Manganese exposure and cognitive performance: A meta-analytical approach

Area of Science:

• Neuroscience
• Occupational Health
• Toxicology

Background:

• Occupational manganese exposure is linked to manganism, a serious neurological disorder.
• Previous meta-analyses on manganese and cognitive function yielded conflicting results.
• Recent studies suggest a need to re-evaluate the impact of manganese on cognitive performance.

Purpose of the Study:

• To systematically review and meta-analyze current evidence on occupational manganese exposure and cognitive function.
• To quantify the relationship between manganese exposure levels and cognitive performance deficits.
• To identify specific cognitive domains affected by occupational manganese exposure.

Main Methods:

• Systematic literature search conducted until October 2022 across multiple electronic databases.
• Inclusion of 18 studies with 75 effect sizes (888 controls, 1092 exposed).
• Meta-analysis using a random effects model (Hedge's g) to synthesize cognitive performance differences; publication bias and exposure-effect relationships investigated.

Main Results:

• Significantly lower cognitive performance observed in workers exposed to manganese across multiple domains.
• Impaired functions include processing speed, attention, working memory, reaction time, and visual attention.
• Regression analysis indicated a potential exposure-effect relationship, with suggestions of quadratic effects.

Conclusions:

• Occupational manganese exposure is associated with significant, widespread cognitive impairments in working adults.
• The findings underscore the importance of monitoring and mitigating manganese exposure in occupational settings.
• Further research is recommended to explore dose-response relationships and long-term effects in workplace safety contexts.