Ectopic fat, defined as a specific organ or compartment with the accumulation of fat tissue surrounding organs, is highly associated with obesity which has been identified as a risk factor for cognitive impairment and dementia. However, the relationship between ectopic fat and changes in brain structure or cognition is yet to be elucidated. Here, we investigated the effects of ectopic fat on brain structure and cognitive function via systemic review and meta-analysis. A total of 21 studies were included from electronic databases up to July 9, 2022. We found ectopic fat was associated with decreased total brain volumeand increased lateral ventricle volume. In addition, ectopic was associated with decreased cognitive scores and negatively correlated with cognitive function. More specifically, dementia development were correlated with increased levels of visceral fat. Overall, our data suggested that increased ectopic fat was associated with prominent structural changes in the brain and cognitive decline, an effect driven mainly by increases in visceral fat, while subcutaneous fat may be protective. Our results suggest that patients with increased visceral fat are at risk of developing cognitive impairment and, therefore, represent a subset of population in whom appropriate and timely preventive measures could be implemented.Copyright © 2023 Elsevier Inc. All rights reserved.