{"id":644564,"date":"2024-11-18T17:43:05","date_gmt":"2024-11-18T14:43:05","guid":{"rendered":"https:\/\/en.buradabiliyorum.com\/when-more-dopamine-means-more-tremor\/"},"modified":"2024-11-18T17:43:05","modified_gmt":"2024-11-18T14:43:05","slug":"when-more-dopamine-means-more-tremor","status":"publish","type":"post","link":"https:\/\/buradabiliyorum.com\/en\/when-more-dopamine-means-more-tremor\/","title":{"rendered":"#When more dopamine means more tremor"},"content":{"rendered":"<div id=\"ez-toc-container\" class=\"ez-toc-v2_0_84 counter-hierarchy ez-toc-counter ez-toc-custom ez-toc-container-direction\">\n<p class=\"ez-toc-title\" style=\"cursor:inherit\">Table of Contents<\/p>\n<label for=\"ez-toc-cssicon-toggle-item-6a2e739ac952c\" class=\"ez-toc-cssicon-toggle-label\"><span class=\"\"><span class=\"eztoc-hide\" style=\"display:none;\">Toggle<\/span><span class=\"ez-toc-icon-toggle-span\"><svg style=\"fill: #dd3333;color:#dd3333\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\" class=\"list-377408\" width=\"20px\" height=\"20px\" viewBox=\"0 0 24 24\" fill=\"none\"><path d=\"M6 6H4v2h2V6zm14 0H8v2h12V6zM4 11h2v2H4v-2zm16 0H8v2h12v-2zM4 16h2v2H4v-2zm16 0H8v2h12v-2z\" fill=\"currentColor\"><\/path><\/svg><svg style=\"fill: #dd3333;color:#dd3333\" class=\"arrow-unsorted-368013\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\" width=\"10px\" height=\"10px\" viewBox=\"0 0 24 24\" version=\"1.2\" baseProfile=\"tiny\"><path d=\"M18.2 9.3l-6.2-6.3-6.2 6.3c-.2.2-.3.4-.3.7s.1.5.3.7c.2.2.4.3.7.3h11c.3 0 .5-.1.7-.3.2-.2.3-.5.3-.7s-.1-.5-.3-.7zM5.8 14.7l6.2 6.3 6.2-6.3c.2-.2.3-.5.3-.7s-.1-.5-.3-.7c-.2-.2-.4-.3-.7-.3h-11c-.3 0-.5.1-.7.3-.2.2-.3.5-.3.7s.1.5.3.7z\"\/><\/svg><\/span><\/span><\/label><input type=\"checkbox\"  id=\"ez-toc-cssicon-toggle-item-6a2e739ac952c\" checked aria-label=\"Toggle\" \/><nav><ul class='ez-toc-list ez-toc-list-level-1 ' ><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-1\" href=\"https:\/\/buradabiliyorum.com\/en\/when-more-dopamine-means-more-tremor\/#The_dopamine_paradox\" >The dopamine paradox<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-2\" href=\"https:\/\/buradabiliyorum.com\/en\/when-more-dopamine-means-more-tremor\/#An_overlooked_player_in_tremor\" >An overlooked player in tremor?<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-3\" href=\"https:\/\/buradabiliyorum.com\/en\/when-more-dopamine-means-more-tremor\/#challenging_conventional_classifications\" >challenging conventional classifications<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-4\" href=\"https:\/\/buradabiliyorum.com\/en\/when-more-dopamine-means-more-tremor\/#Implications_for_treatment_and_future_research\" >Implications for treatment and future research<\/a><\/li><\/ul><\/nav><\/div>\n<div>\n<div class=\"article-gallery lightGallery\">\n<div data-thumb=\"https:\/\/scx1.b-cdn.net\/csz\/news\/tmb\/2024\/parkinsons-paradox-whe.jpg\" data-src=\"https:\/\/scx2.b-cdn.net\/gfx\/news\/hires\/2024\/parkinsons-paradox-whe.jpg\" data-sub-html=\"Reduced dopamine loss is linked to tremor in Parkinson's patients, challenging common beliefs. Credit: Neural Circuits Dysfunction Lab, Champalimaud Foundation\">\n<figure class=\"article-img\">\n            <img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/scx1.b-cdn.net\/csz\/news\/800a\/2024\/parkinsons-paradox-whe.jpg\" alt=\"Parkinson's Paradox: When more dopamine means more tremor\" title=\"Reduced dopamine loss is linked to tremor in Parkinson's patients, challenging common beliefs. Credit: Neural Circuits Dysfunction Lab, Champalimaud Foundation\" width=\"800\" height=\"530\"\/><figcaption class=\"text-darken text-low-up text-truncate-js text-truncate mt-3\">\n                Reduced dopamine loss is linked to tremor in Parkinson&#8217;s patients, challenging common beliefs. Credit: Neural Circuits Dysfunction Lab, Champalimaud Foundation<br \/>\n            <\/figcaption><\/figure>\n<\/p><\/div>\n<\/div>\n<p>Researchers from the Champalimaud Foundation have shed light on the puzzling relationship between dopamine and rest tremor in Parkinson&#8217;s disease, finding that preserved dopamine in certain brain regions may actually contribute to tremor symptoms, challenging common beliefs.<\/p>\n<p>Parkinson&#8217;s disease (PD) is a progressive neurological disorder known for its characteristic motor symptoms: tremor, rigidity, and slowness of movement. Among these, rest tremor\u2014a shaking that occurs when muscles are relaxed\u2014is one of the most recognizable yet least understood.<\/p>\n<p>A study from the Champalimaud Foundation <a rel=\"nofollow\" target=\"_blank\" href=\"https:\/\/www.nature.com\/articles\/s41531-024-00818-8\" target=\"_blank\">published<\/a> in <i>npj Parkinson&#8217;s Disease<\/i>, led by the Neural Circuits Dysfunction Lab in collaboration with the Neuropsychiatry and Nuclear Medicine Labs, offers fresh insights into the complex relationship between rest tremor and dopamine, a chemical messenger that plays a key role in coordinating movement.<\/p>\n<h2><span class=\"ez-toc-section\" id=\"The_dopamine_paradox\"><\/span>The dopamine paradox<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p>Dopamine loss in brain regions like the putamen, associated with movement regulation, is a well-established hallmark of PD. However, while some patients experience significant tremor relief with dopamine replacement therapies like L-DOPA, others see little to no improvement, or even a worsening of symptoms.<\/p>\n<p>&#8220;Tremor is a common and often debilitating symptom for PD patients, but it has always been a bit of a puzzle,&#8221; says Marcelo Mendon\u00e7a, one of the study&#8217;s lead authors. &#8220;We know dopamine is involved, but the way it affects tremor isn&#8217;t as direct as with other motor symptoms.&#8221;<\/p>\n<p>Conventional wisdom suggests that less dopamine should correspond to more severe symptoms. However, the researchers found the opposite to be true when it comes to rest tremor.<\/p>\n<p>&#8220;Paradoxically, we discovered that patients who exhibit tremor have more dopamine preserved in the caudate nucleus, a part of the brain important for movement planning and cognition,&#8221; explains Mendon\u00e7a. &#8220;This challenges our traditional understanding of how dopamine loss relates to PD symptoms.&#8221;<\/p>\n<h2><span class=\"ez-toc-section\" id=\"An_overlooked_player_in_tremor\"><\/span>An overlooked player in tremor?<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p>Using data from patients at the Champalimaud Clinical Center and public databases, the researchers analyzed information from over 500 patients. This diverse dataset included clinical assessments, DaT scans to visualize dopaminergic neurons, and wearable motion sensors that precisely measure tremor severity.<\/p>\n<p>&#8220;Wearable motion sensors gave us a clearer, more objective measurement of tremor,&#8221; says co-first author Pedro Ferreira. &#8220;On the surface, patients with and without dopamine loss in the caudate seem similar. However, sensors reveal subtle differences in tremor oscillations that traditional clinical rating scales might miss, and they&#8217;re relatively easy to use, allowing us to reliably connect symptoms with what&#8217;s h<a href=\"https:\/\/buradabiliyorum.com\/en\/category\/download-scripts-themes-apps\/\" data-internallinksmanager029f6b8e52c=\"9\" title=\"Download Scripts &amp; Themes &amp; Apps\" target=\"_blank\" rel=\"noopener\">app<\/a>ening in the brain.&#8221;<\/p>\n<p>&#8220;By combining imaging data with measurements from these sensors, we observed a clear link between dopamine function in the caudate nucleus and global severity of resting tremor,&#8221; continues Ferreira. &#8220;Our analysis suggests that the more dopamine activity preserved in the caudate, the stronger the tremor.&#8221;<\/p>\n<p>Senior author Joaquim Alves da Silva, head of the Neural Circuits Dysfunction Lab, said, &#8220;This is the first large study to clearly show a link between better-preserved dopamine levels in the caudate and the presence of rest tremor. Although patients with rest tremor have lost dopamine-releasing nerve endings in the caudate, they actually have more of these nerve endings preserved compared to patients without tremor.&#8221;<\/p>\n<p>One of the most intriguing findings of the study was that the more dopamine was preserved in the caudate on one side of the brain (each hemisphere has its own caudate), the more tremor there was on the same side of the body.<\/p>\n<p>&#8220;This was quite unexpected,&#8221; says Alves da Silva. &#8220;Usually, each side of the brain controls movement on the opposite side of the body.&#8221; Their computational model found that this &#8216;same-side&#8217; effect could arise spuriously from two factors: the <a href=\"https:\/\/buradabiliyorum.com\/en\/category\/general\/\" data-internallinksmanager029f6b8e52c=\"3\" title=\"General\" target=\"_blank\" rel=\"noopener\">general<\/a>ly higher dopamine in both caudates in tremor patients and the uneven way PD affects each side of the brain.<\/p>\n<h2><span class=\"ez-toc-section\" id=\"challenging_conventional_classifications\"><\/span>challenging conventional classifications<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p>This study builds on earlier work by the same team, published in <i><a rel=\"nofollow\" target=\"_blank\" href=\"https:\/\/www.sciencedirect.com\/science\/article\/pii\/S0969996124002912\" target=\"_blank\">Neurobiology of Disease<\/a><\/i>, which showed the value of treating rest tremor separately from other motor symptoms\u2014a departure from traditional approaches that have lumped these symptoms together.<\/p>\n<p>Their prior research revealed that rest tremor varies with the type of PD progression: tremor, particularly when resistant to treatment, is more common in patients presenting a &#8220;brain-first&#8221; PD, while those without tremor present a symptom pattern more aligned with a &#8220;gut-first&#8221; PD, where the disease process starts in the gut and spreads to the brain.<\/p>\n<p>This new study extends that line of inquiry, showing that the severity of rest tremor may be linked to specific brain circuits. &#8220;Dopamine loss in PD is not uniform\u2014different patients may lose dopamine in distinct circuits,&#8221; notes Alves da Silva.<\/p>\n<p>&#8220;By focusing on rest tremor in isolation, we are in a better position to pinpoint the specific neural pathways involved. For instance, could tremor result from an imbalance in dopamine between the caudate and putamen? Identifying reliable biological correlates for individual symptoms is critical, as it paves the way for more targeted therapies aimed at relieving them.&#8221;<\/p>\n<p>&#8220;Not all dopamine cells are alike,&#8221; adds Mendon\u00e7a. &#8220;They have different genetic makeups, connections, and functions. This means that which cells a patient loses or keeps could affect their symptoms. For example, tremor might be tied to the loss or preservation of specific dopamine populations that connect to certain brain areas. This variation in cell type loss could further explain the wide range of symptoms among PD patients.&#8221;<\/p>\n<h2><span class=\"ez-toc-section\" id=\"Implications_for_treatment_and_future_research\"><\/span>Implications for treatment and future research<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p>The team is already looking ahead, says Alves da Silva. &#8220;It&#8217;s difficult to establish causality between dopamine preservation in the caudate and rest tremor in humans, which is why we&#8217;d like to test this in animal models, where we can manipulate specific cells and observe the effects on tremor.<\/p>\n<p>&#8220;We&#8217;d also like to use advanced imaging techniques, like high-resolution dopamine PET scans and MRI, to identify key nodes in the dopamine system and link them to specific motor symptoms. This approach could help us better understand why PD symptoms differ from one patient to another.&#8221;<\/p>\n<p>The research highlights the importance of looking beyond general classifications in PD and underscores the need for more nuanced approaches informed by underlying biology.<\/p>\n<p>&#8220;By identifying the specific neural circuits involved, we hope to clear the mist surrounding the heterogeneity of PD symptoms and contribute to more precise interventions that can improve the quality of life for those affected by this disease,&#8221; concludes Mendon\u00e7a.<\/p>\n<div class=\"article-main__more p-4\">\n<p><strong>More information:<\/strong><br \/>\n                                                    Marcelo D. Mendon\u00e7a et al, Relative sparing of dopaminergic terminals in the caudate nucleus is a feature of rest tremor in Parkinson&#8217;s disease, <i>npj Parkinson&#8217;s Disease<\/i> (2024). <a rel=\"nofollow\" target=\"_blank\" data-doi=\"1\" href=\"https:\/\/dx.doi.org\/10.1038\/s41531-024-00818-8\" target=\"_blank\">DOI: 10.1038\/s41531-024-00818-8<\/a><\/p>\n<\/p><\/div>\n<p>\n\t\t\t\t\t\t\t\t\t\t\t\tProvided by<br \/>\n\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\tChampalimaud Centre for the Unknown<\/p>\n<p>                                        <!-- print only --><\/p>\n<div class=\"d-none d-print-block\">\n<p>\n                                                 <strong>Citation<\/strong>:<br \/>\n                                                 Parkinson&#8217;s paradox: When more dopamine means more tremor (2024, November 18)<br \/>\n                                                 retrieved 18 November 2024<br \/>\n                                                 from https:\/\/medicalxpress.com\/<a href=\"https:\/\/buradabiliyorum.com\/en\/category\/news\/\" data-internallinksmanager029f6b8e52c=\"2\" title=\"News\" target=\"_blank\" rel=\"noopener\">news<\/a>\/2024-11-parkinson-paradox-dopamine-tremor.html\n                                            <\/p>\n<p>\n                                            This document is subject to copyright. 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Credit: Neural Circuits Dysfunction Lab, Champalimaud Foundation Researchers from the Champalimaud Foundation have shed light on the puzzling relationship between dopamine and rest tremor in Parkinson&#8217;s disease, finding that preserved dopamine in certain brain regions may actually contribute to tremor symptoms, challenging&#8230;<\/p>\n","protected":false},"author":1,"featured_media":644565,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"fifu_image_url":"https:\/\/scx2.b-cdn.net\/gfx\/news\/hires\/2024\/parkinsons-paradox-whe.jpg","fifu_image_alt":"","footnotes":""},"categories":[16],"tags":[],"class_list":["post-644564","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-sciencee"],"_links":{"self":[{"href":"https:\/\/buradabiliyorum.com\/en\/wp-json\/wp\/v2\/posts\/644564","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/buradabiliyorum.com\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/buradabiliyorum.com\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/buradabiliyorum.com\/en\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/buradabiliyorum.com\/en\/wp-json\/wp\/v2\/comments?post=644564"}],"version-history":[{"count":0,"href":"https:\/\/buradabiliyorum.com\/en\/wp-json\/wp\/v2\/posts\/644564\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/buradabiliyorum.com\/en\/wp-json\/wp\/v2\/media\/644565"}],"wp:attachment":[{"href":"https:\/\/buradabiliyorum.com\/en\/wp-json\/wp\/v2\/media?parent=644564"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/buradabiliyorum.com\/en\/wp-json\/wp\/v2\/categories?post=644564"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/buradabiliyorum.com\/en\/wp-json\/wp\/v2\/tags?post=644564"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}