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Douglas Mental Health University Institute

Hospital / health systemMontreal, Canada

Research output, citation impact, and the most-cited recent papers from Douglas Mental Health University Institute (Canada). Aggregated across the NobleBlocks index of 300M+ scholarly works.

Total works
10.3K
Citations
1.3M
h-index
398
i10-index
15.2K
Also known as
Centre de recherche DouglasDouglas HospitalDouglas Mental Health University InstituteDouglas Research CentreHôpital DouglasInstitut universitaire en santé mentale douglas

Top-cited papers from Douglas Mental Health University Institute

Maternal Care, Gene Expression, and the Transmission of Individual Differences in Stress Reactivity Across Generations
Michael J. Meaney
2001· Annual Review of Neuroscience2.7Kdoi:10.1146/annurev.neuro.24.1.1161

Naturally occurring variations in maternal care alter the expression of genes that regulate behavioral and endocrine responses to stress, as well as hippocampal synaptic development. These effects form the basis for the development of stable, individual differences in stress reactivity and certain forms of cognition. Maternal care also influences the maternal behavior of female offspring, an effect that appears to be related to oxytocin receptor gene expression, and which forms the basis for the intergenerational transmission of individual differences in stress reactivity. Patterns of maternal care that increase stress reactivity in offspring are enhanced by stressors imposed on the mother. These findings provide evidence for the importance of parental care as a mediator of the effects of environmental adversity on neural development.

Analysis of shared heritability in common disorders of the brain
Verneri Anttila, Brendan Bulik‐Sullivan, Hilary K. Finucane, Raymond K. Walters +4 more
2018· Science2.0Kdoi:10.1126/science.aap8757

Disorders of the brain can exhibit considerable epidemiological comorbidity and often share symptoms, provoking debate about their etiologic overlap. We quantified the genetic sharing of 25 brain disorders from genome-wide association studies of 265,218 patients and 784,643 control participants and assessed their relationship to 17 phenotypes from 1,191,588 individuals. Psychiatric disorders share common variant risk, whereas neurological disorders appear more distinct from one another and from the psychiatric disorders. We also identified significant sharing between disorders and a number of brain phenotypes, including cognitive measures. Further, we conducted simulations to explore how statistical power, diagnostic misclassification, and phenotypic heterogeneity affect genetic correlations. These results highlight the importance of common genetic variation as a risk factor for brain disorders and the value of heritability-based methods in understanding their etiology.

Canadian 24-Hour Movement Guidelines for Children and Youth: An Integration of Physical Activity, Sedentary Behaviour, and Sleep
Mark S. Tremblay, Valerie Carson, Jean‐Philippe Chaput, Sarah Connor Gorber +4 more
2016· Applied Physiology Nutrition and Metabolism2.0Kdoi:10.1139/apnm-2016-0151

Leaders from the Canadian Society for Exercise Physiology convened representatives of national organizations, content experts, methodologists, stakeholders, and end-users who followed rigorous and transparent guideline development procedures to create the Canadian 24-Hour Movement Guidelines for Children and Youth: An Integration of Physical Activity, Sedentary Behaviour, and Sleep. These novel guidelines for children and youth aged 5-17 years respect the natural and intuitive integration of movement behaviours across the whole day (24-h period). The development process was guided by the Appraisal of Guidelines for Research Evaluation (AGREE) II instrument and systematic reviews of evidence informing the guidelines were assessed using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach. Four systematic reviews (physical activity, sedentary behaviour, sleep, integrated behaviours) examining the relationships between and among movement behaviours and several health indicators were completed and interpreted by expert consensus. Complementary compositional analyses were performed using Canadian Health Measures Survey data to examine the relationships between movement behaviours and health indicators. A stakeholder survey was employed (n = 590) and 28 focus groups/stakeholder interviews (n = 104) were completed to gather feedback on draft guidelines. Following an introductory preamble, the guidelines provide evidence-informed recommendations for a healthy day (24 h), comprising a combination of sleep, sedentary behaviours, light-, moderate-, and vigorous-intensity physical activity. Proactive dissemination, promotion, implementation, and evaluation plans have been prepared in an effort to optimize uptake and activation of the new guidelines. Future research should consider the integrated relationships among movement behaviours, and similar integrated guidelines for other age groups should be developed.

Nongenomic Transmission Across Generations of Maternal Behavior and Stress Responses in the Rat
Darlene Francis, Josie Diorio, Dong Liu, Michael J. Meaney
1999· Science2.0Kdoi:10.1126/science.286.5442.1155

In the rat, variations in maternal care appear to influence the development of behavioral and endocrine responses to stress in the offspring. The results of cross-fostering studies reported here provide evidence for (i) a causal relationship between maternal behavior and stress reactivity in the offspring and (ii) the transmission of such individual differences in maternal behavior from one generation of females to the next. Moreover, an environmental manipulation imposed during early development that alters maternal behavior can then affect the pattern of transmission in subsequent generations. Taken together, these findings indicate that variations in maternal care can serve as the basis for a nongenomic behavioral transmission of individual differences in stress reactivity across generations.

Preclinical Alzheimer's disease: Definition, natural history, and diagnostic criteria
Bruno Dubois, Harald Hampel, Howard Feldman, Philip Scheltens +4 more
2016· Alzheimer s & Dementia1.9Kdoi:10.1016/j.jalz.2016.02.002

During the past decade, a conceptual shift occurred in the field of Alzheimer's disease (AD) considering the disease as a continuum. Thanks to evolving biomarker research and substantial discoveries, it is now possible to identify the disease even at the preclinical stage before the occurrence of the first clinical symptoms. This preclinical stage of AD has become a major research focus as the field postulates that early intervention may offer the best chance of therapeutic success. To date, very little evidence is established on this "silent" stage of the disease. A clarification is needed about the definitions and lexicon, the limits, the natural history, the markers of progression, and the ethical consequence of detecting the disease at this asymptomatic stage. This article is aimed at addressing all the different issues by providing for each of them an updated review of the literature and evidence, with practical recommendations.

Brain charts for the human lifespan
Richard A. I. Bethlehem, Jakob Seidlitz, Simon R. White, Jacob W. Vogel +4 more
2022· Nature1.7Kdoi:10.1038/s41586-022-04554-y

Abstract Over the past few decades, neuroimaging has become a ubiquitous tool in basic research and clinical studies of the human brain. However, no reference standards currently exist to quantify individual differences in neuroimaging metrics over time, in contrast to growth charts for anthropometric traits such as height and weight 1 . Here we assemble an interactive open resource to benchmark brain morphology derived from any current or future sample of MRI data ( http://www.brainchart.io/ ). With the goal of basing these reference charts on the largest and most inclusive dataset available, acknowledging limitations due to known biases of MRI studies relative to the diversity of the global population, we aggregated 123,984 MRI scans, across more than 100 primary studies, from 101,457 human participants between 115 days post-conception to 100 years of age. MRI metrics were quantified by centile scores, relative to non-linear trajectories 2 of brain structural changes, and rates of change, over the lifespan. Brain charts identified previously unreported neurodevelopmental milestones 3 , showed high stability of individuals across longitudinal assessments, and demonstrated robustness to technical and methodological differences between primary studies. Centile scores showed increased heritability compared with non-centiled MRI phenotypes, and provided a standardized measure of atypical brain structure that revealed patterns of neuroanatomical variation across neurological and psychiatric disorders. In summary, brain charts are an essential step towards robust quantification of individual variation benchmarked to normative trajectories in multiple, commonly used neuroimaging phenotypes.

Mild cognitive impairment: a concept in evolution
R. Petersen, Barbara Caracciolo, Carol Brayne, Serge Gauthier +2 more
2014· Journal of Internal Medicine1.6Kdoi:10.1111/joim.12190

The construct of mild cognitive impairment (MCI) has evolved over the past 10 years since the publication of the new MCI definition at the Key Symposium in 2003, but the core criteria have remained unchanged. The construct has been extensively used worldwide, both in clinical and in research settings, to define the grey area between intact cognitive functioning and clinical dementia. A rich set of data regarding occurrence, risk factors and progression of MCI has been generated. Discrepancies between studies can be mostly explained by differences in the operationalization of the criteria, differences in the setting where the criteria have been applied, selection of subjects and length of follow-up in longitudinal studies. Major controversial issues that remain to be further explored are algorithmic versus clinical classification, reliability of clinical judgment, temporal changes in cognitive performances and predictivity of putative biomarkers. Some suggestions to further develop the MCI construct include the tailoring of the clinical criteria to specific populations and to specific contexts. The addition of biomarkers to the clinical phenotypes is promising but requires deeper investigation. Translation of findings from the specialty clinic to the population setting, although challenging, will enhance uniformity of outcomes. More longitudinal population-based studies on cognitive ageing and MCI need to be performed to clarify all these issues.

The Value and Challenges of Participatory Research: Strengthening Its Practice
Margaret Cargo, Shawna L. Mercer
2008· Annual Review of Public Health1.4Kdoi:10.1146/annurev.publhealth.29.091307.083824

The increasing use of participatory research (PR) approaches to address pressing public health issues reflects PR's potential for bridging gaps between research and practice, addressing social and environmental justice and enabling people to gain control over determinants of their health. Our critical review of the PR literature culminates in the development of an integrative practice framework that features five essential domains and provides a structured process for developing and maintaining PR partnerships, designing and implementing PR efforts, and evaluating the intermediate and long-term outcomes of descriptive, etiological, and intervention PR studies. We review the empirical and nonempirical literature in the context of this practice framework to distill the key challenges and added value of PR. Advances to the practice of PR over the next decade will require establishing the effectiveness of PR in achieving health outcomes and linking PR practices, processes, and core elements to health outcomes.

Maternal care during infancy regulates the development of neural systems mediating the expression of fearfulness in the rat
Christian Caldji, Beth Tannenbaum, Shakti Sharma, Darlene Francis +2 more
1998· Proceedings of the National Academy of Sciences1.4Kdoi:10.1073/pnas.95.9.5335

The mothers of infant rats show individual differences in the frequency of licking/grooming and arched-back nursing (LG-ABN) of pups that contribute to the development of individual differences in behavioral responses to stress. As adults, the offspring of mothers that exhibited high levels of LG-ABN showed substantially reduced behavioral fearfulness in response to novelty compared with the offspring of low LG-ABN mothers. In addition, the adult offspring of the high LG-ABN mothers showed significantly (i) increased central benzodiazepine receptor density in the central, lateral, and basolateral nuclei of the amygdala as well as in the locus ceruleus, (ii) increased alpha2 adrenoreceptor density in the locus ceruleus, and (iii) decreased corticotropin-releasing hormone (CRH) receptor density in the locus ceruleus. The expression of fear and anxiety is regulated by a neural circuitry that includes the activation of ascending noradrenergic projections from the locus ceruleus to the forebrain structures. Considering the importance of the amygdala, notably the anxiogenic influence of CRH projections from the amygdala to the locus ceruleus, as well as the anxiolytic actions of benzodiazepines, for the expression of behavioral responses to stress, these findings suggest that maternal care during infancy serves to "program" behavioral responses to stress in the offspring by altering the development of the neural systems that mediate fearfulness.

Early role of vascular dysregulation on late-onset Alzheimer’s disease based on multifactorial data-driven analysis
Yasser Iturria‐Medina, Roberto C. Sotero, P.-J. Toussaint, J.M. Mateos-Pérez +4 more
2016· Nature Communications1.2Kdoi:10.1038/ncomms11934

Multifactorial mechanisms underlying late-onset Alzheimer's disease (LOAD) are poorly characterized from an integrative perspective. Here spatiotemporal alterations in brain amyloid-β deposition, metabolism, vascular, functional activity at rest, structural properties, cognitive integrity and peripheral proteins levels are characterized in relation to LOAD progression. We analyse over 7,700 brain images and tens of plasma and cerebrospinal fluid biomarkers from the Alzheimer's Disease Neuroimaging Initiative (ADNI). Through a multifactorial data-driven analysis, we obtain dynamic LOAD-abnormality indices for all biomarkers, and a tentative temporal ordering of disease progression. Imaging results suggest that intra-brain vascular dysregulation is an early pathological event during disease development. Cognitive decline is noticeable from initial LOAD stages, suggesting early memory deficit associated with the primary disease factors. High abnormality levels are also observed for specific proteins associated with the vascular system's integrity. Although still subjected to the sensitivity of the algorithms and biomarkers employed, our results might contribute to the development of preventive therapeutic interventions.

Effect of Neonatal Handling on Age-Related Impairments Associated with the Hippocampus
Michael J. Meaney, David H. Aitken, Chayann van Berkel, Seema Bhatnagar +1 more
1988· Science1.1Kdoi:10.1126/science.3340858

In rats, an environmental manipulation occurring early in life resulted in changes in the adrenocortical axis that persisted throughout the entire life of the animals and attenuated certain deficits associated with aging. Rats handled during infancy had a permanent increase in concentrations of receptors for glucocorticoids in the hippocampus, a critical region in the negative-feedback inhibition of adrenocortical activity. Increased receptor concentrations led to greater hippocampal sensitivity to glucocorticoids and enhanced negative-feedback efficacy in the handled rats. Thus, at all ages tested, rats that were not handled secreted more glucocorticoids in response to stress than did handled rats. At later ages, nonhandled rats also showed elevated basal glucocorticoid levels, with the result that there was a greater cumulative exposure to glucocorticoids in nonhandled rats. Increased exposure to adrenal glucocorticoids can accelerate hippocampal neuron loss and cognitive impairments in aging. Hippocampal cell loss and pronounced spatial memory deficits emerged with age in the nonhandled rats, but were almost absent in the handled rats. Previous work showed that glucocorticoid hypersecretion, hippocampal neuron death, and cognitive impairments form a complex degenerative cascade of aging in the rat. The present study shows that a subtle manipulation early in life can retard the emergence of this cascade.

Physiological significance of a peripheral tissue circadian clock
Katja Lamia, Kai-Florian Storch, Charles J. Weitz
2008· Proceedings of the National Academy of Sciences1.0Kdoi:10.1073/pnas.0806717105

Mammals have circadian clocks in peripheral tissues, but there is no direct evidence of their physiological importance. Unlike the suprachiasmatic nucleus clock that is set by light and drives rest-activity and fasting-feeding cycles, peripheral clocks are set by daily feeding, suggesting that at least some contribute metabolic regulation. The liver plays a well known role in glucose homeostasis, and we report here that mice with a liver-specific deletion of Bmal1, an essential clock component, exhibited hypoglycemia restricted to the fasting phase of the daily feeding cycle, exaggerated glucose clearance, and loss of rhythmic expression of hepatic glucose regulatory genes. We conclude that the liver clock is important for buffering circulating glucose in a time-of-day-dependent manner. Our findings suggest that the liver clock contributes to homeostasis by driving a daily rhythm of hepatic glucose export that counterbalances the daily cycle of glucose ingestion resulting from the fasting-feeding cycle.

Functional normalization of 450k methylation array data improves replication in large cancer studies
Jean-Philippe Fortin, Aurélie Labbe, Mathieu Lemire, Brent W. Zanke +4 more
2014· Genome biology1.0Kdoi:10.1186/s13059-014-0503-2

We propose an extension to quantile normalization that removes unwanted technical variation using control probes. We adapt our algorithm, functional normalization, to the Illumina 450k methylation array and address the open problem of normalizing methylation data with global epigenetic changes, such as human cancers. Using data sets from The Cancer Genome Atlas and a large case-control study, we show that our algorithm outperforms all existing normalization methods with respect to replication of results between experiments, and yields robust results even in the presence of batch effects. Functional normalization can be applied to any microarray platform, provided suitable control probes are available.

Psychiatric diagnoses in 3275 suicides: a meta-analysis
Geneviève Arsenault‐Lapierre, Caroline Kim, Gustavo Turecki
2004· BMC Psychiatry979doi:10.1186/1471-244x-4-37

BACKGROUND: It is well known that most suicide cases meet criteria for a psychiatric disorder. However, rates of specific disorders vary considerably between studies and little information is known about gender and geographic differences. This study provides overall rates of total and specific psychiatric disorders in suicide completers and presents evidence supporting gender and geographic differences in their relative proportion. METHODS: We carried out a review of studies in which psychological autopsy studies of suicide completers were performed. Studies were identified by means of MEDLINE database searches and by scanning the reference list of relevant publications. Twenty-three variables were defined, 16 of which evaluating psychiatric disorders. Mantel-Haenszel Weighted Odds Ratios were estimated for these 16 outcome variables. RESULTS: Twenty-seven studies comprising 3275 suicides were included, of which, 87.3% (SD 10.0%) had been diagnosed with a mental disorder prior to their death. There were major gender differences. Diagnoses of substance-related problems (OR = 3.58; 95% CI: 2.78-4.61), personality disorders (OR = 2.01; 95% CI: 1.38-2.95) and childhood disorders (OR = 4.95; 95% CI: 2.69-9.31) were more common among male suicides, whereas affective disorders (OR = 0.66; 95% CI: 0.53-0.83), including depressive disorders (OR = 0.53; 95% CI: 0.42-0.68) were less common among males. Geographical differences are also likely to be present in the relative proportion of psychiatric diagnoses among suicides. CONCLUSIONS: Although psychopathology clearly mediates suicide risk, gender and geographical differences seem to exist in the relative proportion of the specific psychiatric disorders found among suicide completers.

Environmental programming of stress responses through DNA methylation: life at the interface between a dynamic environment and a fixed genome
Michael J. Meaney, Moshe Szyf
2005· Dialogues in Clinical Neuroscience940doi:10.31887/dcns.2005.7.2/mmeaney

Early experience permanently alters behavior and physiology. These effects are, in part, mediated by sustained alterations in gene expression in selected brain regions. The critical question concerns the mechanism of these environmental "programming" effects. We examine this issue with an animal model that studies the consequences of variations in mother-infant interactions on the development of individual differences in behavioral and endocrine responses to stress in adulthood. Increased levels of pup licking/grooming by rat mothers in the first week of life alter DNA structure at a glucocorticoid receptor gene promoter in the hippocampus of the offspring. Differences in the DNA methylation pattern between the offspring of high- and low-licking/grooming mothers emerge over the first week of life; they are reversed with cross-fostering; they persist into adulthood; and they are associated with altered histone acetylation and transcription factor (nerve growth factor-induced clone A [NGFIA]) binding to the glucocorticoid receptor promoter. DNA methylation alters glucocorticoid receptor expression through modifications of chromatin structure. Pharmacological reversal of the effects on chromatin structure completely eliminates the effects of maternal care on glucocorticoid receptor expression and hypothalamic-pituitary-adrenal (HPA) responses to stress, thus suggesting a causal relation between the maternally induced, epigenetic modification of the glucocorticoid receptor gene and the effects on stress responses in the offspring. These findings demonstrate that the structural modifications of the DNA can be established through environmental programming and that, in spite of the inherent stability of this epigenomic marker, it is dynamic and potentially reversible.

Uses and abuses of recovery: implementing recovery-oriented practices in mental health systems
Mike Slade, Michaela Amering, Marianne Farkas, Bridget Hamilton +4 more
2014· World Psychiatry920doi:10.1002/wps.20084

An understanding of recovery as a personal and subjective experience has emerged within mental health systems. This meaning of recovery now underpins mental health policy in many countries. Developing a focus on this type of recovery will involve transformation within mental health systems. Human systems do not easily transform. In this paper, we identify seven mis-uses ("abuses") of the concept of recovery: recovery is the latest model; recovery does not apply to "my" patients; services can make people recover through effective treatment; compulsory detention and treatment aid recovery; a recovery orientation means closing services; recovery is about making people independent and normal; and contributing to society happens only after the person is recovered. We then identify ten empirically-validated interventions which support recovery, by targeting key recovery processes of connectedness, hope, identity, meaning and empowerment (the CHIME framework). The ten interventions are peer support workers, advance directives, wellness recovery action planning, illness management and recovery, REFOCUS, strengths model, recovery colleges or recovery education programs, individual placement and support, supported housing, and mental health trialogues. Finally, three scientific challenges are identified: broadening cultural understandings of recovery, implementing organizational transformation, and promoting citizenship.

Reversal of Maternal Programming of Stress Responses in Adult Offspring through Methyl Supplementation: Altering Epigenetic Marking Later in Life
Ian C.G. Weaver, Frances A. Champagne, Shelley E. Brown, Sergiy Dymov +3 more
2005· Journal of Neuroscience901doi:10.1523/jneurosci.3652-05.2005

Stress responses in the adult rat are programmed early in life by maternal care and associated with epigenomic marking of the hippocampal exon 1(7) glucocorticoid receptor (GR) promoter. To examine whether such epigenetic programming is reversible in adult life, we centrally infused the adult offspring with the essential amino acid L-methionine, a precursor to S-adenosyl-methionine that serves as the donor of methyl groups for DNA methylation. Here we report that methionine infusion reverses the effect of maternal behavior on DNA methylation, nerve growth factor-inducible protein-A binding to the exon 1(7) promoter, GR expression, and hypothalamic-pituitary-adrenal and behavioral responses to stress, suggesting a causal relationship among epigenomic state, GR expression, and stress responses in the adult offspring. These results demonstrate that, despite the inherent stability of the epigenomic marks established early in life through behavioral programming, they are potentially reversible in the adult brain.

Systematic review of the relationships between sleep duration and health indicators in school-aged children and youth
Jean‐Philippe Chaput, Casey Gray, Veronica J. Poitras, Valerie Carson +4 more
2016· Applied Physiology Nutrition and Metabolism897doi:10.1139/apnm-2015-0627

The objective of this systematic review was to examine the relationships between objectively and subjectively measured sleep duration and various health indicators in children and youth aged 5-17 years. Online databases were searched in January 2015 with no date or study design limits. Included studies were peer-reviewed and met the a priori-determined population (apparently healthy children and youth aged 5-17 years), intervention/exposure/comparator (various sleep durations), and outcome (adiposity, emotional regulation, cognition/academic achievement, quality of life/well-being, harms/injuries, and cardiometabolic biomarkers) criteria. Because of high levels of heterogeneity across studies, narrative syntheses were employed. A total of 141 articles (110 unique samples), including 592 215 unique participants from 40 different countries, met inclusion criteria. Overall, longer sleep duration was associated with lower adiposity indicators, better emotional regulation, better academic achievement, and better quality of life/well-being. The evidence was mixed and/or limited for the association between sleep duration and cognition, harms/injuries, and cardiometabolic biomarkers. The quality of evidence ranged from very low to high across study designs and health indicators. In conclusion, we confirmed previous investigations showing that shorter sleep duration is associated with adverse physical and mental health outcomes. However, the available evidence relies heavily on cross-sectional studies using self-reported sleep. To better inform contemporary sleep recommendations, there is a need for sleep restriction/extension interventions that examine the changes in different outcome measures against various amounts of objectively measured sleep to have a better sense of dose-response relationships.

Early Environmental Regulation of Forebrain Glucocorticoid Receptor Gene Expression: Implications for Adrenocortical Responses to Stress; pp. 49–60
Michael J. Meaney, Josie Diorio, Darlene Francis, Judith Widdowson +4 more
2007· Developmental Neuroscience883doi:10.1159/000111395

The adrenal glucocorticoids and catecholamines comprise a frontline of defense for mammalian species under conditions which threaten homeostasis (conditions commonly referred to as stress). Glucocorticoids represent the end product of the hypothalamic-pituitary-adrenal (HPA) axis and along with the catecholamines serve to mobilize the production and distribution of energy substrates during stress. The increased secretion of pituitary-adrenal hormones in response to stress is stimulated by the release of corticotropin-releasing hormone (CRH) and/or arginine vasopressin (AVP) from neurons in the nucleus paraventricularis. In this way, a neural signal associated with the stressor is transduced into a set of endocrine and sympathetic responses. The development of the HPA response to stressful stimuli is altered by early environmental events. Animals exposed to short periods of infantile stimulation or handling show decreased HPA responsivity to stress, whereas maternal separation, physical trauma and endotoxin administration enhance HPA responsivity to stress. In all cases, these effects persist throughout the life of the animal and are accompanied by increased hypothalamic levels of the mRNAs for CRH and often AVP. The inhibitory regulation of the synthesis for these ACTH releasing factors is achieved, in part, through a negative feedback loop whereby circulating glucocorticoids act at various neural sites to decrease CRH and AVP gene expression. Such inhibitory effects are initiated via an interaction between the adrenal steroid and an intracellular receptor (either the mineralocorticoid or glucocorticoid receptor). We have found that these early environmental manipulations regulate glucocorticoid receptor gene expression in the hippocampus and frontal cortex, regions that have been strongly implicated as sites for negative-feedback regulation of CRH and AVP synthesis. When the differences in glucocorticoid receptor density are transiently reversed, so too are those in HPA responses to stress. Taken together, our findings indicate that the early postnatal environment alters the differentiation of hippocampal neurons. This effect involves an altered rate of glucocorticoid receptor gene expression, resulting in changes in the sensitivity of the system to the inhibitory effects of glucocorticoids on the synthesis of CRH and AVP in hypothalamic neurons. Changes in CRH and AVP levels, in turn, determine the responsivity of the axis to subsequent stressors; increased releasing factor production is associated with increased HPA responses to stress. Thus, the early environment can contribute substantially to the development of stable individual differences in HPA responsivity to stressful stimuli. These data provide examples of early environmental programming of neural systems. One major objective of our research is to understand how such programming occurs within the brain.

A Canadian Multicenter Placebo-Controlled Study of Fixed Doses of Risperidone and Haloperidol in the Treatment of Chronic Schizophrenic Patients
Guy Chouinard, B. Jones, Gary Remington, D. M. Bloom +4 more
1993· Journal of Clinical Psychopharmacology881doi:10.1097/00004714-199302000-00004

In a double-blind study, 135 inpatients with a diagnosis of chronic schizophrenia were randomly assigned to 8 weeks of treatment with one of six parallel treatments: risperidone (a new central 5-hydroxytryptamine2 and dopamine D2 antagonist), 2, 6, 10, 16 mg/day; haloperidol, 20 mg/day; or placebo, after a single-blind placebo washout period. Doses were increased in fixed increments up to a fixed maintenance dose reached after 1 week. On the Clinical Global Impression-Severity of Illness and Improvement, all active medications were superior to placebo except for risperidone (2 mg) on the Clinical Global Impression-Improvement. On the total Positive and Negative Syndrome Scale (PANSS) score and positive subscale, superiority to placebo was observed for all treatment groups except for haloperidol and risperidone (2 mg), which tended to be superior to placebo on total PANSS and the positive subscale, respectively. On the PANSS negative subscale, only risperidone (6 mg/day) was significantly better than placebo. Risperidone (6 mg) was superior to haloperidol on the total PANSS, General Psychopathology, and Brief Psychiatric Rating Scale subscales. Although there was a linear increase in parkinsonism with increasing risperidone dosage, there were no statistically significant differences between risperidone (2, 6, and 16 mg/day) and placebo. At doses of 6 to 16 mg, risperidone displayed a marked antidyskinetic effect compared with placebo. This effect was more pronounced in patients with severe dyskinesia. By contrast, haloperidol produced significantly more parkinsonism than placebo and risperidone (2, 6 and 16 mg), with no effect on tardive dyskinesia. These data suggest that risperidone, at the optimal therapeutic dose of 6 mg/day, produced significant improvement in both positive and negative symptoms without an increase in drug-induced parkinsonian symptoms and with a significant beneficial effect on tardive dyskinesia.