{"id":837,"date":"2026-10-22T06:44:47","date_gmt":"2026-10-22T06:44:47","guid":{"rendered":"https:\/\/brainfogremedy.com\/articles\/?p=837"},"modified":"2026-10-22T10:14:47","modified_gmt":"2026-10-22T10:14:47","slug":"fibromyalgia-brain-fog","status":"publish","type":"post","link":"https:\/\/brainfogremedy.com\/articles\/fibromyalgia-brain-fog\/","title":{"rendered":"Fibromyalgia and Brain Fog: What Fibro Fog Feels Like"},"content":{"rendered":"\n<p class=\"wp-block-paragraph\"><strong>Fibromyalgia and brain fog go together often enough that the NHS lists cognitive problems, nicknamed fibro fog, among the condition&#8217;s symptoms, and the 2016 diagnostic criteria score trouble thinking or remembering beside fatigue. 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String(window.getSelection()) : '';\n      if (sel && sel.trim()) { return; }\n      var el = e.target.closest('[data-i]'); if (!el) { return; }\n      var i = parseInt(el.getAttribute('data-i'), 10); if (isNaN(i)) { return; }\n      if (!audio.paused && i === curIdx) { return; }\n      lastUser = Date.now();\n      audio.currentTime = starts[i];\n      var p = audio.play(); if (p && p.catch) { p.catch(function(){}); }\n      try { if (typeof gtag === 'function') { gtag('event', 'audio_chapter', { article: location.pathname, source: 'sentence', start: Math.round(starts[i]) }); } } catch (err) {}\n    });\n    audio.addEventListener('seeked', tick);\n    audio.addEventListener('ended', function(){ setNow(-1); });\n  }\n  if (document.readyState === 'loading') { document.addEventListener('DOMContentLoaded', start); } else { start(); }\n})();<\/script>\n<\/div>\n\n\n\n<p class=\"msq-hook wp-block-paragraph\">On this page: the seven kinds of thinking a 37 study meta-analysis measured with the size of each gap, the two 2018 meta-analyses set side by side, the within-day pain and cognition figures, and what eleven people on r\/Fibromyalgia reported between May and September 2026.<\/p>\n\n\n\n<div class=\"msq\" id=\"ms-quiz\" data-slug=\"fibromyalgia-brain-fog\" data-category=\"symptoms\" data-list=\"5\">\n<style>.msq,.msq-hook,.msq-box,.msq-end,.msq-tool{--msq-accent:#1F4E79;--msq-accent-text:#FFFFFF;--msq-line:#CBD8E6;--msq-warn:#B4531A;--msq-muted:#4A5560;--msq-tint:#EEF3F8;--msq-base:#FFFFFF}\n.msq{margin:1.25em 0 1.75em}\n.msq-hook{border-left:3px solid var(--msq-accent);padding:6px 14px;color:var(--msq-muted);font-size:.97em}\n.msq-box{background:var(--msq-tint);border:1px solid var(--msq-line);border-radius:12px;padding:0}\n.msq-box>summary{cursor:pointer;list-style:none;padding:14px 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0 6px;font-size:1.15em}\n.msq-tool p{margin:0 0 10px}\n.msq-tool .msq-note{font-size:.85em;color:var(--msq-muted);margin:10px 0 0}\n.msq-check label{display:flex;gap:10px;align-items:flex-start;padding:9px 0;border-bottom:1px solid var(--msq-line);cursor:pointer;line-height:1.4}\n.msq-check label:last-of-type{border-bottom:0}\n.msq-check input{margin-top:5px;flex:0 0 auto;width:18px;height:18px;accent-color:var(--msq-accent)}\n.msq-check-count{font-weight:700;margin:10px 0 0}\n.msq-verdict-box{margin:12px 0 0;padding:10px 14px;border-radius:8px;background:var(--msq-base);border-left:3px solid var(--msq-warn)}\n.msq-verdict-box[hidden]{display:none}\n.msq-calc{display:grid;grid-template-columns:1fr 1fr;gap:10px 16px}\n.msq-calc label{display:flex;flex-direction:column;gap:4px;font-size:.92em}\n.msq-calc input,.msq-calc select{padding:8px 10px;border:1px solid var(--msq-muted);border-radius:8px;font:inherit;background:#fff}\n.msq-calc-out{grid-column:1 \/ -1;margin-top:6px;padding:12px 14px;background:var(--msq-base);border-radius:8px;border:1px solid var(--msq-line)}\n.msq-calc-out strong{font-size:1.15em}\n.msq-choose label{display:block;padding:9px 12px;margin:0 0 8px;background:var(--msq-base);border:1px solid var(--msq-line);border-radius:8px;cursor:pointer}\n.msq-choose input{margin-right:8px;accent-color:var(--msq-accent)}\n.msq-choice-result{margin-top:10px;padding:12px 14px;background:var(--msq-base);border-left:3px solid var(--msq-accent);border-radius:0 8px 8px 0}\n.msq-choice-result[hidden]{display:none}\n@media (max-width:600px){.msq-calc{grid-template-columns:1fr}}\nh2.wp-block-heading[id]{scroll-margin-top:24px}<\/style>\n<noscript><style>.msq-explain{display:block !important}<\/style><\/noscript>\n<details class=\"msq-box\">\n<summary>Think you already know this? Five questions, one minute.<\/summary>\n<div class=\"msq-body\">\n<p class=\"msq-intro\">Every answer is on this page. Answer from what you know now; the page fills in the rest.<\/p>\n<ol class=\"msq-list\">\n<li class=\"msq-q\" data-q=\"1\" data-answer=\"a\" data-title=\"Is brain fog a recognised symptom of fibromyalgia?\" data-section=\"#is-brain-fog-a-recognised-symptom-of-fibromyalgia\">\n<p class=\"msq-question\">1. Which three symptoms does the symptom severity scale in the 2016 fibromyalgia criteria rate from 0 to 3 over the past week?<\/p>\n<div class=\"msq-options\" role=\"group\" aria-label=\"Question 1 options\"><button type=\"button\" class=\"msq-opt\" data-opt=\"a\">Fatigue, waking unrefreshed, and trouble thinking or remembering<\/button><button type=\"button\" class=\"msq-opt\" data-opt=\"b\">Pain, stiffness and headache<\/button><button type=\"button\" class=\"msq-opt\" data-opt=\"c\">Anxiety, depression and dizziness<\/button><\/div>\n<p class=\"msq-explain\" hidden><span class=\"msq-verdict\"><\/span>The <a href=\"https:\/\/www.fai2r.org\/wp-content\/uploads\/2018\/11\/Anx_tuto_fibromyalgie_FAI2R-wolfe2016.pdf\" target=\"_blank\" rel=\"noopener\">2016 revision by Wolfe and colleagues<\/a> rates fatigue, waking unrefreshed and cognitive symptoms each from 0 to 3, then adds up to 3 more points for headaches, lower abdominal pain and depression. <a class=\"msq-section\" href=\"#is-brain-fog-a-recognised-symptom-of-fibromyalgia\">Read the section<\/a><\/p>\n<\/li>\n<li class=\"msq-q\" data-q=\"2\" data-answer=\"b\" data-title=\"Which kinds of thinking does fibromyalgia affect most?\" data-section=\"#which-kinds-of-thinking-does-fibromyalgia-affect-most\">\n<p class=\"msq-question\">2. In the 2018 meta-analysis of 37 studies by Bell and colleagues, which kind of thinking showed the largest gap between people with fibromyalgia and controls?<\/p>\n<div class=\"msq-options\" role=\"group\" aria-label=\"Question 2 options\"><button type=\"button\" class=\"msq-opt\" data-opt=\"a\">Set shifting, at g 0.30<\/button><button type=\"button\" class=\"msq-opt\" data-opt=\"b\">Inhibitory control, at g 0.61<\/button><button type=\"button\" class=\"msq-opt\" data-opt=\"c\">Processing speed, at g 0.46<\/button><\/div>\n<p class=\"msq-explain\" hidden><span class=\"msq-verdict\"><\/span><a href=\"https:\/\/pmc.ncbi.nlm.nih.gov\/articles\/PMC6151134\" target=\"_blank\" rel=\"noopener\">Bell and colleagues<\/a> found the largest difference in inhibitory control at g 0.61, the smallest in set shifting at 0.30, with processing speed at 0.46 in between. <a class=\"msq-section\" href=\"#which-kinds-of-thinking-does-fibromyalgia-affect-most\">Read the section<\/a><\/p>\n<\/li>\n<li class=\"msq-q\" data-q=\"3\" data-answer=\"c\" data-title=\"Why can a cognitive test come back normal when the fog is obvious?\" data-section=\"#why-can-a-cognitive-test-come-back-normal-when-the-fog-is-ob\">\n<p class=\"msq-question\">3. In the eight days of home phone testing by Kratz and colleagues, on which task did the fibromyalgia group not differ from controls?<\/p>\n<div class=\"msq-options\" role=\"group\" aria-label=\"Question 3 options\"><button type=\"button\" class=\"msq-opt\" data-opt=\"a\">Working memory<\/button><button type=\"button\" class=\"msq-opt\" data-opt=\"b\">Self rated thinking<\/button><button type=\"button\" class=\"msq-opt\" data-opt=\"c\">Processing speed<\/button><\/div>\n<p class=\"msq-explain\" hidden><span class=\"msq-verdict\"><\/span><a href=\"https:\/\/pmc.ncbi.nlm.nih.gov\/articles\/PMC7153985\/\" target=\"_blank\" rel=\"noopener\">Kratz and colleagues<\/a> found the fibromyalgia group reported worse thinking and scored worse on working memory at home, but the groups did not differ on the processing speed task. <a class=\"msq-section\" href=\"#why-can-a-cognitive-test-come-back-normal-when-the-fog-is-ob\">Read the section<\/a><\/p>\n<\/li>\n<li class=\"msq-q\" data-q=\"4\" data-answer=\"b\" data-title=\"Does pain make the fog worse in the moment?\" data-section=\"#does-pain-make-the-fog-worse-in-the-moment\">\n<p class=\"msq-question\">4. When Whibley and colleagues looked at which came first within a day, what did they find in the fibromyalgia group?<\/p>\n<div class=\"msq-options\" role=\"group\" aria-label=\"Question 4 options\"><button type=\"button\" class=\"msq-opt\" data-opt=\"a\">Higher pain predicted worse thinking at the next check in<\/button><button type=\"button\" class=\"msq-opt\" data-opt=\"b\">A worse working memory score predicted higher pain at the next check in, and pain did not predict worse thinking<\/button><button type=\"button\" class=\"msq-opt\" data-opt=\"c\">Neither predicted the other in either direction<\/button><\/div>\n<p class=\"msq-explain\" hidden><span class=\"msq-verdict\"><\/span>In <a href=\"https:\/\/pmc.ncbi.nlm.nih.gov\/articles\/PMC8669069\/\" target=\"_blank\" rel=\"noopener\">Whibley and colleagues, 2022<\/a>, a worse working memory score predicted higher pain at the next assessment, and there was no evidence that pain preceded worse thinking. The authors call the findings tentative. <a class=\"msq-section\" href=\"#does-pain-make-the-fog-worse-in-the-moment\">Read the section<\/a><\/p>\n<\/li>\n<li class=\"msq-q\" data-q=\"5\" data-answer=\"a\" data-title=\"What do people with fibromyalgia say fibro fog feels like?\" data-section=\"#what-do-people-with-fibromyalgia-say-fibro-fog-feels-like\">\n<p class=\"msq-question\">5. Across the eleven r\/Fibromyalgia accounts read for this page, which complaint came up most often?<\/p>\n<div class=\"msq-options\" role=\"group\" aria-label=\"Question 5 options\"><button type=\"button\" class=\"msq-opt\" data-opt=\"a\">Losing words, speech and following a conversation<\/button><button type=\"button\" class=\"msq-opt\" data-opt=\"b\">Being unable to read<\/button><button type=\"button\" class=\"msq-opt\" data-opt=\"c\">Arithmetic<\/button><\/div>\n<p class=\"msq-explain\" hidden><span class=\"msq-verdict\"><\/span>Seven of the eleven mentioned words, speech or following a conversation, starting with <a href=\"https:\/\/www.reddit.com\/r\/Fibromyalgia\/comments\/1uh35is\/fibro_fog_is_weird\/\" target=\"_blank\" rel=\"noopener\">the June 2026 thread<\/a>; the accounts split on reading. These are accounts, not findings. <a class=\"msq-section\" href=\"#what-do-people-with-fibromyalgia-say-fibro-fog-feels-like\">Read the section<\/a><\/p>\n<\/li>\n<\/ol>\n<div class=\"msq-result\" hidden><\/div>\n<\/div>\n<\/details>\n<script>(function(){\n  if (window.__msqInit) { return; }\n  window.__msqInit = true;\n  var root = document.getElementById('ms-quiz');\n  if (!root) { return; }\n  var meta = { slug: root.getAttribute('data-slug'), category: root.getAttribute('data-category'),\n               list: root.getAttribute('data-list') || '1' };\n  function qs(el, s){ return el.querySelector(s); }\n  function qsa(el, s){ return Array.prototype.slice.call(el.querySelectorAll(s)); }\n  function track(name, params){\n    try { if (typeof gtag === 'function') { var p = params || {}; p.article = meta.slug; gtag('event', name, p); } } catch (e) {}\n  }\n  function jumpList(missed){\n    if (!missed.length) { return ''; }\n    return '<ul class=\"msq-jump\">' + missed.map(function(q){\n      return '<li><a href=\"' + q.getAttribute('data-section') + '\">' + q.getAttribute('data-title') + '<\/a><\/li>';\n    }).join('') + '<\/ul>';\n  }\n  function emailForm(){\n    return '<div class=\"msq-sub\"><p><strong>Get the next one.<\/strong> We publish new articles on ' + meta.category\n      + ' most weeks and recheck this page on Sundays. 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Calculators carry their own small script. *\/\n  function initTools(){\n    qsa(document, '.msq-check').forEach(function(box){\n      var key = 'msq-check-' + meta.slug + '-' + (box.getAttribute('data-id') || 'x');\n      var boxes = qsa(box, 'input[type=checkbox]'), count = qs(box, '.msq-check-count');\n      var yes = qs(box, '.msq-verdict-yes'), no = qs(box, '.msq-verdict-no');\n      var saved = {};\n      try { saved = JSON.parse(localStorage.getItem(key) || '{}'); } catch (e) {}\n      boxes.forEach(function(cb, i){ if (saved[i]) { cb.checked = true; } });\n      function refresh(){\n        var n = boxes.filter(function(cb){ return cb.checked; }).length, state = {};\n        boxes.forEach(function(cb, i){ if (cb.checked) { state[i] = 1; } });\n        try { localStorage.setItem(key, JSON.stringify(state)); } catch (e) {}\n        if (count) { count.textContent = n + ' of ' + boxes.length + (box.getAttribute('data-verb') || ' done'); }\n        if (yes && no) { yes.hidden = n === 0; no.hidden = n !== 0; }\n      }\n      boxes.forEach(function(cb){ cb.addEventListener('change', function(){ refresh(); track('tool_check', { tool: box.getAttribute('data-id') }); }); });\n      refresh();\n    });\n    qsa(document, '.msq-choose').forEach(function(box){\n      var results = qsa(box, '.msq-choice-result');\n      qsa(box, 'input[type=radio]').forEach(function(r){\n        r.addEventListener('change', function(){\n          results.forEach(function(el){ el.hidden = el.getAttribute('data-for') !== r.value; });\n          track('tool_choose', { tool: box.getAttribute('data-id'), choice: r.value });\n        });\n      });\n    });\n  }\n  \/\/ read progress: how far down the article the reader has scrolled, fired once per quarter\n  (function(){\n    var art = root.closest('article') || root.parentNode, fired = {};\n    function check(){\n      var top = art.getBoundingClientRect().top + window.pageYOffset, h = art.offsetHeight || 1;\n      var seen = (window.pageYOffset + window.innerHeight - top) \/ h * 100;\n      [25, 50, 75, 100].forEach(function(m){ if (seen >= m && !fired[m]) { fired[m] = true; track('read_progress', { percent: m }); } });\n    }\n    window.addEventListener('scroll', check, { passive: true }); window.addEventListener('load', check);\n  })();\n  if (document.readyState === 'loading') { document.addEventListener('DOMContentLoaded', initTools); } else { initTools(); }\n})();<\/script>\n<\/div>\n\n\n\n<p class=\"wp-block-paragraph\">Most health websites explain fibro fog by listing its causes and sharing tips to manage it. But they often miss what research has actually found, how much it affects people, why medical tests can still appear normal, and what it feels like in everyday life. This article looks at all four in simple terms, one by one.<br><\/p>\n\n\n\n<h2 id=\"is-brain-fog-a-recognised-symptom-of-fibromyalgia\" class=\"wp-block-heading\">Is brain fog a recognised symptom of fibromyalgia?<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">Yes, by the people who write the criteria, not just by the people who have it. The <a href=\"https:\/\/www.nhs.uk\/conditions\/fibromyalgia\/symptoms\/\" target=\"_blank\" rel=\"noopener\">NHS fibromyalgia symptoms page<\/a>, last reviewed 12 October 2022, lists cognitive problems under the name fibro-fog and says you may have trouble remembering and learning new things, problems with attention and concentration, and slowed or confused speech. The <a href=\"https:\/\/www.fai2r.org\/wp-content\/uploads\/2018\/11\/Anx_tuto_fibromyalgie_FAI2R-wolfe2016.pdf\" target=\"_blank\" rel=\"noopener\">2016 revision of the diagnostic criteria<\/a> by Wolfe and colleagues goes further: its symptom severity scale rates three things over the past week, fatigue, waking unrefreshed, and trouble thinking or remembering, each from 0 to 3. Thinking is a third of that score. A condition whose diagnosis partly rests on how foggy you are is not a condition where the fog is imaginary.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">How many people that covers is less tidy. An <a href=\"https:\/\/archive.cdc.gov\/www_cdc_gov\/arthritis\/types\/fibromyalgia.htm\" target=\"_blank\" rel=\"noopener\">archived CDC page<\/a> put fibromyalgia at about 4 million US adults, around 2 percent; the <a href=\"https:\/\/www.cdc.gov\/chronic-disease\/fibromyalgia\/index.html\" target=\"_blank\" rel=\"noopener\">current CDC page<\/a> says only millions, and an analysis of the <a href=\"https:\/\/pmc.ncbi.nlm.nih.gov\/articles\/PMC4575027\/\" target=\"_blank\" rel=\"noopener\">2012 National Health Interview Survey<\/a> estimated 1.75 percent of adults, or 3.94 million people. Within that population the fog sits near the top of the complaint list: in a <a href=\"https:\/\/pmc.ncbi.nlm.nih.gov\/articles\/PMC1829161\/\" target=\"_blank\" rel=\"noopener\">2007 internet survey of 2,569 people<\/a> with fibromyalgia, forgetfulness and poor concentration were each rated 5.9 out of 10 for severity, behind only morning stiffness, fatigue, unrefreshing sleep and pain.<\/p>\n\n\n\n<h2 id=\"which-kinds-of-thinking-does-fibromyalgia-affect-most\" class=\"wp-block-heading\">Which kinds of thinking does fibromyalgia affect most?<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">This is the question the ranking pages answer with a shrug and a stock photo. The studies are more specific. The largest meta-analysis, <a href=\"https:\/\/pmc.ncbi.nlm.nih.gov\/articles\/PMC6151134\" target=\"_blank\" rel=\"noopener\">Bell and colleagues, 2018<\/a>, pooled 37 studies and sorted every test into seven kinds of thinking. The fibromyalgia group scored lower on all seven. The gap is given as Hedges g, which is the difference between the two groups measured in standard deviations: 0.2 is usually called small, 0.5 medium, 0.8 large.<\/p>\n\n\n\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><thead><tr><th>Kind of thinking<\/th><th>What the tests ask<\/th><th>Difference, Hedges g<\/th><th>95 percent interval<\/th><th>Studies<\/th><\/tr><\/thead><tbody><tr><td>Inhibitory control<\/td><td>Ignore a distraction, stop a habit<\/td><td>0.61<\/td><td>0.38 to 0.83<\/td><td>18<\/td><\/tr><tr><td>Short term memory<\/td><td>Hold a list for a few seconds<\/td><td>0.51<\/td><td>0.29 to 0.74<\/td><td>12<\/td><\/tr><tr><td>Updating<\/td><td>Keep a running tally in mind<\/td><td>0.51<\/td><td>0.33 to 0.69<\/td><td>17<\/td><\/tr><tr><td>Long term memory<\/td><td>Recall it later<\/td><td>0.50<\/td><td>0.28 to 0.72<\/td><td>11<\/td><\/tr><tr><td>Processing speed<\/td><td>Do a simple task quickly<\/td><td>0.46<\/td><td>0.25 to 0.67<\/td><td>10<\/td><\/tr><tr><td>Accessing<\/td><td>Fetch words, as in naming as many animals as you can<\/td><td>0.38<\/td><td>0.03 to 0.73<\/td><td>6<\/td><\/tr><tr><td>Set shifting<\/td><td>Switch between two rules<\/td><td>0.30<\/td><td>0.11 to 0.49<\/td><td>7<\/td><\/tr><\/tbody><\/table><figcaption class=\"wp-element-caption\">Every row is from the <a href=\"https:\/\/pmc.ncbi.nlm.nih.gov\/articles\/PMC6151134\" target=\"_blank\" rel=\"noopener\">Bell and colleagues, 2018<\/a> meta-analysis in the Journal of Clinical and Experimental Neuropsychology, which pooled 37 studies, 964 people with fibromyalgia and 1,025 age matched controls. A positive number means the fibromyalgia group scored lower. The plain descriptions in the second column are this page&#8217;s, not the paper&#8217;s. The paper gives 18 studies for inhibitory control in its results and 17 in its limitations.<\/figcaption><\/figure>\n\n\n\n<p class=\"wp-block-paragraph\">The biggest gap was in inhibitory control, the ability to shut out a distraction or stop an automatic response. Memory in its three forms sat around 0.5, processing speed a little behind, and the two smallest gaps were in fetching words and switching rules. The authors lean on an older argument from <a href=\"https:\/\/pubmed.ncbi.nlm.nih.gov\/10349356\/\" target=\"_blank\" rel=\"noopener\">Eccleston and Crombez<\/a>, that pain demands attention and competes with everything else for it, which would explain why the attention heavy domains come off worst.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">A second meta-analysis the same year, <a href=\"https:\/\/journals.lww.com\/bsam\/fulltext\/2018\/06000\/cognitive_impairment_in_fibromyalgia__a.5.aspx\" target=\"_blank\" rel=\"noopener\">Wu and colleagues, 2018<\/a>, found bigger gaps from a smaller pool: an overall difference of 0.87, with attention and psychomotor speed at 1.22 and learning and memory at 0.94. The two papers agree on the direction and disagree on the size, so the honest summary is a real difference, moderate to large on average, varying a lot from study to study. No detox tea was harmed in the making of either.<\/p>\n\n\n\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><thead><tr><th><\/th><th><a href=\"https:\/\/pmc.ncbi.nlm.nih.gov\/articles\/PMC6151134\" target=\"_blank\" rel=\"noopener\">Bell and colleagues, 2018<\/a><\/th><th><a href=\"https:\/\/journals.lww.com\/bsam\/fulltext\/2018\/06000\/cognitive_impairment_in_fibromyalgia__a.5.aspx\" target=\"_blank\" rel=\"noopener\">Wu and colleagues, 2018<\/a><\/th><\/tr><\/thead><tbody><tr><td>Journal<\/td><td>Journal of Clinical and Experimental Neuropsychology<\/td><td>Psychosomatic Medicine<\/td><\/tr><tr><td>Studies pooled<\/td><td>37<\/td><td>23<\/td><\/tr><tr><td>People<\/td><td>964 with fibromyalgia, 1,025 controls<\/td><td>2,096 in total<\/td><\/tr><tr><td>Overall difference<\/td><td>Not pooled into one number<\/td><td>g 0.87, interval 0.60 to 1.15<\/td><\/tr><tr><td>Largest gap<\/td><td>Inhibitory control, g 0.61<\/td><td>Attention and psychomotor speed, g 1.22<\/td><\/tr><tr><td>Smallest gap<\/td><td>Set shifting, g 0.30<\/td><td>Executive function, g 0.72<\/td><\/tr><tr><td>Memory<\/td><td>g 0.50 to 0.51<\/td><td>Learning and memory, g 0.94<\/td><\/tr><tr><td>What moved the numbers<\/td><td>Older samples showed smaller memory gaps<\/td><td>Depression and anxiety scores tracked the size of the gap<\/td><\/tr><\/tbody><\/table><figcaption class=\"wp-element-caption\">The two meta-analyses were published the same year from overlapping study pools and do not agree on the size of the difference, only on its direction. Wu grouped tests into fewer, broader domains, which tends to produce bigger numbers, and both say the studies they pooled varied a lot.<\/figcaption><\/figure>\n\n\n\n<figure class=\"wp-block-image size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1376\" height=\"768\" src=\"https:\/\/brainfogremedy.com\/articles\/wp-content\/uploads\/2026\/10\/kitchen-tasks-affected-by-fibromyalgia-and-brain-fog.jpg\" alt=\"Hands hesitating over kitchen jars show the daily impact of fibromyalgia and brain fog on simple tasks.\" class=\"wp-image-835\" srcset=\"https:\/\/brainfogremedy.com\/articles\/wp-content\/uploads\/2026\/10\/kitchen-tasks-affected-by-fibromyalgia-and-brain-fog.jpg 1376w, https:\/\/brainfogremedy.com\/articles\/wp-content\/uploads\/2026\/10\/kitchen-tasks-affected-by-fibromyalgia-and-brain-fog-300x167.jpg 300w, https:\/\/brainfogremedy.com\/articles\/wp-content\/uploads\/2026\/10\/kitchen-tasks-affected-by-fibromyalgia-and-brain-fog-1024x572.jpg 1024w, https:\/\/brainfogremedy.com\/articles\/wp-content\/uploads\/2026\/10\/kitchen-tasks-affected-by-fibromyalgia-and-brain-fog-768x429.jpg 768w\" sizes=\"auto, (max-width: 1376px) 100vw, 1376px\" \/><figcaption class=\"wp-block-image__caption\">Ignoring a distraction and keeping a running tally in mind were the two biggest gaps the studies found.<\/figcaption><\/figure>\n\n\n\n<figure class=\"wp-block-image size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1600\" height=\"900\" src=\"https:\/\/brainfogremedy.com\/articles\/wp-content\/uploads\/2026\/10\/fibromyalgia-brain-fog-chart.png\" alt=\"Bar chart of fibromyalgia and brain fog test gaps by kind of thinking, inhibitory control largest at 0.61.\" class=\"wp-image-839\" srcset=\"https:\/\/brainfogremedy.com\/articles\/wp-content\/uploads\/2026\/10\/fibromyalgia-brain-fog-chart.png 1600w, https:\/\/brainfogremedy.com\/articles\/wp-content\/uploads\/2026\/10\/fibromyalgia-brain-fog-chart-300x169.png 300w, https:\/\/brainfogremedy.com\/articles\/wp-content\/uploads\/2026\/10\/fibromyalgia-brain-fog-chart-1024x576.png 1024w, https:\/\/brainfogremedy.com\/articles\/wp-content\/uploads\/2026\/10\/fibromyalgia-brain-fog-chart-768x432.png 768w, https:\/\/brainfogremedy.com\/articles\/wp-content\/uploads\/2026\/10\/fibromyalgia-brain-fog-chart-1536x864.png 1536w\" sizes=\"auto, (max-width: 1600px) 100vw, 1600px\" \/><figcaption class=\"wp-block-image__caption\">Each bar is the pooled difference between people with fibromyalgia and age matched controls in the 2018 meta-analysis by Bell and colleagues, 964 patients and 1,025 controls across 37 studies. A higher bar means a bigger gap. 0.2 is usually called small, 0.5 medium and 0.8 large, and the confidence intervals in the table above overlap, so the order of the bars is approximate.<\/figcaption><\/figure>\n\n\n\n<h2 id=\"why-can-a-cognitive-test-come-back-normal-when-the-fog-is-ob\" class=\"wp-block-heading\">Why can a cognitive test come back normal when the fog is obvious?<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">Because a group difference is not a personal verdict. A gap of 0.5 standard deviations means the average person with fibromyalgia scores below about 69 percent of controls, which is a real shift. It also means about 31 percent of healthy controls score below that average patient. The two curves overlap heavily, so a person whose thinking has dropped from the top of the range to the middle will test as normal, and unless somebody tested them before, nobody can see the drop. That arithmetic is this page&#8217;s, worked from the effect sizes above; it is simply what a g of 0.5 means.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">The daily life studies back this up from another angle. <a href=\"https:\/\/pmc.ncbi.nlm.nih.gov\/articles\/PMC7153985\/\" target=\"_blank\" rel=\"noopener\">Kratz and colleagues, 2020<\/a> gave 50 people with fibromyalgia and 50 matched controls a clinic test, then eight days of five a day phone tests at home. In the clinic the fibromyalgia group did worse on three measures. At home they reported worse thinking and did worse on a working memory task, but not on a processing speed task. The link between how people felt their thinking was going and how they actually scored was about the same in both groups, which the authors read as evidence that people with fibromyalgia are not overstating the problem. The fog is measurable. It is just not always measurable on the test you happened to be given, on the day you happened to be given it.<\/p>\n\n\n\n<h2 id=\"does-pain-make-the-fog-worse-in-the-moment\" class=\"wp-block-heading\">Does pain make the fog worse in the moment?<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">Slightly, and the direction of travel is not what you might expect. <a href=\"https:\/\/pmc.ncbi.nlm.nih.gov\/articles\/PMC8669069\/\" target=\"_blank\" rel=\"noopener\">Whibley and colleagues, 2022<\/a>, in the journal Pain, re-analysed the same hundred people over seven days, matching each pain rating to the thinking test taken at the same moment. For every one point rise in pain on a 0 to 10 scale, self rated cognitive trouble rose 0.27 points in the fibromyalgia group against 0.17 in the controls, and response times on the speed test slowed by 1.73 milliseconds, while the controls actually got faster. The working memory test did not move with pain at all in the fibromyalgia group.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Those are small numbers, and the authors call them tentative. The more interesting result was the order of events: a worse working memory score predicted higher pain at the next check in, and there was no evidence that pain predicted worse thinking at the next one. Fog and pain seem to rise and fall together rather than one pushing the other, which is a more honest picture than the &#8220;pain causes fog&#8221; line most pages carry, and it fits what <a href=\"https:\/\/brainfogremedy.com\/articles\/rheumatoid-arthritis-brain-fog\/\">the rheumatoid arthritis studies<\/a> and <a href=\"https:\/\/brainfogremedy.com\/articles\/lupus-brain-fog\/\">the lupus studies<\/a> keep finding: the fog tracks the whole condition, not one dial on it.<\/p>\n\n\n\n<h2 id=\"what-do-people-with-fibromyalgia-say-fibro-fog-feels-like\" class=\"wp-block-heading\">What do people with fibromyalgia say fibro fog feels like?<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">Three threads on r\/Fibromyalgia were read for this page, posted between May and September 2026 and carrying 31 comments between them, in which eleven people described their own thinking. These are accounts, not findings, and nothing in them says what is happening to any reader.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">The thread with the most detail, <a href=\"https:\/\/www.reddit.com\/r\/Fibromyalgia\/comments\/1uh35is\/fibro_fog_is_weird\/\" target=\"_blank\" rel=\"noopener\">from June 2026<\/a>, was started by someone three years into a diagnosis and finishing a science doctorate. Their word recall had got markedly worse, to the point that a lost word in conversation is now left lost; arithmetic and spelling had gone the same way; writing was the hardest task of all. Reading was untouched, even in a flare, so it had become their bad day default. A reply from someone tested repeatedly reported being told they were &#8220;within normal parameters&#8221; with no earlier baseline to compare; they talk around missing words with the vocabulary they still have and cannot follow a television series without a recap. A third person found the fog worsened in the premenstrual week and the period week, giving two usable weeks in four. A fourth, still at school, found reading comprehension was precisely the part that failed, the opposite of the first account.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">In <a href=\"https:\/\/www.reddit.com\/r\/Fibromyalgia\/comments\/1wqla2w\/what_does_fibro_fog_feel_like_for_you_and_how_do\/\" target=\"_blank\" rel=\"noopener\">a thread from September 2026<\/a> the original poster described walking into a table while carrying dishes and being unable to account for it, losing the thread of conversations they knew they had had, and two hours of sleep behind it all. One reply described mixing up words and being unable to pronounce familiar ones, like wading through something thick, with concentration gone; another forgets what a partner said and loses words mid sentence. And in <a href=\"https:\/\/www.reddit.com\/r\/Fibromyalgia\/comments\/1tiy1vk\/fibro_fog_moment\/\" target=\"_blank\" rel=\"noopener\">a thread from May 2026<\/a>, filed under Funny, people traded the comic end of the range: frozen peas poured into a water bottle and not noticed until drinking, a phone found ringing in the fridge next to the gap where the cheese had been, cat food spooned into steeping tea.<\/p>\n\n\n\n<figure class=\"wp-block-image size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1376\" height=\"768\" src=\"https:\/\/brainfogremedy.com\/articles\/wp-content\/uploads\/2026\/10\/resting-at-home-with-fibromyalgia-and-brain-fog.jpg\" alt=\"A man at a kitchen table with his head in his hands, worn down by fibromyalgia and brain fog.\" class=\"wp-image-836\" srcset=\"https:\/\/brainfogremedy.com\/articles\/wp-content\/uploads\/2026\/10\/resting-at-home-with-fibromyalgia-and-brain-fog.jpg 1376w, https:\/\/brainfogremedy.com\/articles\/wp-content\/uploads\/2026\/10\/resting-at-home-with-fibromyalgia-and-brain-fog-300x167.jpg 300w, https:\/\/brainfogremedy.com\/articles\/wp-content\/uploads\/2026\/10\/resting-at-home-with-fibromyalgia-and-brain-fog-1024x572.jpg 1024w, https:\/\/brainfogremedy.com\/articles\/wp-content\/uploads\/2026\/10\/resting-at-home-with-fibromyalgia-and-brain-fog-768x429.jpg 768w\" sizes=\"auto, (max-width: 1376px) 100vw, 1376px\" \/><figcaption class=\"wp-block-image__caption\">Flares, bad nights and the menstrual cycle were the triggers people named most often.<\/figcaption><\/figure>\n\n\n\n<p class=\"wp-block-paragraph\">The pattern across the eleven: seven mentioned words, speech or following a conversation, more than any other thing. Recent memory came next. Flares, bad sleep and the menstrual cycle were the named triggers, and the accounts split on reading. Where they agree with the studies: attention and recent memory are the heavy losses, and bad sleep makes everything worse, which is why <a href=\"https:\/\/brainfogremedy.com\/articles\/brain-fog-lack-of-sleep\/\">brain fog from lack of sleep<\/a> is worth reading alongside this. Where they do not: word fetching had one of the smallest gaps in the Bell table, at 0.38, yet it is the thing people complain about first. Naming animals for a minute and holding a conversation at dinner are not the same test, and the mismatch is worth knowing before a normal result is taken as the last word.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">A published study found the same themes in a bigger sample. <a href=\"https:\/\/pmc.ncbi.nlm.nih.gov\/articles\/PMC10851761\/\" target=\"_blank\" rel=\"noopener\">Millar and colleagues, 2024<\/a>, in the Journal of Patient Experience, analysed posts from two public fibromyalgia support groups of at least 500 members each and found six themes: the struggle to describe the fog, no longer trusting one&#8217;s own memory, choosing between pain and the cognitive side effects of the medicines that ease it, feeling judged, withdrawing from conversation, and grieving a lost identity. The authors note that patients often rank the fog as a top treatment priority while clinicians tend to rank it lower.<\/p>\n\n\n\n<h2 id=\"when-should-fibro-fog-be-raised-with-a-doctor\" class=\"wp-block-heading\">When should fibro fog be raised with a doctor?<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">Whenever it is affecting work, safety or relationships, and whenever it is new or getting worse. The NHS lists cognitive problems as part of fibromyalgia, but nothing on this page can tell a reader that their fog is fibromyalgia rather than something else, and several of the <a href=\"https:\/\/brainfogremedy.com\/articles\/brain-fog-causes\/\">common causes of brain fog<\/a> are treatable and easy to test for. A doctor can check those; a web page cannot. <a href=\"https:\/\/brainfogremedy.com\/articles\/thyroid-brain-fog\/\">An underactive thyroid<\/a> in particular produces a fog that people describe in nearly the same words.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">What makes the appointment useful is specifics, because the fog is hard to describe and the appointment is short. Which tasks fail: words, recent memory, reading, numbers. When: in a flare, after a bad night, at a point in the cycle. Whether a medicine changed and the fog changed with it. A short written record of fog, pain and sleep by day gives the doctor something to read rather than a feeling to interpret.<\/p>\n\n\n\n<div class=\"msq-tool\" id=\"fibro-fog-diary\">\n<h3>Fog, pain and sleep notes by day, to take to the doctor<\/h3>\n<p>A plain record of what the fog was like each day beside the pain and the sleep behind it. It stays in this browser, it scores nothing, and it does not say what any entry means; that is the doctor&#8217;s job.<\/p>\n<div class=\"msq-calc\">\n<label>Date<input type=\"date\" name=\"date\"><\/label>\n<label>What failed today<select name=\"fog\"><option value=\"\">Choose<\/option><option>Words or following a conversation<\/option><option>Recent memory<\/option><option>Reading<\/option><option>Numbers<\/option><option>Nothing much today<\/option><\/select><\/label>\n<label>Pain today<input type=\"text\" name=\"pain\" placeholder=\"in your own words, or a number out of 10 if you use one\"><\/label>\n<label>Sleep last night<input type=\"text\" name=\"sleep\" placeholder=\"hours, and whether broken\"><\/label>\n<label>Flare, period, or a medicine change<input type=\"text\" name=\"flare\" placeholder=\"anything that changed\"><\/label>\n<label>One concrete example<input type=\"text\" name=\"note\" placeholder=\"lost a word mid sentence, reread a page twice\"><\/label>\n\n<div class=\"msq-calc-out\"><button type=\"button\" class=\"msq-btn\" id=\"fibro-fog-diary-add\">Add this entry<\/button> <a href=\"#\" class=\"msq-no\" id=\"fibro-fog-diary-clear\">Clear all<\/a>\n<div id=\"fibro-fog-diary-list\" style=\"margin-top:10px;overflow-x:auto\"><\/div><\/div>\n<\/div>\n<p class=\"msq-note\">General information only. This record interprets nothing. Take it to a doctor if the fog is new, worsening, or affecting work, safety or relationships.<\/p>\n<\/div>\n<script>\n(function(){\n  var root = document.getElementById('fibro-fog-diary'); if (!root) { return; }\n  var names = ['date','fog','pain','sleep','flare','note'], key = 'msq-log-fibromyalgia-brain-fog-fibro-fog-diary';\n  var ins = names.map(function(n){ return root.querySelector('[name=\"' + n + '\"]'); });\n  var list = document.getElementById('fibro-fog-diary-list');\n  function load(){ try { return JSON.parse(localStorage.getItem(key) || '[]'); } catch (e) { return []; } }\n  function save(rows){ try { localStorage.setItem(key, JSON.stringify(rows)); } catch (e) {} }\n  function esc(s){ return String(s).replace(\/&\/g, '&amp;').replace(\/<\/g, '&lt;').replace(\/>\/g, '&gt;'); }\n  function render(){\n    var rows = load();\n    if (!rows.length) { list.innerHTML = '<p class=\"msq-note\">Nothing logged yet.<\/p>'; return; }\n    var h = '<table><thead><tr><th>Date<\/th><th>What failed today<\/th><th>Pain today<\/th><th>Sleep last night<\/th><th>Flare, period, or a medicine change<\/th><th>One concrete example<\/th><\/tr><\/thead><tbody>';\n    rows.slice(0, 30).forEach(function(r){ h += '<tr>' + names.map(function(n){ return '<td>' + esc(r[n] || '') + '<\/td>'; }).join('') + '<\/tr>'; });\n    list.innerHTML = h + '<\/tbody><\/table><p class=\"msq-note\">' + rows.length + ' entries, newest first.<\/p>';\n  }\n  document.getElementById('fibro-fog-diary-add').addEventListener('click', function(){\n    var r = {}; var any = false;\n    ins.forEach(function(el, i){ r[names[i]] = el ? el.value : ''; if (el && el.value) { any = true; } });\n    if (!any) { return; }\n    var rows = load(); rows.unshift(r); save(rows); render();\n    ins.forEach(function(el){ if (el && el.type !== 'date') { el.value = ''; } });\n    try { if (typeof gtag === 'function') { gtag('event', 'tool_log', { tool: 'fibro-fog-diary', article: 'fibromyalgia-brain-fog' }); } } catch (e) {}\n  });\n  document.getElementById('fibro-fog-diary-clear').addEventListener('click', function(e){ e.preventDefault(); save([]); render(); });\n  render();\n})();\n<\/script>\n\n\n\n<h2 id=\"frequently-asked-questions\" class=\"wp-block-heading\">Frequently asked questions<\/h2>\n\n\n<div id=\"rank-math-faq\" class=\"rank-math-block\">\n<div class=\"rank-math-list \">\n<div id=\"faq-q-1\" class=\"rank-math-list-item\">\n<h3 class=\"rank-math-question \">What is the difference between fibro fog and brain fog?<\/h3>\n<div class=\"rank-math-answer \">\n\n<p>Fibro fog is the name people with fibromyalgia, and the NHS, give to the cognitive problems that come with the condition. Brain fog is the general term for the same kind of slow, forgetful, unfocused thinking from any cause. The symptoms described overlap almost completely.<\/p>\n\n<\/div>\n<\/div>\n<div id=\"faq-q-2\" class=\"rank-math-list-item\">\n<h3 class=\"rank-math-question \">Is fibro fog part of the fibromyalgia diagnosis?<\/h3>\n<div class=\"rank-math-answer \">\n\n<p>Partly. The 2016 revision of the diagnostic criteria includes trouble thinking or remembering in its symptom severity scale, scored 0 to 3 alongside fatigue and waking unrefreshed. The scale is one half of the criteria; widespread pain is the other.<\/p>\n\n<\/div>\n<\/div>\n<div id=\"faq-q-3\" class=\"rank-math-list-item\">\n<h3 class=\"rank-math-question \">How big is the thinking difference in fibromyalgia?<\/h3>\n<div class=\"rank-math-answer \">\n\n<p>Moderate on average. The 2018 meta-analysis by Bell and colleagues found gaps between 0.30 and 0.61 standard deviations across seven kinds of thinking; Wu and colleagues the same year found an overall gap of 0.87. Both found wide variation between studies.<\/p>\n\n<\/div>\n<\/div>\n<div id=\"faq-q-4\" class=\"rank-math-list-item\">\n<h3 class=\"rank-math-question \">Does fibro fog show up on a memory test?<\/h3>\n<div class=\"rank-math-answer \">\n\n<p>Often, as a group. For an individual it may not, because the two groups overlap heavily and a drop from a high starting point can still land in the normal range. Daily life testing found the gap in working memory but not in processing speed.<\/p>\n\n<\/div>\n<\/div>\n<div id=\"faq-q-5\" class=\"rank-math-list-item\">\n<h3 class=\"rank-math-question \">Does fibro fog get worse during a flare?<\/h3>\n<div class=\"rank-math-answer \">\n\n<p>The within-day study found self rated thinking worsened slightly as pain rose, by about a quarter of a point per pain point, and the accounts on this page all describe flares as bad fog days. Whether pain drives the fog or both rise together is not settled; the study leaned towards together.<\/p>\n\n<\/div>\n<\/div>\n<div id=\"faq-q-6\" class=\"rank-math-list-item\">\n<h3 class=\"rank-math-question \">Does fibro fog mean dementia is coming?<\/h3>\n<div class=\"rank-math-answer \">\n\n<p>Nothing on this page shows that. The studies measured differences between groups at one time, not change over years, and the meta-analysis found memory gaps were smaller in older samples, not larger. New or worsening memory loss is a reason to see a doctor, whatever the cause.<\/p>\n\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n\n\n<div class=\"msq-end\" id=\"ms-quiz-end\">\n<p><strong>Finished the page?<\/strong> The same five questions from the top, to see what stuck.<\/p>\n<button type=\"button\" class=\"msq-btn msq-start-test\">Test Your Understanding of This Article<\/button>\n<div class=\"msq-mount\"><\/div>\n<\/div>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<p class=\"wp-block-paragraph\"><em>This article is general information, not medical advice, and is not a substitute for care from a qualified healthcare professional. Speak to your doctor about your own situation.<\/em><\/p>\n","protected":false},"excerpt":{"rendered":"<p>The seven kinds of thinking the fibromyalgia studies measured and how far each fell, why a clinic test can still come back normal, and what eleven people on r\/Fibromyalgia said the fog is like.<\/p>\n","protected":false},"author":1,"featured_media":834,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":"","rank_math_title":"Fibromyalgia and Brain Fog: What Fibro Fog Feels Like","rank_math_description":"Fibromyalgia and brain fog: what the NHS and the 2016 criteria say, which kinds of thinking 37 studies found most affected, and what eleven people report.","rank_math_focus_keyword":"fibromyalgia and brain fog","rank_math_canonical_url":"","rank_math_breadcrumb_title":"","rank_math_facebook_title":"","rank_math_facebook_description":"","rank_math_facebook_image":"","rank_math_twitter_title":"","rank_math_twitter_description":"","rank_math_twitter_image":"","rank_math_pillar_content":"","rank_math_robots":[],"rank_math_advanced_robots":[]},"categories":[4],"tags":[],"class_list":["post-837","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-symptoms"],"_links":{"self":[{"href":"https:\/\/brainfogremedy.com\/articles\/wp-json\/wp\/v2\/posts\/837","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/brainfogremedy.com\/articles\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/brainfogremedy.com\/articles\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/brainfogremedy.com\/articles\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/brainfogremedy.com\/articles\/wp-json\/wp\/v2\/comments?post=837"}],"version-history":[{"count":5,"href":"https:\/\/brainfogremedy.com\/articles\/wp-json\/wp\/v2\/posts\/837\/revisions"}],"predecessor-version":[{"id":846,"href":"https:\/\/brainfogremedy.com\/articles\/wp-json\/wp\/v2\/posts\/837\/revisions\/846"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/brainfogremedy.com\/articles\/wp-json\/wp\/v2\/media\/834"}],"wp:attachment":[{"href":"https:\/\/brainfogremedy.com\/articles\/wp-json\/wp\/v2\/media?parent=837"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/brainfogremedy.com\/articles\/wp-json\/wp\/v2\/categories?post=837"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/brainfogremedy.com\/articles\/wp-json\/wp\/v2\/tags?post=837"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}