Iron deficiency anemia (IDA) is a major perioperative risk factor affecting nearly 2 billion people worldwide and occurs in 30–60% of patients undergoing major surgery, with particularly high rates in colorectal (58%) and gynecologic procedures (64%). Preoperative anemia is linked to increased perioperative morbidity, though its relationship with postoperative neurological complications is less clearly defined. This narrative review evaluates the association between preoperative IDA and postoperative neurological complications, including postoperative delirium (POD), postoperative cognitive dysfunction (POCD), and stroke, in adults undergoing major surgery. PubMed and Google Scholar were searched for studies published between 2015 and 2025 using keywords related to IDA, preoperative anemia, and neurological outcomes. 36 studies met the inclusion criteria, including randomized controlled trials, systematic reviews, meta-analyses, and observational studies. IDA may increase neurological vulnerability during surgical stress through reduced oxygen delivery, impaired neurovascular regulation, and disruption of iron-dependent cellular processes such as mitochondrial function and myelination. Most studies assessed preoperative anemia rather than confirmed IDA, limiting the ability to isolate iron‑specific effects. Across observational studies, preoperative IDA was consistently associated with increased risk of POD and POCD, particularly in older adults and high risk surgical populations. In a cohort of 62,600 patients aged ≥60 years, POD incidence within 7 days postoperatively was 3.9%. Lower preoperative hemoglobin (<11.1 g/dL) correlated with higher delirium risk. POCD incidence reached 14.75%, with moderate anemia linked to greater cognitive decline. Evidence connecting preoperative anemia to postoperative stroke is limited and heterogeneous, with reported rates ranging from 0.3–8%. Preoperative anemia is also associated with longer hospital stays and increased healthcare costs. Overall, IDA is an under-recognized yet modifiable risk factor for postoperative neurological complications. Routine preoperative screening and optimization of iron status may improve outcomes, though further research using standardized definitions and confirmed IDA cohorts is needed.
