BackgroundReal-world decision-making often relies on practical judgment—the ability to evaluate information, anticipate consequences, and respond in an adaptive manner. Despite its importance for preserving independence in aging, this construct is understudied in older adults without dementia. Moreover, there is a gap in knowledge about the association of objective and informant-rated measures of judgment and other variables that impact everyday functioning such as scam vulnerability and white matter integrity, given that structural white matter changes may precede objective cognitive decline.MethodsCommunity-dwelling older adults classified as cognitively unimpaired (CU; n = 30, Mage = 73.57 ± 1.22 years), or as having subjective cognitive decline (SCD; n = 33, Mage = 72.49 ± 1.13 years) or mild cognitive impairment (MCI; n = 30, Mage = 78.43 ± 1.53 years) completed the Test of Practical Judgment (TOP-J), an ecologically useful measure of everyday judgment, along with a self-report measure of scam susceptibility (Susceptibility to Scams). Informants provided ratings of participants’ practical judgment abilities (TOP-J Informant) and vulnerability to exploitation with the Social Vulnerability Scale and a binary item measuring scam engagement. Kruskal-Wallis and Spearman correlation tests were used to examine group differences and associations between practical judgment and measures of vulnerability. Participants underwent structural MRI; diffusion imaging data were used to extract fractional anisotropy (FA) values and exploratory region-to-region connectivity metrics for the uncinate fasciculus (UF). Associations between UF integrity and structural connectivity with judgment were examined in the overall sample using regression analyses controlling for age, and group differences in white matter integrity were examined using ANCOVA.ResultsGreater structural connectivity of the UF in right temporal-frontal and frontal–frontal regions was significantly associated with better informant-reported judgment in the overall sample. Better objective and informant-based practical judgment scores were significantly associated with lower informant-reported scam engagement. Objective and informant-rated judgment abilities were significantly worse among participants with MCI compared to CU.ConclusionFindings highlight the value of using objective and informant sources to capture real-world judgment ability, with implications for the prevention of harmful outcomes. Our results also suggest that structural connectivity within the UF may be a promising biomarker of impaired judgment in older adults without dementia.