Intellect rating
An intellect rating was a measure of intelligence.
Intellect ratings could be affected by long-term exposure to detrimental substances. In 2269, Leonard McCoy noted that the intellect ratings of the Troglytes were nearly twenty percent below average, which Spock found surprising, as they and the Stratos city-dwellers were the same species, Ardanan. McCoy then chalked up the difference to the Troglyte's heavy exposure to zenite. (TOS: "The Cloud Minders")