission tomography (PET) is opening new avenues for the investigation of the neurochemical disturbances underlying drug abuse and addiction and the in vivo mechanisms by which medications might ameliorate these conditions. PET can identify vulnerable human populations, treatment strategies and monitor treatment efficacy. Thus, with this tool and the knowledge it provides, the potential for developing novel drugs and treatment strategies for drug addiction is now close at hand.

Alcohol and gene expression in the central nervous system

AIMS

To describe recent research focusing on the analysis of gene and protein expression relevant to understanding ethanol consumption, dependence and effects, in order to identify common themes.

METHODS

A selective literature search was used to collate the relevant data.

RESULTS

Over 160 genes have been individually assessed before or after ethanol administration, as well as in genetically selected lines. Techniques for studying gene expression include northern blots, differential display, real time reverse transcriptase-polymerase chain reaction (RT-PCR) and in situ hybridization. More recently, high throughput functional genomic technology, such as DNA microarrays, has been used to examine gene expression. Recent gene expression analyses have dramatically increased the number of candidate genes (nine array papers have illuminated 600 novel gene transcripts that may contribute to alcohol abuse and alcoholism).

CONCLUSIONS

Although functional genomic experiments (transcriptome analysis) have failed to identify a single alcoholism gene, they have illuminated important pathways and gene products that may contribute to the risk of alcohol abuse and alcoholism.