General, crystallized and fluid intelligence are not associated with functional global network efficiency: A...

Area of Science:

• Neuroscience
• Cognitive Science
• Network Science

Background:

• A prominent theory suggests general intelligence relies on efficient brain network architecture.
• However, empirical evidence supporting this link between global functional network efficiency and intelligence is limited.
• Previous studies often used small sample sizes, raising concerns about reproducibility.

Purpose of the Study:

• To replicate the association between general intelligence and global functional network efficiency.
• To extend the investigation by examining crystallized and fluid intelligence separately.
• To test associations with global efficiency, characteristic path length, and global clustering coefficient.

Main Methods:

• Utilized the large, high-quality dataset from the Human Connectome Project.
• Analyzed functional brain connectivity networks across various definition schemes (voxel-level to 100-node networks).
• Assessed global efficiency, characteristic path length, and global clustering coefficient in relation to intelligence measures.

Main Results:

• No robust associations were found between general intelligence and global functional network efficiency.
• Weak, non-significant effects (maximal R² = 0.01) were observed across network definitions.
• The strongest, though non-significant, effects appeared in voxel-level networks.

Conclusions:

• The study failed to replicate the proposed association between general intelligence and functional brain network efficiency.
• Low statistical power and publication bias in prior research may have contributed to false positive findings.
• The widely accepted notion of intelligence being linked to global network efficiency requires re-evaluation.