Immediate and Delayed Neuropsychological Effects of Carbon Monoxide Poisoning: A Meta-analysis

Background: Carbon monoxide (CO) poisoning is the leading cause of accidental poisoning worldwide. This study undertook a meta-analysis to examine differences in neuropsychological functioning in patients with CO poisoning as compared to healthy controls, and examined the longer-term neuropsychological effects of CO poisoning. Methods: Studies performed between the years 1995 and 2016 were identified through a search of the electronic databases Medline and PsycInfo. Data from the papers identified were pooled to determine standard mean differences using a random-effects model. Results: Ten studies were included in the analysis, with healthy controls performing significantly better than CO poisoned participants on the domains of divided attention, immediate memory, and processing speed. No statistically significant differences were found for sustained attention, recent memory, working memory, visuospatial/constructional ability, and expressive language. Performance by participants with CO poisoning for the domains of sustained attention, recent memory, visuospatial/constructional abilities, and working memory significantly improved over time after initial exposure, demonstrating recovery of these functions over time. No statistically significant differences were evident for divided attention or expressive language. Conclusions: This evidence indicates that healthy controls perform better than do individuals with CO poisoning on a range of neuropsychological domains; however, it also indicates that performance in some domains does improve over time.