RESUMO
Objectives: Brain imaging studies carried out in patients suffering from generalized anxiety disorder (GAD) have contributed to better characterize the pathophysiological mechanisms underlying this disorder. The present study reviews the available functional and structural brain imaging evidence on GAD, and suggests further strategies for investigations in this field. Methods: A systematic literature review was performed in PubMed, PsycINFO, and Google Scholar, aiming to identify original research evaluating GAD patients with the use of structural and functional magnetic resonance imaging as well as diffusion tensor imaging. Results: The available studies have shown impairments in ventrolateral and dorsolateral prefrontal cortex, anterior cingulate, posterior parietal regions, and amygdala in both pediatric and adult GAD patients, mostly in the right hemisphere. However, the literature is often tentative, given that most studies have employed small samples and included patients with comorbidities or in current use of various medications. Finally, different methodological aspects, such as the type of imaging equipment used, also complicate the generalizability of the findings. Conclusions: Longitudinal neuroimaging studies with larger samples of both juvenile and adult GAD patients, as well as at risk individuals and unaffected relatives, should be carried out in order to shed light on the specific biological signature of GAD.
Assuntos
Humanos , Transtornos de Ansiedade/diagnóstico por imagem , Encéfalo/diagnóstico por imagem , Imageamento por Ressonância Magnética , Neuroimagem Funcional , Transtornos de Ansiedade/fisiopatologia , Encéfalo/fisiopatologiaRESUMO
OBJECTIVES: Brain imaging studies carried out in patients suffering from generalized anxiety disorder (GAD) have contributed to better characterize the pathophysiological mechanisms underlying this disorder. The present study reviews the available functional and structural brain imaging evidence on GAD, and suggests further strategies for investigations in this field. METHODS: A systematic literature review was performed in PubMed, PsycINFO, and Google Scholar, aiming to identify original research evaluating GAD patients with the use of structural and functional magnetic resonance imaging as well as diffusion tensor imaging. RESULTS: The available studies have shown impairments in ventrolateral and dorsolateral prefrontal cortex, anterior cingulate, posterior parietal regions, and amygdala in both pediatric and adult GAD patients, mostly in the right hemisphere. However, the literature is often tentative, given that most studies have employed small samples and included patients with comorbidities or in current use of various medications. Finally, different methodological aspects, such as the type of imaging equipment used, also complicate the generalizability of the findings. CONCLUSIONS: Longitudinal neuroimaging studies with larger samples of both juvenile and adult GAD patients, as well as at risk individuals and unaffected relatives, should be carried out in order to shed light on the specific biological signature of GAD.
Assuntos
Transtornos de Ansiedade/diagnóstico por imagem , Encéfalo/diagnóstico por imagem , Neuroimagem Funcional , Imageamento por Ressonância Magnética , Transtornos de Ansiedade/fisiopatologia , Encéfalo/fisiopatologia , HumanosRESUMO
OBJECTIVE: Generalized anxiety disorder (GAD) in older adults is associated with persistent deficits in emotion reactivity (ER) and regulation, yet the neural basis of these deficits has not been explored. This study focuses on the neural basis of ER deficits in late-life GAD and the association with cerebrovascular burden. METHODS: Twenty elderly nonanxious participants and 17 late-life GAD participants were included. The faces-shapes functional magnetic resonance imaging task was used to assess ER; the Hamilton Anxiety Rating Scale and the Penn State Worry Questionnaire to measure global anxiety and worry, respectively; linear regression models to examine the association between ER and global anxiety severity and between ER and worry severity; and mediation analysis to explore the effect of ER on the relationship between global anxiety/worry severity and cerebrovascular burden. RESULTS: A positive association was found between ER and global anxiety in the left parahippocampus, left and right precuneus, and right superior occipital gyrus. A negative association was found between ER and worry severity in the left and right precuneus. The association between cerebrovascular burden and anxiety/worry severity was indirectly mediated by increased ER in limbic and paralimbic areas and by decreased ER in prefrontal regulatory regions. CONCLUSION: These results indicate that ER is associated with different neural activation patterns for worry and global anxiety and that ER-related functional connectivity indirectly mediates the relationship between cerebrovascular burden and late-life GAD. This latter result supports a yet-unexplored cerebrovascular pathway involved in the pathophysiology of late-life anxiety.
Assuntos
Transtornos de Ansiedade/diagnóstico por imagem , Encéfalo/diagnóstico por imagem , Transtornos Cerebrovasculares/diagnóstico por imagem , Transtornos de Início Tardio/diagnóstico por imagem , Idoso , Transtornos de Ansiedade/fisiopatologia , Encéfalo/fisiopatologia , Estudos de Casos e Controles , Transtornos Cerebrovasculares/fisiopatologia , Emoções , Feminino , Neuroimagem Funcional , Humanos , Processamento de Imagem Assistida por Computador , Transtornos de Início Tardio/fisiopatologia , Imageamento por Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Lobo Occipital/diagnóstico por imagem , Lobo Occipital/fisiopatologia , Giro Para-Hipocampal/diagnóstico por imagem , Giro Para-Hipocampal/fisiopatologia , Lobo Parietal/diagnóstico por imagem , Lobo Parietal/fisiopatologia , Autocontrole , Índice de Gravidade de DoençaRESUMO
Animal and human studies indicate that cannabidiol (CBD), a major constituent of cannabis, has anxiolytic properties. However, no study to date has investigated the effects of this compound on human pathological anxiety and its underlying brain mechanisms. The aim of the present study was to investigate this in patients with generalized social anxiety disorder (SAD) using functional neuroimaging. Regional cerebral blood flow (rCBF) at rest was measured twice using (99m)Tc-ECD SPECT in 10 treatment-naïve patients with SAD. In the first session, subjects were given an oral dose of CBD (400 mg) or placebo, in a double-blind procedure. In the second session, the same procedure was performed using the drug that had not been administered in the previous session. Within-subject between-condition rCBF comparisons were performed using statistical parametric mapping. Relative to placebo, CBD was associated with significantly decreased subjective anxiety (p < 0.001), reduced ECD uptake in the left parahippocampal gyrus, hippocampus, and inferior temporal gyrus (p < 0.001, uncorrected), and increased ECD uptake in the right posterior cingulate gyrus (p < 0.001, uncorrected). These results suggest that CBD reduces anxiety in SAD and that this is related to its effects on activity in limbic and paralimbic brain areas.