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Buenos Aires, Argentina

Vasquez R.M.Z.,Clinica de la Esquizofrenia | Saracco-Alvarez R.A.,Clinica de la Esquizofrenia | Olvera J.G.,Investigaciones Clinicas
Salud Mental | Year: 2010

Schizophrenia is one of the most studied diseases in psychiatry and different dysfunctions of thinking, emotions, perception, movement, and behavior converge in it. These dysfunctions affect the quality of life of the patients in different ways. It is a disease that has been observed in the whole world, with a 0.5 to 1.5% prevalence among adults. Although the biological basis of schizophrenia is not clear enough, the dopaminergic hypothesis is preponderant in our understanding of the symptoms of the disease. A mesolimbic pathway hyperactivity is related to a positive symptomathology, while a prefrontal dopaminergic hypofunction relates to negative symptoms. It has been observed that using serotoninergic antagonists, which promote dopaminergic activity in the prefrontal cortex, translates in to a reduction of the intensity of negative symptoms. This negative syndrome includes a difficulty to initiate new activities (apathy), speech and creativity impoverishment (alogia), alterations in emotional expression, and a lack of capacity to experiment joy. Patients with negative symptoms present gray and white matter loss in left-sided cerebral structures, including temporal lobe, anterior cingulated, and medial frontal cortex. Such a loss seems to be more evident in prefrontal regions, such as the dorsolateral prefrontal region, which connects with anterior temporal structures. Persistent negative symptomathology is a concept proposed by Buchanan, which must fulfill the following criteria: symptoms are primary to the disease or secondary but have not responded to current treatment; interfere with the patient́s capacity to accomplish normal functioning; persist during periods of clinical stability, and represent an unresolved therapeutic need. They must be measurable by clinical scales and persist, at least, six months. The Food and Drug Administration has recently considered negative symptoms as an investigation target or new treatments due to their prevalence and high negative impact in the life of the schizophrenic population. Nowadays, the current treatments available for such an entity are second generation antipshycotics and glutamatergic agents -such as d-cycloserine and glicine-, amisulpiride and seleginine, even though their efficacy is limited. Dysfunction of the human prefrontal cortex is considered to be implicated in the pathophisiology of negative symptoms. This cerebral region is essential in the regulation of emotions and cognition. Multiple neural networks begin in the prefrontal cortex and go towards other cortical association areas, to insular region, thalamic structures, basal ganglia and limbic system. It regulates dopaminergic mesencephalic activity through activating and inhibitory pathways, allowing a precise regulation of dopaminergic activity. This double modulation model of dopaminergic pathways has been recently sustained by studies which prove that extracellular dopaminergic concentration in nucleus accumbens increases or reduces after a high or low frequency stimulation of the prefrontal cortex, respectively. A prefrontal cortex lesion causes a syndrome similar to the negative symptomathology in schizophrenia. Transcraneal magnetic stimulation (TMS) could be effective in the treatment of negative symptoms by activating the prefrontal cortex, maybe by stimulating the liberation of dopamine in the mesolimbic and mesoestriatal pathways which have a crucial role in the pathogenesis of negative symptoms such as apathy and anhedonia. TMS was introduced in 1985 and since the early 90́s its potential as a treatment has been tested in numerous neurological and psychiatric conditions. It is a noninvasive means of stimulating nervous cells in superficial areas of the brain. During a TMS procedure, an electrical current passes through a wire coil placed over the scalp. This induces a magnetic field that can produce a substantive electrical field in the brain. This electrical field produces in turn a depolarization of nervous cells resulting in the stimulation or disruption of brain activity. TMS may be applied as a single stimulus or repeated many times per second (repetitive TMS), with variations in the intensity, site, and orientation of the magnetic field. Most research and interest has focused on the potential application of repetitive TMS (rTMS) in the treatment of depression. In addition, in recent years an increasing number of open and double-blinded studies of rTMS were conducted in patients with schizophrenia. Most investigators have chosen to focus on the treatment of specific refractory symptoms or syndromes within the disorder such as refractory auditory hallucinations or persistent negative symptoms. TMS has become widely used in research, especially as a method to probe normal and abnormal brain function, motor cortical physiology, and cognition. Regarding negative symptoms in schizophrenia, eleven studies using TMS were carried out until 2006, with a total of 172 patients studied. These studies are difficult to compare because they used different stimulation parameters and the symptoms described were heterogenic. Six studies were blind and five were open, using high frequency TMS in all of them (frequencies above 1 Hz), which is the type of stimulation most commonly used in treatment studies. Six of these studies found a reduction in the severity of the symptoms, but the reduction was not significant in two of them. Ten were the maximum number of sessions included in every study, except for one, in which 20 sessions of TMS were given. In this study, the score of negative subscale of the PANSS was reduced in 33%, which is considered a significant response, and this result was sustained within the next month. In one of these studies, researchers compared 3- and 20-Hz stimulation with sham stimulation and stimulation provided at the patient's individual alpha frequency. Alpha-frequency stimulation was calculated as the patient's peak alpha frequency from five frontal EEG leads. Stimulation of alpha frequency resulted in a significantly greater reduction in negative symptoms than the other conditions. This finding could suggest that negative symptoms may specifically relate to alpha EEG oscillations, which is interesting and requires further exploration and confirmation. Another two studies were conducted in 2007; in the first one, no improvement in negative, positive of affective symptoms was found. The second one, which was a double-blinded clinical trial, found a significant reduction in the intensity of negative, positive, and general symptoms with the active TMS. We should remark that TMS produces changes in the cortical activity in ventral and dorsoestratial regions, but other cerebral regions could be stimulated too, since some activation abnormalities in the left globus palidus, bilateral caudate nucleus, prefrontal, and temporal right cortex have been found and are associated with the etiology of the negative syndrome. In addition, it will be interesting to see whether changes in subcortical dopamine release, which were shown with rTMS in normal volunteers, can be demonstrated in clinical populations, such as patients with schizophrenia, and how this may relate to response to treatment. There is still a need for a larger number of controlled studies, with larger samples, longer periods of evaluation, and constant stimulation parameters, so they can be compared between them and the exact efficacy of TMS as a treatment for negative symptoms can be established. Source

Giganti M.J.,Vanderbilt University | Luz P.M.,Institute Pesquisa Clinica Evandro Chagas | Caro-Vega Y.,Instituto Nacional Of Ciencias Medicas Y Nutricion | Cesar C.,Investigaciones Clinicas | And 6 more authors.
AIDS Research and Human Retroviruses | Year: 2015

Many studies of HIV/AIDS aggregate data from multiple cohorts to improve power and generalizability. There are several analysis approaches to account for cross-cohort heterogeneity; we assessed how different approaches can impact results from an HIV/AIDS study investigating predictors of mortality. Using data from 13,658 HIV-infected patients starting antiretroviral therapy from seven Latin American and Caribbean cohorts, we illustrate the assumptions of seven readily implementable approaches to account for across cohort heterogeneity with Cox proportional hazards models, and we compare hazard ratio estimates across approaches. As a sensitivity analysis, we modify cohort membership to generate specific heterogeneity conditions. Hazard ratio estimates varied slightly between the seven analysis approaches, but differences were not clinically meaningful. Adjusted hazard ratio estimates for the association between AIDS at treatment initiation and death varied from 2.00 to 2.20 across approaches that accounted for heterogeneity; the adjusted hazard ratio was estimated as 1.73 in analyses that ignored across cohort heterogeneity. In sensitivity analyses with more extreme heterogeneity, we noted a slightly greater distinction between approaches. Despite substantial heterogeneity between cohorts, the impact of the specific approach to account for heterogeneity was minimal in our case study. Our results suggest that it is important to account for across cohort heterogeneity in analyses, but that the specific technique for addressing heterogeneity may be less important. Because of their flexibility in accounting for cohort heterogeneity, we prefer stratification or meta-analysis methods, but we encourage investigators to consider their specific study conditions and objectives. © Copyright 2015, Mary Ann Liebert, Inc. 2015. Source

Cesar C.,Investigaciones Clinicas | Koethe J.R.,Vanderbilt University | Giganti M.J.,Vanderbilt University | Rebeiro P.,Vanderbilt University | And 16 more authors.
Journal of the International AIDS Society | Year: 2016

Introduction: Latinos living with HIV in the Americas share a common ethnic and cultural heritage. In North America, Latinos have a relatively high rate of new HIV infections but lower rates of engagement at all stages of the care continuum, whereas in Latin America antiretroviral therapy (ART) services continue to expand to meet treatment needs. In this analysis, we compare HIV treatment outcomes between Latinos receiving ART in North America versus Latin America. Methods: HIV-positive adults initiating ART at Caribbean, Central and South America Network for HIV (CCASAnet) sites were compared to Latino patients (based on country of origin or ethnic identity) starting treatment at North American AIDS Cohort Collaboration on Research and Design (NA-ACCORD) sites in the United States and Canada between 2000 and 2011. Cox proportional hazards models compared mortality, treatment interruption, antiretroviral regimen change, virologic failure and loss to follow-up between cohorts. Results: The study included 8400 CCASAnet and 2786 NA-ACCORD patients initiating ART. CCASAnet patients were younger (median 35 vs. 37 years), more likely to be female (27% vs. 20%) and had lower nadir CD4 count (median 148 vs. 195 cells/μL, p<0.001 for all). In multivariable analyses, CCASAnet patients had a higher risk of mortality after ART initiation (adjusted hazard ratio (AHR) 1.61; 95% confidence interval (CI):1.32 to 1.96), particularly during the first year, but a lower hazard of treatment interruption (AHR: 0.46; 95% CI: 0.42 to 0.50), change to second-line ART (AHR: 0.56; 95% CI: 0.51 to 0.62) and virologic failure (AHR: 0.52; 95% CI: 0.48 to 0.57). Conclusions: HIV-positive Latinos initiating ART in Latin America have greater continuity of treatment but are at higher risk of death than Latinos in North America. Factors underlying these differences, such as HIV testing, linkage and access to care, warrant further investigation. Copyright: - 2016 Cesar C et al;. Source

Rebeiro P.F.,Vanderbilt University | Hanna D.B.,Yeshiva University | Padgett D.,Instituto Hondureno Of Seguridad Social | Horberg M.A.,Kaiser Permanente | And 20 more authors.
Journal of the International AIDS Society | Year: 2016

Introduction: Maps are powerful tools for visualization of differences in health indicators by geographical region, but multicountry maps of HIV indicators do not exist, perhaps due to lack of consistent data across countries. Our objective was to create maps of four HIV indicators in North, Central, and South American countries. Methods: Using data from the North American AIDS Cohort Collaboration on Research and Design (NA-ACCORD) and the Caribbean, Central, and South America network for HIV epidemiology (CCASAnet), we mapped median CD4 at presentation for HIV clinical care, proportion retained in HIV primary care, proportion prescribed antiretroviral therapy (ART), and the proportion with suppressed plasma HIV viral load (VL) from 2010 to 2012 for North, Central, and South America. The 15 Canadian and US clinical cohorts and 7 clinical cohorts in Argentina, Brazil, Chile, Haiti, Honduras, Mexico, and Peru represented approximately 2-7% of persons known to be living with HIV in these countries. Results: Study populations were selected for each indicator: median CD4 at presentation for care was estimated among 14,811 adults; retention was estimated among 87,979 adults; ART use was estimated among 84,757 adults; and suppressed VL was estimated among 51,118 adults. Only three US states and the District of Columbia had a median CD4 at presentation ≥350 cells/mm3. Haiti, Mexico, and several states had ≥85% retention in care; lower (50-74%) retention in care was observed in the US West, South, and Mid-Atlantic, and in Argentina, Brazil, and Peru. ART use was highest (90%) in Mexico. The percentages of patients with suppressed VL in the US South and Northeast were lower than in most of Central and South America. Conclusions: These maps provide visualization of gaps in the quality of HIV care and allow for comparison between and within countries as well as monitoring policy and programme goals within geographical boundaries. Copyright: - 2016 Althoff KN et al;. Source

Crabtree-Ramirez B.,Instituto Nacional Of Ciencias Medicas Y Nutricion | Caro-Vega Y.,Instituto Nacional Of Ciencias Medicas Y Nutricion | Shepherd B.E.,Vanderbilt University | Wehbe F.,Vanderbilt University | And 11 more authors.
PLoS ONE | Year: 2011

Background: Starting HAART in a very advanced stage of disease is assumed to be the most prevalent form of initiation in HIV-infected subjects in developing countries. Data from Latin America and the Caribbean is still lacking. Our main objective was to determine the frequency, risk factors and trends in time for being late HAART initiator (LHI) in this region. Methodology: Cross-sectional analysis from 9817 HIV-infected treatment-naïve patients initiating HAART at 6 sites (Argentina, Chile, Haiti, Honduras, Peru and Mexico) from October 1999 to July 2010. LHI had CD4+ count ≤200cells/mm3 prior to HAART. Late testers (LT) were those LHI who initiated HAART within 6 months of HIV diagnosis. Late presenters (LP) initiated after 6 months of diagnosis. Prevalence, risk factors and trends over time were analyzed. Principal Findings: Among subjects starting HAART (n = 9817) who had baseline CD4+ available (n = 8515), 76% were LHI: Argentina (56%[95%CI:52-59]), Chile (80%[95%CI:77-82]), Haiti (76%[95%CI:74-77]), Honduras (91%[95%CI:87-94]), Mexico (79%[95%CI:75-83]), Peru (86%[95%CI:84-88]). The proportion of LHI statistically changed over time (except in Honduras) (p≤0.02; Honduras p = 0.7), with a tendency towards lower rates in recent years. Males had increased risk of LHI in Chile, Haiti, Peru, and in the combined site analyses (CSA). Older patients were more likely LHI in Argentina and Peru (OR 1.21 per +10-year of age, 95%CI:1.02-1.45; OR 1.20, 95%CI:1.02-1.43; respectively), but not in CSA (OR 1.07, 95%CI:0.94-1.21). Higher education was associated with decreased risk for LHI in Chile (OR 0.92 per +1-year of education, 95%CI:0.87-0.98) (similar trends in Mexico, Peru, and CSA). LHI with date of HIV-diagnosis available, 55% were LT and 45% LP. Conclusion: LHI was highly prevalent in CCASAnet sites, mostly due to LT; the main risk factors associated were being male and older age. Earlier HIV-diagnosis and earlier treatment initiation are needed to maximize benefits from HAART in the region. © 2011 Crabtree-Ramírez et al. Source

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