Manganese concentrations in biological matrices and amyotrophic lateral sclerosis (ALS): a systematic review and...

Area of Science:

• Neuroscience
• Environmental Health
• Toxicology

Background:

• Manganese (Mn) is an essential trace element with neurotoxic potential.
• Its role in neurodegenerative diseases like amyotrophic lateral sclerosis (ALS) is not well understood.
• Investigating Mn levels in ALS is crucial for understanding disease mechanisms.

Purpose of the Study:

• To systematically review and meta-analyze existing studies on manganese concentrations in ALS patients versus controls.
• To determine if there is a significant difference in Mn levels between these groups.
• To identify potential sources of heterogeneity in current research.

Main Methods:

• Systematic search of major scientific databases (PubMed, EMBASE, Web of Science, Scopus).
• Inclusion of observational studies comparing Mn concentrations in ALS patients and healthy controls.
• Meta-analysis using random-effects models to pool standardized mean differences (SMDs) and assess heterogeneity (I² statistic) and publication bias (Egger's test).

Main Results:

• Twelve studies involving 446 ALS cases and 652 controls were analyzed.
• No significant difference in Mn concentrations was found between ALS patients and controls (SMD = 0.05; 95% CI: -0.20 to 0.30).
• Subgroup analyses and meta-regression indicated analytical methods contributed to heterogeneity, but no consistent patterns emerged across biological matrices.

Conclusions:

• Peripheral manganese concentrations do not show significant differences between individuals with ALS and healthy controls.
• Current evidence does not support a direct association between peripheral Mn levels and ALS.
• Future research should focus on longitudinal studies, central nervous system (CNS) targeted approaches, and standardized analytical protocols for Mn assessment.