Exposure to ambient carbon monoxide and cognitive decrease in a memory clinic

Abstract

Background

Ambient air pollution is a known global health risk, but its short-term impact on cognitive function, particularly in people with neurodegenerative diseases like Alzheimer's disease (AD) or mild cognitive impairment (MCI), is not well understood.

Objective

This study examined the association between short-term carbon monoxide (CO) exposure and cognitive changes in older adults with MCI or AD.

Methods

Data were obtained from 717 patients diagnosed with MCI or AD at a South Korean medical center. CO exposure was estimated using the inverse distance weighting method, based on the proximity between air monitoring stations and participants’ residential addresses. Exposure periods ranged from 1 day to 1 month. Cognitive performance was assessed via the Mini-Mental State Examination (MMSE), and changes were analyzed using generalized estimating equations within a generalized linear model. Subgroup analyses were conducted by diagnosis.

Results

Of the 717 participants (mean age 77.4), 473 had AD. Compared to the MCI group, AD patients were older, less educated, had lower MMSE scores, and more hypertension. Higher 7-day average CO exposure was linked to lower MMSE scores (RR 0.89, 95% CI 0.82–0.96), with a stronger effect in the AD group (RR 0.85, 95% CI 0.76–0.94).

Conclusion

Short-term CO exposure is suggestive of worsening cognitive performance in older adults, particularly in those with AD. These findings emphasize the potential impact of ambient air pollutants on neurodegenerative processes and highlight the need for public health strategies—such as strengthening air quality regulations and issuing targeted health advisories—to protect cognitively vulnerable populations.