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      An investigation of regional cerebral blood flow and tissue structure changes after acute administration of antipsychotics in healthy male volunteers : Investigation of Regional Cerebral Blood Flow

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          Abstract

          Chronic administration of antipsychotic drugs has been linked to structural brain changes observed in patients with schizophrenia. Recent MRI studies have shown rapid changes in regional brain volume following just a single dose of these drugs. However, it is not clear if these changes represent real volume changes or are artefacts (“apparent” volume changes) due to drug‐induced physiological changes, such as increased cerebral blood flow (CBF). To address this, we examined the effects of a single, clinical dose of three commonly prescribed antipsychotics on quantitative measures of T1 and regional blood flow of the healthy human brain. Males ( n  = 42) were randomly assigned to one of two parallel groups in a double‐blind, placebo‐controlled, randomized, three‐period cross‐over study design. One group received a single oral dose of either 0.5 or 2 mg of risperidone or placebo during each visit. The other received olanzapine (7.5 mg), haloperidol (3 mg), or placebo. MR measures of quantitative T1, CBF, and T1‐weighted images were acquired at the estimated peak plasma concentration of the drug. All three drugs caused localized increases in striatal blood flow, although drug and region specific effects were also apparent. In contrast, all assessments of T1 and brain volume remained stable across sessions, even in those areas experiencing large changes in CBF. This illustrates that a single clinically relevant oral dose of an antipsychotic has no detectable acute effect on T1 in healthy volunteers. We further provide a methodology for applying quantitative imaging methods to assess the acute effects of other compounds on structural MRI metrics. Hum Brain Mapp 39:319–331, 2018 . © 2017 Wiley Periodicals, Inc.

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          Long-term antipsychotic treatment and brain volumes: a longitudinal study of first-episode schizophrenia.

          Progressive brain volume changes in schizophrenia are thought to be due principally to the disease. However, recent animal studies indicate that antipsychotics, the mainstay of treatment for schizophrenia patients, may also contribute to brain tissue volume decrement. Because antipsychotics are prescribed for long periods for schizophrenia patients and have increasingly widespread use in other psychiatric disorders, it is imperative to determine their long-term effects on the human brain. To evaluate relative contributions of 4 potential predictors (illness duration, antipsychotic treatment, illness severity, and substance abuse) of brain volume change. Predictors of brain volume changes were assessed prospectively based on multiple informants. Data from the Iowa Longitudinal Study. Two hundred eleven patients with schizophrenia who underwent repeated neuroimaging beginning soon after illness onset, yielding a total of 674 high-resolution magnetic resonance scans. On average, each patient had 3 scans (≥2 and as many as 5) over 7.2 years (up to 14 years). Brain volumes. During longitudinal follow-up, antipsychotic treatment reflected national prescribing practices in 1991 through 2009. Longer follow-up correlated with smaller brain tissue volumes and larger cerebrospinal fluid volumes. Greater intensity of antipsychotic treatment was associated with indicators of generalized and specific brain tissue reduction after controlling for effects of the other 3 predictors. More antipsychotic treatment was associated with smaller gray matter volumes. Progressive decrement in white matter volume was most evident among patients who received more antipsychotic treatment. Illness severity had relatively modest correlations with tissue volume reduction, and alcohol/illicit drug misuse had no significant associations when effects of the other variables were adjusted. Viewed together with data from animal studies, our study suggests that antipsychotics have a subtle but measurable influence on brain tissue loss over time, suggesting the importance of careful risk-benefit review of dosage and duration of treatment as well as their off-label use.
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            Is Open Access

            Can parametric statistical methods be trusted for fMRI based group studies?

            The most widely used task fMRI analyses use parametric methods that depend on a variety of assumptions. While individual aspects of these fMRI models have been evaluated, they have not been evaluated in a comprehensive manner with empirical data. In this work, a total of 2 million random task fMRI group analyses have been performed using resting state fMRI data, to compute empirical familywise error rates for the software packages SPM, FSL and AFNI, as well as a standard non-parametric permutation method. While there is some variation, for a nominal familywise error rate of 5% the parametric statistical methods are shown to be conservative for voxel-wise inference and invalid for cluster-wise inference; in particular, cluster size inference with a cluster defining threshold of p = 0.01 generates familywise error rates up to 60%. We conduct a number of follow up analyses and investigations that suggest the cause of the invalid cluster inferences is spatial auto correlation functions that do not follow the assumed Gaussian shape. By comparison, the non-parametric permutation test, which is based on a small number of assumptions, is found to produce valid results for voxel as well as cluster wise inference. Using real task data, we compare the results between one parametric method and the permutation test, and find stark differences in the conclusions drawn between the two using cluster inference. These findings speak to the need of validating the statistical methods being used in the neuroimaging field.
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              The cerebellum communicates with the basal ganglia.

              The cerebral cortex is interconnected with two major subcortical structures: the basal ganglia and the cerebellum. How and where cerebellar circuits interact with basal ganglia circuits has been a longstanding question. Using transneuronal transport of rabies virus in macaques, we found that a disynaptic pathway links an output stage of cerebellar processing, the dentate nucleus, with an input stage of basal ganglia processing, the striatum.
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                Author and article information

                Journal
                Human Brain Mapping
                Hum. Brain Mapp.
                Wiley
                10659471
                January 2018
                January 2018
                October 23 2017
                : 39
                : 1
                : 319-331
                Affiliations
                [1 ]Centre for Neuroimaging Sciences; Institute of Psychiatry, Psychology and Neuroscience, King's College London; London United Kingdom
                [2 ]Department of Basic and Clinical Neuroscience; Institute of Psychiatry, Psychology and Neuroscience, King's College London; London United Kingdom
                [3 ]MRC Centre for Neurodevelopmental Disorders, King's College London; London United Kingdom
                [4 ]Department of Basic Medical Science, Neuroscience and Sense Organs; University of Bari Aldo Moro; Bari BA Italy
                [5 ]Department of Experimental and Clinical Medical Sciences; University of Udine; Udine Italy
                [6 ]Translational Medicine Neuroscience and Biomarkers; F. Hoffmann-La Roche Ltd; Basel Switzerland
                [7 ]CNS Therapeutic Area Unit, Takeda Development Centre Europe; London United Kingdom
                [8 ]Pharma Research and Early Development, F. Hoffmann-La Roche Ltd; Basel Switzerland
                [9 ]Institute of Psychiatry, Psychology & Neuroscience, King's College London; London United Kingdom
                Article
                10.1002/hbm.23844
                6866296
                29058358
                6b6e7649-1433-4270-98ab-d2e569002b5e
                © 2017

                http://doi.wiley.com/10.1002/tdm_license_1.1

                http://onlinelibrary.wiley.com/termsAndConditions#vor

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