Neuroscientists in Germany recruited 259 participants, both men and women, to take IQ tests and have their brains imaged. Testing provided a measure of each participant’s intelligence, while neurite orientation dispersion and density imaging revealed the number of dendrites, or neural connections, in each participant’s brain.
The research revealed a strong correlation between the number of dendrites in a person’s cerebral cortex and their intelligence. The smartest participants had fewer neural connections in their cerebral cortex.
Researchers confirmed the correlation in a followup survey using data sourced from the Human Connectome Project, including IQ scores and brain images of 500 individuals.