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In JoVE (1)
Other Publications (24)
- Human Psychopharmacology
- AJNR. American Journal of Neuroradiology
- Neuropsychopharmacology : Official Publication of the American College of Neuropsychopharmacology
- The Journal of Neuropsychiatry and Clinical Neurosciences
- Synapse (New York, N.Y.)
- European Neuropsychopharmacology : the Journal of the European College of Neuropsychopharmacology
- Neuropsychopharmacology : Official Publication of the American College of Neuropsychopharmacology
- International Journal of Methods in Psychiatric Research
- Journal of Psychopharmacology (Oxford, England)
- Journal of Psychopharmacology (Oxford, England)
- Journal of Psychopharmacology (Oxford, England)
- Neuropsychopharmacology : Official Publication of the American College of Neuropsychopharmacology
- Annals of Neurology
- The British Journal of Psychiatry : the Journal of Mental Science
- Brain : a Journal of Neurology
- International Journal of Radiation Oncology, Biology, Physics
- Human Brain Mapping
- PloS One
- Human Brain Mapping
- Developmental Cognitive Neuroscience
- Journal of Neurology, Neurosurgery, and Psychiatry
Articles by Liesbeth Reneman in JoVE
The Use of Pharmacological-challenge fMRI in Pre-clinical Research: Application to the 5-HT System
Anne Klomp1, Jordi L. Tremoleda2, Anouk Schrantee1, Willy Gsell2, Liesbeth Reneman1
1Department of Radiology, Brain Imaging Center, Academic Medical Center Amsterdam, 2Biological Imaging Centre, MRC Clinical Sciences Centre, Imperial College London
The goal of this technique is to assess serotonin (5-HT) neurotransmitter function in the live and free-breathing animal with pharmacological magnetic resonance imaging (phMRI) and an intravenous challenge with a selective serotonin reuptake inhibitor (SSRI), fluoxetine.
Other articles by Liesbeth Reneman on PubMed
Human Psychopharmacology. Dec, 2001 | Pubmed ID: 12404537
Human users of 3,4-methylenedioxymethamphetamine (MDMA, 'Ecstasy') users may be at risk of developing MDMA-induced neuronal injury. Previously, no methods were available for directly evaluating the neurotoxic effects of MDMA in the living human brain. However, development of in vivo neuroimaging tools has begun to provide insights into the effects of MDMA in the human brain. In this review, contributions of brain imaging studies on the potential neurotoxic effects of MDMA and functional consequences are highlighted. An overview is given of PET, SPECT and MR spectroscopy studies, most of which show evidence of neuronal injury in MDMA users. Different neuroimaging tools are discussed that have investigated potential functional consequences of MDMA-induced 5-HT neurotoxic lesions. Finally, the contribution of brain imaging in future studies is discussed, emphasising the crucial role it will play in our understanding of MDMA's short- and long-term effects in the human brain. Copyright 2001 John Wiley & Sons, Ltd.
Reduced N-acetylaspartate Levels in the Frontal Cortex of 3,4-methylenedioxymethamphetamine (Ecstasy) Users: Preliminary Results
AJNR. American Journal of Neuroradiology. Feb, 2002 | Pubmed ID: 11847047
The perceived safety of the recreational drug methylenedioxymethamphetamine (MDMA), or Ecstasy, conflicts with animal evidence indicating that MDMA damages cortical serotonin (5-HT) neurons at doses similar to those used by humans. Few data are available about the effects of MDMA on the human brain. This study was designed to evaluate MDMA-related alterations in metabolite ratios with single-voxel proton ((1)H) MR spectroscopy.
The Acute and Chronic Effects of MDMA ("ecstasy") on Cortical 5-HT2A Receptors in Rat and Human Brain
Neuropsychopharmacology : Official Publication of the American College of Neuropsychopharmacology. Mar, 2002 | Pubmed ID: 11850153
While the pre-synaptic effects of 3,4-methylenedioxymethamphetamine (MDMA) on serotonin (5-HT) neurons have been studied extensively, little is known about its effects on post-synaptic 5-HT(2) receptors. Therefore, cortical 5-HT(2A) receptor densities and 5-HT concentration were studied in MDMA treated rats (10 mg/kg s.c.). Furthermore, 5-HT(2A) post-synaptic receptor densities in the cerebral cortex of recent as well as ex-MDMA users were studied using [123I]R91150 SPECT. In rats we observed a decrease followed by a time-dependent recovery of cortical 5-HT(2A) receptor densities, which was strongly and positively associated with the degree of 5-HT depletion. In recent MDMA users, post-synaptic 5-HT(2A) receptor densities were significantly lower in all cortical areas studied, while 5-HT(2A) receptor densities were significantly higher in the occipital cortex of ex-MDMA users. The combined results of this study suggest a compensatory upregulation of post-synaptic 5-HT(2A) receptors in the occipital cortex of ex-MDMA users due to low synaptic 5-HT levels.
Use of Amphetamine by Recreational Users of Ecstasy (MDMA) is Associated with Reduced Striatal Dopamine Transporter Densities: a [123I]beta-CIT SPECT Study--preliminary Report
Psychopharmacology. Jan, 2002 | Pubmed ID: 11862367
Tablets sold as ecstasy often contain not only 3,4-methylenedioxymethamphetamine (MDMA) but other compounds well known to cause dopaminergic neurotoxicity, such as (meth)amphetamine. Furthermore, the use of ecstasy in the Netherlands is often combined with the use of amphetamine. However, little is known about the effects of ecstasy use or the combination of ecstasy and amphetamine use on dopamine (DA) neurones in the human brain.
The Journal of Neuropsychiatry and Clinical Neurosciences. 2002 | Pubmed ID: 11983786
Synapse (New York, N.Y.). Dec, 2002 | Pubmed ID: 12325046
Recent [123I]beta-CIT single-photon emission computed tomography (SPECT) studies revealed decreased serotonin transporters (SERT) density in the brain of humans with a history of MDMA ("Ecstasy") use. However, [123I]beta-CIT SPECT has until now not been validated as a method for detecting such serotonergic lesions. Therefore, the present study was undertaken. Following baseline [123I]beta-CIT SPECT scans, a rhesus monkey was treated with MDMA (5 mg/kg, s.c. twice daily for 4 consecutive days). SPECT studies 4, 10, and 31 days after MDMA treatment revealed decreases in [123I]beta-CIT binding ratios in the SERT-rich brain region studied (hypothalamic/midbrain region), with SERT density reduced by 39% in this brain region 31 days after treatment. Data obtained with SPECT studies correlated well with SERT density determined with autoradiography after sacrifice of the animal (-34%). In addition, ex vivo [123I]beta-CIT binding studies in rats 1 week after treatment with neurotoxic doses of MDMA (20 mg/kg s.c. twice daily for 4 consecutive days) revealed significant reductions in [123I]beta-CIT binding in SERT-rich regions (including the hypothalamus) when compared to saline-treated rats. The combined results of these studies indicate that SPECT imaging of SERT with [123I]beta-CIT can detect changes in SERT density secondary to MDMA-induced neurotoxicity in the hypothalamic/midbrain region, and possibly other brain regions.
Mood Disorders and Serotonin Transporter Density in Ecstasy Users--the Influence of Long-term Abstention, Dose, and Gender
Psychopharmacology. May, 2004 | Pubmed ID: 14726997
Neurotoxic effects of 3,4-methylenedioxymethamphetamine (MDMA, "ecstasy") on the serotonin (5-HT) system have been described in animals and humans, but little is known about long-term effects of ecstasy use on mood.
European Neuropsychopharmacology : the Journal of the European College of Neuropsychopharmacology. May, 2004 | Pubmed ID: 15056477
This study investigated the ability of a high-resolution pinhole single-photon emission computed tomography (SPECT) system, with [(123)I]beta-CIT as a radiotracer, to detect 3,4-methelenedioxymethamphetamine (MDMA, 'Ecstasy')-induced loss of serotonin transporters (SERTs) in the living rat brain. In vivo striatal and thalamic [(123)I]beta-CIT binding ratios, representing specific binding to dopamine and serotonin transporters, respectively, were determined 7 days before as well as 10 days after treatment of rats with neurotoxic doses of MDMA using SPECT. At the end of the experiment, radioactivity ratios were also determined ex vivo, and compared to control data. Both in vivo and ex vivo, thalamic, but not striatal, uptake ratios were statistical significantly reduced after MDMA treatment. These data show that [(123)I]beta-CIT SPECT may be able to detect MDMA-induced loss of SERTs. Therefore, this may be a promising technique to perform serial studies on MDMA-induced serotonergic neurotoxicity in living small animals.
Validation of [(123)I]beta-CIT SPECT to Assess Serotonin Transporters in Vivo in Humans: a Double-blind, Placebo-controlled, Crossover Study with the Selective Serotonin Reuptake Inhibitor Citalopram
Neuropsychopharmacology : Official Publication of the American College of Neuropsychopharmacology. May, 2005 | Pubmed ID: 15770240
Disturbances in the serotonin (5-HT) system are associated with various neuropsychiatric disorders. The 5-HT system can be studied in vivo by measuring 5-HT transporter (SERT) densities using (123)iodine-labeled 2beta-carbomethoxy-3beta(4-iodophenyl)tropane ([(123)I]beta-CIT) and single photon emission computed tomography (SPECT). Validation of this technique is important because [(123)I]beta-CIT does not bind selectively to SERTs. Some studies have validated this technique in vivo in the human brain in SERT-rich areas, but the technique has not been validated yet in SERT-low cortical areas. The aim of this study was to further validate [(123)I]beta-CIT SPECT in assessing SERTs in vivo in humans in both SERT-rich and SERT-low areas. A double-blind, placebo-controlled, crossover design was used with the selective 5-HT reuptake inhibitor (SSRI) citalopram. Six male subjects underwent two [(123)I]beta-CIT SPECT sessions: one after pretreatment with citalopram and one after placebo. Scans were acquired 4 h and 22-27 h p.i., and both region-of-interest and voxel-by-voxel analyses were performed. Citalopram reduced [(123)I]beta-CIT binding ratios in SERT-rich midbrain and (hypo)thalamus. Binding ratios were also lower after citalopram in SERT-low cortical areas, but statistical significance was only reached in several cortical areas using voxel-by-voxel analysis. In addition, citalopram increased binding ratios in the DAT-rich striatum and increased absolute uptake in the cerebellum. The results show that [(123)I]beta-CIT SPECT is a valid technique to study SERT binding in vivo in human brain in SERT-rich areas. Although we provide some evidence that [(123)I]beta-CIT SPECT may be used to measure SERTs in SERT-low cortical areas, these measurements must be interpreted with caution.
The Netherlands XTC Toxicity (NeXT) Study: Objectives and Methods of a Study Investigating Causality, Course, and Clinical Relevance
International Journal of Methods in Psychiatric Research. 2005 | Pubmed ID: 16395871
This paper describes the objectives and methods of The Netherlands XTC Toxicity (NeXT) study focussing on the causality, course, and clinical relevance of ecstasy neurotoxicity. Previous studies suggest that ecstasy (3,4 methylene-dioxymethamphetamine, MDMA, XTC) is toxic toward brain serotonin axons, but most of these studies have serious methodological limitations. The current study is a combination of different approaches with three substudies: (1) a crosssectional substudy among heavy ecstasy users and controls with variation in drug use, which will provide information about potential neurotoxic consequences of ecstasy in relation to other drugs; (2) a prospective cohort substudy in ecstasy-naive subjects with high risk for future ecstasy use, which will provide information on the causality and short-term course of ecstasy use and potential neurotoxicity, and (3) a retrospective cohort substudy in lifetime ecstasy users and matched controls of an existing epidemiological sample that will provide information on long-term course and outcome of ecstasy use in the general population. Neurotoxicity is studied using (a) different imaging techniques (beta-CIT SPECT, 1H-MR spectroscopy, diffusion tensor imaging, perfusion weighted imaging and functional magnetic resonance imaging), and (b) neuropsychological and psychiatric assessments of memory, depression, and personality. The combined results will lead to conclusions that can be used in prevention messages, clinical decision making, and the development of an (inter)national ecstasy policy.
Journal of Psychopharmacology (Oxford, England). Mar, 2006 | Pubmed ID: 16510475
Users of ecstasy (3,4-methylenedioxymethamphetamine; MDMA) may be at risk of developing MDMA-induced injury to the serotonin (5-HT) system. Previously, there were no methods available for directly evaluating the neurotoxic effects of MDMA in the living human brain. However, development of in vivoneuroimaging tools have begun to provide insights into the effects of ecstasy on the human brain. Single photon emission computed tomography (SPECT), positron emission computed tomography (PET) and proton magnetic resonance spectroscopy (1H-MRS) studies which have evaluated ecstasy's neurotoxic potential will be reviewed and discussed in terms of technical aspects, conceptual issues and future prospects. Although PET and SPECT may be limited by several factors such as the low cortical uptake and the use of a non-optimal reference region (cerebellum) the few studies conducted so far provide suggestive evidence that people who heavily use ecstasy are at risk of developing subcortical, and probably also cortical reductions in serotonin transporter (SERT) densities, a marker of 5-HT neurotoxicity. There seem to be dose-dependent and transient reductions in SERT for which females may be more vulnerable than males. 1H-MRS appears to be a less sensitive technique for studying ecstasy's neurotoxic potential. Whether individuals with a relatively low ecstasy exposure also demonstrate loss of SERT needs to be determined. Because most studies have had a retrospective design, in which evidence is indirect and differs in the degree to which any causal links can be implied, longitudinal studies in human ecstasy users are needed to draw definite conclusions.
Ecstasy Use and Self-reported Depression, Impulsivity, and Sensation Seeking: a Prospective Cohort Study
Journal of Psychopharmacology (Oxford, England). Mar, 2006 | Pubmed ID: 16510480
Although there are indications that ecstasy users have higher levels of depression, impulsivity, and sensation seeking, it is unknown whether these are consequences of ecstasy use or predisposing factors for starting ecstasy use. We prospectively assessed the predictive value of depression, impulsivity, and sensation seeking on future first time ecstasy use. We also assessed whether depression, impulsivity, and sensation seeking had changed after first ecstasy use. Depression, impulsivity, and sensation seeking were assessed using self-report questionnaires in 188 ecstasy-naive volunteers with high probability for future ecstasy use. After a mean follow-up of 17 months, measurements were repeated in 59 incident ecstasy users (mean 6.0 tablets) and 61 matched persistent ecstasy-naive volunteers. Only experience seeking (subscale of the sensation seeking scale) predicted future ecstasy use (OR -- 1.05, 95% CI 1.00 to 1.10), but after adjustment for potential confounders this was not significant anymore. At follow-up, significant effects of ecstasy use on the general and the disinhibition subscale of the sensation seeking scale were observed (after adjustment for potential confounders: regression coefficient B 0.51, 95% CI 0.20 to 0.83 and B -- 3.25, 95% CI 1.74 to 4.76, respectively). These data indicate that depression, impulsivity, and sensation seeking do not predict first time ecstasy use in a population of young adults with the intention to start using ecstasy and that low level ecstasy use does not seem to cause depression or impulsivity. However, low level ecstasy use may increase (certain aspects of) sensation seeking.
Journal of Psychopharmacology (Oxford, England). May, 2006 | Pubmed ID: 16574713
Although 3,4-methylenedioxymethamphetamine (MDMA or ecstasy) has been shown to damage brain serotonin (5-HT) neurons in animals and possibly humans, little is known about the long-term consequences of MDMA-induced 5-HT neurotoxic lesions on functions in which 5-HT is involved, such as cognitive function. Because 5-HT transporters play a key element in the regulation of synaptic 5-HT transmission it may be important to control for the potential covariance effect of a polymorphism in the 5-HT transporter promoter gene region (5-HTTLPR) when studying the effects of MDMA as well as cognitive functioning. The aim of the study was to investigate the effects of moderate and heavy MDMA use on cognitive function, as well as the effects of long-term abstention from MDMA, in subjects genotyped for 5-HTTLPR. A second aim of the study was to determine whether these effects differ for females and males. Fifteen moderate MDMA users (<55 lifetime tablets), 22 heavy MDMA+ users (>55 lifetime tablets), 16 ex-MDMA+ users (last tablet > 1 year ago) and 13 controls were compared on a battery of neuropsychological tests. DNA from peripheral nuclear blood cells was genotyped for 5-HTTLPR using standard polymerase chain reaction methods.A significant group effect was observed only on memory function tasks (p = 0.04) but not on reaction times (p = 0.61) or attention/executive functioning (p = 0.59). Heavy and ex-MDMA+ users performed significantly poorer on memory tasks than controls. In contrast, no evidence of memory impairment was observed in moderate MDMA users. No significant effect of 5-HTTLPR or gender was observed. While the use of MDMA in quantities that may be considered "moderate" is not associated with impaired memory functioning, heavy use of MDMA use may lead to long lasting memory impairments. No effect of 5-HTTLPR or gender on memory function or MDMA use was observed.
A Prospective Cohort Study on Sustained Effects of Low-dose Ecstasy Use on the Brain in New Ecstasy Users
Neuropsychopharmacology : Official Publication of the American College of Neuropsychopharmacology. Feb, 2007 | Pubmed ID: 17077812
It is debated whether ecstasy use has neurotoxic effects on the human brain and what the effects are of a low dose of ecstasy use. We prospectively studied sustained effects (>2 weeks abstinence) of a low dose of ecstasy on the brain in ecstasy-naive volunteers using a combination of advanced MR techniques and self-report questionnaires on psychopathology as part of the NeXT (Netherlands XTC Toxicity) study. Outcomes of proton magnetic resonance spectroscopy (1H-MRS), diffusion tensor imaging (DTI), perfusion-weighted imaging (PWI), and questionnaires on depression, impulsivity, and sensation seeking were compared in 30 subjects (12M, 21.8+/-3.1 years) in two sessions before and after first ecstasy use (1.8+/-1.3 tablets). Interval between baseline and follow-up was on average 8.1+/-6.5 months and time between last ecstasy use and follow-up was 7.7+/-4.4 weeks. Using 1H-MRS, no significant changes were observed in metabolite concentrations of N-acetylaspartate (NAA), choline (Cho), myo-inositol (mI), and creatine (Cr), nor in ratios of NAA, Cho, and mI relative to Cr. However, ecstasy use was followed by a sustained 0.9% increase in fractional anisotropy (FA) in frontoparietal white matter, a 3.4% decrease in apparent diffusion (ADC) in the thalamus and a sustained decrease in relative regional cerebral blood volume (rrCBV) in the thalamus (-6.2%), dorsolateral frontal cortex (-4.0%), and superior parietal cortex (-3.0%) (all significant at p<0.05, paired t-tests). After correction for multiple comparisons, only the rrCBV decrease in the dorsolateral frontal cortex remained significant. We also observed increased impulsivity (+3.7% on the Barratt Impulsiveness Scale) and decreased depression (-28.0% on the Beck Depression Inventory) in novel ecstasy users, although effect sizes were limited and clinical relevance questionable. As no indications were found for structural neuronal damage with the currently used techniques, our data do not support the concern that incidental ecstasy use leads to extensive axonal damage. However, sustained decreases in rrCBV and ADC values may indicate that even low ecstasy doses can induce prolonged vasoconstriction in some brain areas, although it is not known whether this effect is permanent. Additional studies are needed to replicate these findings.
Annals of Neurology. May, 2008 | Pubmed ID: 18412121
Worldwide, many workers experience occupational exposure to organic solvents, which may induce chronic solvent-induced encephalopathy (CSE). Disturbances within the frontostriatothalamic (FST) circuitry might explain the symptomatology of CSE. We tested the hypothesis of FST circuitry abnormalities in CSE, as well as associations with performance of psychomotor speed, attention, and solvent exposure. To detect preclinical, solvent-related effects, we also studied the FST circuitry in solvent-exposed, but asymptomatic workers.
The British Journal of Psychiatry : the Journal of Mental Science. Oct, 2008 | Pubmed ID: 18827290
Neurotoxic effects of ecstasy have been reported, although it remains unclear whether effects can be attributed to ecstasy, other recreational drugs or a combination of these.
Brain : a Journal of Neurology. Nov, 2008 | Pubmed ID: 18842607
Previous studies have suggested toxic effects of recreational ecstasy use on the serotonin system of the brain. However, it cannot be excluded that observed differences between users and non-users are the cause rather than the consequence of ecstasy use. As part of the Netherlands XTC Toxicity (NeXT) study, we prospectively assessed sustained effects of ecstasy use on the brain in novel ecstasy users using repeated measurements with a combination of different neuroimaging parameters of neurotoxicity. At baseline, 188 ecstasy-naive volunteers with high probability of first ecstasy use were examined. After a mean period of 17 months follow-up, neuroimaging was repeated in 59 incident ecstasy users and 56 matched persistent ecstasy-naives and their outcomes were compared. Neuroimaging included [(123)I]beta-carbomethoxy-3beta-(4-iodophenyl)tropane (CIT) SPECT to measure serotonin transporter densities as indicators of serotonergic function; (1)H-MR spectroscopy ((1)H-MRS) to measure brain metabolites as indicators of neuronal damage; diffusion tensor imaging (DTI) to measure the apparent diffusion coefficient and fractional anisotropy (FA) of the diffusional motion of water molecules in the brain as indicators of axonal integrity; and perfusion weighted imaging (PWI) to measure regional relative cerebral blood volume (rrCBV) which indicates brain perfusion. With this approach, both structural ((1)H-MRS and DTI) and functional ([(123)I]beta-CIT SPECT and PWI) aspects of neurotoxicity were combined. Compared to persistent ecstasy-naives, novel low-dose ecstasy users (mean 6.0, median 2.0 tablets) showed decreased rrCBV in the globus pallidus and putamen; decreased FA in thalamus and frontoparietal white matter; increased FA in globus pallidus; and increased apparent diffusion coefficient in the thalamus. No changes in serotonin transporter densities and brain metabolites were observed. These findings suggest sustained effects of ecstasy on brain microvasculature, white matter maturation and possibly axonal damage due to low dosages of ecstasy. Although we do not know yet whether these effects are reversible or not, we cannot exclude that ecstasy even in low doses is neurotoxic to the brain.
White Matter Fractional Anisotropy Correlates with Speed of Processing and Motor Speed in Young Childhood Cancer Survivors
International Journal of Radiation Oncology, Biology, Physics. Jul, 2009 | Pubmed ID: 19117694
To determine whether childhood medulloblastoma and acute lymphoblastic leukemia (ALL) survivors have decreased white matter fractional anisotropy (WMFA) and whether WMFA is related to the speed of processing and motor speed.
Human Brain Mapping. Aug, 2011 | Pubmed ID: 20669165
Chemotherapy is associated with cognitive impairment in a subgroup of breast cancer survivors, but the neural circuitry underlying this side effect is largely unknown. Moreover, long-term impairment has not been studied well. In the present study, functional magnetic resonance imaging (fMRI) and neuropsychological testing were performed in breast cancer survivors almost 10 years after high-dose adjuvant chemotherapy (chemo group, n = 19) and in breast cancer survivors for whom chemotherapy had not been indicated (control group, n = 15). BOLD activation and performance were measured during an executive function task involving planning abilities (Tower of London) and a paired associates task for assessment of episodic memory. For the chemo group versus the control group, we found hyporesponsiveness of dorsolateral prefrontal cortex in the Tower of London, and of parahippocampal gyrus in the paired associates task. Also, the chemo group showed significantly impaired planning performance and borderline significantly impaired recognition memory as compared to findings in the control group. Whole-brain analyses demonstrated hyporesponsiveness of the chemo versus the control group in very similar regions of bilateral posterior parietal cortex during both the Tower of London and the paired associates task. Neuropsychological testing showed a relatively stable pattern of cognitive impairment in the chemo group over time. These results indicate that high-dose adjuvant chemotherapy is associated with long-term cognitive impairments. These impairments are underpinned by (a) task-specific hyporesponsiveness of dorsolateral prefrontal cortex and parahippocampal gyrus, and (b) a generalized hyporesponsiveness of lateral posterior parietal cortex encompassing attentional processing.
PloS One. 2011 | Pubmed ID: 21304948
The selective serotonin reuptake inhibitor (SSRI) Prozac® (fluoxetine) is the only registered antidepressant to treat depression in children and adolescents. Yet, while the safety of SSRIs has been well established in adults, serotonin exerts neurotrophic actions in the developing brain and thereby may have harmful effects in adolescents. Here we treated adolescent and adult rats chronically with fluoxetine (12 mg/kg) at postnatal day (PND) 25 to 46 and from PND 67 to 88, respectively, and tested the animals 7-14 days after the last injection when (nor)fluoxetine in blood plasma had been washed out, as determined by HPLC. Plasma (nor)fluoxetine levels were also measured 5 hrs after the last fluoxetine injection, and matched clinical levels. Adolescent rats displayed increased behavioral despair in the forced swim test, which was not seen in adult fluoxetine treated rats. In addition, beneficial effects of fluoxetine on wakefulness as measured by electroencephalography in adults was not seen in adolescent rats, and age-dependent effects on the acoustic startle response and prepulse inhibition were observed. On the other hand, adolescent rats showed resilience to the anorexic effects of fluoxetine. Exploratory behavior in the open field test was not affected by fluoxetine treatment, but anxiety levels in the elevated plus maze test were increased in both adolescent and adult fluoxetine treated rats. Finally, in the amygdala, but not the dorsal raphe nucleus and medial prefrontal cortex, the number of PSA-NCAM (marker for synaptic remodeling) immunoreactive neurons was increased in adolescent rats, and decreased in adult rats, as a consequence of chronic fluoxetine treatment. No fluoxetine-induced changes in 5-HT(1A) receptor immunoreactivity were observed. In conclusion, we show that fluoxetine exerts both harmful and beneficial age-dependent effects on depressive behavior, body weight and wakefulness, which may relate, in part, to differential fluoxetine-induced neuroplasticity in the amygdala.
Late Effects of High-dose Adjuvant Chemotherapy on White and Gray Matter in Breast Cancer Survivors: Converging Results from Multimodal Magnetic Resonance Imaging
Human Brain Mapping. Sep, 2011 | Pubmed ID: 22095746
The neural substrate underlying cognitive impairments after chemotherapy is largely unknown. Here, we investigated very late (>9 years) effects of adjuvant high-dose chemotherapy on brain white and gray matter in primary breast cancer survivors (n = 17) with multimodal magnetic resonance imaging (MRI). A group of breast cancer survivors who did not receive chemotherapy was scanned for comparison (n = 15). Neuropsychological tests demonstrated cognitive impairments in the chemotherapy group. Diffusion tensor imaging (DTI) with tract-based spatial statistics showed that chemotherapy was associated with focal changes in DTI values indicative for reduced white matter integrity. Single voxel proton MR spectroscopy (1H-MRS) in the left centrum semiovale (white matter) showed a reduction of N-acetylasparate/creatine indicative of axonal injury. Voxel-based morphometry demonstrated a reduction of gray matter volume that overlapped with fMRI hypoactivation (as reported in a previous publication) in posterior parietal areas and colocalized with DTI abnormalities. Also, DTI correlated with 1H-MRS only in the chemotherapy group. These results converge to suggest that high-dose adjuvant chemotherapy for breast cancer is associated with long-term injury to white matter, presumably reflecting a combination of axonal degeneration and demyelination, and damage to gray matter with associated functional deficits. Hormonal treatment with tamoxifen may also have contributed to the observed effects, although results from other studies indicate that it is unlikely that tamoxifen is solely or largely responsible. Using this multimodality approach we provide for the first time insight into the neural substrate underlying cognitive impairments following systemic administration of cytotoxic agents many years after treatment. Hum Brain Mapp, 2011. © 2011 Wiley-Liss, Inc.
Age-dependent Effects of Chronic Fluoxetine Treatment on the Serotonergic System One Week Following Treatment
Psychopharmacology. Dec, 2011 | Pubmed ID: 22205158
RATIONALE: Selective serotonin reuptake inhibitors (SSRIs) such as fluoxetine are increasingly used for the treatment of depression in children. Limited data are, however, available on their effects on brain development and their efficacy remains debated. Moreover, previous experimental studies are seriously hampered in their clinical relevance. OBJECTIVES: The aim of the present study was to investigate putative age-related effects of a chronic treatment with fluoxetine (5 mg/kg, either orally or i.p. for 3 weeks, 1 week washout) using conventional methods (behavioral testing and binding assay using [(123)I]β-CIT) and a novel magnetic resonance imaging (MRI) approach. METHODS: Behavior was assessed, as well as serotonin transporter (SERT) availability and function through ex vivo binding assays and in vivo pharmacological MRI (phMRI) with an acute fluoxetine challenge (10 mg/kg oral or 5 mg/kg i.v.) in adolescent and adult rats. RESULTS: Fluoxetine caused an increase in anxiety-like behavior in treated adult, but not adolescent, rats. On the binding assays, we observed increased SERT densities in most cortical brain regions and hypothalamus in adolescent, but not adult, treated rats. Finally, reductions in brain activation were observed with phMRI following treatment, in both adult and adolescent treated animals. CONCLUSION: Collectively, our data indicate that the short-term effects of fluoxetine on the 5-HT system may be age-dependent. These findings could reflect structural and functional rearrangements in the developing brain that do not occur in the matured rat brain. phMRI possibly will be well suited to study this important issue in the pediatric population.
How the Aging Brain Translates Motivational Incentive into Action: The Role of Individual Differences in Striato-cortical White Matter Pathways
Developmental Cognitive Neuroscience. Oct, 2011 | Pubmed ID: 22436569
The anticipation of reward enhances actions that lead to those rewards, but individuals differ in how effectively motivational incentives modulate their actions. Such individual differences are particularly prominent in aging. In order to account for such inter-individual variability among older adults, we approach the neurobiological mechanisms of motivated behavior from an individual differences perspective focusing on white matter pathways in the aging brain. Using analyses of probabilistic tractography seeded in the striatum, we report that the estimated strength of cortico-striatal and intra-striatal white matter pathways among older adults correlated with how effectively motivational incentives modulated their actions. Specifically, individual differences in the extent to which elderly participants utilized reward cues to prepare and perform more efficient antisaccades predicted structural connectivity of the striatum with cortical areas involved in reward anticipation and oculomotor control. These striatal connectivity profiles endow us with a network account for individual differences in motivated behavior among older adults. More generally, the data suggest that capturing individual differences may be crucial to better understand developmental trajectories in motivated behavior.
Journal of Neurology, Neurosurgery, and Psychiatry. Jan, 2012 | Pubmed ID: 21444322
Various studies have shown that ecstasy (3,4-methylenedioxymethamphetamine) users display significant memory impairments, whereas their performance on other cognitive tests is generally normal. The hippocampus plays an essential role in short-term memory. There are, however, no structural human data on the effects of ecstasy on the hippocampus. The objective of this study was to investigate whether the hippocampal volume of chronic ecstasy users is reduced when compared with healthy polydrug-using controls, as an indicator of hippocampal damage. The hippocampus was manually outlined in volumetric MRI scans in 10 male ecstasy users (mean age 25.4 years) and seven healthy age- and gender-matched control subjects (21.3 years). Other than the use of ecstasy, there were no statistically significant differences between both groups in exposure to other drugs of abuse and alcohol. The ecstasy users were on average drug-free for more than 2 months and had used on average 281 tablets over the past six and a half years. The hippocampal volume in the ecstasy using group was on average 10.5% smaller than the hippocampal volume in the control group (p=0.032). These data provide preliminary evidence that ecstasy users may be prone to incurring hippocampal damage, in line with previous reports of acute hippocampal sclerosis and subsequent atrophy in chronic users of this drug.