Anemia happens when your body does not have enough healthy red blood cells to carry oxygen around. This lack of oxygen can reach the brain and cause problems with thinking and memory over time.
Iron deficiency is one of the most common reasons for anemia. When iron is low, the brain gets less oxygen. This leads to issues like trouble remembering things, confusion, and a shorter attention span. Studies show people with anemia score lower on tests for memory, focus, and problem-solving skills compared to those without it. For example, every 1 g/dL increase in hemoglobin, the protein in red blood cells that carries oxygen, links to better scores on brain function tests.
Low hemoglobin levels tie directly to weaker brain performance. Research finds that for every 1.4 g/dL drop in hemoglobin, the risk of dementia and cognitive decline rises by 15 percent. A drop from 12.3 to 9.3 g/dL over five months means a big jump in that risk.
Anemia also shows up in older adults and connects to faster thinking decline. In people over 90, it pairs with worse memory and other brain changes. Even in menopause, low iron before full anemia sets in can bring brain fog and fatigue, which hurt daily thinking tasks.
Other types of anemia matter too. Vitamin B12 shortages can lead to cognitive issues without obvious signs like large red blood cells. Low B12 raises markers like MMA, which link to poorer memory, slower thinking speed, and smaller brain volume. Fixing B12 and folate levels in older folks with mild thinking problems can slow decline, especially if homocysteine, a blood chemical, is high.
Early iron lack in kids predicts later troubles like attention issues and behavior problems. In adults after brain bleeds like strokes, anemia at the start means worse recovery and more disability three months later. Bigger bleeds and inflammation make it harder for the brain to heal.
Treating anemia early helps protect the brain. Doctors check hemoglobin and ferritin levels to catch it soon. Raising iron or fixing other causes improves oxygen flow and brain test results.
Sources
https://int.livhospital.com/does-anemia-cause-memory-loss-best-facts/
https://pmc.ncbi.nlm.nih.gov/articles/PMC12729217/
https://www.frontiersin.org/journals/nutrition/articles/10.3389/fnut.2025.1718261/full
https://www.droracle.ai/articles/595336/can-a-drop-in-hemoglobin-hgb-from-123-to
https://www.consultant360.com/articles/vitamin-b12-considerations-maintaining-optimum-health-elders
https://jisn.org/index.php/jisn/article/view/67
https://vajenda.substack.com/p/menopause-iron-and-cognition
https://www.cureus.com/articles/438425-clinical-characteristics-and-management-of-anemia-in-nonagenarians-a-retrospective-cohort-study
