Cerebral perfusion abnormalities in abstinent cocaine abusers: a perfusion MRI and SPECT study

Chronic Cocaine Use and Parkinson's Disease: An Interpretative Model

Over the years, the growing "epidemic" spread of cocaine use represents a crucial public health and social problem worldwide. According to the 2023 World Drug Report, 0.4% of the world's population aged 15 to 64 report using cocaine; this number corresponds to approximately 24.6 million cocaine users worldwide and approximately 1 million subjects with cocaine use disorder (CUD). While we specifically know the short-term side effects induced by cocaine, unfortunately, we currently do not have exhaustive information about the medium/long-term side effects of the substance on the body. The scientific literature progressively highlights that the chronic use of cocaine is related to an increase in cardio- and cerebrovascular risk and probably to a greater incidence of psychomotor symptoms and neurodegenerative processes. Several studies have highlighted an increased risk of antipsychotic-induced extrapyramidal symptoms (EPSs) in patients with psychotic spectrum disorders comorbid with psychostimulant abuse. EPSs include movement dysfunction such as dystonia, akathisia, tardive dyskinesia, and characteristic symptoms of Parkinsonism such as rigidity, bradykinesia, and tremor. In the present paper, we propose a model of interpretation of the neurobiological mechanisms underlying the hypothesized increased vulnerability in chronic cocaine abusers to neurodegenerative disorders with psychomotor symptoms. Specifically, we supposed that the chronic administration of cocaine produces significant neurobiological changes, causing a complex dysregulation of various neurotransmitter systems, mainly affecting subcortical structures and the dopaminergic pathways. We believe that a better understanding of these cellular and molecular mechanisms involved in cocaine-induced neuropsychotoxicity may have helpful clinical implications and provide targets for therapeutic intervention.

Cocaine-induced structural and functional impairments of the glymphatic pathway in mice

The glymphatic system plays a central role in the clearance of extracellular wastes from the brain. Cocaine exposure can lead to pathologies that affect the entire brain, resulting in addictive disorders involving motivational and cognitive impairment. However, it remains unknown whether cocaine exposure impairs glymphatic function. In the present study, using a mouse model of noncontingent cocaine exposure, we evaluated glymphatic function including cerebrospinal fluid (CSF)-interstitial fluid (ISF) exchange and solute clearance during repeated exposures and withdrawal. We found that cocaine treatment, both during repeated exposure and withdrawal, significantly induced widespread astrogliosis and reduced cerebral blood flow (CBF), cerebrovascular pulsatility, and aquaporin-4 (AQP4) polarity. Glymphatic function was greatly impaired in mice after cocaine treatment, as evidenced by reduced CSF influx from paravascular pathways into the brain parenchyma and decreased efflux of interstitial molecules out of the parenchyma. These findings provide evidence that cocaine exposure impairs the clearance of wastes from the brain, which may contribute to the development of neurocognitive disorders in patients with drug addictions.

Variability of physiological brain perfusion in healthy subjects - A systematic review of modifiers. Considerations for multi-center ASL studies

Quantitative measurements of brain perfusion are influenced by perfusion-modifiers. Standardization of measurement conditions and correction for important modifiers is essential to improve accuracy and to facilitate the interpretation of perfusion-derived parameters. An extensive literature search was carried out for factors influencing quantitative measurements of perfusion in the human brain unrelated to medication use. A total of 58 perfusion modifiers were categorized into four groups. Several factors (e.g., caffeine, aging, and blood gases) were found to induce a considerable effect on brain perfusion that was consistent across different studies; for other factors, the modifying effect was found to be debatable, due to contradictory results or lack of evidence. Using the results of this review, we propose a standard operating procedure, based on practices already implemented in several research centers. Also, a theory of 'deep MRI physiotyping' is inferred from the combined knowledge of factors influencing brain perfusion as a strategy to reduce variance by taking both personal information and the presence or absence of perfusion modifiers into account. We hypothesize that this will allow to personalize the concept of normality, as well as to reach more rigorous and earlier diagnoses of brain disorders.

Adolescent brain cognitive development (ABCD) study: Overview of substance use assessment methods

One of the objectives of the Adolescent Brain Cognitive Development (ABCD) Study (https://abcdstudy.org/) is to establish a national longitudinal cohort of 9 and 10 year olds that will be followed for 10 years in order to prospectively study the risk and protective factors influencing substance use and its consequences, examine the impact of substance use on neurocognitive, health and psychosocial outcomes, and to understand the relationship between substance use and psychopathology. This article provides an overview of the ABCD Study Substance Use Workgroup, provides the goals for the workgroup, rationale for the substance use battery, and includes details on the substance use module methods and measurement tools used during baseline, 6-month and 1-year follow-up assessment time-points. Prospective, longitudinal assessment of these substance use domains over a period of ten years in a nationwide sample of youth presents an unprecedented opportunity to further understand the timing and interactive relationships between substance use and neurocognitive, health, and psychopathology outcomes in youth living in the United States.

Cocaine attenuates blood flow but not neuronal responses to stimulation while preserving neurovascular coupling for resting brain activity

Cocaine affects neuronal activity and constricts cerebral blood vessels, making it difficult to determine whether cocaine-induced changes in cerebral blood flow (CBF) reflect neuronal activation or its vasoactive effects. Here we assessed the effects of acute cocaine on both resting-state and stimulation responses to investigate cocaine's effects on neurovascular coupling and to differentiate its effects on neuronal activity from its vasoactive actions. We concurrently measured cortical field potentials via thinned-skull electroencephalography recordings and CBF with laser Doppler flowmetry in the rat's somatosensory cortex for both resting state and forepaw stimulation before and following cocaine administration (1 mg kg(-1), intravenously). Results show both resting-state field potentials and CBF were depressed after cocaine administration (19.8±4.7% and 52.1±13.4%, respectively) and these changes were strongly correlated with each other (r=0.81, P<0.001), indicating that cocaine did not affect neurovascular coupling at rest and that the reduction in resting CBF reflected reduction in synchronized spontaneous neuronal activity rather than vasoconstriction. In contrast, the forepaw stimulation-evoked neuronal activity was not changed by cocaine (P=0.244), whereas the CBF to the stimulation was reduced 49.9±2.6% (P=0.028) gradually recovering ∼20 min after cocaine injection, indicating that neurovascular coupling during stimulation was temporarily disrupted by cocaine. Neurovascular uncoupling by cocaine during stimulation but not during rest indicates that distinct processes might underlie neurovascular regulation for both stimulation and spontaneous activity. The greater reductions by cocaine to the stimulation-induced CBF increases than to the background CBF should be considered when interpreting functional MRI studies comparing activation responses between controls and cocaine abusers. Neurovascular uncoupling could contribute to cocaine's neurotoxicity, particularly for stimulation conditions when CBF might be insufficient to cover for the energetic demands of neuronal tissue.

A Bidirectional Relationship between Executive Function and Health Behavior: Evidence, Implications, and Future Directions

Physically active lifestyles and other health-enhancing behaviors play an important role in preserving executive function into old age. Conversely, emerging research suggests that executive functions facilitate participation in a broad range of healthy behaviors including physical activity and reduced fatty food, tobacco, and alcohol consumption. They do this by supporting the volition, planning, performance monitoring, and inhibition necessary to enact intentions and override urges to engage in health damaging behavior. Here, we focus firstly on evidence suggesting that health-enhancing behaviors can induce improvements in executive function. We then switch our focus to findings linking executive function to the consistent performance of health-promoting behaviors and the avoidance of health risk behaviors. We suggest that executive function, health behavior, and disease processes are interdependent. In particular, we argue that a positive feedback loop may exist whereby health behavior-induced changes in executive function foster subsequent health-enhancing behaviors, which in turn help sustain efficient executive functions and good health. We conclude by outlining the implications of this reciprocal relationship for intervention strategies, the design of research studies, and the study of healthy aging.

The Influence of Neurocognitive Impairment on HIV Risk Behaviors and Intervention Outcomes among High-Risk Substance Users: A Systematic Review

Neurocognitive impairment (NCI) among high-risk substance users poses a substantial barrier to reducing risk behaviors in this population. Previous work suggests that NCI is intertwined in a close, reciprocal relationship with risk behaviors. Not only does substance use worsen cognitive impairment but cognitive impairment may also reduce the efficacy of interventions aimed at reducing risk and improving medication adherence. In this systematic review, we examine the potential impact of substance abuse and cognitive functioning in the context of HIV risk behaviors and risk-reduction intervention outcomes. The findings thus far suggest that, in order to be effective, risk-reduction interventions must take into account the impact of NCI on learning, memory, and behavior.

Altered Functional Connectivity Strength in Abstinent Chronic Cocaine Smokers Compared to Healthy Controls

Past research involving cocaine and resting-state functional connectivity (RSFC) has shown altered functional connectivity within the frontal and between the frontal and other cortical and subcortical brain regions in chronic users of cocaine. However, there have been discrepancies in literature regarding the relationship between RSFC between brain regions and cocaine use behavior. This study explored the RSFC between brain regions in cocaine smokers abstinent from cocaine use for 72 h and healthy controls. Also, the relationship between RSFC between brain regions and various cocaine use measures (cocaine use duration; frequency, and money spent on cocaine/week) was examined. Twenty chronic cocaine users and 17 controls completed a resting-state scan and an anatomical MPRAGE scan. Group independent component analysis performed on functional magnetic resonance imaging data identified 13 ICs pertaining to distinct resting-state networks, and group-level differences were examined. To examine inter-network functional connectivity between brain regions, these 13 ICs were divided into 61 distinct regions of interest (ROIs). Correlations were calculated between 61 ROI time series. For the ROI pairs that significantly differed from controls in connectivity strength, correlations were computed between connectivity strength and cocaine use measures. Results showed an enhanced RSFC within the sensory motor cortex and the left frontal-parietal network in cocaine users than controls. An increased inter-network RSFC between frontal-temporal and frontal-parietal brain regions, and a decreased RSFC between parietal-parietal, occipital-limbic, occipital-occipital, and occipital-parietal brain regions was found in cocaine users. This study demonstrated that intra-network connectivity strength of sensory motor cortex was negatively correlated with years of cocaine use. Inter-network connectivity strength between occipital-limbic brain regions was positively correlated with years of cocaine use, while connectivity strength within occipital brain regions was negatively related to cocaine use frequency and money spent on cocaine per week in abstinent cocaine users.

Sex-Related Differences in Self-Reported Neurocognitive Impairment among High-Risk Cocaine Users in Methadone Maintenance Treatment Program

BACKGROUND

Previous research has suggested possible sex-related differences in executive functioning among cocaine users; however, no studies specifically explain sex-related differences in neurocognitive impairment (NCI) among cocaine users receiving clinical care. Knowledge about this association can aid in the development of targeted prevention strategies to reduce adverse health outcomes. This study was designed to examine the sex-related differences in NCI among high-risk cocaine users receiving substance-abuse treatment.

METHODS

The Neuropsychological Impairment Scale (NIS) was administered to 199 cocaine users (98 men; 101 women), receiving methadone maintainance treatment, to assess self-reported NCI by identifying the patients’ awareness of neuropsychological symptoms. We used T-test comparison to find differences in NCI between men and women and multiple regression analysis to explore the relative contribution of sex to NCI.

RESULTS

Consistent with prior work, high NCI was evident within this sample, as indicated by high scores on most of the NIS subscales. Women reported greater impairment than men, as evidenced by significantly higher scores on several NIS subscales, after controlling for demographic and other confounding variables. Interestingly, cocaine craving significantly predicted NCI among men but not among women, as suggested by the significant association between cocaine craving and all except one of the NIS subscales.

CONCLUSIONS

These findings suggest that cocaine users enter into treatment with a range of NCI – with women having significantly more neurocognitive deficits than men – that may contribute to differential treatment outcomes. This highlights the need to include additional services such as neuropsychological screening and sex-specific treatment programs to optimally reduce adverse health outcomes in these high-risk, cognitively impaired patients.

Neuropsychological Consequences of Chronic Drug Use: Relevance to Treatment Approaches

Heavy use of drugs impacts of the daily activities of individuals in these activities. Several groups of investigators have indeed documented changes in cognitive performance by individuals who have a long history of chronic drug use. In the case of marijuana, a wealth of information suggests that heavy long-term use of the drug may have neurobehavioral consequences in some individuals. In humans, heavy cocaine use is accompanied by neuropathological changes that might serve as substrates for cognitive dysfunctions. Similarly, methamphetamine users suffer from cognitive abnormalities that may be consequent to alterations in structures and functions. Here, we detail the evidence for these neuropsychological consequences. The review suggests that improving the care of our patients will necessarily depend on the better characterization of drug-induced cognitive phenotypes because they might inform the development of better pharmacological and behavioral interventions, with the goal of improving cognitive functions in these subsets of drug users.

Error-related functional connectivity of the thalamus in cocaine dependence

Error processing is a critical component of cognitive control, an executive function that has been widely implicated in substance misuse. In previous studies we showed that error related activations of the thalamus predicted relapse to drug use in cocaine addicted individuals (Luo et al., 2013). Here, we investigated whether the error-related functional connectivity of the thalamus is altered in cocaine dependent patients (PCD, n = 54) as compared to demographically matched healthy individuals (HC, n = 54). The results of a generalized psychophysiological interaction analysis showed negative thalamic connectivity with the ventral medial prefrontal cortex (vmPFC), in the area of perigenual and subgenual anterior cingulate cortex, in HC but not PCD (p < 0.05, corrected, two-sample t test). This difference in functional connectivity was not observed for task-residual signals, suggesting that it is specific to task-related processes during cognitive control. Further, the thalamic-vmPFC connectivity is positively correlated with the amount of cocaine use in the prior month for female but not for male PCD. These findings add to recent literature and provide additional evidence for circuit-level biomarkers of cocaine dependence.

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Error-related thalamic-vmPFC connectivity is altered in cocaine misuse.

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This altered connectivity is associated with impaired self control.

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This deficit is associated with recent cocaine use in women but not men.

Caudolateral orbitofrontal regional cerebral blood flow is decreased in abstinent cocaine-addicted subjects in two separate cohorts

The orbitofrontal cortex (OFC) is crucial for the inhibition of extraneous stimuli, evaluation of aversive information and emotional regulation-all behaviors impaired in cocaine addiction. Previous studies suggest that cocaine-addicted subjects have decreased basal activity in the OFC. In this study, we examined regional cerebral blood flow (rCBF) during a saline infusion in two independent populations of abstinent cocaine- (and mostly nicotine-) addicted (n=33 and 26) and healthy control (n=35 and 20) men and women. Isolated rCBF decreases (P<0.001) were observed in the left caudolateral OFC, as well as left superior temporal cortex, in cocaine-addicted subjects relative to controls in both cohorts and bilaterally in the combined cohort. An anatomically defined region of the caudolateral OFC showed similar findings and were evident in both male and female addicted subjects. The reliability of these findings across two cohorts reveals a functional disruption in the lateral OFC, a brain region implicated in the evaluation of behavior-terminating stimuli. This may contribute to an addicted individual's persistent drug use despite negative consequences.

Substance Abuse, Hepatitis C, and Aging in HIV: Common Cofactors that Contribute to Neurobehavioral Disturbances

Although the prevalence of neurocognitive disturbances among individuals with HIV has decreased in recent years, rates of impairment still remain high. This review presents findings from comorbid conditions that may contribute to further neurocognitive impairments in this already vulnerable population. We will focus on three co-factors that have received substantial attention in the neuroAIDS literature: drug use, hepatitis C co-infection (HCV), and aging. All three conditions commonly co-occur with HIV and likely interact with HIV in complex ways. Collectively, the extant literature suggests that drug use, HCV, and aging serve to worsen the neurocognitive profile of HIV through several overlapping mechanisms. A better understanding of how specific comorbidities interact with HIV may reveal specific phenotypes of HIV-associated neurocognitive disorder that may aid in the development of more targeted behavioral and pharmacological treatment efforts.

Contributions of neuroimaging to understanding sex differences in cocaine abuse

A consistent observation in drug abuse research is that males and females show differences in their response to drugs of abuse. In order to understand the neurobiology underlying cocaine abuse and effective treatments, it is important to consider the role of sex differences. Sex hormones have been investigated in both behavioral and molecular studies, but further evidence addressing drug abuse and dependence in both sexes would expand our knowledge of sex differences in response to drugs of abuse. Neuroimaging is a powerful tool that can offer insight into the biological bases of these differences and meet the challenges of directly examining drug-induced changes in brain function. As such, neuroimaging has drawn much interest in recent years. Specifically, positron emission tomography (PET), single photon emission computed tomography (SPECT), and magnetic resonance imaging (MRI) technology have emerged as effective noninvasive approaches for human and animal models. Studies have revealed sex-specific changes in patterns of brain activity in response to acute cocaine injection and after prolonged cocaine use. SPECT and PET studies have demonstrated changes in the dopamine transporter but are less clear on other components of the dopaminergic system. This review highlights contributions of neuroimaging toward understanding the role of sex differences in the drug abuse field, specifically regarding cocaine, and identifies relevant questions that neuroimaging can effectively address.

Assessing white matter integrity as a function of abstinence duration in former cocaine-dependent individuals

Current cocaine-dependent users show reductions in white matter (WM) integrity, especially in cortical regions associated with cognitive control that have been associated with inhibitory dysfunction. A key question is whether these white matter differences are present following abstinence from drug use. To address this, WM integrity was examined using diffusion tensor imaging (DTI) obtained on 43 cocaine abstinent patients (abstinence duration ranged between five days and 102 weeks) and 43 non-using controls. Additionally, a cross-sectional comparison separated the patients into three groups (short-term, mid-term and long-term) based upon duration of cocaine abstinence. The 43 cocaine abstinent patients showed lower fractional anisotropy (FA) in the left anterior callosal fibers, left genu of the corpus callosum, right superior longitudinal fasciculus, right callosal fibers and the superior corona radiata bilaterally when compared against non-using controls. Higher FA in the cocaine abstinent patients was observed in the splenium of the corpus callosum and right superior longitudinal fasciculus. Differences between the cocaine abstinent groups were observed bilaterally in the inferior longitudinal fasciculus, right anterior thalamic radiation, right ventral posterolateral nucleus of the thalamus, left superior corona radiata, superior longitudinal fasciculus bilaterally, right cingulum and the WM of the right precentral gyrus. The results identified WM differences between cocaine abstinent patients and controls as well as distinct differences between abstinent subgroups. The findings suggest that specific white matter differences persist throughout abstinence while other, spatially distinct, differences discriminate as a function of abstinence duration. These differences may, therefore, represent brain changes that mark recovery from addiction.

Brain hypoperfusion in adolescents dependent of multiple drugs

Brain SPECT imaging (BSI) with statistical parametric mapping (SPM) offers a clear and accurate vision of perfusion changes.

OBJECTIVE

To study brain perfusion abnormalities in adolescents' dependent of multiple drugs.

METHOD

Sixteen male patients (15.1 + or - 2.1 years) were submitted to (99m)Tc-HMPAO BSI with SPM.

RESULTS

Cortical hypoperfusion occurred in 7/16 patients (44%). There was a significant inverse correlation between the number of hypoperfused regions and the patient's age (p= -0.6737; p=0.004) and with the age when the drug dependence began (p= -0.5616; p=0.023). There was also a tendency towards an inverse correlation between regions of hypoperfusion and the duration of the drug dependence.

CONCLUSION

BSI with SPM can help detect hypoperfusion in adolescents dependent on multiple drugs. The younger the patients, the more regions of hypoperfusion are noted. Probably, the neuronal plasticity has an important role in this phenomenon because the highest neural activity occurs in childhood.

Perfusion magnetic resonance imaging in psychiatry

INTRODUCTION

Cerebral perfusion imaging using magnetic resonance imaging (MRI) is widely used in the research and clinical fields to assess the profound changes in blood flow related to ischemic events such as acute stroke, chronic steno-occlusive disease, vasospasm, and abnormal vessel formations from congenital conditions or tumoral neovascularity. With continuing improvements in the precision of MRI-based perfusion techniques, it is increasingly feasible to use this tool in the study of the subtle brain perfusion changes occurring in psychiatric illnesses. This article aims to review the existing literature on applications of perfusion MRI in psychiatric disorder and substance abuse research. The article also provides a brief introductory overview of dynamic susceptibility contrast MRI and arterial spin labeling techniques. An outlook of necessary steps to bring perfusion MRI into the realm of clinical psychiatry as a diagnostic tool is brought forth. Opportunities for research in unexplored disorders and with higher field strengths are briefly examined.

METHODS

PubMed, ISI Web of Knowledge & Scopus were used to search the literature and cross reference several neuropsychiatric disorders with a search term construct, including "magnetic resonance imaging," "dynamic susceptibility contrast," "arterial spin labeling," perfusion or "cerebral blood flow" or "cerebral blood volume" or "mean transit time." The list of disorders used in the search included schizophrenia, depression and bipolar disorder, dementia and Alzheimer's disease, Parkinson's disease, posttraumatic stress disorder, autism, Asperger disease, attention deficit, Tourette syndrome, obsessive-compulsive disorder, Huntington's disease, bulimia nervosa, anorexia nervosa, and substance abuse. For each disorder for which perfusion MRI studies were found, a brief overview of the disorder symptoms, treatment, prevalence, and existing models is provided, and previous findings from nuclear medicine-based perfusion imaging are overviewed. Findings of perfusion MRI studies are then summarized, and overlap of findings are discussed. Overarching conclusions are made, or an outlook for future work in the area is offered, where appropriate.

RESULTS

Despite the now fairly broad availability of perfusion MRI, only a limited number of studies were found using this technology. The search produced 13 studies of schizophrenia, 7 studies in major depression, 12 studies in Alzheimer's disease, and 2 studies in Parkinson's disease. Drug abuse and other disorders have mainly been studied with nuclear medicine-based perfusion imaging. The literature concerning the use of perfusion imaging in psychiatry has not been reviewed in the last 5 years or more. The use of MRI for perfusion measurements in psychiatry has not been reviewed in 10 years.

CONCLUSIONS

Although MRI-based perfusion imaging in psychiatry has mainly been used as a research tool, a path is progressively being cleared for its application in clinical diagnostic and treatment monitoring. The precision of perfusion MRI methods now rivals that of nuclear medicine-based perfusion imaging techniques. Because of their noninvasive nature, arterial spin labeling methods have gained popularity in studies of neuropsychiatric disorders such as schizophrenia, depression, Alzheimer's, and Parkinson's diseases. Perfusion imaging measurements have yet to be included within the diagnostic criteria of neuropsychiatric disorders despite having shown to have great discriminant power in specific disorders. As this young methodology continues to improve and research studies demonstrate the correlation of measured perfusion abnormalities to microcirculatory abnormalities and neuropsychiatric symptomatology, the idea of including such a test within diagnostic criteria for certain mental illnesses becomes increasingly plausible.

Decreased frontal white-matter integrity in abstinent methamphetamine abusers

This study explored differences in frontal white-matter (WM) integrity between methamphetamine (MA) abusers and healthy comparison subjects using diffusion tensor imaging (DTI). Fractional anisotropy (FA) values, which indicate WM integrity, were calculated for regions-of-interest in frontal WM on diffusion tensor images of 32 MA abusers and 30 healthy comparison subjects. Frontal executive functions were also assessed by the Wisconsin Card Sorting test (WCST). MA abusers had significantly lower FA values in bilateral frontal WM at the anterior commissure-posterior commissure (AC-PC) plane and the right frontal WM 5 mm above the AC-PC plane relative to healthy comparison subjects. MA abusers had more total, perseveration and non-perseveration errors in the WCST relative to healthy comparison subjects. FA values of the right frontal WM 5 mm above the AC-PC plane negatively correlated with the number of total and non-perseveration errors in the WCST in MA abusers. In the sub-analysis for gender differences, lower FA values in frontal WM and more errors in the WCST were found only in male MA abusers, not in female MA abusers, relative to comparison subjects of the respective gender. We report that frontal WM integrity of MA abusers is compromised. This finding may also be related to impairment in frontal executive function. In addition, the neurotoxic effect of MA on frontal WM may be less prominent in women than in men, possibly due to oestrogen's neuroprotective effect.

Regional cerebral blood flow in patients with sickle cell disease: study with single photon emission computed tomography

OBJECTIVE

Neurological complications have been reported in patients with sickle-cell disease (SCD) using positron emission tomography (PET), magnetic resonance imaging (MRI), and computed tomography (CT), but not with single photon emission computed tomography (SPECT). The objective of this study was to investigate brain perfusion in the patients with SCD using SPECT after technetium-99m hexamethylpropylene amine oxime (99mTc-HMPAO), was administered and compare the findings with those of demography, physical examination, MRI and hematological profile.

METHODS

The study involved 21 patients (12 males, 9 females, age at study 8-45 years) who were known to be having SCD for a duration of at least 5 years. The patients were not in acute crisis and had normal neurological assessments with no known history of stroke or transient ischemic episode or previous abnormal CT or MRI brain scan, and were right-handed. The brain SPECT was performed after intravenous injection of 740 MBq (20 mCi) 99mTc-HMPAO in adults or an appropriate dose in pediatric patients. The scans were visually interpreted by two nuclear medicine physicians and a decision was reached by consensus. An MRI done 3 months later was interpreted by a radiologist. The demographic data and hematological profile were obtained from the medical records of the patients.

RESULTS

Of the 21 patients, 7 (age 11-22 years) had brain perfusion deficit mostly in the frontal lobe either alone or in combination with temporal and/or parietal lobe. The MRI was abnormal in 2 patients. The brain perfusion deficit was not associated with the demographic data of the patients or hematological profiles.

CONCLUSIONS

The findings show that SPECT was useful in detecting brain perfusion deficit in SCD patients, and such an early detection may be clinically useful in the subsequent follow-up of such patients, since it is known that cerebral perfusion deficit can lead to silent infarct and/or overt stroke, and affect cognitive skills.

Cerebellar gray matter volume correlates with duration of cocaine use in cocaine-dependent subjects

This study was conducted to explore differences in gray and white matter volume between cocaine-dependent and healthy comparison subjects using optimized voxel-based morphometry (VBM). Brain magnetic resonance imaging (MRI) and neuropsychological function tests were performed for 40 cocaine-dependent subjects (41.4+/-6.9 years, 27 men) and 41 healthy age- and sex-matched comparison subjects (38.7+/-8.8 years, 26 men). Optimally normalized whole brain MR images were segmented, modulated, smoothed, and compared between groups with statistical parametric mapping. The cocaine-dependent group had lower gray matter volumes in bilateral premotor cortex (Brodmann area (BA) 6, 8; 16.6%), right orbitofrontal cortex (BA 10, 15.1%), bilateral temporal cortex (BA 20, 38; 15.9%), left thalamus (12.6%), and bilateral cerebellum (13.4%) as well as lower right cerebellar white matter volume (10.0%) relative to the comparison group at a corrected p<0.05 for multiple comparisons. Duration of cocaine use negatively correlated with right and left cerebellar gray matter volumes (r=-0.37, r=-0.39, respectively). In cocaine-dependent subjects, lower cerebellar hemispheric gray and white matter volumes were correlated with deficits in executive function and decreased motor performance. This study reports that cocaine-dependent subjects have lower gray matter volumes in cerebellar hemispheres as well as in frontal, temporal cortex, and thalamus. These findings are the first to suggest that the cerebellum may be vulnerable to cocaine-associated brain volume changes, and that cerebellar deficits may contribute to neuropsychological deficits and motor dysfunction frequently observed in cocaine-dependent subjects.

Chronic cocaine self-administration is associated with altered functional activity in the temporal lobes of non human primates

Previous studies utilizing a nonhuman primate model have shown that cocaine self-administration in its initial stages is accompanied by alterations in functional activity largely within the prefrontal cortex and ventral striatum. Continued cocaine exposure may considerably change this response. The purpose of the present investigation was to characterize the effects of reinforcing doses of cocaine on cerebral metabolism in a nonhuman primate model of cocaine self-administration, following an extended history of cocaine exposure, using the quantitative 2-[(14)C]deoxyglucose (2-DG) method. Rhesus monkeys were trained to self-administer 0.03 mg/kg/injection (n = 4) or 0.3 mg/kg/injection (n = 4) cocaine and compared to monkeys trained to respond under an identical schedule of food reinforcement (n = 6). Monkeys received 30 reinforcers per session for a total of 100 sessions. Metabolic mapping was conducted at the end of the final session. After this extended history, cocaine self-administration dose-dependently reduced glucose utilization throughout the striatum and prefrontal cortex similarly to the initial stages of self-administration. However, glucose utilization was also decreased in a dose-independent manner in large portions of the temporal lobe including the amygdala, hippocampus and surrounding neocortex. The recruitment of temporal structures indicates that the pattern of changes in functional activity has undergone significant expansion beyond limbic regions into association areas that mediate higher order cognitive and emotional processing. These data strongly contribute to converging evidence from human studies demonstrating structural and functional abnormalities in temporal and prefrontal areas of cocaine abusers, and suggest that substance abusers may undergo progressive cognitive decline with continued exposure to cocaine.

Widespread axonal damage in the brain of drug abusers as evidenced by accumulation of beta-amyloid precursor protein (beta-APP): an immunohistochemical investigation

BACKGROUND

In drug abusers, white matter changes have been described by neuroimaging analyses in different brain regions. A specific pattern of involvement or a predominance of a specific brain region could not be drawn.

AIMS

To examine alterations of the white matter as a possible morphological substrate of the neuroimaging findings.

METHODS

Brain specimens of 30 polydrug abusers and 20 controls were obtained at autopsy. The white matter from 11 different brain regions was analysed by means of immunohistochemistry for beta-amyloid precursor protein (beta-APP), a marker of axonal damage.

FINDINGS

In the white matter of polydrug abusers, beta-APP-immunopositive accumulations were increased significantly compared to controls. They were more prominent in the brains of younger drug abusers than in those of the elderly. With the exception of five cases (four polydrug abusers and one control case), there were no significant white matter changes seen on myelin-stained sections, but there was a concomitant microglial activation.

CONCLUSIONS

Our results show a significant axonal damage in the brains of polydrug abusers, which might represent the morphological substrate of a chronic-progressive drug-induced toxic-metabolic process. It is yet to be established if the observed changes are responsible for the alterations seen in different neuroimaging analyses and which drugs of abuse might be of major pathogenetic significance.

Sex differences in medial and lateral orbitofrontal cortex hypoperfusion in cocaine-dependent men and women

BACKGROUND

The different clinical trajectories of cocaine-dependent men and women may be a consequence of distinct neurobiological substrates. Hypoperfusion of the orbitofrontal cortex (OFC) has previously been reported in individuals addicted to cocaine and has been posited as a biological mediator of relapse due to impulsivity or impaired decision making.

OBJECTIVE

This study assessed regional cerebral blood flow (rCBF) between abstinent cocaine-dependent men and women and sex-matched healthy controls.

METHODS

Cocaine-dependent subjects were abstinent from cocaine for 11 to 28 days and had no other major mental health or substance use disorders. rCBF was assessed with single photon emission computed tomography after administration of a placebo saline infusion. A resting scan was also obtained in a subset of cocaine-dependent and control men.

RESULTS

In the 35 cocaine-dependent and 37 healthy control subjects examined, a sex-by-group effect was observed for the left lateral (P=0.001), right lateral (P=0.002), and medial (P<0.02) OFC. Cocaine-dependent men demonstrated significantly lower right and left lateral, but not medial, OFC rCBF compared with sex-matched healthy controls after placebo infusion (P<or=0.001). Similar bilateral OFC decreases were observed in male cocaine-dependent subjects at rest. In contrast, cocaine-dependent women showed lower rCBF in the medial, but not lateral, OFC relative to sex-matched healthy controls after placebo infusion (P<0.01). Male cocaine-dependent subjects also showed decreased rCBF (P<0.01) in the bilateral anterolateral temporal cortex and anterior cingulate, whereas decreased rCBF was observed in female cocaine-dependent subjects in the bilateral superior frontal gyri. Large and diffuse areas of increased rCBF were observed after placebo infusion in cocaine-dependent men, but not in women, relative to sex-matched healthy controls.

CONCLUSIONS

rCBF appears to be reduced in the bilateral OFC in cocaine-dependent men and in the medial OFC in cocaine-dependent women. Sex differences in the medial and lateral OFC rCBF may be relevant to understanding relapse characteristics differentiating men and women addicted to cocaine.

Increased white matter hyperintensities in male methamphetamine abusers

BACKGROUND

The current study was conducted to compare the prevalence, severity, and location of white matter signal hyperintensities (WMH) on brain magnetic resonance (MR) imaging in methamphetamine (MA) abusers.

METHODS

Thirty-three MA abusers and 32 age- and gender-matched healthy comparison subjects were studied. Axial T-2 weighted images and fluid attenuated inversion recovery axial images were obtained using 3.0 T MR scanner. The severity of WMH was assessed separately for deep and periventricular WMH. Ordinal logistic regression models were used to assess the odds ratio for WMH.

RESULTS

MA abusers had greater severity of WMH than the healthy comparison subjects (odds ratio: 7.06, 8.46, and 4.56 for all, deep, and periventricular WMH, respectively). Severity of deep WMH correlated with total cumulative dose of MA (p = 0.027). Male MA abusers had greater severity of WMH than female MA abusers (odds ratio = 10.00). While male MA abusers had greater severity of WMH than male comparison subjects (odds ratio = 18.86), there was no significant difference in WMH severity between female MA abusers and female comparison subjects.

CONCLUSIONS

The current study reports increased WMH in MA abusers, which may be related to MA-induced cerebral perfusion deficits. In addition, female MA abusers had less severe WMH than male MA abusers, possibly due to estrogen's protective effect against ischemic or neurotoxic effects of MA.

Neuroimaging study of sex differences in the neuropathology of cocaine abuse

BACKGROUND

Female and male substance abusers differ in their disease patterns and clinical outcomes. An important question in addiction neuroscience thus concerns the neural substrates underlying these sex differences.

OBJECTIVE

This article aims to examine what is known of the neural mechanisms involved in the sex differences between substance abusers.

METHODS

We reviewed neuroimaging studies that addressed sex differences in cerebral perfusion deficits after chronic cocaine use and in regional brain activation during pharmacologic challenge and cue-induced craving. We also present results from a preliminary study in which cocaine-dependent men and women participated in script-guided imagery of stress- and drug cue-related situations while blood oxygenation level-dependent signals of their brain were acquired in a 1.5T scanner. Spatial pre-processing and statistical analysis of brain images were performed. Regional brain activation was compared between stress and drug cue trials in men versus women.

RESULTS

The results of our study showed greater activation in the left uncus and right claustrum (both, statistical threshold of P = 0.01, uncorrected; extent = 10 voxels) in men (n = 5) during drug cue trials compared with stress trials. No brain regions showed greater activation during stress trials compared with drug cue trials. In contrast, women (n = 6) showed greater activation in the right medial and superior frontal gyri during stress trials compared with drug cue trials at the same statistical threshold. No brain regions showed more activation during drug cue trials than during stress trials.

CONCLUSIONS

The studies reviewed underscore the need to consider sex-related factors in examining the neuropathology of cocaine addiction. Our preliminary results also suggest important sex differences in the effect of stress- and drug cue-associated brain activation in individuals with cocaine use disorder.

Executive dysfunction in cocaine addiction: evidence for discordant frontal, cingulate, and cerebellar activity

Using a GO-NOGO response inhibition task in which working memory (WM) demands can be varied, we demonstrate that the compromised abilities of cocaine users to exert control over strong prepotent urges are associated with reduced activity in anterior cingulate and right prefrontal cortices, two regions thought to be critical for implementing cognitive control. Furthermore, unlike drug-naive controls, and opposite to the anterior cingulate pattern, cocaine users showed an over-reliance on the left cerebellum, a compensatory pattern previously seen in alcohol addiction. The results indicate that cocaine users find it difficult to inhibit their own actions, particularly when WM demands, which have been shown previously to increase during cue-induced craving for the drug, are increased. The results reveal a neuroanatomical basis for this dysexecutive component to addiction, supporting the suggested importance cognitive functions may play in prolonging abuse or predisposing users toward relapse.

Alterations of the vascular basal lamina in the cerebral cortex in drug abuse: a combined morphometric and immunohistochemical investigation

In drug abusers, white matter hyperintensities, perfusion deficits, and metabolic disturbances are detected by neuroimaging analyses in different brain regions. A specific pattern of involvement or a predominance of a specific brain region cannot be drawn. To examine changes of the cerebral microvasculature as a possible morphological substrate of the neuroimaging findings, brain specimens of 12 polydrug abusers and 8 controls were obtained at autopsy. The basal lamina of blood vessels from the frontal, temporal, parietal, and occipital lobes was analysed by means of immunohistochemistry for collagen type IV. The numerical density of vessels was determined in the gray and white matter, and their staining intensity was rated using a three-point scale. In the gray and white matter of polydrug abusers, the number of vessels showing strong immunoreactivity for collagen type IV was significantly reduced, whereas the number of vessels with mild and moderate immunoreactivity was increased as compared to controls. The total numerical density of vessels was not significantly changed. Our results show a significant reduction in immunoreactivity for collagen type IV in the brains from polydrug abusers compared to controls, which may be due to a thinning of the basal lamina of cerebral vessels. The data of the present study show morphological changes of the basal lamina in the brain of polydrug abusers, which might represent the morphological substrate of a disturbed blood-brain barrier. However, it remains yet to be established if the observed changes are responsible for the alterations seen in different neuroimaging analyses and which drug might be of major pathogenetic significance.

Frontal glucose hypometabolism in abstinent methamphetamine users

Changes in relative regional cerebral glucose metabolism (rCMRglc) and their potential gender differences in abstinent methamphetamine (MA) users were explored. Relative rCMRglc, as measured by (18)F-fluorodeoxyglucose positron emission tomography, and frontal executive functions, as assessed by Wisconsin card sorting test (WCST), were compared between 35 abstinent MA users and 21 healthy comparison subjects. In addition, male and female MA users and their gender-matched comparison subjects were compared to investigate potential gender differences. MA users had lower rCMRglc levels in the right superior frontal white matter and more perseveration and nonperseveration errors in the WCST, relative to healthy comparison subjects. Relative rCMRglc in the frontal white matter correlated with number of errors in the WCST in MA users. In the subanalysis for gender differences, lower rCMRglc in the frontal white matter and more errors in the WCST were found only in male MA users, not in female MA users, relative to their gender-matched comparison subjects. The current findings suggest that MA use causes persistent hypometabolism in the frontal white matter and impairment in frontal executive function. Our findings also suggest that the neurotoxic effect of MA on frontal lobes of the brain might be more prominent in men than in women.

Reduced anterior corpus callosum white matter integrity is related to increased impulsivity and reduced discriminability in cocaine-dependent subjects: diffusion tensor imaging

Brain imaging studies find evidence of prefrontal cortical dysfunction in cocaine-dependent subjects. Similarly, cocaine-dependent subjects have problems with behaviors related to executive function and impulsivity. Since prefrontal cortical axonal tracts cross between hemispheres in the corpus callosum, it is possible that white matter integrity in the corpus callosum could also be diminished in cocaine-dependent subjects. The purpose of this study was to compare corpus callosum white matter integrity as measured by the fractional anisotropy (FA) on diffusion tensor imaging (DTI) between 18 cocaine-dependent subjects and 18 healthy controls. The Barratt Impulsiveness Scale (BIS-11) and a continuous performance test: the Immediate and Delayed Memory Task (IMT/DMT) were also collected. Results of the DTI showed significantly reduced FA in the genu and rostral body of the anterior corpus callosum in cocaine-dependent subjects compared to controls. Cocaine-dependent subjects also had significantly higher BIS-11 scores, greater impulsive (commission) errors, and reduced ability to discriminate target from catch stimuli (discriminability) on the IMT/DMT. Within cocaine dependent subjects there was a significant negative correlation between FA in the anterior corpus callosum and behavioral laboratory measured impulsivity, and there was a positive correlation between FA and discriminability. The finding that reduced integrity of anterior corpus callosum white matter in cocaine users is related to impaired impulse control and reduced ability to discriminate between target and catch stimuli is consistent with prior theories regarding frontal cortical involvement in impaired inhibitory control in cocaine-dependent subjects.

Gender-specific vulnerability for rCBF abnormalities among cocaine abusers

Fifty abstinent cocaine-dependent patients and 20 healthy controls were evaluated with 99mTc-HMPAO SPECT to examine gender differences in perfusion. Group contrasts with statistical parametric mapping revealed male and female patients exhibited not only different regions, but different types of perfusion abnormality, including decreased perfusion in the anterior cingulate/frontal regions among cocaine-dependent men, and increased perfusion in the posterior cingulate of cocaine-dependent women. The findings suggested that cocaine-dependent men have perfusion deficits previously associated with cocaine withdrawal and impaired response inhibition, whereas, cocaine-dependent women demonstrated perfusion abnormalities consistent with heightened stress responsivity and worse treatment outcome. The possibility of different neural mechanisms underlying relapse in men and women, and the implications for utilizing specialized treatments are discussed.

Abnormal brain activation to visual stimulation in cocaine abusers

Chronic cocaine abuse has been associated with cerebrovascular pathology. This is likely to reflect its vasoactive effects; cocaine produces vasoconstriction and reduces cerebral blood flow. We propose that cerebrovascular pathology in chronic cocaine abusers would result in abnormal BOLD [blood oxygenation level dependent] responses to activation stimuli. Here, we used fMRI to compared the BOLD response to photic visual stimulation in neurologically intact active cocaine abusers to that in non-drug-using healthy controls. Cocaine abusers showed a significantly enhanced positive BOLD response to photic stimulation when compared to control subjects. The enhanced activation in the cocaine abusers could result from low resting cerebral blood flow secondary to increased vasoconstriction and/or from low oxidative metabolism during activation. Alternatively, the larger signal intensity in the cocaine abusers could result from inefficient neuronal processing as has been shown to occur in other conditions of cerebral pathology. These findings provide evidence of cerebral dysfunction with chronic cocaine abuse, which could reflect cerebral blood flow or neuronal changes. Further studies are required to determine if the cerebrovascular changes we observed in the cocaine abusers recover with detoxification and to assess their functional consequences.

A pilot trial of piracetam and ginkgo biloba for the treatment of cocaine dependence

BACKGROUND

Chronic cocaine use is associated with cognitive deficits that may reduce the effectiveness of psychosocial treatment and promote relapse in newly abstinent cocaine-dependent patients. Nootropic agents, such as piracetam and ginkgo biloba, may improve cognitive function and reduce the incidence of relapse in these patients.

METHODS

This was a 10-week, double-blind, placebo-controlled pilot trial involving 44 cocaine-dependent subjects. Subjects received either piracetam (4.8 g/day), ginkgo biloba (120 mg/day), or placebo. Subjects were required to attain abstinence from cocaine during a 2-week baseline phase demonstrated by providing at least one benzoylecgonine (BE)-negative urine toxicology screen. Outcome measures included treatment retention, urine toxicology screens, Clinical Global Impression (CGI) scores, and results from the Addiction Severity Index (ASI).

RESULTS

Ginkgo biloba was not superior to placebo in any outcome measure. Piracetam was associated with more cocaine use and lower CGI scores compared to placebo.

CONCLUSIONS

Neither piracetam nor ginkgo biloba appears to be a promising medication for the treatment of cocaine dependence.

Addiction

Alcohol and psycho-active substance misuse has far-reaching social, psychological and physical consequences. Advances in neuroimaging technology have allowed neurobiological theories of addiction to become better characterized. We describe the neurobiology of dependence, withdrawal, abstinence and craving states in alcohol, stimulant and opiate misuse. Structural neuroimaging techniques such as CT and MRI with new analytical approaches such as voxel-based morphometry have shown wide-spread changes in stimulant and opiate abuse and atrophy, particularly in the frontal lobes, in alcoholism. Functional neuroimaging techniques such as PET, SPECT and fMRI reveal altered regional cerebral activity by all drugs of abuse. The neurochemistry of addiction, particularly involving dopamine, serotonin, opiate and GABA, has been studied with PET and SPECT and similarities between all drugs of abuse have been found such as reduced dopaminergic markers. The evidence derived from these advances in neuroimaging is likely to herald the emergence of new biological treatments in this important field.

Cerebral perfusion defects in combined cocaine and alcohol dependence

BACKGROUND

Cocaine abuse has been associated with widely distributed areas of significant cerebral blood flow (CBF) reductions or hypo-perfusion as well as CBF hyper-perfusion, but these perfusion abnormalities have not been examined using newer technologies such as statistical parametric mapping (SPM). These areas of abnormal CBF may be more likely among those who abuse cocaine and alcohol together.

METHODS

Using SPECT with HMPAO for CBF we compared proportional scaling (PS) to histogram normalization (HEQ) in SPM among 20 controls and 32 recently abstinent cocaine abusers. We then separated the cocaine abusers into two groups (12 cocaine plus alcohol abusers and 20 cocaine alone abusers) and compared both groups to the 20 controls for brain areas of hypo- and hyper-perfusion.

RESULTS

Sensitivity to hypo-perfusion was greater with HEQ than PS. Hypo-perfused areas were more likely in the 12 alcohol plus cocaine abusers than in the 20 cocaine alone abusers or 20 controls, and hyper-perfused areas were significantly more likely among the cocaine abusers than controls. The type of CBF abnormality varied by brain location with hypo-perfusion significantly more likely in occipital and temporal cortex or cerebellum and hyper-perfusion more likely in frontal and parietal cortex.

CONCLUSIONS

These abnormalities in brain perfusion are consistent with previous non-SPM approaches that showed more hypo-perfusion in cocaine abusers than controls and appear to reflect vasospasm and potential compensations in cerebral blood flow.

Outcome related electrophysiological subtypes of cocaine dependence

We previously described the existence of two quantitative EEG (QEEG) subtypes of cocaine dependent males, identified at baseline, displaying differential proneness to relapse. The current study expands the population to include females and enhances the measure set to include both QEEG and somatosensory EP (SEP) features. Fifty-seven cocaine dependent adults (16 F, 41 M) were evaluated 5-14 days after last cocaine use, while in residence at a drug-free therapeutic community. The median length of stay in treatment (continued abstinence) was 25 weeks. Using a small subset of QEEG and SEP baseline features, three subtypes (CLUS) were identified. CLUS 2 (n = 25) and CLUS 3 (n = 23) replicated the published subtypes, while CLUS 1 (n = 9) was previously undescribed. Cluster membership was significantly associated with length of stay in treatment (chi 2 = 13.789, P < 0.001), but not with length of exposure to crack cocaine or to any demographic or clinical features. Seventy-eight percent of CLUS 1 and 65% of CLUS 3 left treatment < or = 25 weeks, whereas 80% of CLUS 2 remained in treatment > 25 weeks. The existence of outcome related subtypes may reflect: [1] differential neurophysiological vulnerability, "traits," predisposing individuals to cocaine addiction; or [2] differential neurosensitivity, "states," due to the effects of chronic cocaine exposure, and associated differences in treatment outcome. Using Variable Resolution Electrical Tomographic Analysis (VARETA), the mathematically most probable neuroanatomical source of the scalp recorded EEG data was localized. Computation of VARETA on the baseline Cluster profiles suggest significant differences in the underlying pathophysiology of these subtypes.